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ImmunoGen
Annual Report 2012

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FY2012 Annual Report · ImmunoGen
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2012 Form 10-K Annual Report 

 
 
Highlights of the Past Year* 

Trastuzumab emtansine (T-DM1) – Lead compound with our TAP technology; in development by Roche 

• 

• 

Positive results from the EMILIA Phase III trial were presented at ASCO in June 2012. In August, Roche reported that it 
has applied for T-DM1 marketing approval in the US and was about to apply in Europe. EMILIA was designed to assess 
T-DM1 as a treatment for metastatic HER2+ breast cancer (BC) previously treated with Herceptin® (trastuzumab) and a 
taxane.  T-DM1  was  found  to  significantly  improve  both  progression-free  survival  and  overall  survival  compared  to 
standard-of-care for this setting. 

Patient enrollment has completed in the MARIANNE Phase III trial, which evaluates T-DM1 for first-line treatment of 
metastatic HER2+ BC. Roche expects to apply in 2014 for marketing approval for this use. 

•  Roche  disclosed  in  June  its  plans  to  initiate  registration  trials  beginning in  2013 to  evaluate  T-DM1  for  three  earlier-
stage  HER2+  BC  settings:  adjuvant  use;  neoadjuvant  use;  and  treatment  of  patients  with  residual  invasive  disease 
following standard neoadjuvant therapy. 

•  Roche has begun evaluating T-DM1 for the treatment of advanced HER2+ gastric cancer.  

Our Wholly Owned Product Candidates  

• 

• 

• 

In March 2012, we advanced our IMGN901 TAP compound into Phase II testing for first-line treatment of small-cell lung 
cancer. This Phase II assessment is referred to as the NORTH trial. 

In  April  2012,  we  initiated  clinical  testing  of  our  IMGN529  TAP  compound,  a  potential  treatment  for  non-Hodgkin’s 
lymphoma (NHL) and other CD37+ hematological cancers.  

In  June  2012,  we  began  clinical  testing  of  our  IMGN853  folate  receptor  1-targeting  TAP  compound,  a  potential 
treatment for the majority of cases of ovarian cancer and for the most prevalent type of lung cancer. 

•  We  made  solid  progress  with  compounds  in  our  preclinical  pipeline,  and  expect  to  advance  our  next  wholly  owned 

product candidate to IND stage by mid-2013 and into clinical testing shortly thereafter. 

Other Clinical-Stage Product Candidates 

• 

• 

In addition to T-DM1, there are now seven other TAP compounds and one naked antibody in clinical testing through 
our partnerships. We expect some of these eight partner compounds to progress into pivotal testing in the later part of 
2013.  

Sanofi  advanced  SAR3419  into  Phase  II  testing  in  October  2011.  This  TAP  compound  is  now  being  evaluated  for  the 
treatment of both acute lymphoblastic leukemia and for a type of NHL in Phase II trials.  

Business Development 

• 

In  December  2011,  Eli  Lilly  licensed  certain  rights  to  use  our  TAP  technology  to  develop  novel  anticancer  products, 
joining  Roche,  Sanofi,  Novartis,  Amgen,  Bayer  HealthCare  and  other  major  healthcare  companies  licensing  access  to 
our TAP technology. 

* TAP=Targeted Antibody Payload. ASCO=American Society of Clinical Oncology annual meeting. More details on each 
compound and collaboration are in the included Form 10-K. 

 
 
 
Dear Fellow Shareholders,   

As can be seen from the Highlights at left, this 

past year has been one of notable progress.  

Roche reported impressive results from its EMILIA 

Phase III trial at ASCO and is pursuing marketing 
approval for T-DM1 in the US and Europe. Assuming all 
goes as expected, by mid-2013 we should start earning 
royalties on T-DM1 sales – the beginning of an 
important new stage for the Company.  

In EMILIA, treatment with T-DM1 was found to 

improve survival and provide better tolerability 
compared to standard-of-care for the cancer setting. 
We are proud that our technology can make such a 
difference for patients. 

The EMILIA data reported at ASCO led several 
clinicians to remark on the potential of drugs like  
T-DM1 to transform the treatment of cancer. We 
agree. We also believe that we can generate the 
greatest value for you, our Shareholders, by not only 
working with quality partners but by also developing 
and advancing our own highly promising TAP 
compounds.  

We started rebuilding our pipeline of wholly 
owned product candidates after we completed our 
research commitments to Sanofi. At the time, we had 
a strong scientific team, but needed to build 
capabilities on the development side. Over the past 
few years we have markedly enhanced our clinical 
development and regulatory functions, and also added 
individuals to our Board who have extensive 
experience in the development and commercialization 
of major new therapeutics. 

The impact of these changes is starting to be 

seen. In the past six months, we advanced our lead 
wholly owned compound, IMGN901, into its first 
randomized, Phase II trial and two new compounds, 
IMGN853 and IMGN529, into Phase I clinical testing. 
We expect to progress our next wholly owned 
compound to IND stage by mid-2013 and to begin its 
clinical testing shortly thereafter.  

By industry standards, creating three promising 
new compounds and advancing them to IND stage in 
such a short period is a remarkable achievement. Our 
ability to do this stems from a combination of the 
depth of our knowledge about cancer targets and 
antibody development and also from the productivity 
of our TAP technology.  

For example, the target of IMGN901, CD56, 
occurs on the surface of a number of types of cancer, 
but has no apparent role in the disease process. Thus, 
it is not a useful target for developers of naked 
antibody or small molecule therapeutics, but is useful 

for our approach since TAP compounds do not rely on 
a target-based mechanism to kill cancer cells. 
IMGN901 potentially could be the first targeted 
therapy for a number of different CD56+ cancers that 
have limited treatment options today.  

IMGN901 is now in Phase II testing – in our 

NORTH trial – for first-line treatment of SCLC. We 
chose to focus on SCLC because it is a prevalent CD56+ 
cancer with a high unmet need. Today, median 
survival for treated patients with extensive disease 
SCLC is only about 9-11 months.  

Our IMGN853 TAP compound targets folate 
receptor α (FOL) and is a potential new therapy for 
FOL-overexpressing cancers. These include the 
majority of ovarian cancer cases as well as the most 
common type of lung cancer (adenocarcinoma non-
small cell lung cancer).  

 Our Phase I trial evaluates IMGN853 specifically 

for these cancers in its expansion cohorts, and we 
believe it will enable us to establish IMGN853’s 
registration pathway(s). IMGN853 is the first TAP 
compound to use a new linker we developed to 
counteract the multi-drug resistance seen in many 
cancers.  

IMGN529 is, to our knowledge, the first antibody-

drug conjugate for NHL that contains an active 
antibody – one that has demonstrated its own potent 
anticancer activity in preclinical testing. IMGN529 
employs the same cell-killing agent and linker as  
T-DM1, which also contains an active antibody. Our 
Phase I program is designed to establish the 
development program for this highly promising TAP 
compound. 

We believe the path we are on will enable us to 

make the greatest difference for patients with cancer 
while also generating significant value for our 
shareholders. I want to thank you, our Shareholders, 
for your support of our progress. 

Sincerely,  

Daniel M. Junius 
President and Chief Executive Officer 
September 14, 2012 

 
 
 
 
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10-K

(cid:2) ANNUAL  REPORT  PURSUANT  TO  SECTION  13 OR 15(d)  OF THE

SECURITIES EXCHANGE  ACT  OF 1934

(cid:3)

For the fiscal year ended June 30, 2012
OR

TRANSITION REPORT PURSUANT TO SECTION 13  OR  15(d) OF  THE
SECURITIES EXCHANGE  ACT  OF 1934
For the transition period from 

 to 

Commission file number 0-17999

ImmunoGen, Inc.

Massachusetts
(State or other jurisdiction
of incorporation or organization)

04-2726691
(I.R.S. Employer
Identification No.)

830 Winter Street, Waltham, MA 02451
(Address of principal executive offices, including zip code)

(781) 895-0600
(Registrant’s telephone number, including area code)

Securities  registered pursuant to Section 12(b) of the Act:

Title of Each Class

Name of  Each Exchange on Which Registered

Common Stock, $.01  par value

NASDAQ Global Select Market

Indicate by  check  mark  if  the registrant  is a  well-known seasoned issuer, as defined in Rule 405 of the Securities

Act.  (cid:2)  Yes (cid:3) No

Indicate by  check  mark  if  the registrant  is not  required to file reports pursuant to Section 13 or Section 15(d) of the

Act.  (cid:3) Yes (cid:2) No

Indicate by  check  mark  whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the

Securities Exchange  Act of  1934 during the  preceding 12 months (or for such shorter period that the registrant was required to
file  such reports), and (2) has been  subject  to  such  filing requirements for the past 90 days. (cid:2) Yes (cid:3)  No

Indicate by  check  mark  whether the registrant has submitted electronically and posted on its corporate Website, if any,

every Interactive Data  File required to be submitted  and posted pursuant to Rule 405 of Regulation S-T (§229.405 of this
chapter)  during  the preceding  12 months  (or  for  such shorter period that the registrant was required to submit and post such
files). (cid:2) Yes (cid:3)  No

Indicate by  check  mark  if  disclosure  of delinquent filers pursuant to Item 405 of Regulation S-K (§229.405 of this chapter)

is  not  contained herein, and will  not be  contained,  to the best of registrant’s knowledge, in definitive proxy or information
statements incorporated by reference  in Part  III  of  this Form 10-K or any amendment to this Form 10-K.  (cid:2)

Indicate by  check  mark  whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a
smaller reporting company.  See definitions  of  ‘‘large accelerated filer,’’ ‘‘accelerated filer,’’ and ‘‘smaller reporting company’’ in
Rule  12b-2 of the Exchange Act.  (Check  one):
Large  accelerated  filer (cid:2)

Smaller reporting company  (cid:3)

Accelerated filer (cid:3)

Non-accelerated filer  (cid:3)
(Do not check if a smaller reporting
company)

Indicate by  check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange

Act).  (cid:3)  Yes (cid:2)  No

Aggregate market value,  based upon the closing sale price of the shares as reported by the NASDAQ Global Market, of

voting  stock held by non-affiliates at  December 31,  2011: $886,501,851 (excludes shares held by executive officers and directors).
Exclusion  of  shares  held by any  person  should not be construed to indicate that such person possesses the power, direct or
indirect, to direct  or  cause the direction  of management or policies of the registrant, or that such person is controlled by or
under common control with the registrant. Common Stock outstanding at August 21, 2012: 84,104,625 shares.

Portions of the  definitive Proxy Statement to be delivered to shareholders in connection with the Annual Meeting of

Shareholders  to be held on November  13, 2012  are incorporated by reference into Part III.

DOCUMENTS INCORPORATED BY REFERENCE

ImmunoGen, Inc.

Form 10-K

TABLE OF CONTENTS

Item

1.
1A.
1B.
2.
3.
3.1
4.

5.

6.
7.

7A.
8.
9.

9A.
9B.

10.
11.
12.

13.
14.

15.

Part I
Business . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Risk Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unresolved Staff Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Legal Proceedings
Executive Officers of the Registrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mine Safety Disclosures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Part II

Market for Registrant’s Common  Equity,  Related Stockholder  Matters and Issuer

Purchases of Equity Securities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Selected Financial Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Management’s Discussion and Analysis of  Financial Condition and Results of

Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Quantitative and Qualitative Disclosures  About Market Risk . . . . . . . . . . . . . . . . . . .
Financial Statements and Supplementary Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changes in and Disagreements  with Accountants on Accounting  and Financial

Disclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Controls and Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Part III
Directors, Executive Officers  and  Corporate Governance . . . . . . . . . . . . . . . . . . . . . .
Executive Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Security Ownership of Certain  Beneficial  Owners and  Management and Related

Stockholder Matters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Certain Relationships and Related Transactions,  and Director Independence . . . . . . . .
Principal Accounting Fees and Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Part IV
Exhibits, Financial Statement Schedules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Signatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page
Number

3
26
40
41
41
41
42

43
43

44
59
60

103
103
105

106
106

106
106
106

107

108

2

Item 1. Business

In this Annual Report on Form 10-K, ImmunoGen,  Inc. (ImmunoGen, Inc., together with  its

subsidiaries, is referred to in this document as ‘‘we’’, ‘‘us’’, ‘‘ImmunoGen’’, or the  ‘‘Company’’),
incorporates by reference certain information from  parts of other documents filed with  the Securities
and Exchange Commission. The Securities and Exchange  Commission allows us to disclose important
information by referring to it in that manner.  Please  refer to all such  information when reading this
Annual Report on Form 10-K. All information is  as of June 30, 2012  unless otherwise indicated. For  a
description of the risk factors affecting or  applicable to our business, see  ‘‘Risk  Factors,’’  below.

The Company

We  develop novel, targeted, antibody-based therapeutics  for  the treatment of  cancer  using our
expertise in cancer biology, monoclonal antibodies, highly  potent cytotoxic, or cell-killing, agents,  and
the design of linkers that enable these agents to remain stably  attached to the antibodies while  in the
blood stream and be released in their fully active form  after delivery to a  cancer  cell.  An anticancer
compound made using our Targeted  Antibody Payload, or TAP, technology  consists of  a monoclonal
antibody  that binds specifically to an antigen target found  on cancer cells with multiple copies of one of
our  proprietary cell-killing agents attached using one of our engineered linkers. Its antibody component
enables a TAP compound to bind specifically to cancer cells that express its target antigen, the highly
potent cytotoxic agent serves to kill the  cancer  cell  and the  engineered linker controls the  release and
activation of the cytotoxic agent inside  the cancer cell. With some  TAP compounds, the antibody
component also has anticancer activity of its own. Our TAP technology  is designed to enable the
creation of highly effective, well-tolerated anticancer products.

The most advanced compound with our  TAP technology is  trastuzumab  emtansine, often referred

to as T-DM1, which is in global development  by Roche through our  collaboration  with Genentech,  a
member of the Roche Group. Positive  findings  from the lead T-DM1 Phase III trial have been
reported, and, in August 2012, Roche  announced that  it  has submitted the  T-DM1 marketing
application in the U.S. and will submit  it  soon in Europe.  Under  the collaboration agreement, we are
entitled to receive royalties on T-DM1 sales, if any, as well  as milestone payments on defined
regulatory events.

We  have three wholly owned clinical-stage product candidates—IMGN901, IMGN853, and

IMGN529—and other TAP compounds in  earlier stages of development. IMGN901 is a  potential
treatment for small-cell lung cancer, or  SCLC, and  other cancers that  express CD56 and is  in Phase  II
testing for the first-line treatment of SCLC. IMGN853 is a potential  treatment for ovarian cancer,
non-small cell lung cancer, or NSCLC, and other cancers  that over-express its folate receptor target
and began Phase I testing in mid-2012.  IMGN529 is a potential treatment  for non-Hodgkin’s
lymphoma, or NHL, and chronic lymphocytic leukemia and began Phase  I testing in  early 2012.  We
also have earlier stage compounds in  development and expect to advance our next wholly owned
compound to Investigational New Drug, or  IND, application stage in  mid-2013.  In  addition to our
product  programs,  we continue to invest  in  our TAP technology, including  the development of
additional cytotoxic agents and engineered linkers, to maintain a leadership  position in our  field.

Part of our business model is to establish collaborations with other  companies in order to provide
us with cash and revenue short term and potential  significant value long term. Collaborations  also help
expand the utilization of our TAP technology. Our  current collaborative  partners  are: Amgen Inc.,
Bayer HealthCare (a subgroup of Bayer AG), Biotest AG,  Eli Lilly  and  Company, or Lilly,  Novartis
Institutes for BioMedical Research, Inc.,  or Novartis,  Genentech, Inc.  and  Sanofi. These partners have
certain rights to use our TAP technology  to development anticancer therapies and have product
candidates in clinical and/or preclinical  testing. Eight compounds, including T-DM1, are in  clinical
testing through our collaborations.

3

We  were organized as a Massachusetts corporation in 1981.  Our principal offices are located  at
830 Winter Street, Waltham, Massachusetts (MA) 02451, and  our telephone number is (781) 895-0600.
We  maintain a website at www.immunogen.com, where certain information about us is available. Please
note that information contained on the  website is  not a part of this document. Our Annual Reports on
Form 10-K, Quarterly Reports on Form  10-Q,  Current Reports on Form 8-K, and any amendments to
those reports are available free of charge through the ‘‘Investor Information’’ section of our website as
soon as reasonably practicable after those materials have  been electronically  filed with, or furnished to,
the Securities and Exchange Commission. We  have adopted  a Code of Corporate Conduct that applies
to all our directors, officers and employees and  a Senior Officer and Financial  Personnel Code of
Ethics that applies to our senior officers  and  financial personnel.  Our Code of  Corporate Conduct and
Senior Officer and Financial Personnel  Code of Ethics  are available  free of charge through the
‘‘Investor Information’’ section of our website.

Product  Candidates

There are eleven compounds in clinical trials  through our own programs and our collaborations
with other companies; these are listed in  the table below. The results in early clinical  trials may not be
predictive of results obtained in subsequent clinical trials and there can be no assurance  that  each  of
our  or our collaborators’ product candidates will  advance or will demonstrate the level of safety and
efficacy necessary  to obtain regulatory approval.

Current Stage

Lead Compound in Development through a  Collaborative Partner

Trastuzumab emtansine (T-DM1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Registration

Compounds in Development by ImmunoGen

IMGN901 (lorvotuzumab mertansine) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMGN853 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMGN529 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Phase II
Phase I
Phase I

Other Compounds in Development through Collaborative Partners

SAR3419 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BT-062 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SAR650984* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SAR566658 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BAY 94-9343 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
First  Amgen TAP compound ‘‘Amgen  1’’
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Second Amgen TAP compound ‘‘Amgen  2’’

Phase II
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I

*

Non-conjugated or ‘‘naked’’ antibody therapeutic

Trastuzumab Emtansine (T-DM1)

Trastuzumab emtansine, often referred to as T-DM1,  is the most advanced compound in

development using our TAP technology. T-DM1 consists of trastuzumab, which  is the active component
of Genentech’s antibody therapeutic,  Herceptin(cid:4) (trastuzumab), with our DM1 cell-killing agent
attached using our SMCC engineered  linker. T-DM1 is in global  development by Genentech’s parent
company, Roche, under a license with us.

T-DM1 is in Phase III testing for the treatment of HER2+ metastatic  breast cancer,  or mBC, and
in June  2012 Roche reported its plans to initiate  registration trials evaluating it for early  stage HER2+
breast cancer, or eBC. Roche also is initiating a  trial evaluating T-DM1 for  HER2+ gastric  cancer.

4

Evaluation for HER2+ mBC

For HER2+ mBC previously treated with  Herceptin and with  a taxane—Roche’s lead T-DM1
Phase III trial, EMILIA, compares T-DM1,  used  alone,  with Tykerb(cid:4) (lapatinib) used together with
Xeloda(cid:4) (capecitabine) to treat HER2+ mBC in patients  who have previously received  Herceptin with
a taxane. EMILIA has two co-primary  endpoints: progression-free survival, or PFS, and overall  survival,
or OS. Findings from EMILIA were  reported  in June 2012 at the American Society  of Clinical
Oncology, or ASCO, annual meeting. Among the findings reported was that treatment with T-DM1
significantly improved PFS compared  to  treatment with  Tykerb plus  Xeloda, with a hazard ratio of
0.65 (p<0.0001). As expected, the OS data were not mature  at  the time of  this  analysis. A sufficient
number of events (deaths) had occurred  to establish median OS in the  Tykerb plus Xeloda treatment
arm but not in the T-DM1 treatment arm, and longer follow  up is required.  The  EMILIA data
reported also included that fewer T-DM1-treated patients  experienced Grade 3  or higher adverse
events, which are severe adverse events,  than  the patients treated with  Tykerb plus Xeloda. In
August 2012, Roche announced that,  in  updated results,  treatment with T-DM1 significantly improved
OS compared to treatment with Tykerb plus Xeloda, and thus both of the co-primary  endpoints of the
EMILIA trial had now been met. Roche  also  disclosed that it  has submitted  a Biologics License
Application, or BLA, for T-DM1 to the U.S. Food  and Drug  Administration, or  FDA, and  that  it
expects to soon submit a Marketing Authorization Application, or  MAA, to  the European  Medicines
Agency, or EMA.

For first-line treatment of HER2+ mBC—In  July 2010,  Roche  began  a  Phase III trial,

MARIANNE, to assess T-DM1 for first-line treatment of HER2+ mBC. Current standard-of-care for
this  cancer is Herceptin used with a taxane, and MARIANNE compares  T-DM1 to this treatment,  both
when used alone and when used with Roche’s Perjeta(cid:4) (pertuzumab) antibody. Roche intends to use
MARIANNE results, if favorable, to  apply  in 2014 for approval of T-DM1  in the United States and
Europe to treat this cancer, both used  alone and used together with  Perjeta.

For HER2+ mBC previously treated with  Herceptin and with  Tykerb—Roche also has a Phase  III

trial, TH3RESA, underway assessing T-DM1  for this use. Patient dosing in this  trial began  in
September 2011.

Evaluation for HER2+ eBC

In June 2012 Roche presented its three-pronged approach to developing T-DM1 for the treatment

of HER2+ eBC: development for neoadjuvant use,  for adjuvant  use, and for  patients with residual
invasive disease following surgery. Roche has  announced that  it plans  to  initiate registration  trials with
T-DM1 in each of these uses in 2013.

Lorvotuzumab mertansine (IMGN901)

Our most advanced wholly owned product candidate is the TAP compound  lorvotuzumab

mertansine, which we also call IMGN901.  We developed IMGN901 to target CD56,  which is  found on
SCLC, Merkel cell carcinoma, multiple  myeloma, ovarian cancers, carcinoid  tumors,  and other cancers
of neuroendocrine origin. In early clinical  testing,  IMGN901 demonstrated evidence of  activity when
used alone to treat CD56+ cancers that had  recurred  after treatment  with approved anticancer drugs.

We  are evaluating IMGN901 for the  first-line treatment  of SCLC. Assuming this clinical trial is

successful we intend to advance IMGN901  into pivotal clinical testing for this indication.  We also are
completing a Phase I clinical trial assessing IMGN901 for the treatment of multiple myeloma.

5

Evaluation for SCLC

In March 2012 we began Phase II evaluation of IMGN901, used in combination with  etoposide/
carboplatin (E/C), as a treatment for newly diagnosed metastatic SCLC.  E/C is a current  standard care
for this cancer. Patients enrolled in this  trial, called NORTH, are randomized  to  receive either E/C or
E/C  plus IMGN901, with two patients  randomized to the E/C plus IMGN901  group for  every  one
patient randomized to the E/C alone group.  The IMGN901 dose  being  used in the NORTH trial was
established in the Phase I part of this  trial.

The NORTH trial is designed to assess whether  the addition  of  IMGN901 to E/C meaningfully
improves patient outcomes. The primary  endpoint of the NORTH  trial is PFS. Secondary endpoints
include PFS at 6 months, OS at 12 months, time to progression,  OS,  and  overall response rate. An
interim analysis focused on PFS at 6 months is planned after enrollment of the  first  59 patients. The
full NORTH trial is designed to include  120 patients.

Evaluation for Multiple Myeloma

IMGN901 is being assessed in a Phase I  clinical trial for  the treatment of  multiple myeloma,  used

in combination with lenalidomide plus dexamethasone, a standard of care for  this  cancer.  Promising
data were presented at the ASCO meeting in June  2011 from  the  dose-finding portion  of  this  clinical
trial. Based on clinical findings to date,  we believe IMGN901 is  a  promising treatment for multiple
myeloma. However, because of the significant  unmet medical need in SCLC, we have  focused
development on SCLC and currently have no plans to advance IMGN901 into pivotal  testing for the
treatment of multiple myeloma.

IMGN853

Our IMGN853 TAP compound targets folate receptor 1, or FOLR1,  which is over-expressed on

many  cases of ovarian cancer, or OC, and also on  other  types of solid tumors, including  NSCLC.
IMGN853 consists of a FOLR1-targeting antibody with  one  of  our potent cell-killing agents  attached
using one of our linkers engineered to counteract the multi-drug resistance that many cancers  develop.

In July 2012 we advanced IMGN853  into clinical testing in  a Phase  I  clinical trial intended to

enable us to establish the path(s) to  potential regulatory approval for IMGN853.  The  maximum-
tolerated dose, or MTD, of IMGN853 will be established in the dose-escalation  portion of this trial,
which  allows for single-patient cohorts at  the initial, lower dose levels. Once  the MTD  is established,
we plan to evaluate IMGN853 in patients with  previously  treated  epithelial  OC and in  patients  with
previously treated adenocarcinoma NSCLC.

IMGN529

Our IMGN529 TAP compound targets CD37,  which is expressed on B-cell malignancies  such as

NHL and chronic lymphocytic leukemia.  Scientists have  found  the expression profile of CD37 on NHL
subtypes to be similar to that of CD20,  the target of Rituxan(cid:4) (rituximab).

IMGN529 comprises an antibody that, in  preclinical testing, has demonstrated  meaningful
anticancer activity, our DM1 cell-killing agent,  and our SMCC engineered  linker,  thus paralleling
T-DM1 in design. We believe IMGN529 is  a highly  differentiated product  candidate for B-cell
malignancies because it combines the anticancer  activity of its antibody component with  the actions of
our  potent cell-killing agent. In April 2012, we  began  Phase I clinical testing  of IMGN529 for  the
treatment of NHL.

6

Compounds in Development by Our Partners

In addition to T-DM1, seven other compounds are  in clinical testing through our  collaborations
with other companies. Several of our collaborative partners also  have TAP compounds  in earlier stages
of development, including our newest partners  Novartis and Lilly.

SAR3419

We  created the SAR3419 TAP compound and licensed it to Sanofi from our  preclinical pipeline as

part of a broader collaboration. SAR3419  targets CD19 and is a potential new treatment for
CD19-expressing B-cell malignancies  including NHL and B-cell  acute  lymphoblastic  leukemia, or
B-ALL. In Phase I clinical testing, SAR3419 showed encouraging efficacy and tolerability  in the
treatment of NHL previously treated  with  approved anticancer agents. Sanofi  initiated  Phase II  clinical
testing of SAR3419 in October 2011  and is evaluating  it for both diffuse large  B-cell  lymphoma, a type
of NHL, and in B-ALL.

BT-062

BT-062 was created by Biotest under a  license agreement  with us  that grants Biotest rights to use

our  TAP technology with antibodies that  target CD138, an  antigen found on multiple myeloma and
certain solid tumors. We have opt-in  rights with respect  to  BT-062  in the  United States. Encouraging
early stage clinical data have been reported  with BT-062  used as a single agent to treat  multiple
myeloma that had recurred after treatment  with approved anticancer agents. In  July 2012 Biotest  began
patient dosing in an early stage trial assessing BT-062 used as part of a combination regimen for  this
cancer. Biotest also is assessing BT-062  preclinically for  the treatment  of CD138-expressing solid
tumors.

SAR650984 and SAR566658

These compounds also were licensed  to Sanofi  preclinically  as part of a broader collaboration, and

both are in early stage clinical testing.  SAR650984 is a CD38-targeting therapeutic  antibody  for
hematological malignancies. SAR566658 is a  TAP compound for DS6-expressing solid  tumors, including
ovarian cancers. DS6 is also known as CA6.

BAY 94-9343

BAY 94-9343 was created by Bayer under a license agreement with us  that grants Bayer rights  to

use our TAP technology with antibodies  that target  mesothelin. BAY 94-9343 advanced  into  Phase I
clinical testing for the treatment of mesothelin-expressing  solid  tumors in September 2011.

Amgen 1 and Amgen 2

Two TAP compounds that we refer to  as Amgen  1 and  Amgen 2  advanced into clinical testing  in

early 2012 through our collaboration with Amgen. Both compounds  were created  by  Amgen under
license agreements with us granting Amgen rights to use our  TAP  technology with  antibodies  binding to
the targets of Amgen 1 and Amgen 2.

Incidence of Relevant Cancers

Cancer remains a leading cause of death worldwide, and is the  second leading cause of death  in
the U.S.  The American Cancer Society  estimates that in 2012 approximately  1.6 million new  cases of
cancer will be diagnosed in the U.S.  and  that approximately 577,000 people  will  die from the disease.
The total number of people living with cancer significantly exceeds the number of patients diagnosed
with cancer in a given year as patients can live with  cancer for  a year or longer. Additionally, the
potential market for anticancer drugs exceeds the  number of patients treated as many types of cancer
typically are treated with multiple compounds  at the  same time  and because patients often receive  a
number of drug regimens sequentially.

7

T-DM1—Based on American Cancer  Society and  Roche estimates, we believe approximately

57,000 new cases of HER2+ breast cancer will be diagnosed in the U.S. in  2012. These  include
diagnoses for both early stage, or localized, disease and  advanced,  or  metastatic, disease.

The first approvals of T-DM1 are expected  to  be  for metastatic  disease. Based on information
reported by Roche in late 2011, we believe that  the metastatic HER2+ breast cancer market in  the
U.S. consists of approximately 21,100 patients: 7,800 eligible  for first-line  treatment;  5,900 eligible for
second-line treatment; 4,300 eligible for  third-line treatment; and 3,100  eligible  for fourth-line
treatment.

IMGN901—We are assessing this compound  in the clinic for the treatment of CD56+  SCLC and

multiple myeloma. Based on our own  studies and scientific literature, we  believe that CD56  is
expressed on approximately 89% of SCLC and 76% of  multiple myeloma cases.  Based on American
Cancer Society estimates and other sources, we believe  that approximately 29,400 new cases of SCLC
will be diagnosed in the U.S. in 2012.  SCLC  tends to spread broadly  through the  body quite early in
the course of the disease, and—according  to the American Cancer Society—approximately  two-thirds  of
SCLC patients have extensive disease  at the  time of  diagnosis.  Based  on  American Cancer Society
estimates, we also believe that approximately 21,700 new  cases of multiple  myeloma will be diagnosed
in the U.S. in 2012.

IMGN853—We are assessing our IMGN853 compound  for  the  treatment of epithelial ovarian

cancer and adenocarcinoma NSCLC. Based on  American Cancer Society  estimates, we  believe
approximately 19,000 and 90,000 new cases of these cancers will be diagnosed in the U.S. in 2012,
respectively.

IMGN529—We are assessing our IMGN529 compound  for  the  treatment of NHL. Based on

American Cancer Society estimates, we  believe approximately 70,000 new cases of NHL will be
diagnosed in the U.S. in 2012.

Out-licenses and Collaborations

We  selectively out-license restricted access to our TAP  technology to other companies to provide

us with cash to fund our own product  programs and to expand the utilization of  our technology. These
agreements typically provide the licensee with rights to use  our TAP  technology with  any of  its
antibodies and apply them to a defined  target to develop products. The licensee is  generally responsible
for the development, clinical testing,  manufacturing,  registration and commercialization of any resulting
product  candidate. As part of these agreements,  we are  generally  entitled to receive upfront fees,
potential milestone payments, royalties on the sales of any resulting  products and research and
development funding based on activities  performed at our collaborative partner’s request. We  are also
compensated for preclinical and clinical materials  supplied to our partners.

We  will not receive royalty payments from  a TAP technology out-license  until  a product candidate

developed under the license is approved  for marketing and  commercialized,  nor do we  expect to
receive significant individual milestones  payments under our existing collaborations prior to the
commencement of pivotal clinical trials or,  in some cases, product  approval. Achievement of product
approval requires, at a minimum, favorable completion  of  preclinical development  and evaluation,
assessment of early-stage clinical trials,  advancement into pivotal Phase  II and/or  Phase III clinical
testing, completion of this later-stage  clinical  testing with favorable results, and completion of
regulatory submissions and review. The only  collaboration that may provide  us with royalty  revenue and
significant milestone payments in the  foreseeable future is our collaboration  with Roche relating  to

8

T-DM1. Below is a table setting forth  our active  collaborations, the number of targets licensed  and
current status of the product candidates  being  developed thereunder:

Agreement Type

Effective Date(s)

Development Status1

Collaborator

Roche2

Amgen3

Sanofi

Sanofi4

Biotest

Multiple single-targets

Right-to-test and
single-targets

Multiple single-targets

Right-to-test

Single-target

Bayer HealthCare

Single-target

Novartis4

Lilly4

Right-to-test

Right-to-test

2000

2000

2003

2006

2006

2008

2010

2011

Registration

Phase I

Phase II

Research/Preclinical

Phase I

Phase  I

Research/Preclinical

Research/Preclinical

1

2

3

4

For collaborations involving multiple  targets,  development status denotes  the most advanced
program under the collaboration.

Roche has five single-target licenses. Pursuant to the  license  covering  the target HER2, which was
entered into in 2000, a product candidate, T-DM1,  has been  developed  and Roche has  submitted a
marketing application for the compound. The remaining four licenses  were entered into between
2005 and 2008, and the development status of product candidates under each of those licenses is
research/preclinical.

Amgen has multiple outstanding exclusive and non-exclusive options providing it  with the right to
take single-target licenses, on pre-negotiated terms, to specified targets during the  respective
option periods. As of June 30, 2012,  Amgen has  taken two single-target  licenses  pursuant  to  the
terms of its right-to-test agreement.

Sanofi,  Novartis and Lilly each has the right  to  take multiple  exclusive  options providing it with the
right to take single-target licenses, on pre-negotiated terms,  to  specified targets during the
respective option periods.

Roche

In May 2000, we granted Roche, through its Genentech unit,  an exclusive development and
commercialization license to our maytansinoid TAP technology  for use with antibodies  or other
proteins that target HER2, such as trastuzumab.  The  product candidate T-DM1 is currently  in
development under this agreement. We  received a $2 million  upfront payment  from Roche upon
execution of the agreement. We are also entitled to receive up  to  a  total of $44  million in milestone
payments, plus tiered royalties in the  mid-single digits on the commercial  sales of  any resulting
products. On an individual country basis,  royalties  on commercial sales will be reduced to the low-single
digits at  any time during the applicable royalty  period that the product  is not covered by ImmunoGen
patent rights in that country.

Roche may terminate this agreement  for convenience at any  time upon 90 days’  prior written
notice to us. The agreement may also be terminated  by  either party for a material breach by the  other,
subject to notice and cure provisions. Unless earlier  terminated, the agreement will  continue in  effect
until the expiration of Roche’s royalty obligations.  For each product and country,  Roche’s royalty
obligations commence with the first commercial  sale of that product in that country,  and extend  for a
period of 10 years from the date of that first  commercial sale  in that country, although  if  the product

9

(or its manufacture, use or sale) is covered by an  ImmunoGen patent in that country on such  tenth
anniversary, then the period during which royalties are payable  is extended until  12 years from the date
of the first commercial sale in that country.

Through June 30, 2012, we have received  and recognized a total of  $13.5 million in milestone

payments under this agreement. The next  potential milestone we will be entitled to receive will  be  a
regulatory milestone for marketing approval of T-DM1.  As this could occur  first  in either the  U.S. or
Europe, the next potential milestone due  will  be  either $10.5 million with first approval in  the U.S.  or
$5 million with first approval in Europe.

Amgen

In September 2000, we entered into a  ten-year right-to-test agreement  with Abgenix, Inc.  which

was later acquired by Amgen. The agreement provides  Amgen with  the right to (a) test  our
maytansinoid TAP technology with Amgen’s antibodies under a right-to-test, or research, license,
(b) take options, with certain restrictions,  to  individual targets  selected  by Amgen on either an exclusive
or non-exclusive basis for specified option periods and (c) upon exercise of those  options,  take
exclusive or non-exclusive licenses to  use our maytansinoid TAP technology to develop and
commercialize products directed to the  specified targets on previously agreed-upon terms. Amgen no
longer has the right to take additional  options  under the  right-to-test agreement, although multiple
outstanding options remain in effect  for  the remainder of their respective option  periods.

For each exclusive development and commercialization license taken, we  are entitled to receive an
exercise fee of $1 million and up to a  total of $34 million in  milestone payments, plus royalties on the
commercial sales of any resulting products.

Amgen may terminate each development and  commercialization license  for  convenience upon
prior notice to us. Each license may also be terminated by either  party for a  material  breach  by  the
other, subject to notice and cure provisions. Unless earlier terminated, each license will continue  in
effect until the expiration of Amgen’s royalty obligations,  which are  determined on  a
product-by-product and country-by-country basis. For each  product and  country, Amgen’s  royalty
obligations commence with the first commercial  sale of that product in that country,  and extend  until
the later of either the expiration of the last-to-expire ImmunoGen patent covering that product in that
country or the expiration for that country of  the minimum royalty  period specified  in each development
and commercialization license.

Under the right-to-test agreement, in September 2009 and November  2009, we  entered into two
development and commercialization licenses with  Amgen and  received an exercise fee of $1  million
with each license taken. In November 2011, the Investigational  New  Drug  (IND) applications for two
compounds developed under the separate development and commercialization licenses became active,
which  triggered two $1 million milestone payments to us. The next potential  milestone we  will  be
entitled to receive under either of these development and commercialization licenses will be a
development milestone for the first dosing of a patient in  a Phase  II clinical trial, which will result in a
$3 million payment being due.

Sanofi

Collaboration Agreement

In July 2003, we entered into a broad collaboration agreement  with Sanofi  (formerly Aventis) to
discover, develop and commercialize antibody-based  products.  The  collaboration  agreement provides
Sanofi with worldwide development and  commercialization rights to new antibody-based  products
directed to targets  that are included in  the collaboration, including  the right to use our  TAP technology
and our humanization technology in the  creation  of products directed to these targets. The product

10

candidates (targets) currently in development under the collaboration  include SAR3419 (CD19),
SAR650984 (CD38), SAR566658 (DS6, also known as CA6) and  at  least  one earlier-stage compound
that has yet to be disclosed. For each  of the targets  included in  the collaboration at  this time, we are
entitled to receive up to a total of $21.5  million in milestone payments,  plus royalties on the
commercial sales of any resulting products.

The agreement may be terminated by either party for  a material breach by the other, subject  to
notice and cure provisions. Unless earlier  terminated,  the agreement will continue in effect until  the
expiration of Sanofi’s royalty obligations, which are determined on a product-by-product and
country-by-country basis. For each product and country, Sanofi’s  royalty obligations commence  upon
first commercial sale of that product in that country, and extend  until  the later  of  either the expiration
of the last-to-expire ImmunoGen patent covering that product  in that country or the  expiration for that
country of the minimum royalty period specified in the  agreement.

The collaboration  agreement also provides us an  option to certain  co-promotion rights  in the U.S.
on a product-by-product basis. The terms  of  the collaboration agreement allow Sanofi to terminate our
co-promotion rights if there is a change  in  control  of our company.

Through June 30, 2012, we have received  and recognized a total of  $16 million in milestone
payments related to compounds covered  under  this  agreement now and in the  past, including  a total of
$8 million in milestone payments related  to two product candidates previously in the collaboration  that
have been returned to us along with  the  rights to the respective targets. The next potential milestone
we will be entitled to receive with respect  to each of SAR566658  and  for SAR650984 will be a
development milestone for initiation  of a  Phase IIb clinical trial  (as defined in  the agreement), which
will result in each  case in a $3 million payment being due. The next potential milestone we will be
entitled to receive with respect to SAR3419 will be for initiation of a Phase  III clinical trial, which will
result in a $3 million payment being due. The next potential  milestone we will be entitled to receive for
each  of the unidentified targets will be a  development milestone for commencement of a Phase I
clinical trial, which will result in a $1  million  payment being due, or a preclinical milestone which will
result in a $500,000 payment being due.

Right-to-Test Agreement

In December 2006, we entered into a separate right-to-test  agreement with Sanofi. The agreement
provides Sanofi with the right to (a)  test  our maytansinoid TAP technology  with Sanofi’s antibodies to
targets that were not included in the  collaboration  agreement described above under  a right-to-test, or
research, license, (b) take exclusive options, with  certain restrictions, to individual targets selected by
Sanofi for specified time periods and  (c) upon  exercise  of those options, take exclusive licenses to use
our  maytansinoid TAP technology to  develop and  commercialize products directed  to  the specified
targets on terms agreed upon at the inception  of  the right-to-test agreement. The right-to-test
agreement had a three-year original term  from  the activation date  that was extended on a one-time
basis by Sanofi in August 2011for an  additional three years  by payment of a  $2 million extension fee.

For each development and commercialization license taken, we are entitled to receive an exercise

fee of $2 million and up to a total of $30 million in  milestone payments, plus royalties  on the
commercial sales of any resulting products.

Each  development and commercialization license  may  be  terminated by either  party for  a material

breach by the other, subject to notice and  cure provisions. Unless earlier  terminated, each  license will
continue in effect until the expiration of Sanofi’s royalty obligations, which are  determined on  a
product-by-product and country-by-country basis. For each  product and  country, Sanofi’s  royalty
obligations commence with the first commercial  sale of that product in that country,  and extend  until
the later of either the expiration of the last-to-expire ImmunoGen patent covering that product in that
country or the expiration for that country of  the minimum royalty  period specified  in each development

11

and commercialization license. No development  and commercialization license  has yet  been taken
under the right-to-test agreement.

Biotest

In July 2006, we granted Biotest an exclusive  development and  commercialization license to our
maytansinoid TAP technology for use  with antibodies that target CD138.  The product candidate BT-062
is currently in development under this  agreement.  We received  a  $1 million upfront payment from
Biotest upon execution of the agreement.  We  are also  entitled to receive  up to a total of  $35.5 million
in milestone payments, plus royalties  on  the commercial sales of any resulting products.

The agreement also provides us with  the right to elect, at specific stages during the clinical

evaluation of any compound created under the agreement,  to  participate  in the  United States
development and commercialization of that compound in lieu of receiving  the milestone payments not
yet earned and royalties on sales in the United States. We can  exercise this  right during an exercise
period specified in the agreement by  notice and payment to Biotest of an agreed  upon opt-in  fee of
$5 million or $15 million, depending on the stage of  development. Upon exercise of this right, we
would share equally with Biotest the  associated costs  of  product development  and commercialization  in
the United States along with the profit, if  any, from  product sales in the  United States.

Biotest may terminate the agreement  for convenience at any  time prior to  our election  to
participate in the U.S. development and  commercialization of a compound  created under this
agreement upon prior notice to us. The agreement may also be terminated by either  party for  a
material breach by the other, subject  to  notice and cure provisions. Unless earlier terminated, the
agreement will continue in effect until the  expiration of  Biotest’s  royalty obligations, which  are
determined on a product-by-product  and country-by-country basis. For each product and country,
Biotest’s royalty obligations commence upon first commercial sale  of  that  product in  that  country, and
extend until the later of either the expiration of the last-to-expire ImmunoGen  patent  covering that
product  in that country or the expiration for that country of the minimum royalty  period specified in
the agreement.

Through June 30, 2012, we have received  and recognized a total of  $500,000 in milestone payments
under this agreement. The next potential  milestone  we will be entitled to receive will be a development
milestone for commencement of a Phase IIb clinical trial (as defined in  the agreement) which will
result in a $2 million payment being due.

Bayer HealthCare

In October 2008, we granted BayerHealthCare an exclusive development  and commercialization

license to our maytansinoid TAP technology for use  with antibodies or other proteins  that  target
mesothelin. The product candidate BAY 94-9343 is currently  in development under  this  agreement. We
received a $4 million upfront payment upon  execution of the agreement.  We are  also entitled  to
receive, for each product developed and marketed by Bayer HealthCare under  this  agreement, up to a
total of $170.5 million in milestone payments, plus royalties on the  commercial sales  of any  resulting
products.

Bayer HealthCare may terminate the agreement for convenience  at  any time upon  prior written
notice to us. The agreement may also be terminated  by  either party for a material breach by the  other,
subject to notice and cure provisions. We may also terminate the agreement upon the occurrence  of
specified events. Unless earlier terminated, the  agreement will  continue in effect until the expiration of
Bayer HealthCare’s royalty obligations,  which  are determined  on a  product-by-product and
country-by-country basis. For each product and country, Bayer  HealthCare’s royalty obligations
commence upon first commercial sale  of that product  in that country, and extend until  the later  of

12

either the expiration of the last-to-expire  ImmunoGen patent covering  that  product in  that  country  or
the expiration for that country of the  minimum  royalty period specified  in the  agreement.

Through June 30, 2012, we have received  and recognized a total of  $3 million in milestone
payments under this agreement. The next  potential milestone we will be entitled to receive will  be  a
development milestone for commencement of a non-pivotal Phase II clinical trial, which  will  result in a
$4 million payment being due.

Novartis

In October 2010, we entered into a right-to-test agreement with Novartis Institutes  for BioMedical
Research, Inc. (Novartis). The agreement  provides  Novartis  with a right to (a)  test our TAP technology
with Novartis’ antibodies directed to individual  targets selected by Novartis under a right-to-test, or
research, license, (b) take exclusive options, with  certain restrictions, to individual targets selected by
Novartis for specified option periods,  and  (c) upon exercise of those options take exclusive licenses  to
use our TAP technology to develop and commercialize  products  for a  specified number  of  individual
targets on terms agreed upon at the inception  of  the right-to-test agreement. The initial term of the
right-to-test agreement is three years,  which may  be  extended by Novartis for up to two additional
one-year periods by the payment of additional  consideration. Novartis must exercise its options for  the
development and commercialization licenses by the end  of  the term of the right-to-test  agreement, after
which  any then outstanding options will  lapse.

We  received a $45 million upfront payment in  connection with the execution of the  right-to-test
agreement, and we are also entitled to receive additional payments under the  agreement for  research
and development activities performed on behalf of Novartis during the term  of  the agreement. For
each  development and commercialization license taken, we are entitled to  receive an exercise fee of
$1 million and up to a total of $199.5  million in milestone payments,  plus royalties on the commercial
sales of any resulting products.

Novartis may terminate any development and commercialization  license  for convenience  upon
prior notice to us. Each license may also be terminated by either  party for a  material  breach  by  the
other, subject to notice and cure provisions. Unless earlier terminated, each development and
commercialization license will continue in  effect until the expiration of  Novartis’  royalty obligations,
which  are determined on a product-by-product  and  country-by-country  basis. For each product  and
country, Novartis’ royalty obligations  commence upon first commercial sale of that product  in that
country, and extend until the later of either the expiration of the last-to-expire ImmunoGen  patent
covering that product in that country  or  the expiration for that country of the  minimum royalty period
specified in each license. No development and commercialization  license has  yet been taken  under the
right-to-test agreement.

Lilly

In December 2011, the Company entered into a three-year right-to-test  agreement with  Eli Lilly
and Company (Lilly). The agreement provides Lilly with  the right to (a) take exclusive options,  with
certain restrictions, to individual targets selected by Lilly  for specified  option  periods, (b) test our
maytansinoid TAP technology with Lilly’s  antibodies directed to the optioned targets under a
right-to-test, or research, license, and  (c) upon exercise of those options take exclusive licenses  to  use
our  maytansinoid TAP technology to  develop and  commercialize products for  a specified number of
individual targets on terms agreed upon  at the  inception of the right-to-test agreement.  Lilly must
exercise its options for the development  and commercialization licenses by the end  of the term of  the
right-to-test agreement, after which any then outstanding options will lapse.

We  received a $20 million upfront payment in  connection with the execution of the  agreement, and
we are also entitled to receive additional payments  under the agreement for  research  and development

13

activities performed under the agreement on behalf of  Lilly during the term of the research license. For
the first development and commercialization  license taken, we  are  entitled to receive up to a total of
$200.5 million in milestone payments, plus  tiered royalties in  the mid-single to low-double digits  on the
commercial sales of any resulting products. For  each  subsequent development and commercialization
license taken, we are entitled to receive an  exercise fee  of $2 million and up  to  a total of $199 million
in milestone payments, plus royalties  on  the commercial sales of any resulting products.

Lilly may terminate any development and commercialization license for  convenience upon  prior
notice to us. Each license may also be terminated  by  either party for a material breach by the  other,
subject to notice and cure provisions. We may also terminate the agreement upon the occurrence  of
specified events. Unless earlier terminated, each  development and commercialization license  will
continue in effect until the expiration of Lilly’s royalty obligations, which are determined on a
product-by-product and country-by-country basis. For each  product and  country, Lilly’s  royalty
obligations commence upon first commercial sale of that  product in that country,  and extend until the
later of either the expiration of the last-to-expire  ImmunoGen patent covering that product in that
country or the expiration for that country of  the minimum royalty  period specified  in each license. No
development and commercialization license has yet been  taken under the right-to-test agreement.

In-Licenses

From time to time we may in-license  certain rights to targets or technologies for use  in conjunction

with our internal efforts to develop TAP compounds  and  related technologies. These  licenses include
rights to certain antibodies. In exchange, we may be obligated to pay upfront  fees,  potential  milestone
payments and royalties on any product  sales.

Patents, Trademarks and Trade Secrets

Our intellectual property strategy centers  on obtaining  patent  protection for our proprietary

technologies and product candidates.  As  of  June  30, 2012, our  patent portfolio had a total  of  381 issued
patents worldwide and 438 pending patent applications worldwide that we own or license from third
parties. We seek to protect our TAP technology and our  product candidates  through a multi-pronged
approach. In this regard, we have patents and patent applications covering antibodies and other
cell-binding agents, linkers, maytansinoid and other cell-killing agents, and complete antibody-drug
conjugates, or immunoconjugates, comprising these components  and methods  of making and using each
of the above. Typically, multiple issued  patents and pending  patent  applications cover various aspects of
each  product candidate.

We  consider our maytansinoid technology  to  be  a key component of our overall corporate  strategy.
We  currently own 34 issued U.S. patents covering various embodiments of  our  maytansinoid technology
including claims directed to certain maytansinoids, antibody-maytansinoid  conjugates and  other
cell-binding agents used with maytansinoids, and methods of making and  using the same.  In all cases,
we have received or are applying for  comparable  patents  in other  jurisdictions  including Europe and
Japan. We have issued patents that cover  numerous aspects of the  manufacture of both our DM1  and
DM4 cell-killing agents. These issued  patents remain  in force  until various times between 2020 and
2026. We also have several composition  of matter  patents covering various aspects of our DM4
cell-killing agent and antibody-maytansinoid conjugates  incorporating DM4 that are expected to remain
in force until 2024-2025.

Our intellectual property strategy also includes  pursuing patents directed to linkers, antibodies,

conjugation methods, immunoconjugate formulations and the use of specific  antibodies  and
immunoconjugates to treat certain diseases. In this regard, we have  issued patents and  pending  patent
applications related to many of our linker technologies.  These issued patents, expiring  in 2021-2027,
and any patents which may issue from the patent applications, cover antibody-maytansinoid conjugates

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using these linkers. We also have issued U.S.  patents and pending patent applications covering methods
of assembling immunoconjugates from their constituent antibody, linker and cell-killing agent moieties.
These issued patents will expire in 2021-2027,  while any patents that  may  issue from  pending patent
applications also covering various aspects of these technologies will, if issued, expire between 2021 and
2032. We also have issued patents and  pending patent applications related to monoclonal antibodies
that may be a component of a TAP compound or may be developed as  a therapeutic, or  ‘‘naked,’’
antibody  anticancer compound. Among  these  patents is an issued U.S. patent claiming a method of
humanizing murine antibodies to avoid  their detection by the human immune system.  We have received
patents in other jurisdictions, including Europe and Japan,that correspond to our antibody
humanization U.S. patent. These patents will expire between  2013 and  2014.

We  expect our continued work in each of these areas  will  lead to other patent applications. In all
such cases, we will either be the assignee  or  owner of such patents  or have  an exclusive license  to  the
technology covered by the patents. For example,  we also  own issued patents covering proprietary
derivatives of non-maytansinoid cell-killing molecules. However, we  do not currently consider  these
additional patent families to be material  to our business.

We  have in-licensed intellectual property relating to our IMGN901 product  candidate from
Dana-Farber Cancer Institute. We do  not  believe that the terms  of this  license  are material to our
business or prospects.

We  cannot provide assurance that the  patent  applications will  issue as  patents  or that any  patents,

if issued, will provide us with adequate  protection  against competitors with respect to the  covered
products, technologies or processes. Defining the  scope  and term  of patent protection  involves complex
legal and  factual analyses and, at any  given  time, the  result of  such analyses may be uncertain. In
addition, other parties may challenge  our patents  in litigation or administrative proceedings resulting  in
a partial or complete loss of certain patent rights  owned or controlled by  ImmunoGen,  Inc.
Furthermore, as a patent does not confer  any  specific freedom to operate, other parties may  have
patents that may block or otherwise hinder  the development and commercialization of our technology.

In addition, many of the processes and much of the  know-how that  are  important to us depend
upon the skills, knowledge and experience of our key scientific and  technical personnel, which skills,
knowledge and experience are not patentable.  To  protect our rights in these areas, we require that all
employees, consultants, advisors and  collaborators enter into confidentiality agreements with  us.
Further, we require that all employees enter into assignment of invention  agreements as a  condition of
employment. We cannot provide assurance,  however, that these agreements  will  provide adequate or
any meaningful protection for our trade  secrets,  know-how or other proprietary  information in the
event of any unauthorized use or disclosure of such trade secrets,  know-how  or proprietary  information.
Further, in the absence of patent protection, we  may be exposed to competitors who independently
develop substantially equivalent technology  or otherwise gain access to our trade  secrets,  know-how or
other proprietary information.

Competition

We  focus on highly competitive areas of product development. Our competitors include  major
pharmaceutical companies and other biotechnology firms.  For example, Pfizer,  Seattle Genetics, Roche
and Bristol-Myers Squibb have programs  to attach  a proprietary  cell-killing small  molecule to an
antibody  for targeted delivery to cancer cells. Pharmaceutical and  biotechnology companies, as well  as
other institutions, also compete with us  for promising targets for  antibody-based therapeutics and in
recruiting highly qualified scientific personnel.  Many  competitors and  potential competitors  have
substantially greater scientific, research and product development capabilities, as  well as greater
financial, marketing and human resources  than we  do.  In addition, many specialized biotechnology

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firms have formed collaborations with large,  established companies  to  support  the research,
development and commercialization of products that may be competitive  with ours.

In particular, competitive factors within the antibody and cancer therapeutic  market  include:

(cid:129) the safety and efficacy of products;

(cid:129) the timing of regulatory approval and commercial  introduction;

(cid:129) special regulatory designation of products,  such as  Orphan Drug designation; and

(cid:129) the effectiveness of marketing, sales, and reimbursement efforts.

Our competitive position depends on our ability to develop effective proprietary products,

implement clinical development programs,  production plans and marketing plans,  including
collaborations with other companies with greater marketing resources than ours, and  to  obtain  patent
protection and secure sufficient capital  resources.

Continuing development of conventional and  targeted chemotherapeutics by large pharmaceutical

companies and biotechnology companies  may result in new compounds that may  compete with our
product  candidates. In addition, antibodies  developed by certain  of these  companies have been
approved for use as cancer therapeutics.  In the  future, additional antibodies may  compete with our
product  candidates. In addition, other companies have created or have programs to create potent
cell-killing agents for attachment to antibodies.  These companies may compete with us for  technology
out-license arrangements.

Because of the acceptance of combination therapy  for  the treatment of cancer and  the variety  of

genes and targets implicated in cancer  incidence and progression, we believe that products resulting
from applications of new technologies may be complementary to our own.

Such new technologies include, but are not limited to:

(cid:129) the use of genomics technology to identify new  gene-based targets for the development of

anticancer drugs;

(cid:129) the use of high-throughput screening to identify  and optimize  lead compounds;

(cid:129) the use of gene therapy to deliver  genes to regulate gene  function; and

(cid:129) the use of therapeutic vaccines.

Regulatory Matters

Government Regulation and Product Approval

Government authorities in the U.S.,  at  the federal, state and local level, and other  countries
extensively regulate, among other things, the research, development,  testing, manufacture,  quality
control, approval, labeling, packaging,  storage,  record-keeping, promotion, advertising, distribution,
marketing and export and import of  products such as those we are developing. A new drug must be
approved by the FDA through the new drug application, or  NDA, process and  a new  biologic must be
approved by the FDA through the biologics  license application, or BLA, process before  it may  be
legally marketed in the U.S.

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U.S. Drug Development Process

In the U.S., the FDA regulates drugs under  the federal  Food, Drug, and  Cosmetic  Act,  or FDCA,

and in the case of biologics, also under the Public  Health Service  Act, or PHSA,  and implementing
regulations. The process of obtaining regulatory approvals and the subsequent compliance with
appropriate federal, state, local, and foreign statutes  and regulations require the expenditure of
substantial time and financial resources.  Failure to comply  with the applicable U.S. requirements at any
time during the product development process, approval process or after  approval, may subject an
applicant to administrative or judicial  sanctions.  These sanctions could  include the FDA’s refusal to
approve pending applications, withdrawal of an approval, a clinical hold, warning letters,  product
recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines,
refusals of government contracts, restitution,  disgorgement, or civil or criminal penalties. Any agency or
judicial enforcement action could have a  material adverse effect on us.  The process required  by  the
FDA before a drug or biologic may be  marketed in  the U.S. generally involves the following:

(cid:129) completion of preclinical laboratory tests,  animal studies and formulation studies  according to

Good Laboratory Practices or other  applicable regulations;

(cid:129) submission to the FDA of an IND which  must become effective before human  clinical trials  may

begin;

(cid:129) performance of adequate and well-controlled  human clinical trials according  to  Good Clinical

Practices to establish the safety and efficacy of the  proposed drug for its intended  use;

(cid:129) submission to the FDA of an NDA  or BLA;

(cid:129) satisfactory completion of an FDA  inspection  of the manufacturing facility or facilities at which
the drug is produced to assess compliance with current  good manufacturing practice, or cGMP,
to assure that the facilities, methods and controls are adequate to preserve the  drug’s identity,
strength, quality and purity; and

(cid:129) FDA review and approval of the NDA or BLA.

Once a pharmaceutical candidate is identified for development it enters the  preclinical testing
stage. Preclinical tests include laboratory  evaluations of product chemistry, toxicity  and formulation,  as
well as animal studies. An IND sponsor must submit the  results of the  preclinical tests, together with
manufacturing information and analytical  data, to the  FDA as part of the IND.  The sponsor will also
include a protocol detailing, among other things,  the objectives of the  first  phase of the clinical trial,
the parameters to be used in monitoring safety, and the effectiveness criteria to be evaluated, if the
first phase lends itself to an efficacy evaluation. Some preclinical testing may continue even after the
IND is submitted. The IND automatically  becomes effective 30 days  after receipt by the FDA,  unless
the FDA, within the 30-day time period, places the clinical trial on a clinical hold. In such  a case, the
IND sponsor and the FDA must resolve  any  outstanding concerns before the clinical trial can  begin.
Clinical holds also  may be imposed by the FDA  at any time before or during studies due to safety
concerns or non-compliance.

All clinical trials must be conducted  under the supervision of one or more qualified investigators in

accordance with good clinical practice regulations. They must  be  conducted  under protocols detailing
the objectives of the trial, dosing procedures, subject selection  and  exclusion  criteria and the safety  and
effectiveness criteria to be evaluated.  Each protocol must be submitted  to the  FDA as part of the IND,
and progress reports detailing the results  of the  clinical  trials must  be  submitted at  least annually. In
addition, timely safety reports must be submitted to the  FDA  and the investigators for serious and
unexpected adverse events. An institutional review  board,  or IRB,  at  each  institution participating in
the clinical trial must review and approve each protocol before a clinical trial  commences at  that
institution and must also approve the information  regarding the  trial and  the consent form that must be

17

provided to each trial subject or his or her legal representative, monitor  the  study until completed and
otherwise comply with IRB regulations.

Human clinical trials are typically conducted  in three  sequential phases that may overlap or be

combined:

(cid:129) Phase I: The product candidate is initially introduced into healthy  human subjects  and tested for
safety, dosage tolerance, absorption,  metabolism, distribution and excretion. In the  case of some
products for severe or life-threatening diseases, such as cancer, especially  when the product may
be too inherently toxic to ethically administer to healthy  volunteers, the  initial human testing is
often conducted in patients.

(cid:129) Phase II: This phase involves studies in a limited  patient population to identify  possible adverse
effects and safety risks, to preliminarily evaluate the efficacy of the product for specific targeted
diseases  and to determine dosage tolerance and optimal dosage.

(cid:129) Phase III: Clinical trials are undertaken to further evaluate dosage, clinical  efficacy and safety  in
an expanded patient population at geographically  dispersed clinical study sites. These  studies are
intended to establish the overall risk-benefit ratio of the  product candidate  and provide,  if
appropriate, an adequate basis for product  labeling.

The FDA or the sponsor may suspend a clinical trial at any  time  on various grounds, including a

finding that the research subjects or patients are being exposed to an unacceptable health risk.
Similarly, an IRB can suspend or terminate approval of a clinical trial at its institution if  the clinical
trial is not being conducted in accordance with  the IRB’s  requirements or if  the drug has been
associated with unexpected serious harm to patients. Phase  I,  Phase II,  and Phase III testing  may not
be completed successfully within any  specified  period, if at all.

During  the development of a new drug,  sponsors  are given  opportunities  to meet with the FDA at

certain points. These points may be prior  to  submission  of  an IND,  at the end  of Phase 2, and  before
an NDA or BLA is submitted. Meetings  at other times may  be  requested.  These meetings  can provide
an opportunity for the sponsor to share information about the data  gathered to date, for  the FDA to
provide advice, and for the sponsor and  FDA to reach  agreement on  the next phase  of  development.
Sponsors typically use the End of Phase  2 meeting  to  discuss  their Phase 2  clinical results and present
their plans for the pivotal Phase 3 clinical trial that  they believe  will support approval of the  new drug.
If this type of discussion occurred, a sponsor  may  be  able  to  request a Special Protocol Assessment, or
SPA, the purpose of which is to reach agreement  with the  FDA on the  design of the Phase 3 clinical
trial protocol design and analysis that  will  form the primary basis  of an efficacy claim.

According to FDA guidance for industry on  the SPA  process, a sponsor which meets the

prerequisites may make a specific request for  a special protocol assessment  and provide  information
regarding the design and size of the proposed clinical trial.  The  FDA is supposed to evaluate  the
protocol within 45  days of the request to assess whether  the proposed trial  is adequate, and  that
evaluation may result in discussions and  a request for  additional  information. A SPA request  must  be
made before the proposed trial begins, and all open issues must  be  resolved  before  the trial begins. If a
written agreement is reached, it will  be  documented and made part of the record. The agreement  will
be binding on the  FDA and may not  be  changed by the  sponsor  or the FDA  after the trial begins
except with the written agreement of the  sponsor and the FDA or if the FDA determines that a
substantial scientific issue essential to  determining the safety or efficacy of the drug was identified  after
the testing began. Also, if the sponsor  makes  any  unilateral changes to the approved protocol, the
agreement will be invalidated.

Concurrent with clinical trials, companies usually complete additional animal studies and  must  also
develop additional information about the  chemistry and physical characteristics of the drug and finalize
a process for manufacturing the product in commercial quantities in  accordance with cGMP

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requirements. The manufacturing process must be capable  of consistently  producing quality batches of
the product candidate and, among other things,  the manufacturer must develop methods  for testing the
identity, strength, quality and purity of the final drug. Additionally,  appropriate  packaging must be
selected  and tested and stability studies must  be  conducted  to  demonstrate  that  the product candidate
does not undergo unacceptable deterioration over its shelf life.

U.S. Review and Approval Processes

The results of product development, preclinical studies and clinical trials, along  with descriptions of

the manufacturing process, analytical tests conducted on the chemistry of the  drug, proposed labeling,
and other relevant information are submitted to the FDA as part of an NDA or  BLA requesting
approval to market the product. The submission of an  NDA or BLA  is subject to the  payment of user
fees; a waiver of such fees may be obtained under certain limited circumstances. The FDA  reviews all
NDAs and BLAs submitted to ensure that  they are  sufficiently complete for substantive review  before
it accepts them for filing. The FDA may request additional information rather than accept a  NDA or
BLA for filing. In this event, the NDA  or  BLA must be resubmitted  with the  additional information.
The resubmitted application also is subject  to  review before the FDA accepts it  for filing. Once the
submission is accepted for filing, the  FDA begins an  in-depth substantive review. FDA may refer the
NDA  or  BLA to an advisory committee for  review, evaluation and recommendation as to whether the
application should be approved and under what conditions. The FDA is not  bound by the
recommendation of an advisory committee, but it  generally follows such recommendations. The
approval process is lengthy and often difficult, and the FDA  may  refuse  to approve an NDA or BLA if
the applicable regulatory criteria are  not  satisfied or may  require additional clinical or other  data  and
information. Even if such data and information is submitted, the FDA may ultimately decide that the
NDA  or  BLA does not satisfy the criteria  for approval. Data  obtained  from clinical trials are  not
always conclusive and the FDA may  interpret  data differently than we interpret  the same data. The
FDA may issue a complete response letter, which  may require additional  clinical  or other data or
impose other conditions that must be  met in order to secure  final approval  of  the NDA or BLA,  or an
approved letter following satisfactory completion of all aspects  of the review process. The FDA  reviews
an NDA to determine, among other things,  whether  a product is safe and effective for its intended use
and whether its manufacturing is cGMP-compliant to assure and preserve  the product’s  identity,
strength, quality and purity. The FDA  reviews  a BLA to determine, among other things whether the
product  is safe, pure and potent and  the facility  in which it  is manufactured, processed, packed  or held
meets standards designed to assure the  product’s continued safety, purity and  potency.  Before
approving an NDA or BLA, the FDA will  inspect  the facility  or facilities where the product is
manufactured.

NDAs or BLAs receive either standard or priority  review. A drug representing a significant

improvement in treatment, prevention or  diagnosis of disease may  receive priority review.  Priority
review for an NDA for a new molecular  entity and original BLAs  will be 6  months from  the date that
the NDA or BLA is filed. In addition,  products studied for their safety and effectiveness in  treating
serious or life-threatening illnesses and that provide  meaningful  therapeutic benefit over  existing
treatments may receive accelerated approval and may be approved on the  basis of adequate and
well-controlled clinical trials establishing  that  the drug product has an  effect on a  surrogate endpoint
that is reasonably likely to predict clinical benefit or on  the basis  of  an effect on  a clinical  endpoint
other than survival or irreversible morbidity. As a condition of approval, the FDA  may require that a
sponsor  of a drug receiving accelerated  approval  perform  adequate and well-controlled post-marketing
clinical trials. Priority review and accelerated approval do  not  change the standards  for approval,  but
may expedite the approval process.

If a  product receives regulatory approval, the approval may be significantly  limited to specific
diseases  and dosages or the indications for  use may otherwise  be  limited, which could restrict  the

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commercial value of the product. In addition, the  FDA may require  us to conduct Phase IV testing
which  involves clinical trials designed to further  assess a drug’s safety  and effectiveness after  NDA or
BLA approval, and may require testing and surveillance  programs to monitor the safety of approved
products which have been commercialized.

The recently enacted Food and Drug Administration Safety and Innovation  Act, or FDASIA, made
permanent the Pediatric Research Equity  Act, or PREA, which requires  a sponsor to conduct pediatric
studies for most drugs and biologicals, for  a new  active ingredient,  new indication, new  dosage form,
new dosing regimen or new route of administration. Under PREA, original  NDAs, BLAs and
supplements thereto, must contain a  pediatric assessment  unless the sponsor has received  a deferral or
waiver. The required assessment must  assess  the safety and effectiveness of the product for the claimed
indications in all relevant pediatric subpopulations and support dosing and administration for each
pediatric subpopulation for which the product  is safe and effective. The  sponsor or FDA may  request  a
deferral of pediatric studies for some  or all of the pediatric subpopulations. A deferral may be granted
for several reasons, including a finding that the  drug or biologic  is ready for approval for use  in adults
before pediatric studies are complete or that additional safety or effectiveness data needs to be
collected before the pediatric studies begin. After April 2013, the FDA must send a  non-compliance
letter to any sponsor that fails to submit the  required assessment,  keep a deferral current or  fails to
submit a request for approval of a pediatric formulation.

Patent Term Restoration and Marketing  Exclusivity

Depending upon the timing, duration and specifics of FDA approval of our drugs, some of our

U.S. patents may be eligible for limited  patent term extension under the Drug Price Competition  and
Patent Term Restoration Act of 1984,  referred  to  as the Hatch-Waxman Amendments. The Hatch-
Waxman Amendments permit a patent restoration term of up to five years as compensation for  patent
term lost during product development and  the FDA regulatory review process. However, patent term
restoration cannot  extend the remaining  term of a patent beyond a total of 14 years from the  product’s
approval date. The patent term restoration period  is generally one-half the  time between  the effective
date  of  an IND, and the submission  date of an NDA  or BLA, plus  the time  between  the submission
date  of  an NDA or BLA and the approval of that application. Only one patent applicable to an
approved drug is eligible for the extension, and the  extension must  be  applied for  prior to expiration  of
the patent. The United States Patent and Trademark Office, in consultation  with the FDA,  reviews and
approves the application for any patent term extension  or restoration. In the  future, we intend  to  apply
for restorations of patent term for some of  our currently owned or licensed patents to add  patent  life
beyond their current expiration date,  depending on the expected length of clinical trials and other
factors involved in the filing of the relevant NDA.

Market exclusivity provisions under the FDCA  also can delay the submission or the approval  of

certain applications. The FDCA provides  a five-year period of non-patent marketing exclusivity  within
the U.S.  to the first applicant to gain  approval  of  an NDA for a new chemical entity. A drug is a  new
chemical entity if the FDA has not previously approved any other  new drug  containing the same  active
moiety, which is the molecule or ion responsible for the action of the drug substance. During the
exclusivity period,  the FDA may not accept  for  review an abbreviated  new  drug  application,  or ANDA,
or a 505(b)(2) NDA submitted by another company for another version  of  such drug where the
applicant does not own or have a legal right  of  reference to all the data  required  for approval.
However, an application may be submitted after four years  if it contains a certification of  patent
invalidity or non-infringement. The FDCA also  provides three years of  marketing  exclusivity for  an
NDA,  505(b)(2) NDA or supplement to an  existing NDA if new clinical  investigations, other than
bioavailability studies, that were conducted or sponsored by the applicant are deemed  by  FDA to be
essential to the approval of the application,  for example, for new indications, dosages, or strengths  of
an existing drug. This three-year exclusivity covers only the conditions associated with the  new clinical

20

investigations and does not prohibit the FDA from approving ANDAs  for drugs containing  the original
active  agent. Five-year and three-year exclusivity will not delay the submission or  approval of a full
NDA; however, an applicant submitting  a full NDA would be required  to  conduct or  obtain  a right of
reference to all of the preclinical studies  and  adequate and  well-controlled  clinical trials  necessary  to
demonstrate safety and effectiveness.

Pediatric exclusivity is another type of marketing exclusivity  available in the U.S. The FDASIA

made permanent the Best Pharmaceuticals for Children  Act, or BPCA, which provides  for an
additional six months of marketing exclusivity if a sponsor conducts clinical trials in  children in
response to a written request from the FDA, or  a Written Request. If  the  Written Request does not
include studies in neonates, the FDA  is required to include its rationale  for  not  requesting those
studies.  The FDA may request studies  on  approved or unapproved indications in separate Written
Requests. The issuance of a Written  Request does not require  the  sponsor to undertake the described
studies.  To date, we have not received any Written  Requests.

Biologics Price Competition and Innovation  Act of 2009

On March 23, 2010, President Obama signed into law the Patient Protection  and Affordable  Care

Act which included the Biologics Price  Competition  and Innovation  Act  of  2009, or BPCIA. The
BPCIA amended the PHSA to create an  abbreviated approval pathway for two  types of ‘‘generic’’
biologics—biosimilars and interchangeable biologic products, and provides for a twelve-year exclusivity
period for the first approved biological product, or reference product, against which  a biosimilar  or
interchangeable application is evaluated;  however  if pediatric  studies are performed and accepted  by
the FDA, the twelve-year exclusivity  period will be extended for an additional six  months A  biosimilar
product  is defined as one that is highly  similar to a reference product notwithstanding  minor
differences in clinically inactive components and  for which there are no clinically meaningful differences
between the biological product and the  reference product in terms  of the safety,  purity  and potency of
the product. An interchangeable product  is a biosimilar product that  may be substituted for the
reference product without the intervention  of the health care provider who  prescribed the reference
product.

The biosimilar applicant must demonstrate that the  product is  biosimilar based on  data  from

(1) analytical studies showing that the biosimilar product is highly  similar  to  the reference product;
(2) animal studies (including toxicity);  and (3)  one or more clinical  studies to demonstrate safety, purity
and potency in one or more appropriate  conditions  of use for  which the reference  product is approved.
In addition, the applicant must show that  the biosimilar and  reference  products have  the same
mechanism of action for the conditions of  use on the  label, route of administration, dosage  and
strength, and the production facility must meet standards designed to assure product  safety, purity
and potency.

An application for a biosimilar product may not be submitted until four years after the date on
which  the reference product was first  approved. The first approved interchangeable  biologic product
will be granted an exclusivity period of up to one year after it is first  commercially marketed, but  the
exclusivity period may be shortened under certain circumstances.

In February 2012, the FDA issued 3 draft guidance documents  on  biosimilar product development.

The draft guidance documents are: ‘‘Scientific Considerations  in Demonstrating Biosimilarity to a
Reference Product,’’ ‘‘Quality Considerations in  Demonstrating Biosimilarity to a  Reference Protein
Product,’’ and ‘‘Biosimilars: Questions  and  Answers Regarding Implementation of the Biologics Price
Competition and Innovation Act of 2009.’’  The guidance documents provide FDA’s current thinking on
approaches to demonstrating that a proposed biological product  is biosimilar to a reference  product.
The FDA received public comments on  the draft documents and  intends to issue final  guidance

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documents in the future. Nevertheless,  the absence of a final guidance document does  not  prevent a
sponsor  for seeking licensure of a biosimilar under the BPCIA.

Orphan Drug Designation

Under the Orphan Drug Act, the FDA may grant orphan  drug  designation  to  a drug intended to

treat a rare disease or condition, which is  generally a disease or condition  that  affects fewer  than
200,000 individuals in the U.S., or more than 200,000  individuals  in the  U.S. and for which there  is no
reasonable expectation that the cost of developing and making available in the U.S. a drug for this type
of disease or condition will be recovered from sales in the  U.S.  for that  drug. Orphan drug designation
must be requested before submitting an  NDA or  BLA. After  the FDA grants orphan drug designation,
the identity of the therapeutic agent and  its potential orphan use are disclosed  publicly by the FDA.
Orphan  drug designation does not convey  any advantage  in or shorten  the duration of  the regulatory
review and approval process.

If a  product that has orphan drug designation subsequently  receives the  first  FDA approval for the

disease for which it has such designation,  the product  is entitled  to  orphan product  exclusivity, which
means that the FDA may not approve any other applications to market the same  drug for  the same
indication, except in very limited circumstances,  for seven years. Orphan drug exclusivity,  however, also
could block the approval of one of our  products for seven years if a competitor obtains approval of the
same drug as defined by the FDA or if our product candidate is  determined to be contained within the
competitor’s product for the same indication or disease.

The FDA also administers a clinical research grants program, whereby  researchers may compete
for funding to conduct clinical trials to  support the approval  of drugs, biologics, medical devices, and
medical foods for rare diseases and conditions. A product  does not have  to  be  designated as an orphan
drug to be eligible for the grant program.  An application for  an orphan grant should propose one
discrete  clinical study to facilitate FDA  approval  of  the product for  a  rare disease or condition. The
study may address an unapproved new  product  or an unapproved new use  for a  product already on
the market.

The FDA granted Orphan Drug designation to our lorvotuzumab mertansine  compound when

used for the treatment of Merkel cell  carcinoma  (MCC),  small-cell lung cancer (SCLC) and multiple
myeloma (MM). Orphan drug designation provides ImmunoGen with  seven  years  of  market  exclusivity
that begins once lorvotuzumab mertansine receives FDA marketing approval for the use for  which the
orphan drug status was granted. Also, through a separate process,  lorvotuzumab mertansine has  been
granted orphan medicinal product designation for the treatment of MCC,  SCLC and MM in the
European Union. Orphan medicinal  product designation provides  ImmunoGen  with ten years of
market exclusivity that begins once lorvotuzumab mertansine receives  European  approval for the use
for which it was granted. We may pursue these designations for other  indications for  lorvotuzumab
mertansine, and for other product candidates intended for qualifying  patient  populations.

Expedited Review and Approval

The FDA has various programs, including Fast Track, priority review, and accelerated  approval,
which  are intended to expedite or simplify the  process for reviewing  drugs, and/or provide  for approval
on the basis of surrogate endpoints. Even if a drug qualifies for one or more  of these  programs,  the
FDA may later decide that the drug no longer  meets  the conditions for qualification or that the  time
period for FDA review or approval will not be shortened.  Generally, drugs that may be eligible  for
these programs are those for serious  or life-threatening conditions, those  with the potential to address
unmet medical needs, and those that offer meaningful benefits over  existing treatments.  For example,
Fast Track is a process designed to facilitate the  development, and expedite the review of  drugs to treat
serious diseases and fill an unmet medical need. Priority  review is  designed to give drugs  that  offer

22

major advances in treatment or provide  a treatment where  no  adequate therapy exists  an initial review
within six months as compared to a standard review  time of  10 months. Although Fast  Track and
priority review do not affect the standards  for approval, the FDA will attempt to facilitate early and
frequent meetings with a sponsor of a  Fast Track designated drug and expedite  review of the
application for a drug designated for  priority  review. Accelerated approval  provides an earlier  approval
of drugs to treat serious diseases, and  that fill  an unmet medical need based  on a surrogate endpoint,
which  is a laboratory measurement or  physical sign  used  as an indirect or substitute measurement
representing a clinically meaningful outcome.  As a  condition  of  approval, the  FDA may require that a
sponsor  of a drug receiving accelerated  approval  perform  post-marketing  clinical trials.

Post-Approval Requirements

Once an approval is granted, the FDA may withdraw the approval if compliance with regulatory

standards is not maintained or if problems  occur after  the product reaches the market. Later discovery
of previously  unknown problems with a product  may result  in restrictions  on the  product or even
complete withdrawal of the product from the  market.  After approval,  some types  of changes to the
approved product, such as adding new indications,  manufacturing  changes and  additional labeling
claims, are subject to further FDA review and approval. Drug manufacturers and  other  entities involved
in the manufacture and distribution of  approved drugs are required to register their establishments with
the FDA and certain state agencies, and are subject  to  periodic  unannounced inspections by the  FDA
and certain state agencies for compliance  with cGMP and other  laws and regulations. We  rely,  and
expect to continue to rely, on third parties for the production of clinical and commercial quantities of
our  products. Future inspections by the  FDA and other regulatory agencies may identify compliance
issues at the facilities of our contract manufacturers  that may disrupt production  or distribution, or
require substantial resources to correct.

Any drug products manufactured or  distributed  by us  pursuant  to  FDA approvals are subject  to

continuing regulation by the FDA, including, among other things, record-keeping requirements,
reporting of adverse experiences with the  drug, providing the FDA with  updated safety and efficacy
information, drug sampling and distribution requirements, complying with certain  electronic records and
signature requirements, and complying with  FDA  promotion and advertising  requirements. FDA  strictly
regulates labeling, advertising, promotion  and other types of information  on products that are placed
on the market. Drugs may be promoted only for  the approved indications and in accordance  with the
provisions of the approved label.

From time to time, legislation is drafted,  introduced  and  passed in  Congress that could significantly

change the statutory provisions governing the approval,  manufacturing  and  marketing of  products
regulated by the FDA. It is impossible to predict whether further legislative  changes will  be  enacted, or
FDA regulations, guidance or interpretations changed  or what the impact of such  changes, if  any,
may be.

Foreign Regulation

In addition to regulations in the United  States,  we will be subject  to  a  variety  of foreign

regulations governing clinical trials and commercial sales  and distribution of our products.  Whether or
not we obtain FDA approval for a product, we must obtain approval by the comparable regulatory
authorities of foreign countries or economic  areas, such  as the European Union,  before  we may
commence clinical trials or market products in those countries or areas. The approval  process and
requirements governing the conduct of  clinical trials, product licensing, pricing and  reimbursement vary
greatly from place to place, and the time may be longer  or shorter than that required  for FDA
approval.

23

Under European Union regulatory systems, a company may submit marketing authorization
applications either under a centralized  or  decentralized  procedure. The centralized procedure, which is
compulsory for medicinal products produced by biotechnology  or those medicinal  products containing
new active substances for specific indications  such as the  treatment of  AIDS, cancer, neurodegenerative
disorders, diabetes, viral diseases and  designated orphan medicines, and optional for other medicines
which  are highly innovative. Under the  centralized procedure,  a marketing application is  submitted to
the European Medicines Agency where it  will  be  evaluated by  the Committee  for Medicinal Products
for Human Use and a favorable opinion  typically results in the  grant by  the European Commission  of a
single marketing authorization that is valid for  all  European Union member states  within 67  days of
receipt of the opinion. The initial marketing  authorization is valid for  five  years,  but once  renewed is
usually valid for an unlimited period.  The  decentralized procedure provides for approval by one or
more ‘‘concerned’’ member states based on an  assessment of an  application  performed by one  member
state, known as the ‘‘reference’’ member state.  Under the  decentralized  approval procedure,  an
applicant submits an application, or dossier,  and related materials to the  reference member state and
concerned member states. The reference member state  prepares a draft assessment and drafts  of  the
related materials within 120 days after receipt of  a valid application. Within 90 days  of receiving  the
reference member state’s assessment  report, each concerned member  state must decide whether to
approve the assessment report and related materials.  If a member state does  not  recognize the
marketing authorization, the disputed  points are  eventually referred to the European Commission,
whose decision is binding on all member  states.

As in the United States, we may apply for designation of a product as  an  orphan drug for the

treatment of a specific indication in the  European Union before the  application  for marketing
authorization is made. Orphan drugs in Europe enjoy economic  and marketing benefits,  including up to
10 years of market exclusivity for the  approved indication unless  another applicant  can show  that  its
product  is safer, more effective or otherwise clinically  superior to the orphan-designated product.

Reimbursement

Sales of pharmaceutical products depend in  significant part on the availability  of  third-party
reimbursement. Third-party payors include  government  healthcare programs, managed care  providers,
private  health insurers and other organizations. We anticipate  third-party payors will provide
reimbursement for our products. However, these third-party payors are increasingly challenging  the
price and examining the cost-effectiveness of  medical products and  services. In addition, significant
uncertainty exists as to the reimbursement status  of newly approved  healthcare products. We may need
to conduct expensive pharmacoeconomic studies  in order to demonstrate  the cost-effectiveness of our
products. Our product candidates may  not be considered cost-effective. It is  time consuming  and
expensive for us to seek reimbursement from third-party payors.  Reimbursement may not be available
or sufficient to allow us to sell our products on  a competitive and profitable basis.

The Medicare Prescription Drug, Improvement, and Modernization Act  of 2003, or the  MMA,

imposed new requirements for the distribution and pricing of prescription drugs  for Medicare
beneficiaries, and included a major expansion of  the prescription drug benefit  under Medicare Part D.
Under Part D, Medicare beneficiaries  may enroll in prescription  drug plans  offered by private entities
which  provide coverage of outpatient prescription drugs.  Part D plans  include  both stand-alone
prescription drug benefit plans and prescription drug coverage as  a supplement to Medicare  Advantage
plans. Unlike Medicare Part A and B,  Part  D coverage is not standardized. Part  D prescription drug
plan  sponsors are not required to pay  for all covered Part D drugs, and each drug plan  can develop its
own drug formulary that identifies which  drugs  it  will cover and at  what tier or level. However, Part D
prescription drug formularies must include drugs within each therapeutic  category and class  of covered
Part D drugs, though not necessarily all the drugs in each category or class. Any formulary used by a

24

Part D prescription drug plan must be developed and reviewed by a pharmacy and  therapeutic
committee.

It  is not clear what effect the MMA  has had on the  prices paid for currently approved drugs and

the pricing options for future approved drugs. Government payment for some of the costs of
prescription drugs may increase demand for  products for which we receive marketing approval.
However, any negotiated prices for our products covered  by  a Part D  prescription drug plan  will  likely
be lower than the  prices we might otherwise obtain. Moreover, while  the MMA applies only to drug
benefits for Medicare beneficiaries, private payors  often  follow  Medicare coverage policy and payment
limitations in setting their own payment  rates. Any reduction in  payment that results from the MMA
may result in a similar reduction in payments from non-governmental payors.

The American Recovery and Reinvestment Act of 2009  provides funding for the federal

government to compare the effectiveness  of different treatments for the same illness. A  plan for the
research will be developed by the Department  of  Health and Human  Services, the Agency for
Healthcare Research and Quality and  the  National  Institutes for  Health, and periodic reports on the
status of the research and related expenditures will be made to Congress. Although the results of the
comparative effectiveness studies are not intended to mandate coverage policies for public or private
payors, it is not clear what effect, if any, the  research will  have on the sales of our product  candidates,
if any such product or the condition  that it is  intended to treat is  the subject of  a study. It  is also
possible that comparative effectiveness  research demonstrating benefits in  a competitor’s product could
adversely affect the sales of our product  candidates. If third-party payors  do not consider our products
to be cost-effective compared to other available  therapies, they may not cover our products  after
approval as a benefit under their plans  or, if  they  do,  the level of  payment may not be sufficient to
allow us to sell our products on a profitable basis.

We  expect that there will continue to  be  a number of federal  and state proposals  to  implement

governmental pricing controls and limit the growth of healthcare costs, including the cost of
prescription drugs. For example, the Patient  Protection and Affordable Care Act,  as amended by the
Health Care and Education Affordability  Reconciliation  Act  of  2010 (collectively, ACA) enacted  in
March 2010, is expected to have a significant impact on  the health care industry. ACA is expected  to
expand coverage for the uninsured while  at the  same time  containing overall healthcare costs. With
regard to pharmaceutical products, among  other things,  ACA is expected to expand and  increase
industry rebates for drugs covered under Medicaid  programs and  make changes  to  the coverage
requirements under the Medicare Part D  program. We cannot  predict  the impact of ACA on
pharmaceutical companies as many of  the ACA  reforms require  the promulgation of detailed
regulations implementing the statutory provisions which has not yet occurred. In  addition,  although the
United States Supreme Court recently  upheld  the constitutionality  of most of the  ACA, some states
have stated their intentions to not implement certain  sections of ACA and some members of  Congress
are still working to repeal ACA. These  challenges add to the  uncertainty of the  changes enacted as part
of ACA.

In addition, in some foreign countries, the  proposed pricing for a drug must be approved before  it

may be lawfully marketed. The requirements governing drug pricing vary widely from country to
country. For example, the European  Union provides  options for its member states  to  restrict the range
of medicinal products for which their national  health insurance  systems  provide reimbursement and to
control the prices of medicinal products for human  use. A  member state may  approve a specific price
for the medicinal product or it may instead adopt a  system of direct  or indirect controls on  the
profitability of the company placing the  medicinal product  on the  market.  There can be no assurance
that any country that has price controls or reimbursement limitations for pharmaceutical products  will
allow favorable reimbursement and pricing arrangements for  any of our products. Historically, products
launched in the European Union do  not  follow price structures of  the  United States and generally tend
to by significantly lower.

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Research and Development Spending

During  each of the three years ended  June 30, 2012,  2011 and  2010, we spent approximately

$69.2 million, $63.5 million and $50.3  million, respectively,  on research  and development activities.

Raw Materials and Manufacturing

We  procure certain raw material components of finished conjugate,  including antibodies,  DM1,
DM4, and linker, for ourselves and on  behalf of our  collaborators. In  order to meet  our  commitments
to our collaborators as well as our own  needs, we  are required to enter into  agreements with third
parties to produce these components well  in  advance of our production needs. Our principal  suppliers
for these components include Boehringer  Ingelheim, Cytovance Biologics LLC, SAFC, Inc. and Societ`a
Italiana Corticosteroidi S.r.l.

In addition, we operate a conjugate manufacturing facility. A portion  of  the cost  of operating this
facility, including the cost of manufacturing personnel, is reimbursed by our  collaborators  based on  the
number of batches of preclinical and  clinical materials produced on  their behalf. Over the past few
years, we have expanded and upgraded  the capabilities of our manufacturing facility.

Employees

As of June 30, 2012, we had 245 full-time employees,  of  whom 205 were  engaged  in research and
development activities. Ninety-seven  research and development employees hold post-graduate degrees,
of which 45 hold Ph.D. degrees and  six hold M.D. degrees. We consider our relations with  our
employees to be good. None of our employees is  covered by  a  collective bargaining  agreement.

We  have entered into confidentiality agreements with all  of  our employees, members of our board
of directors and consultants. Further, we  have entered into assignment of invention agreements  with all
of our employees.

Third-Party Trademarks

Herceptin(cid:4) and Perjeta(cid:4) are registered trademarks of Genentech.  Xeloda(cid:4) is a registered

trademark of Hoffman-La Roche Inc. Tykerb(cid:4) is a registered trademark of the GlaxoSmithKline group.
Rituxan(cid:4) is a registered trademark of Biogen Idec Inc.

Item 1A. Risk Factors

THE RISKS AND UNCERTAINTIES  DESCRIBED  BELOW ARE THOSE THAT WE  CURRENTLY
BELIEVE MAY MATERIALLY AFFECT  OUR COMPANY. ADDITIONAL  RISKS AND
UNCERTAINTIES THAT WE ARE UNAWARE OF OR  THAT WE CURRENTLY DEEM
IMMATERIAL ALSO MAY BECOME IMPORTANT  FACTORS  THAT  AFFECT  OUR COMPANY.

We have a history of operating losses and expect to incur significant  additional operating losses.

We  have generated operating losses since our inception. As  of June 30, 2012,  we had an

accumulated deficit of $504.0 million.  For the years ended June 30, 2012, 2011, and 2010, we generated
losses of $73.3 million, $58.3 million  and $50.9  million,  respectively. We  may never  be  profitable.  We
expect to incur substantial additional  operating expenses over the  next several years as  our research,
development, preclinical testing, clinical trials and collaborator support activities continue. We intend to
continue to invest significantly in our  product candidates.  Further,  we expect to invest  significant
resources supporting our existing collaborators  as they  work  to  develop, test and commercialize TAP
and other antibody compounds. We or our collaborators may encounter technological or regulatory
difficulties as part  of this development and  commercialization process that we  cannot overcome  or
remedy. We may also incur substantial  marketing  and other costs in  the future if we decide  to  establish

26

marketing and sales capabilities to commercialize  our  product candidates.  None of our or our
collaborators’ product candidates has  generated any commercial  revenue and our only revenues  to  date
have been primarily from upfront and  milestone payments, research and development support  and
clinical materials reimbursement from  our collaborative partners. We do not expect to generate
revenues from the  commercial sale of  our  internal product  candidates in the  near future,  and we may
never generate revenues from the commercial sale of internal products. Even  if  we do successfully
develop products that can be marketed and sold commercially, we  will need  to  generate significant
revenues from those products to achieve and maintain profitability. Even if we do become  profitable,
we may not be able to sustain or increase  profitability on a quarterly  or  annual  basis.

If we are unable to obtain additional  funding when needed, we may have to delay  or  scale back some
of our programs or grant rights to third parties to  develop and  market our  product candidates.

We  will continue to expend substantial  resources developing new and existing  product candidates,

including costs associated with research  and development, acquiring new technologies,  conducting
preclinical studies and clinical trials, obtaining regulatory approvals and manufacturing products as well
as providing certain support to our collaborators  in the development of their  products. We  believe that
our  current working capital, including $94  million of net  proceeds resulting  from a public stock offering
in July 2012, and expected future payments  from our existing collaboration arrangements will be
sufficient to meet our current and projected  operating and capital requirements through fiscal 2015.
However, we cannot provide assurance that  such collaborative agreement funding will, in  fact, be
received. Should such future collaborator  payments not be earned and paid  as currently anticipated,  we
expect we could seek additional funding  from other sources. We may need additional  financing  sooner
due to a number of other factors as well,  including:

(cid:129) if  either we incur higher than expected  costs or  we or  any of our  collaborators experience slower
than expected progress in developing product candidates and obtaining regulatory approvals;

(cid:129) acquisition of technologies and other  business opportunities that  require financial commitments.

Additional funding may not be available to us on favorable terms, or  at all. We  may raise

additional funds through public or private  financings, collaborative arrangements or other
arrangements. Debt financing, if available, may involve covenants that could restrict our business
activities. If we are unable to raise additional funds through equity or  debt financing when needed, we
may be required to delay, scale back or eliminate expenditures for some of our development  programs
or grant rights to develop and market  product candidates  that we would  otherwise prefer to internally
develop and market. If we are required  to  grant such rights, the ultimate value  of  these  product
candidates to us may be reduced.

If our TAP technology does not produce safe, effective and  commercially viable  products,  our business
will be severely harmed.

Our TAP technology yields novel product candidates for the treatment of cancer. To  date, no TAP

product  candidate has obtained regulatory  approval. Our TAP product candidates and/or  our
collaborators’ TAP product candidates  may not prove to be safe, effective  or commercially  viable
treatments for cancer and our TAP technology may not result in  any future meaningful benefits to us
or for our current or potential collaborative partners. Furthermore, we are  aware  of only two
compounds that are a conjugate of an antibody and a cytotoxic  small molecule that have obtained
approval by the FDA and are based on  technology similar  to  our TAP technology. One of these
products was later taken off the market  by its owner  due to toxicity concerns. If our  TAP technology
fails to generate product candidates that are safe, effective and  commercially viable treatments for
cancer, or fails to obtain FDA approval, our business will be  severely  harmed.

27

Clinical trials for our and our collaborative partners’ product  candidates will be lengthy  and expensive
and their outcome is uncertain.

Before obtaining regulatory approval  for the  commercial sale  of  any product candidates,  we and
our  collaborative partners must demonstrate  through clinical testing that our product candidates  are
safe and effective for use in humans.  Conducting  clinical trials  is a time-consuming, expensive and
uncertain process and typically requires  years  to  complete. The most advanced product  candidate
incorporating our TAP technology is in Phase  III clinical testing. In our industry, the results from
preclinical studies and early clinical trials  often are not predictive of results obtained in later-stage
clinical trials. Some compounds that  have  shown promising results in preclinical studies or  early clinical
trials subsequently fail to establish sufficient safety and efficacy data necessary to obtain regulatory
approval. At any time during the clinical trials, we, our  collaborative  partners, or the FDA might delay
or halt any clinical trials of our product candidates  for various reasons,  including:

(cid:129) occurrence of unacceptable toxicities or side effects;

(cid:129) ineffectiveness of the product candidate;

(cid:129) insufficient drug supply;

(cid:129) negative or inconclusive results from the clinical trials,  or  results that necessitate  additional

studies  or clinical trials;

(cid:129) delays in obtaining or maintaining required approvals from institutions,  review boards  or other

reviewing entities at clinical sites;

(cid:129) delays in patient enrollment;

(cid:129) insufficient funding or a reprioritization of financial or  other resources; or

(cid:129) other reasons that are internal to the businesses of our collaborative partners, which  they may

not share with us.

Any failure or substantial delay in successfully completing  clinical  trials  and  obtaining  regulatory
approval for our product candidates or  our collaborative partners’ product candidates could severely
harm our business.

We and our collaborative partners are  subject to  extensive government regulations and  we and  our
collaborative  partners may not be able  to  obtain necessary regulatory approvals.

We  and our collaborative partners may not receive  the regulatory  approvals necessary to

commercialize our product candidates, which would cause  our business to be severely harmed.
Pharmaceutical product candidates, including those in development  by us  and our collaborative
partners, are subject to extensive and rigorous government regulation.  The FDA regulates, among other
things, the development, testing, manufacture, safety,  record-keeping,  labeling, storage, approval,
advertising, promotion, sale and distribution  of  pharmaceutical products. If  our  potential  products or
our  collaborators’ potential products are marketed  abroad, they will also  be  subject to extensive
regulation by foreign governments. None  of our product candidates has been  approved for sale in the
U.S. or any foreign market. The regulatory  review and approval process, which includes preclinical
studies and clinical trials of each product candidate, is  lengthy, complex, expensive  and uncertain.
Securing FDA approval requires the  submission  of extensive preclinical  and clinical data and  supporting
information to the FDA for each indication to establish the  product candidate’s  safety and  efficacy.
Data obtained from preclinical studies  and  clinical trials  are susceptible to  varying interpretation, which
may delay, limit or prevent regulatory approval. The  approval process may take many years to complete
and may involve ongoing requirements for post-marketing studies. In  light of the  limited  regulatory
history of monoclonal antibody-based  therapeutics, regulatory  approvals for our or our collaborative

28

partners’ product candidates may not  be  obtained without lengthy  delays, if at  all.  Any  FDA or other
regulatory approvals of our or our collaborative  partners’  product candidates,  once obtained, may be
withdrawn. The effect of government regulation may be to:

(cid:129) delay marketing of potential products for a considerable period of time;

(cid:129) limit the indicated uses for which potential products  may  be  marketed;

(cid:129) impose costly requirements on our  activities; and

(cid:129) place us at a competitive disadvantage to other pharmaceutical and biotechnology  companies.

We  may encounter delays or rejections in the  regulatory approval process  because of additional
government regulation from future legislation or administrative action  or changes in  FDA policy during
the period of product development, clinical trials and  FDA regulatory  review. Failure  to  comply with
FDA or other applicable regulatory requirements may result  in criminal prosecution,  civil  penalties,
recall or seizure of products, total or  partial suspension of production or  injunction, as well as  other
regulatory action against our product candidates or  us. Outside the  U.S., our ability to market a
product  is contingent upon receiving clearances  from the appropriate regulatory authorities. The
foreign regulatory  approval process includes similar  risks to those associated with the FDA approval
process. In addition, we are, or may become,  subject to various  federal, state and  local laws, regulations
and recommendations relating to safe working conditions,  laboratory and manufacturing practices, the
experimental use of animals and the use and disposal  of  hazardous substances, including radioactive
compounds and infectious disease agents, used in  connection with  our research  work. If  we fail to
comply  with the laws and regulations pertaining to our business, we  may be subject to sanctions,
including the temporary or permanent suspension of operations,  product recalls, marketing restrictions
and civil and criminal penalties.

Our and our collaborative partners’ product candidates will remain subject  to ongoing regulatory
review even if they receive marketing  approval. If we  or our  collaborative partners fail to comply with
continuing regulations, we could lose  these approvals and the sale of  our products could  be suspended.

Even if we or our collaborative partners receive  regulatory approval to market  a particular product

candidate, the approval could be conditioned  on us  or our  collaborative  partners conducting  costly
post-approval studies or could limit the  indicated uses included in product labeling.  Moreover, the
product  may later cause adverse effects that limit or  prevent its widespread use, force us  or our
collaborative partners to withdraw it from  the  market  or impede  or  delay our or  our collaborative
partners’ ability to obtain regulatory  approvals in  additional countries.  In addition, the  manufacturer of
the product and its facilities will continue  to  be  subject to FDA review  and  periodic  inspections to
ensure adherence to applicable regulations. After  receiving marketing approval, the manufacturing,
labeling, packaging, adverse event reporting,  storage, advertising, promotion and  record-keeping related
to the product remain subject to extensive regulatory  requirements.  We or our collaborative partners
may be slow to adapt, or we or our collaborative partners may never adapt,  to  changes in existing
regulatory requirements or adoption  of  new regulatory requirements.

If we  or our collaborative partners fail to comply with  the regulatory  requirements of the  FDA and
other applicable U.S. and foreign regulatory authorities, or if  previously unknown problems with our  or
our  partners’ products, manufacturers or  manufacturing processes are discovered, we could be subject
to administrative or judicially imposed sanctions, including:

(cid:129) restrictions on the products, manufacturers or manufacturing  processes;

(cid:129) warning letters;

(cid:129) civil or criminal penalties;

29

(cid:129) fines;

(cid:129) injunctions;

(cid:129) product seizures or detentions;

(cid:129) import bans;

(cid:129) voluntary or mandatory product recalls and publicity requirements;

(cid:129) suspension or withdrawal of regulatory approvals;

(cid:129) total or partial suspension of production;  and

(cid:129) refusal to approve pending applications for marketing approval  of  new  drugs or supplements to

approved applications.

Any one of these could have a material adverse  effect on  our business or  financial condition.

If our collaborative partners fail to perform their obligations under our agreements with them,  or
determine not to continue with clinical trials for  particular product candidates, our business  could be
severely impacted.

Our strategy for the development and commercialization of our product candidates depends, in
large part, upon the formation and maintenance of collaborative arrangements. Collaborations provide
an opportunity for us to:

(cid:129) generate cash flow and revenue;

(cid:129) fund some of the costs associated with our internal research and development,  preclinical

testing, clinical trials and manufacturing;

(cid:129) seek and obtain regulatory approvals  faster than we  could  on our own;

(cid:129) successfully commercialize existing  and future  product candidates; and

(cid:129) secure access to targets which, due to intellectual property restrictions, would otherwise be

unavailable to our technology.

If we  fail to secure or maintain successful  collaborative  arrangements, the  development and
marketing of compounds that use our technology may be delayed, scaled back or otherwise  may not
occur. In addition, we may be unable to negotiate other collaborative arrangements  or, if  necessary,
modify  our existing arrangements on acceptable  terms. We cannot  control the amount and timing of
resources our collaborative partners may  devote to our product candidates. Our  collaborative partners
may separately pursue competing product candidates, therapeutic approaches or  technologies to
develop treatments for the diseases targeted  by us  or our collaborative efforts, or  may decide,  for
reasons not known to us, to discontinue  development of product candidates under our agreements  with
them. Any of our collaborative partners  may  slow or discontinue the  development of a product
candidate covered by a collaborative arrangement for reasons that  can include, but are not limited to:

(cid:129) a change in the collaborative partner’s strategic focus as a  result of merger, management

changes, adverse business events, or other causes;

(cid:129) a change in the priority of the product candidate relative to other programs in the collaborator’s

pipeline;

(cid:129) a reassessment of the patent situation related to the compound  or  its target;

(cid:129) a change in the anticipated competition for the product  candidate;

(cid:129) preclinical studies and clinical trial  results; and

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(cid:129) a reduction in the financial resources  the collaborator can  or  is willing to apply to the

development of new compounds.

Even if our collaborative partners continue  their  collaborative arrangements with  us, they  may

nevertheless determine not to actively  pursue the  development or commercialization of any resulting
products. Also, our collaborative partners may fail to perform their obligations under  the collaborative
agreements or may be slow in performing their obligations. Our collaborative partners can terminate
our  collaborative agreements under certain conditions. The decision to advance a  product that is
covered by a collaborative agreement through clinical trials and ultimately to commercialization is in
the discretion of our collaborative partners. If  any  collaborative partner were to terminate  or breach
our  agreements, fail to complete its obligations to us in a  timely manner, or decide to discontinue its
development of a product candidate, our  anticipated revenue from the agreement  and from  the
development and commercialization of the  products would  be  severely limited. If  we are  not  able to
establish additional collaborations or  any  or all of  our  existing collaborations are terminated and we are
not able to enter into alternative collaborations on acceptable  terms, or at all, our continued
development, manufacture and commercialization  of  our  product candidates  could  be  delayed or  scaled
back as  we may not have the funds or  capability to continue these activities. If our  collaborators  fail to
successfully develop and commercialize TAP  compounds, our business  prospects would  be  severely
harmed.

We depend on a small number of collaborators for a substantial portion  of our revenue.  The  loss of, or
a material reduction in activity by, any  one of  these collaborators could  result  in a substantial  decline
in our revenue.

We  have and will continue to have collaborations  with a limited  number of companies. As a  result,

our  financial performance depends on the  efforts and overall success of these companies. Also, the
failure of any one of our collaborative  partners  to  perform its obligations  under its agreement with us,
including making any royalty, milestone or  other payments to us,  could have an adverse effect on our
financial condition. Further, any material reduction by any one of our collaborative partners in its level
of commitment of resources, funding, personnel,  and  interest in continued development under its
agreement with us could have an adverse  effect  on our financial condition. To date,  we have recorded
$13.5 million in milestone payments with the advancement  of  T-DM1. Our agreement  with Roche,
through its Genentech unit, entitles us to receive up to $44 million in  milestone payments and  also
royalties on commercial sales, if any.  Failure of Roche to continue to advance T-DM1 would have  an
adverse effect on our financial outlook. Also, if consolidation trends  in the healthcare  industry
continue, the number of our potential  collaborators  could  decrease, which  could  have an adverse
impact on our development efforts. If a  present  or future  collaborator of ours were  to  be  involved in  a
business combination, the collaborator’s continued pursuit and  emphasis on our product development
program could be delayed, diminished  or  terminated.

If our collaborative partners’ requirements for  clinical  materials to be manufactured by us are
significantly lower than we have estimated, our financial results  and  condition  could be  adversely
affected.

We  procure certain components of finished conjugate, including DM1,  DM4, and linker, on  behalf
of several of our collaborators. In order  to meet our commitments to our collaborative partners, we are
required to enter into agreements with third parties to produce  these components well in  advance  of
our  production of clinical materials on  behalf  of  our  collaborative partners. If our collaborative partners
do not require as much clinical material  as  we have  contracted  to  produce and we are unable to use
these materials for our own products,  we  may not be able to recover our  investment in  these
components and we may suffer significant  losses. Collaborators have discontinued development of

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product  candidates in the past and in the  periods subsequent to these  discontinuations, we  had
significantly reduced demand for conjugated  material which adversely  impacted our financial results.

In addition, we operate a conjugate manufacturing facility. A portion  of  the cost  of operating this
facility, including the cost of manufacturing personnel, is reimbursed by our  collaborators  based on  the
number of batches of preclinical and  clinical materials produced on  their behalf. If we produce  fewer
batches  of clinical materials for our collaborators, a  smaller amount  of the cost  of  operating the
conjugate manufacturing facility will  be  charged to our collaborative partners and our financial
condition could be adversely affected.

If our product requirements for clinical trials are significantly higher  than  we estimated, the inability
to procure additional antibody or fill/finish  services in  a timely manner could  impair our ability  to
initiate or advance our clinical trials.

We  rely  on third-party suppliers to manufacture antibodies  used  in our own proprietary

compounds. Due to the specific nature of  the antibody and availability of production capacity, there  is
significant lead time required by these  suppliers to provide us with  the needed materials. If our
antibody  requirements for clinical materials to be manufactured are  significantly  higher than  we
estimated, we may not be able to readily procure  additional antibody which would impair our ability to
advance  our clinical trials currently in  process or initiate  additional  trials.  We also rely  on third parties
to convert the bulk drug substance we  manufacture  into  filled and finished vials of drug product  for
clinical use. Unanticipated difficulties or delays in  the fill/finish process could impair our  ability to
advance  our clinical trials currently in  process or initiate  additional  trials.  There can  be  no assurance
that we will not have supply problems  that  could  delay or  stop our clinical trials or otherwise could
have a material adverse effect on our  business.

We currently rely on one third-party manufacturer with commercial production  experience  to produce
our cell-killing agents, DM1 and DM4.

We  rely  on a third-party supplier to manufacture materials used to make TAP compounds.  Our

cell-killing agents DM1 and DM4, collectively  DMx, are manufactured from a precursor, ansamitocin
P3. As part of preparing to produce  TAP compounds for later-stage  clinical trials  and
commercialization, we currently use a single supplier, Societ´a Italiana Corticosteroidi S.r.l., that
converts ansamitocin P3 to DMx. Any delay or  interruption in our supply  of  DMx could lead  to  a delay
or interruption in our manufacturing  operations,  preclinical studies and clinical trials of our product
candidates and our collaborators’ product candidates, which could  negatively affect  our business.

We may be unable to establish the manufacturing capabilities  necessary to develop and commercialize
our and  our collaborative partners’ potential products.

Currently, we have only one conjugate manufacturing facility that  we use  to  manufacture
conjugated compounds for us and our  collaborative partners  for  preclinical studies  and early-stage
clinical testing. Two of our partners have  contracted for  separate,  large-scale manufacturing capacity to
make materials to support potential future commercialization of their TAP  compounds. We do not
currently have the manufacturing capacity needed to make our product candidates for commercial sale.
In addition, our manufacturing capacity may be insufficient to complete all clinical trials contemplated
by us and our collaborative partners over time.  We  intend to rely in  part  on third-party contract
manufacturers to produce sufficiently  large quantities of drug materials  that are and  will be needed for
later-stage clinical trials and commercialization of our potential products. We  are currently in the
process of developing relationships with third-party manufacturers that we believe  will  be  necessary  to
continue the development of our product  candidates. Third-party manufacturers may  not  be  able to
meet our needs with respect to timing, quantity or quality of materials. If  we are  unable to contract  for
a sufficient supply of needed materials on  acceptable terms, or if we should encounter delays or

32

difficulties in our relationships with manufacturers, our clinical trials may  be  delayed, thereby delaying
the submission of product candidates  for regulatory approval  and the market introduction and
subsequent commercialization of our  potential products. Any such  delays may  lower our revenues  and
potential profitability.

We have only one conjugate manufacturing facility and any  prolonged  and significant  disruption at
that facility could impair our ability to manufacture our  and our collaborative  partners’  product
candidates for clinical testing.

Currently, in certain cases, we are contractually obligated to manufacture  Phase I and non-pivotal
Phase II clinical products for companies licensing  our TAP technology. We  manufacture this material,
as well as material for our own product  candidates, in  our conjugate manufacturing  facility.  We have
only one such manufacturing facility in  which we can  manufacture clinical products.  Our current
manufacturing facility contains highly specialized  equipment and utilizes complicated  production
processes developed over a number of  years  that would be difficult, time-consuming and costly to
duplicate. Any prolonged disruption in  the operations of our  manufacturing facility would  have a
significant negative impact on our ability to manufacture  products  for clinical testing on our own  and
would cause us to seek additional third-party manufacturing contracts, thereby increasing our
development costs. Even though we carry business interruption insurance policies, we may  suffer losses
as a result of business interruptions that  exceed the  coverage available  or any losses may  be  excluded
under our insurance policies. Certain  events,  such as natural disasters, fire,  political disturbances,
sabotage or business accidents, which could impact our current or future facilities, could have a
significant negative impact on our operations by disrupting our product  development efforts until such
time as we are able to repair our facility or put in  place third- party contract  manufacturers  to  assume
this  manufacturing role.

Unfavorable pricing regulations, third-party reimbursement practices or healthcare  reform initiatives
applicable to our product candidates could limit our potential product revenue.

Antibody-based anticancer products are often much more costly to produce than traditional
chemotherapeutics and tend to have significantly higher prices. Factors that help justify  the price
include the high mortality associated with  many types  of  cancer and the need for  more and  better
treatment options.

Regulations governing drug pricing and reimbursement vary widely  from  country to country. Some

countries require approval of the sales price of a  drug before  it can be marketed. Some countries
restrict the physicians that can authorize the  use of more  expensive medications.  Some  countries
establish treatment guidelines to help  limit the  use of more  expensive  therapeutics and  the pool of
patients that receive them. In some countries, including  the U.S., third-party payers  frequently  seek
discounts from list prices and are increasingly challenging the  prices charged  for medical products.
Because our product candidates are  in  the development stage, we do not know the level of
reimbursement, if any, we will receive  for  any products that we are able to successfully develop. If  the
reimbursement for any of our product candidates is inadequate in light of our development and other
costs, our ability to achieve profitability would be affected.

We  believe that the efforts of governments and third-party  payors to contain or reduce the cost  of

healthcare will continue to affect the  business and financial condition of pharmaceutical and
biopharmaceutical companies. A number  of  legislative  and regulatory proposals to change the
healthcare system in the U.S. and other major  healthcare markets have  been proposed and  adopted in
recent years. For example, the U.S. Congress enacted a  limited prescription  drug benefit for Medicare
recipients as part of the Medicare Prescription Drug, Improvement  and  Modernization Act of 2003.
While the program established by this  statute may  increase demand for any products  that  we are  able
to successfully develop, if we participate in this program, our  prices will be  negotiated with drug

33

procurement organizations for Medicare  beneficiaries and are likely  to  be lower than prices we might
otherwise obtain. Non-Medicare third-party  drug procurement organizations  may also base the  price
they are willing to pay on the rate paid  by drug procurement organizations for  Medicare beneficiaries.
The PPACA will also require discounts under the Medicare drug benefit program and increased rebates
on drugs covered by Medicaid. In addition, the PPACA imposes an  annual fee, which  will  increase
annually, on sales by branded pharmaceutical manufacturers starting in 2011. The financial impact of
these discounts, increased rebates and fees and the other provisions  of  the PPACA on our business is
unclear and there can be no assurance that our business will not be materially adversely affected by the
PPACA. In addition, ongoing initiatives  in  the U.S. have increased and will continue  to  increase
pressure on drug pricing. The announcement or adoption of any such  initiative  could  have an adverse
effect on potential revenues from any  product candidate that we may successfully  develop.

We may be unable to establish sales  and  marketing  capabilities  necessary  to successfully
commercialize our potential products.

We  currently have no direct sales or marketing capabilities. We anticipate relying on third  parties
to market and sell most of our primary product candidates or we may outlicense these products  prior
to the time when these capabilities are  needed.  If we  decide to market our potential products through
a direct sales force, we would need either  to  hire a sales force with  expertise in  pharmaceutical sales or
to contract with a third party to provide a sales force  which meets  our needs.  We may be unable to
establish marketing, sales and distribution capabilities necessary to commercialize and gain market
acceptance for our potential products and be competitive. In addition, co-promotion  or other marketing
arrangements with third parties to commercialize potential products could significantly limit the
revenues we derive from these potential  products, and these  third parties may fail to commercialize our
compounds successfully.

If our product candidates or those of  our  collaborative partners  do not gain market acceptance, our
business  will suffer.

Even if clinical trials demonstrate the safety and efficacy  of  our and  our collaborative partners’

product  candidates and the necessary  regulatory approvals are obtained, our and our collaborative
partners’ product candidates may not  gain market acceptance  among  physicians, patients,  healthcare
payors and other members of the medical  community. The degree of market acceptance of any product
candidates that we or our collaborative partners develop will depend on a  number of  factors, including:

(cid:129) their degree of clinical efficacy and  safety;

(cid:129) their advantage over alternative treatment  methods;

(cid:129) our/the marketer’s and our collaborative partners’ ability to gain acceptable  reimbursement and

the reimbursement policies of government and third-  party payors;  and

(cid:129) the quality of the distribution capabilities for product  candidates, both ours and our collaborative

partners.

Physicians may not prescribe any of our  future products until such time as clinical  data  or other
factors demonstrate the safety and efficacy  of those  products as compared to conventional drug and
other treatments. Even if the clinical  safety and efficacy of therapies using our products is  established,
physicians may elect not to recommend  the therapies for any number of other reasons,  including
whether the mode of administration of our  products is effective for certain conditions, and whether the
physicians are already using competing products  that satisfy their  treatment objectives. Physicians,
patients, third-party payors and the medical  community may not accept and use any  product candidates
that we, or our collaborative partners,  develop. If our products do  not  achieve significant  market

34

acceptance and use, we will not be able  to  recover  the significant  investment we have  made in
developing such products and our business will be severely harmed.

We may be unable to compete successfully.

The markets in which we compete are well established and  intensely competitive. We  may be
unable to compete successfully against our current and future competitors. Our failure to compete
successfully may result in lower volume sold, pricing  reductions, reduced gross  margins and failure to
achieve market acceptance for our potential products. Our  competitors include research institutions,
pharmaceutical companies and biotechnology  companies, such as  Pfizer, Seattle  Genetics, Roche and
Bristol-Myers Squibb. Many of these  organizations have substantially more experience and more
capital, research and development, regulatory,  manufacturing, human and other resources than we  do.
As a result, they may:

(cid:129) develop products that are safer or  more effective  than  our product candidates;

(cid:129) obtain FDA and other regulatory approvals or reach the market with their products  more

rapidly than we can, reducing the potential sales of our product  candidates;

(cid:129) devote greater resources to market or sell their  products;

(cid:129) adapt more quickly to new technologies and scientific  advances;

(cid:129) initiate or withstand substantial price competition more  successfully than we can;

(cid:129) have greater success in recruiting skilled scientific workers from  the  limited pool of available

talent;

(cid:129) more effectively negotiate third-party licensing  and collaboration  arrangements;  and

(cid:129) take advantage of acquisition or other opportunities more  readily than we  can.

A number of pharmaceutical and biotechnology companies are currently developing products
targeting the same types of cancer that we target, and some of our competitors’ products  have entered
clinical trials or already are commercially  available.

Our product candidates, if approved and  commercialized,  will also compete against

well-established, existing, therapeutic  products that are  currently reimbursed by government  healthcare
programs, private health insurers and  health maintenance organizations. In addition, if our product
candidates are approved and commercialized, we  may  face competition from generic  products if the
product  candidate is a small molecule  drug, or biosimilars if  the product candidate is  a biologic. The
route to market for generic versions of small molecule drugs was  established  with the passage of the
Hatch-Waxman Amendments in 1984  and  for biosimilars  with the  passage of the PPACA  in March
2010. The PPACA establishes a pathway for the FDA approval  of follow-on  biologics and provides
twelve years exclusivity for reference products and an additional  six months exclusivity period if
pediatric studies are conducted. In Europe, the  European  Medicines  Agency  has issued guidelines for
approving products through an abbreviated pathway,  and biosimilars have been approved  in Europe. If
a biosimilar version of one of our potential products were approved in  the United States  or Europe,  it
could have a negative effect on sales  and  gross profits of the  potential  product and our financial
condition.

We  face and will continue to face intense competition from  other companies for collaborative
arrangements with pharmaceutical and  biotechnology companies, for  relationships with  academic and
research institutions and for licenses  to proprietary technology. In addition, we  anticipate that we will
face increased competition in the future  as  new companies enter our markets and as scientific
developments surrounding antibody-based  therapeutics for  cancer continue  to  accelerate. While we will
seek to expand our technological capabilities  to  remain  competitive,  research and  development by

35

others may render our technology or  product  candidates obsolete or noncompetitive or  result in
treatments or cures superior to any therapy  developed by us.

If we are unable to protect our intellectual property rights adequately, the value of our  technology and
our product candidates could be diminished.

Our success depends in part on obtaining,  maintaining  and enforcing our patents and other

proprietary rights and our ability to avoid  infringing the proprietary rights of others. Patent law  relating
to the scope of claims in the biotechnology field  in which we operate  is still  evolving,  is surrounded by
a great deal of uncertainty and involves  complex legal, scientific and factual questions. To date, no
consistent policy has emerged regarding the  breadth of claims allowed  in biotechnology  patents.
Accordingly, our pending patent applications may not result in  issued patents. Although  we own
numerous patents, the issuance of a  patent is not  conclusive  as to its  validity or enforceability. Through
litigation, a third party may challenge the  validity or  enforceability  of a patent after its issuance.

Also, patents and applications owned  or licensed by us may  become the subject  of  interference,
opposition, nullity, or other proceedings  in a  court or  patent office in the United  States or in a  foreign
jurisdiction to determine validity, enforceability  or priority of invention,  which could result  in
substantial cost to us. An adverse decision  in such a  proceeding may result in our loss of rights  under a
patent or patent application. It is unclear  how much protection, if any, will  be  given to our patents if
we attempt to enforce them or if they  are  challenged  in court  or in  other  proceedings. A competitor
may successfully invalidate our patents  or a challenge  could result in  limitations of the  patents’
coverage. In addition, the cost of litigation or interference proceedings to uphold the validity of  patents
can be substantial. If we are unsuccessful  in these proceedings, third  parties may be able to use  our
patented technology without paying us  licensing  fees  or royalties.  Moreover, competitors may  infringe
our  patents or successfully avoid them through  design innovation.  To prevent  infringement or
unauthorized use, we may need to file infringement claims,  which are expensive  and time-consuming. In
an infringement proceeding, a court  may  decide that a patent of ours is not valid. Even if the  validity
of our patents were upheld, a court may  refuse  to  stop the other party from using the  technology at
issue on the ground that its activities are not  covered by our patents.

The Leahy-Smith America Invents Act was signed into law on  September 16, 2011,  but will not
fully take effect until March 16, 2013. In  general,  the legislation attempts to address  issues surrounding
the enforceability of patents and the  increase  in patent litigation by,  among other  things, moving to a
first- inventor-to-file system, establishing new procedures  for challenging patents  and establishing
different methods  for invalidating patents.  While we  cannot predict what form any  new patent reform
regulations ultimately may take, final governmental  rule-making and case law interpreting the new
statute could  introduce new substantive  rules,  procedures and  case law bases for  challenging patents,
and certain reforms that make it easier for competitors to challenge  our patents  could  have a material
adverse effect on our business and prospects.

Policing unauthorized use of our intellectual property is  difficult,  and we may not be able to
prevent misappropriation of our proprietary  rights, particularly in countries where the laws may  not
protect such rights as fully as in the United States.

In addition to our patent rights, we also rely on  unpatented technology, trade secrets, know-how

and confidential information. Third parties may  independently develop substantially equivalent
information and techniques or otherwise gain access to or disclose  our technology. We may not be able
to effectively protect our rights in unpatented technology,  trade secrets, know-how and  confidential
information. We require each of our  employees,  consultants  and corporate  partners  to  execute a
confidentiality agreement at the commencement of an  employment, consulting or collaborative
relationship with us. Further, we require that all employees enter into assignment of invention
agreements as a condition of employment. However, these agreements may not provide effective

36

protection of our information or, in the  event of unauthorized  use or  disclosure, they  may not provide
adequate remedies.

Any inability to license proprietary technologies or processes from third parties  which  we  use in
connection with the development and manufacture of our product candidates may impair our business.

Other companies,  universities and research institutions have or may obtain patents  that  could  limit

our  ability to use, manufacture, market or sell our  product candidates  or  impair  our  competitive
position. As a result, we would have  to  obtain licenses from  other parties before we  could  continue
using, manufacturing, marketing or selling  our potential  products.  Any  necessary licenses may  not  be
available on commercially acceptable terms, if at  all.  If we  do not obtain required  licenses,  we may not
be able to market our potential products at all or we may encounter significant delays in product
development while we redesign products or  methods that are found to infringe on  the patents held by
others.

We may incur substantial costs as a  result  of litigation or other proceedings relating to  patent and
other intellectual property rights held  by  third parties and  we  may be unable  to protect our rights to,
or to commercialize, our product candidates.

Patent litigation is very common in the biotechnology and  pharmaceutical industries. Third parties

may assert patent or other intellectual  property infringement claims  against  us with respect  to  our
technologies, products or other matters.  From time  to  time, we  have received correspondence  from
third parties alleging that we infringe  their intellectual property rights. Any claims that might be
brought against us alleging infringement of patents may cause us to incur significant expenses  and, if
successfully asserted against us, may cause us to pay  substantial damages and  limit our  ability to use the
intellectual property subject to these  claims.  Even if we were to prevail, any litigation would be costly
and time-consuming and could divert the  attention of our management and key personnel from our
business operations. Furthermore, as  a  result of a  patent  infringement suit,  we may be forced  to  stop or
delay developing, manufacturing or selling potential products  that incorporate the challenged
intellectual property unless we enter into  royalty  or license agreements. There may  be  third-party
patents, patent applications and other intellectual  property  relevant  to  our potential  products that may
block or  compete with our products  or processes.  In  addition, we sometimes undertake research and
development with respect to potential  products even  when we are aware of third-party patents  that  may
be relevant to our potential products, on the basis that  such patents may be challenged or  licensed by
us. If our subsequent challenge to such  patents were not to prevail,  we may not be able to
commercialize our potential products  after having already incurred significant  expenditures unless we
are able to license the intellectual property  on commercially  reasonable terms.  We may not be able to
obtain royalty or license agreements on  terms acceptable to us, if at all. Even  if we were able  to  obtain
licenses to such technology, some licenses may be non-exclusive, thereby giving our competitors access
to the same technologies licensed to  us.  Ultimately, we may be unable to  commercialize some  of our
potential products or may have to cease  some of our business operations, which could severely harm
our  business.

We use hazardous materials in our business, and any claims relating  to  improper  handling, storage or
disposal of these materials could harm  our business.

Our research and development and manufacturing activities  involve the controlled use of
hazardous materials, chemicals, biological  materials and  radioactive compounds.  We are subject  to
federal, state and local laws and regulations governing the  use, manufacture,  storage,  handling and
disposal of these materials and certain waste products. Although  we  believe  that  our  safety procedures
for handling and disposing of these materials comply with the standards  prescribed  by  applicable laws
and regulations, we cannot completely  eliminate  the risk of accidental contamination or  injury  from

37

these materials. In the event of such an accident,  we could be held liable for any  resulting damages,
and any liability could exceed our resources. We may be required to incur significant  costs to comply
with these laws in the future. Failure to comply with  these  laws could  result in fines  and the  revocation
of permits, which could prevent us from  conducting our business.

We face product liability risks and may  not be able to  obtain adequate insurance.

While we secure waivers from all participants in our clinical  trials, the use of our product
candidates during testing or after approval entails an  inherent risk of adverse effects, which could
expose us to product liability claims. Regardless of their merit or eventual  outcome, product liability
claims may result in:

(cid:129) decreased demand for our product;

(cid:129) injury to our reputation and significant negative media  attention;

(cid:129) withdrawal of clinical trial volunteers;

(cid:129) costs of litigation;

(cid:129) distraction of management; and

(cid:129) substantial monetary awards to plaintiffs.

We  may not have sufficient resources to satisfy any liability  resulting from these  claims. We
currently have $5 million of product liability insurance  for products which  are in clinical testing. This
coverage may not  be adequate in scope  to protect us  in the event  of a successful  product liability claim.
Further, we may not be able to maintain our current insurance  or obtain general product liability
insurance on reasonable terms and at  an acceptable cost  if we or our collaborative partners begin
commercial production of our proposed product candidates. This insurance, even  if  we can obtain and
maintain it, may not be sufficient to provide us  with adequate coverage against potential liabilities.

We depend on our key personnel and we  must continue  to attract and  retain key employees and
consultants.

We  depend on our key scientific and management personnel. Our ability to pursue the

development of our current and future  product  candidates depends largely  on retaining the services of
our  existing personnel and hiring additional qualified scientific personnel to perform research and
development. We will also need to hire  personnel with expertise in clinical testing,  government
regulation, manufacturing, marketing  and finance.  Attracting and retaining qualified personnel will be
critical to our success. We may not be able to attract and retain personnel on  acceptable terms given
the competition for such personnel among  biotechnology, pharmaceutical and healthcare companies,
universities and non-profit research institutions. Failure  to retain our  existing key management and
scientific personnel or to attract additional  highly qualified personnel could delay the development of
our  product candidates and harm our  business.

Our stock price can fluctuate significantly and  results announced by us and  our collaborators  can
cause our stock price to decline.

Our stock price can fluctuate significantly due to business developments  announced by us and by

our  collaborators, as a result of market trends and daily trading volume. The business developments
that could impact our stock price include disclosures  related to clinical findings with compounds that
make use of our TAP technology, new  collaborations and clinical advancement  or discontinuation of
product  candidates that make use of  our TAP  technology. Our stock  price can also fluctuate
significantly with the level of overall investment  interest  in small-cap biotechnology stocks.

38

Our operating results have fluctuated in the past and are likely to continue to do so in the  future.

Our revenue is unpredictable and may fluctuate due to the timing  of  non-recurring  licensing fees,
decisions of our collaborative partners  with  respect to our agreements with them,  reimbursement for
manufacturing services, the achievement  of  milestones and our receipt of  the  related milestone
payments under new and existing licensing and collaboration agreements. Revenue historically
recognized under our prior collaboration  agreements may not be an  indicator of revenue  from any
future collaborations. In addition, our expenses are unpredictable  and may  fluctuate from quarter to
quarter due to the timing of expenses,  which  may include obligations  to  manufacture  or supply product
or payments owed by us under licensing or collaboration  agreements. It is  possible  that  our quarterly
and/or annual operating results will not  meet the expectations of securities  analysts  or investors, causing
the market price of our common stock to decline. We believe  that quarter-to-quarter and year-to-year
comparisons of our operating results  are not good  indicators of our future performance and  should not
be relied upon to predict the future performance  of our stock price.

The potential sale  of additional shares  of our common stock may cause our stock price  to decline.

Pursuant to shelf registration statements  filed  with the Securities and Exchange Commission, in

July 2012, we sold 6,250,000 shares of our  common  stock at $16.00  per  share in  a public offering
resulting in gross proceeds of $100 million; in fiscal 2011, we sold 7,800,000  shares of our common
stock at $12.00 per share in a public offering resulting in gross proceeds  of $93.6 million;  in fiscal 2010,
we sold 10,350,000 shares of our common  stock at  $8.00 per  share in a public offering  resulting in  gross
proceeds of $82.8 million; and in fiscal  2009, we sold 5,750,000 shares of our  common stock at  $7.00
per  share in a public offering resulting  in  gross proceeds of $40.3 million. Additionally, in fiscal 2008,  a
private  investor purchased 7,812,500 shares  of our common stock at  $3.20 per share resulting in  gross
proceeds of $25 million. The potential  sale of additional shares of our  common  stock may be dilutive to
our  shares outstanding and may cause  our  stock price to decrease.

We do not intend to pay cash dividends  on our common stock.

We  have not paid cash dividends since  our  inception and do not intend to  pay cash  dividends  in
the foreseeable future. Therefore, shareholders will have to rely on appreciation in  our stock  price, if
any, in order to achieve a gain on an investment.

39

A WARNING ABOUT FORWARD-LOOKING  STATEMENTS

This report includes forward-looking  statements  within the meaning  of the Private  Securities
Litigation Reform  Act of 1995. These statements relate to analyses and other information which  are
based on forecasts of future results and  estimates of amounts that are not yet  determinable. These
statements also relate to our future prospects,  developments and business  strategies.

These forward-looking statements are identified  by  their  use of terms  and  phrases,  such as
‘‘anticipate,’’ ‘‘believe,’’ ‘‘could,’’ ‘‘estimate,’’ ‘‘expect,’’  ‘‘intend,’’ ‘‘may,’’ ‘‘plan,’’ ‘‘predict,’’ ‘‘project,’’
‘‘will’’ and other similar terms and phrases, including references to assumptions.  These statements are
contained in the ‘‘Business,’’ ‘‘Risk Factors’’ and  ‘‘Management’s Discussion and Analysis of Financial
Condition and Results of Operations’’  sections,  as well  as other sections of this Annual Report  on
Form 10-K.

Forward-looking statements in this report include, but  are not limited to:

(cid:129) successfully finding and managing the  relationships with collaborative partners;

(cid:129) the uncertainty as to whether our TAP compounds  or those of our collaborators  will succeed in

entering human clinical trials and uncertainty as to the  results of such trials;

(cid:129) the risk that we and/or our collaborators may not be able to obtain regulatory  approvals

necessary to commercialize product candidates;

(cid:129) the potential development of competing products and technologies; uncertainty  whether  our  TAP

technology will produce safe, effective and commercially viable products;

(cid:129) our ability to successfully protect our intellectual property;

(cid:129) our reliance on third-party manufacturers to supply our maytansinoid cell-killing agents, DM1

and DM4, linkers, antibodies and perform fill/finish services;

(cid:129) the risk that we may be unable to  establish the  manufacturing  capabilities necessary to develop

and commercialize our potential products;

(cid:129) the adequacy of our liquidity and capital  resources;

(cid:129) government regulation of our activities,  facilities,  products  and personnel; the dependence  on

key personnel;

(cid:129) uncertainties as to the extent of reimbursement for the costs  of  our potential products  and
related treatments by government and private health insurers and other organizations; the
potential adverse impact of government-  directed health care reform; and

(cid:129) the risk of product liability claims; and  economic conditions, both generally and  those specifically

related to the biotechnology industry.

These forward-looking statements involve known and unknown risks, uncertainties  and other

factors that may cause actual results to be materially different from those contemplated by our  forward-
looking statements. These known and unknown risks,  uncertainties and other factors are described in
detail in the ‘‘Risk Factors’’ section and  in other sections of  this  Annual  Report on Form 10-K. We
disclaim any intention or obligation to  update or  revise any forward-looking  statements,  whether as a
result of new information, future events  or otherwise.

Item 1B. Unresolved Staff Comments

None.

40

Item 2. Properties

We  lease approximately 89,000 square  feet of laboratory and office  space in a  building located at

830 Winter Street, Waltham, MA. The  initial term of the  830 Winter Street lease expires on March 31,
2020, with an option for us to extend the lease  for  two additional five-year terms.  In  December 2009,
we entered into a  sublease, as sublessor,  to rent 14,100 square  feet  of our original office and laboratory
space at 830 Winter Street, Waltham, MA through January  2015. Due to space requirements,  in April
2012, we entered into a sublease agreement for  the rental  of 7,310 square feet  of additional laboratory
and office space at 830 Winter Street, Waltham, MA  for an  initial term of three years with  a
conditional option to extend through October 2017. We also lease approximately 43,850 square feet  of
space in Norwood, MA, which serves  as our conjugate manufacturing facility and office  space. The
Norwood lease expires on June 30, 2018, with  an option for  us to extend  the lease  for an  additional
five-year  term.

Item 3. Legal Proceedings

From time to time we may be a party to various  legal proceedings arising in the ordinary course of

our  business. We are not currently subject to any material legal proceedings.

Item 3.1. Executive Officers of the Registrant

ImmunoGen’s executive officers are  appointed  by the  Board of Directors at  the first meeting of
the Board following the annual meeting  of shareholders or  at other Board meetings as appropriate, and
hold office until the first Board meeting following the next annual meeting of  shareholders and  until a
successor is chosen, subject to prior death, resignation or removal. Information regarding our executive
officers is presented below.

Daniel M. Junius, age 60, joined ImmunoGen in  2005, and has served as  our  President and  Chief
Executive Officer since 2009. Prior to that  he served as  our President and  Chief  Operating Officer  and
Acting Chief Financial Officer from  July  2008 to December 2008, as  our  Executive Vice President and
Chief Financial Officer from 2006 to July 2008, and  as our Senior  Vice President and  Chief  Financial
Officer from 2005 to 2006. Prior to joining  ImmunoGen in 2005,  he  served  as Executive Vice President
and Chief Financial Officer of New England  Business Service, Inc. (NEBS), a  supplier  of business
products and services to small businesses,  from  2002 to 2004, and as  Senior  Vice President and Chief
Financial Officer of NEBS from 1998  to  2002. Mr.  Junius holds  a Masters of Management from
Northwestern University’s Kellogg School  of Management.

John M. Lambert,  Ph.D., age 61, joined ImmunoGen in  1987, and has served as  our Executive

Vice President, Research and Development  and Chief Scientific  Officer since July  2008. Prior to that
he served as our Senior Vice President,  Research and Development and Chief Scientific Officer from
early 2008 to July 2008, as our Senior  Vice President, Pharmaceutical Development, from 2000 to early
2008, as our Vice President, Research and Development, from 1994 to 2000, and  as our Senior Director
of Research from 1987 to 1994. Prior to joining ImmunoGen, Dr.  Lambert  was an assistant professor at
Harvard Medical School working at the Dana-Farber Cancer  Institute. Dr. Lambert holds  a Ph.D. in
Biochemistry from University of Cambridge in England, and completed his  postdoctoral work at  the
University of California at Davis and  at  Glasgow  University in Scotland.

James J. O’Leary,  MD, age 48, joined  ImmunoGen in 2008,  and  has served as our Vice  President
and Chief Medical Officer since that date. Prior to joining ImmunoGen, Dr. O’Leary served as Senior
Medical Director Clinical Oncology of Bayer Corporation, a  pharmaceutical company,  from 2006 to
2008. Prior to that, he served as Medical  Director  Clinical  Oncology  of  Pfizer Global Research and
Development, a pharmaceutical company, from 2003 to 2006, and as  Assistant Medical Director
Clinical Oncology of Pfizer from 2000  to  2003. Prior  to  that, he  served as a Medical Reviewer,  Division
of Oncology Drug Products at the U.S. Food  and Drug Administration from  1998 to 2000. Dr.  O’Leary

41

has a Doctor of Medicine degree from  the State University of New York—Health Science Center at
Brooklyn.

Gregory D. Perry, age 52, joined ImmunoGen in 2009,  and has served as our Executive  Vice
President and Chief Financial Officer  since April 2011. Prior to that, he served as  our Senior  Vice
President and Chief Financial Officer  from 2009  to  April 2011. Prior to joining  ImmunoGen, he  served
as Chief Financial Officer of Elixir Pharmaceuticals, Inc., a pharmaceutical  company, from 2007  to
2008. Prior to that, he served as Chief  Financial Officer for Domantis Ltd., a biopharmaceutical
company, in 2006, and as Senior Vice  President,  Finance and Chief Financial Officer of Transkaryotic
Therapies, Inc., a biopharmaceutical  company, from  2003 to 2005.

Peter J. Williams, age 58, joined ImmunoGen  in August 2009,  and has  served  as our Vice

President, Business Development since that date.  Prior to joining ImmunoGen, he served as a  Senior
Director of Business Development at Alnylam Pharmaceuticals, Inc., a biopharmaceutical company,
from 2006 to August 2009. Prior to that, he served as Vice President of  Business Development of Link
Medicine Corporation, a drug development company, from 2005 to 2006.  Prior to that, he  acted  as an
independent business development consultant from 2003  to 2006.  Prior to that, he served as  a Senior
Director of Business Development at Millennium Pharmaceuticals, Inc., a biopharmaceutical  company,
from 1998 to 2003.

Theresa  G. Wingrove, Ph.D., age 54, joined ImmunoGen  in January 2011, and  has served as our

Vice President, Regulatory Affairs since that date. Prior to joining ImmunoGen,  she  served  as Vice
President, Regulatory and Clinical Affairs, at  Histogenics, Inc., a medical device company,  from 2006 to
January 2011. Prior to that, she served  as  Senior Director, Regulatory  and Clinical Affairs, at
MediSpectra, Inc., a medical device company, from  2000 to 2006. Prior to  that,  she  served in various
regulatory and clinical management capacities  at Infusaid Inc., a subsidiary of Pfizer Inc., a
pharmaceutical company, from 1988 to 1999. Dr. Wingrove holds a Ph.D. in biochemical  toxicology
from the University of Rochester School  of  Medicine and  Dentistry,  and  completed her postdoctoral
work at the University of Rochester  Medical  Center.

Craig Barrows, age 57, joined ImmunoGen  in 2007, and has  served as our Vice  President,  General

Counsel and Secretary since that date. Prior to joining  ImmunoGen, he served as Vice  President and
General Counsel of Mercury Computer Systems,  Inc., a manufacturer of high-performance digital signal
and image processing systems, from 2005  to  2007. Prior to that,  he served as Vice President, General
Counsel and Secretary of New England  Business Service,  Inc. (NEBS), a  supplier of  business  products
and services to small businesses, from 1999 to 2004,  and  as  General Counsel and Secretary of NEBS
from 1998 to 1999.

Item 4. Mine Safety Disclosures

None.

42

PART II

Item 5. Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of

Equity Securities

Market Price of Our Common Stock and  Related  Stockholder Matters

Our common stock is quoted on the  NASDAQ Global Select Market under the symbol ‘‘IMGN.’’
The table below sets forth the high and low closing price per share of our common  stock as reported
by NASDAQ:

Fiscal Year 2012

High

Low

Fiscal Year 2011

High

Low

First  Quarter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Second Quarter . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Third Quarter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fourth Quarter . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$15.55
$14.44
$14.61
$16.74

$ 9.42
$10.09
$11.38
$12.22

$ 9.77
$ 9.94
$ 9.85
$13.58

$5.16
$6.24
$8.26
$8.98

As of August 13, 2012, the closing price per share of our common stock  was  $12.78, as reported  by

NASDAQ, and we had approximately 641 holders of record of  our common stock.

We  have not paid any cash dividends on our  common stock since our  inception and  do  not  intend

to pay any cash dividends in the foreseeable future.

Recent  Sales of Unregistered Securities; Uses of Proceeds  from Registered  Securities;  Issuer
Repurchases of Equity Securities

None.

Item 6. Selected Financial Data

The following table (in thousands, except per share  data) sets  forth our  consolidated financial data
for each  of our five fiscal years through our fiscal  year  ended June  30, 2012. The  information set  forth
below should be read in conjunction  with ‘‘Management’s Discussion and Analysis of Financial
Condition and Results of Operations’’  and  the consolidated  financial  statements and  related notes
included elsewhere in this Annual Report  on Form 10-K.

Year Ended June 30,

2012

2011

2010

2009

2008

Consolidated Statement of Operations  Data:
Total revenues . . . . . . . . . . . . . . . . . . . . . . . .
Total operating expenses . . . . . . . . . . . . . . . . .
Other (expense) income, net . . . . . . . . . . . . . .
(Benefit) provision for income taxes . . . . . . . .

$ 16,357
89,614
(62)
—

$ 19,305
79,493
1,914
—

$ 13,943
65,178
58
(265)

$ 27,988
59,804
(221)
(100)

$ 40,249
74,361
2,119
27

Net loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ (73,319) $ (58,274) $ (50,912) $ (31,937) $(32,020)

Basic and diluted net loss per common  share . .

$

(0.95) $

(0.85) $

(0.87) $

(0.63) $

(0.75)

Basic and diluted weighted average common

shares outstanding . . . . . . . . . . . . . . . . . . . .

76,814

68,919

58,845

51,068

42,969

Consolidated Balance Sheet Data:
Cash, cash equivalents and marketable

securities . . . . . . . . . . . . . . . . . . . . . . . . . .
Total assets
. . . . . . . . . . . . . . . . . . . . . . . . . .
Shareholders’ equity . . . . . . . . . . . . . . . . . . . .

$160,938
180,308
83,890

$191,206
217,641
139,969

$110,298
137,208
102,048

$ 71,125
100,704
66,857

$ 47,871
83,338
55,299

43

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Overview

Since our inception, we have been principally  engaged  in the development of  novel, targeted

antibody-based therapeutics for the treatment of cancer using our  expertise  in cancer biology,
monoclonal antibodies, highly potent  cytotoxic,  or cell-killing, agents,  and the design of linkers that
enable these agents to remain stably attached  to  the antibodies while  in the blood  stream and  released
in their fully active form after delivery to a cancer  cell.  An anticancer compound made using our
Targeted Antibody Payload, or TAP, technology consists of a monoclonal  antibody that binds specifically
to an antigen target found on cancer  cells  with multiple copies of one of  our proprietary cell-killing
agents attached using one of our engineered linkers.  Its antibody component enables a TAP compound
to bind specifically to cancer cells that express  its target antigen, the highly potent cytotoxic agent
serves to kill the cancer cell, and the  engineered linker controls  the release and activation of the
cytotoxic agent inside the cancer cell. With  some TAP compounds, the  antibody component also has
anticancer activity of its own. Our TAP  technology  is designed to enable the creation of highly
effective, well-tolerated anticancer product candidates. All  of the TAP compounds  currently  in clinical
testing contain either DM1 or DM4  as the  cytotoxic agent. Both  DM1 and DM4, collectively DMx, are
our  proprietary derivatives of a naturally  occurring substance called maytansine. We  also use our
expertise in antibodies and cancer biology  to develop ‘‘naked,’’  or non-conjugated, antibody anticancer
product  candidates.

We  have used our proprietary TAP technology in conjunction  with our in-house antibody expertise
to develop our own anticancer product  candidates.  We have also  entered into collaborative agreements
that enable companies to use our TAP technology to develop  commercial product candidates to
specified targets. Under the terms of our  collaborative agreements, we are generally entitled to upfront
fees, milestone payments, and royalties on  any commercial product sales. In addition, under certain
agreements we are compensated for  research and  development activities performed at our collaborative
partner’s request at negotiated prices which are  generally consistent with what other third parties  would
charge. We are compensated to manufacture  preclinical and clinical materials  and deliver cytotoxic
agent at negotiated prices which are  generally consistent with what other  third  parties would charge.
Currently, our collaborative partners  include  Amgen, Bayer HealthCare, Biotest, Eli Lilly  and
Company, Novartis, Roche and Sanofi.  We  expect that substantially all  of  our revenue for the
foreseeable future will result from payments under our collaborative arrangements. Details for some  of
our  major and recent collaborative agreements can be found in  this  Form 10-K under Item 1.  Business.

To date, we have not generated revenues  from commercial product  sales  and we expect to incur

significant operating losses for the foreseeable future. As  of  June 30, 2012,  we had approximately
$160.9 million in cash and cash equivalents compared to $191.2 million as of  June 30, 2011.

We  anticipate that future cash expenditures will  be  partially offset by collaboration-derived

proceeds, including milestone payments,  royalties  and upfront  fees.  Accordingly, period-to-period
operational results may fluctuate dramatically based  upon the  timing of receipt of  the proceeds.  We
believe that our established collaborative  agreements, while subject  to  specified milestone achievements,
will provide funding to assist us in meeting  obligations under  our collaborative agreements while also
assisting in providing funding for the  development of  internal  product candidates  and technologies.
However, we can give no assurances that  such collaborative agreement  funding  will,  in fact, be realized
in the time frames we expect, or at all.  Should we or our partners not meet some or all of the  terms
and conditions of our various collaboration  agreements, we  may  be  required  to  secure alternative
financing arrangements and/or defer or  limit some or all of our research,  development and/or clinical
projects. However, we cannot provide assurance that  any such  opportunities presented by additional
strategic partners or alternative financing  arrangements will  be  entirely available to us, if at all.

44

Critical Accounting Policies

We  prepare our consolidated financial  statements  in accordance with accounting principles

generally accepted in the U.S. The preparation of  these financial statements  requires us to make
estimates and judgments that affect the reported amounts of assets, liabilities, revenues  and expenses
and related disclosure of contingent assets and liabilities. On  an on-going  basis, we evaluate our
estimates, including those related to our  collaborative agreements, inventory and stock-based
compensation. We base our estimates on historical experience and various other assumptions that we
believe to be reasonable under the circumstances. Actual results may differ from these estimates.

We  believe the following critical accounting policies reflect our more significant judgments  and

estimates used in the preparation of our consolidated  financial  statements.

Revenue Recognition

We  enter into licensing and development agreements with collaborative partners for  the

development of monoclonal antibody-based  anticancer therapeutics.  The  terms of these agreements
contain multiple deliverables which may include (i) licenses, or options to  obtain  licenses, to our TAP
technology, (ii) rights to future technological  improvements, (iii)  research activities  to  be  performed on
behalf of the collaborative partner, (iv)  delivery of cytotoxic agents and (v) the  manufacture of
preclinical or clinical materials for the collaborative  partner. Payments  to  us under these agreements
may include non-refundable license fees, option fees, exercise fees, payments for  research  activities,
payments for the manufacture of preclinical  or clinical materials, payments based upon  the achievement
of certain milestones and royalties on product sales. We follow the provisions of the Financial
Accounting Standards Board (FASB) Accounting Standards Codification  (ASC) Topic 605-25, ‘‘Revenue
Recognition—Multiple-Element Arrangements,’’ and ASC  Topic 605-28, ‘‘Revenue Recognition—
Milestone Method,’’ in accounting for these agreements. In  order to account for  these agreements, we
must identify the deliverables included  within the agreement and evaluate which deliverables represent
separate units of accounting based on  if  certain criteria  are met, including  whether the delivered
element has stand-alone value to the  collaborator. The consideration  received  is allocated among the
separate units of accounting, and the  applicable revenue recognition criteria are applied to each of  the
separate units.

At June  30, 2012, we had the following two types of agreements with the  parties identified below:

(cid:129) Exclusive development and commercialization  licenses to use our TAP  technology  and/or certain
other intellectual property to develop  compounds to a single target antigen (referred to herein
as single-target licenses, as distinguished from our right-to-test agreements described elsewhere):

Amgen (two single-target licenses)

Bayer HealthCare (one single-target license)

Biotest (one single-target license)

Roche, through its Genentech unit (five single-target licenses)

Sanofi (license to multiple individual targets)

(cid:129) Option/research agreement for a defined period of time  to  secure development and

commercialization licenses to use our  TAP  technology to develop anticancer  compounds to
specified targets on established terms (referred to herein as right-to-test agreements):

Amgen

Sanofi

Novartis

Eli Lilly and Company

There are no performance, cancellation,  termination  or refund provisions in any of the

arrangements that contain material financial  consequences  to  us.

45

Exclusive Licenses

The deliverables under an exclusive license  agreement generally include the exclusive license  to  our

TAP technology with respect to a specified  antigen target, and  may also  include deliverables related to
rights to future technological improvements,  research activities to be performed on behalf of the
collaborative partner and the manufacture of preclinical  or clinical  materials for the collaborative
partner.

Generally, exclusive license agreements contain non-refundable terms  for payments and, depending

on the terms of the agreement, provide  that we will (i) at the  collaborator’s  request, provide research
services at negotiated prices which are  generally consistent with what other  third  parties would charge,
(ii) at the collaborator’s request, manufacture and provide to  it preclinical and clinical  materials  or
deliver cytotoxic agents at negotiated prices  which are generally consistent with what other third parties
would charge, (iii)  earn payments upon the  achievement of certain milestones and (iv) earn  royalty
payments, generally until the later of the  last applicable  patent  expiration or  10 to 12 years after
product  launch. In the case of trastuzumab emtansine  (T-DM1), however, the minimum  royalty term  is
10 years and the maximum royalty term  is  12 years on  a country-by-country basis.  Royalty rates may
vary over the royalty term depending  on our intellectual property rights.  We may  provide technical
assistance and share any technology improvements  with our collaborators during the  term of the
collaboration agreements. We do not  directly control when any collaborator  will  request  research  or
manufacturing services, achieve milestones or  become liable for royalty payments. As  a result, we
cannot predict when we will recognize  revenues in connection  with any of the foregoing.

In determining the units of accounting, management evaluates  whether  the exclusive license has

stand-alone value from the undelivered  elements  to  the collaborative partner based  on the
consideration of the relevant facts and  circumstances for each arrangement. Factors considered in  this
determination include the research capabilities of the  partner and the availability of TAP technology
research expertise in the general marketplace. If we conclude  that the license has stand  alone  value and
therefore will be accounted for as a separate unit of accounting,  we then  determine the  estimated
selling prices of the license and all other  units  of  accounting based on market conditions, similar
arrangements entered into by third parties, and  entity-specific factors  such as the  terms of our previous
collaborative agreements, recent preclinical and clinical testing  results of therapeutic products that use
our  TAP technology, our pricing practices and  pricing  objectives, the likelihood that technological
improvements will be made, the likelihood  that technological  improvements  made will be used by our
collaborators and the nature of the research services to be performed on behalf  of our  collaborators
and market rates for similar services.

Upfront payments on single-target licenses  are deferred if facts and circumstances  dictate that the
license does not have stand-alone value. Prior to the adoption of Accounting Standards Update (ASU)
No. 2009-13, ‘‘Revenue Arrangements with Multiple Deliverables’’ on July 1, 2010,  we determined  that
our  licenses lacked stand-alone value  and  were combined with other elements of the  arrangement and
any amounts associated with the license  were deferred and  amortized over a certain period, which we
refer to as our period of substantial involvement.  The  determination  of  the length of the  period over
which  to defer revenue is subject to judgment  and  estimation and can have  an impact on  the amount of
revenue recognized in a given period.  Historically our  involvement with  the development of a
collaborator’s product candidate has  been significant at the early stages of development, and  lessens as
it progresses into clinical trials. Also, as a drug  candidate gets closer  to  commencing pivotal testing our
collaborators have sought an alternative site to manufacture  its  product, as  our  facility does not
produce pivotal or commercial drug  product. Accordingly, we generally estimate  this  period of
substantial involvement to begin at the inception of the  collaboration agreement and conclude at  the
end of non-pivotal Phase II testing. We believe this period of substantial involvement  is, depending on
the nature of the license, on average  six  and one-half years. Quarterly,  we  reassess our periods  of
substantial involvement over which we  amortize  our upfront license fees and make adjustments  as

46

appropriate. In the event a collaborator elects to discontinue development  of a specific product
candidate under a single target license,  but retains its right to use our technology to develop an
alternative product candidate to the same  target  or a target  substitute,  we  would cease  amortization of
any remaining portion of the upfront  fee until there is substantial preclinical activity on another
product  candidate and its remaining  period of substantial involvement can be estimated. In the event
that a single target license were to be  terminated, we would  recognize  as revenue  any portion of the
upfront fee that had not previously been  recorded as revenue,  but was classified  as deferred  revenue, at
the date of such termination. Subsequent to the adoption of  ASU No. 2009-13,  we determined  that  our
research licenses lack stand-alone value  and  are considered for aggregation with the  other elements  of
the arrangement and accounted for as one unit of accounting.

Upfront payments on single-target licenses  may be recognized upon delivery  of the license if  facts
and circumstances dictate that the license  has stand-alone value from the undelivered elements,  which
generally include rights to future technological  improvements, research services, delivery  of cytotoxic
agents and the manufacture of preclinical  and  clinical materials.

We  recognize revenue related to research services that represent separate units of  accounting as

they are performed, as long as there is persuasive evidence of an arrangement, the fee is  fixed  or
determinable, and collection of the related  receivable is probable. We  recognize  revenue related to the
rights to future technological improvements  over the estimated term of the applicable license.

We  may also provide cytotoxic agents to our collaborators or produce preclinical  and clinical

materials for them at negotiated prices  which are generally consistent with  what other third parties
would charge. We recognize revenue on cytotoxic agents and  on preclinical and clinical materials when
the materials have passed all quality testing  required for collaborator acceptance and title  and risk of
loss have transferred to the collaborator.  Arrangement consideration  allocated  to  the manufacture of
preclinical and clinical materials in a multiple-deliverable arrangement is  below our full  cost, and our
full cost is not expected to ever be below our contract selling  prices for  our existing collaborations.
During  the fiscal years ended June 30, 2012, 2011 and 2010, the difference between our full  cost to
manufacture preclinical and clinical materials on behalf of  our collaborators as compared to total
amounts received from collaborators  for the manufacture  of  preclinical and clinical  materials was
$85,000, $1.3 million, and $515,000, respectively. The majority of our costs to produce these preclinical
and clinical materials are fixed and then allocated  to  each batch based on the  number of batches
produced during the period. Therefore,  our costs  to  produce  these materials are significantly impacted
by the number of batches produced during the period.  The volume  of preclinical and clinical  materials
we produce is directly related to the number of clinical trials  we and our collaborators are preparing
for or currently have underway, the speed  of  enrollment  in those trials, the dosage  schedule  of  each
clinical trial and the time period such trials last.  Accordingly, the volume of  preclinical and  clinical
materials produced, and therefore our  per batch costs to manufacture these preclinical  and clinical
materials, may vary significantly from period to period.

We  may also produce research material  for  potential  collaborators under material transfer
agreements. Additionally, we perform  research  activities, including developing antibody specific
conjugation processes, on behalf of our collaborators  and potential  collaborators during the  early
evaluation and preclinical testing stages  of drug  development. We record amounts received for  research
materials produced or services performed  as a component of research and development  support
revenue. We also develop conjugation processes for materials for later stage testing and
commercialization for certain collaborators. We are  compensated at negotiated rates and  may receive
milestone payments for developing these  processes which are recorded as  a component of research and
development support revenue.

Our license agreements have milestone payments  which for reporting  purposes are  aggregated into

three categories: (i) development milestones, (ii) regulatory milestones, and (iii)  sales milestones.

47

Development milestones are typically payable when a  product candidate initiates or advances  into
different clinical trial phases. Regulatory milestones are typically payable  upon submission  for
marketing approval with the FDA or other countries’ regulatory authorities or  on receipt  of  actual
marketing approvals for the compound or for additional  indications.  Sales  milestones are  typically
payable when annual sales reach certain  levels.

At the inception of each agreement that includes  milestone payments, we evaluate whether each

milestone is substantive and at risk to both parties on the basis  of the contingent  nature of the
milestone. This evaluation includes an assessment of  whether (a) the  consideration is commensurate
with either (1) the entity’s performance  to  achieve the milestone,  or (2) the enhancement of the value
of the delivered item(s) as a result of  a specific  outcome  resulting from the entity’s performance  to
achieve the milestone, (b) the consideration relates solely  to past performance  and (c) the
consideration is reasonable relative to all  of  the deliverables  and payment  terms within  the
arrangement. We evaluate factors such  as  the scientific, regulatory, commercial and  other risks  that
must be overcome to achieve the respective milestone, the level of effort and investment required to
achieve the respective milestone and  whether the milestone  consideration is reasonable  relative to all
deliverables and payment terms in the  arrangement in making this assessment.

Non-refundable development and regulatory milestones  that are expected to be achieved as a

result of our efforts during the period  of substantial  involvement are considered  substantive  and are
recognized as revenue upon the achievement of the  milestone, assuming  all  other  revenue recognition
criteria are met. Milestones that are not considered substantive because we do not contribute effort to
the achievement of such milestones are generally  achieved after the period  of substantial  involvement
and are recognized as revenue upon  achievement of the  milestone, as there  are no  undelivered
elements remaining and no continuing performance  obligations,  assuming all other  revenue recognition
criteria are met.

Right-to-Test Agreements

The Company’s right-to-test agreements  provide  collaborators the right  to  (a) test our  TAP
technology for a defined period of time through a  right-to-test,  or  research, license,  (b) take options,
for a defined period of time, to specified  targets and  (c) upon  exercise  of those options, secure or
‘‘take’’ licenses to develop and commercialize products for the specified targets  on established  terms.
Under these agreements, fees may be  due to us (i)  at the  inception of the  arrangement (referred to as
‘‘upfront’’ fees or payments), (ii) upon  taking an option  with respect to a specific  target  (referred to as
option fees or payments earned, if any,  when the option is ‘‘taken’’), (iii) upon the exercise of a
previously taken option to acquire a development and commercialization license(s)  (referred to as
exercise fees or payments earned, if any, when  the development and  commercialization license is
‘‘taken’’), or (iv) some combination of all  of these fees.

The accounting for right-to-test agreements is  dependent on the nature  of the option granted to

the collaborative partner. Options are considered  substantive if,  at the  inception of a right-to-test
agreement, we are at risk as to whether  the  collaborative  partner will  choose  to  exercise  the options to
secure development and commercialization licenses. Factors  that are considered in  evaluating  whether
options are substantive include the overall  objective  of  the arrangement,  the benefit the collaborator
might obtain from the agreement without  exercising the  options,  the  cost  to exercise the options
relative to the total upfront consideration,  and the  additional  financial commitments or  economic
penalties imposed on the collaborator  as  a result of  exercising the options.

For right-to-test agreements where the options to secure development and commercialization
licenses to our TAP technology are considered  substantive, we do  not consider the development and
commercialization licenses to be a deliverable at the  inception of the agreement. For  those right-to-test
agreements entered into prior to the  adoption of  ASU No. 2009-13 where the options to secure a

48

development and commercialization license are considered substantive, we have deferred  the upfront
payments received and recognize this revenue over the  period during which the collaborator could elect
to take options for development and commercialization licenses.  These periods are specific to each
collaboration agreement. If a collaborator takes  an option to acquire a  development and
commercialization license under these agreements,  any  substantive option fee is  deferred and
recognized over the life of the option,  generally 12 to 18 months. If  a  collaborator  exercises an option
and takes a development and commercialization license to a specific  target, we  attribute the exercise
fee to the development and commercialization license. Upon exercise of  an  option to acquire a
development and commercialization license, we  would also attribute any remaining  deferred option fee
to the development and commercialization license and apply  the  multiple-element revenue recognition
criteria to the development and commercialization license and  any other deliverables to determine the
appropriate revenue recognition, which will be consistent with our  accounting policy for upfront
payments on single-target licenses. In  the event  a right-to-test  agreement were to be terminated,  we
would recognize as revenue any portion  of  the upfront fee  that had not previously been  recorded as
revenue, but was classified as deferred  revenue, at  the date  of  such termination. None of  our
right-to-test agreements entered into subsequent  to  the adoption of ASU No. 2009-13 has been
determined to contain substantive options.

For right-to-test agreements where the options to secure development and commercialization
licenses to our TAP technology are not considered  substantive, we consider the development  and
commercialization license to be a deliverable  at the inception of the agreement  and apply the multiple-
element revenue recognition criteria to  determine  the appropriate  revenue  recognition. None  of our
right-to-test agreements entered into prior to the adoption of  ASU No. 2009-13  has been determined to
contain non-substantive options.

We  do not directly control when any  collaborator will exercise its  options  for development and
commercialization licenses. As a result,  we cannot predict  when it will  recognize revenues in connection
with any of the foregoing.

Inventory

We  review our estimates of the net realizable value of our inventory  at each reporting  period. Our
estimate of the net realizable value of our  inventory  is subject  to  judgment and estimation. The actual
net realizable value of our inventory  could vary significantly  from  our estimates. We  consider quantities
of raw materials in excess of twelve-month projected usage  that are not supported  by  firm,  fixed
collaborator orders and projections at the  time of  the assessment to be excess. During fiscal years 2012,
2011 and 2010, we obtained additional quantities of DMx  from our supplier which amounted to more
material than would be required by our collaborators over  the next twelve months and as a result, we
recorded  $748,000, $1.7 million and $900,000,  respectively, of charges  to  research and development
expense related to raw material inventory identified as excess. We also  recorded $38,000 and $28,000 to
write down certain raw material inventory to its net  realizable value,  which is also included in  research
and development expense for the years ended  June  30, 2012 and 2010, respectively. Our collaborators’
estimates of their clinical material requirements are  based upon  expectations of their clinical trials,
including the timing, size, dosing schedule and the  maximum tolerated  dose likely to be reached  for the
compound being evaluated. Our collaborators’  actual requirements  for clinical  materials  may vary
significantly from their projections. Significant differences between our collaborators’ actual
manufacturing orders and their projections  could result in our actual twelve-month  usage of raw
materials varying significantly from our estimated usage at an  earlier reporting  period. Reductions in
collaborators’ projections could indicate  that we have additional  excess  raw  material  inventory  and we
would then evaluate the need to record further write-downs, which would be included as charges to
research and development expense.

49

Stock-based Compensation

As of June 30, 2012, the Company is  authorized to grant future awards under one share-based
compensation plan, which is the ImmunoGen, Inc. 2006  Employee,  Director and Consultant Equity
Incentive Plan. The stock-based awards are accounted  for under ASC Topic 718, ‘‘Compensation—
Stock Compensation,’’ pursuant to which  the estimated grant date fair value of awards is  charged to the
statement of operations over the requisite  service  period, which is the  vesting period. Such amounts
have been reduced by our estimate of forfeitures for unvested awards.

The fair value of each stock option is estimated on  the date  of grant using the  Black-Scholes
option-pricing model. Expected volatility  is based exclusively on  historical volatility data of  our stock.
The expected term of stock options granted  is based exclusively  on historical data and represents the
period of time that stock options granted are expected to be outstanding.  The  expected term is
calculated for and applied to one group of stock  options  as  we  do not  expect substantially  different
exercise or post-vesting termination behavior amongst our employee population.  The  risk-free rate of
the stock options is based on the U.S. Treasury rate in  effect at the time  of  grant for  the expected  term
of the stock options. Estimated forfeitures are  based on  historical data  as well as  current trends.  Stock
compensation cost incurred during the years ended  June 30, 2012, 2011  and 2010  was $9.9 million,
$5.5 million and $4.2 million, respectively.

Future stock-based compensation may  significantly  differ based on changes in  the fair value of our

common stock and our estimates of expected volatility and the other relevant assumptions.

Results of Operations

Revenues

Our total revenues for the year ended  June  30, 2012 were $16.4  million compared with

$19.3 million and $13.9 million for the  years ended June 30,  2011 and 2010, respectively. The
$2.9 million decrease in revenues in fiscal  year 2012  from fiscal year 2011 is attributable to lower
revenues from research and development support and clinical  materials revenue,  partially  offset by
higher  revenues from license and milestone fees, as  discussed below.  The  $5.4 million increase in
revenues in fiscal year 2011 from fiscal year 2010 is  attributable to all revenue categories, as discussed
below.

Research and development support was $4.5 million for the  year ended June  30, 2012, $7.3 million

for the year ended June 30, 2011, and $5.4 million  for  the year ended June 30, 2010.  These amounts
primarily represent research funding  earned based  on actual resources utilized under our agreements
with our collaborators as shown in the table below. Also included in  research  and development support
revenue are fees for developing antibody-specific  conjugation processes on behalf of our collaborators
and potential collaborators during the early  evaluation and preclinical testing stages  of  drug
development. The amount of research and development  support revenue  we earn  is directly related to
the number of our collaborators and  potential  collaborators, the stage of development of our
collaborators’ product candidates and the  resources our  collaborators allocate to the  development
effort. As such, the amount of development fees may vary widely from quarter  to  quarter  and year to
year. Total revenue recognized from research and  development support from  each of our collaborative

50

partners in the years ended June 30,  2012, 2011  and  2010 is included in the  following table
(in thousands):

Research and Development Support

Collaborative Partner:

Year Ended June 30,

2012

2011

2010

Amgen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bayer HealthCare . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biogen Idec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biotest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lilly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Novartis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Roche . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sanofi
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$1,011
27
—
627
250
2,588
—
14
—

$3,971
452
2
896
—
1,338
3
144
450

$3,470
96
186
1,041
—
—
424
148
—

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$4,517

$7,256

$5,365

Revenue from license and milestone  fees  for  the year  ended June 30, 2012  increased  approximately

$2.8 million to $9.2 million from $6.4 million  in the year ended  June 30, 2011. Revenue from license
and milestone fees for the year ended  June 30,  2010 was $5.7 million. Included  in license  and milestone
fees for the year ended June 30, 2012  was  a $3  million milestone payment related to the initiation of
Phase II clinical testing of SAR3419  achieved  under our collaboration  agreement with Sanofi and  two
$1 million milestone payments related  to  clinical milestones  achieved  under our license agreements with
Amgen. Also during the year ended June 30,  2012, Biogen Idec terminated its exclusive license  to  our
TAP technology to develop and commercialize therapeutic compounds to the target Cripto and  as a
result, we recognized the remaining $270,000 of the  $1 million upfront fee received from Biogen Idec
upon execution of the license which had  been  previously  deferred. Also,  during fiscal 2012, we made a
change in estimate to our period of substantial involvement as  it relates to  our  exclusive  license with
Bayer HealthCare which resulted in an  increase  to  license and milestone fees of  $1.2 million for  the
fiscal year ending June 30, 2012 compared to amounts that would  have been recognized  pursuant  to  the
Company’s previous estimate. Included in license  and milestone  fees  for  the year  ended June 30, 2011
were a $1.0 million milestone payment related to the initiation of Phase I clinical testing  of  SAR566658
by Sanofi and a $2.0 million milestone payment related to the IND filing  of  BAY 94-9343  by  Bayer
HealthCare. Included in license and  milestone fees for  the year  ended June 30, 2010 were  $1 million
and $500,000 of preclinical milestones earned pursuant  to  our agreements with Bayer HealthCare and
Sanofi, respectively, as well as a $1 million  milestone related to the initiation of Phase I clinical  testing
of SAR650984 by Sanofi. The amount of license and  milestone fees we  earn is directly related  to  the
number of our collaborators, the resources our collaborators allocate to the  advancement of the
product  candidates, the number of clinical  trials our collaborators conduct and  the speed of  enrollment
and overall success in those trials. As such, the  amount  of  license and milestone  fees  may vary widely
from quarter to quarter and year to year. Total revenue recognized from license and milestone fees

51

from each of  our collaborative partners in the years ended June 30,  2012, 2011 and 2010 is included  in
the following table (in thousands):

License and Milestone Fees

Collaborative Partner:

Year Ended June 30,

2012

2011

2010

Amgen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bayer HealthCare . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biogen Idec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biotest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Roche . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sanofi
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$3,118
1,839
270
120
—
3,795
19

$1,123
2,615
28
130
—
2,435
62

$ 689
1,616
157
149
38
2,935
114

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$9,161

$6,393

$5,698

Deferred revenue of $72.1 million at June 30, 2012  represents payments  received from  our
collaborators pursuant to our license agreements, including  a $20  million upfront payment received
from Lilly during fiscal 2012 and a $45  million upfront payment received from  Novartis during fiscal
2011, which we have yet to earn pursuant  to our revenue recognition  policy.

Clinical materials revenue decreased by approximately $3.0 million to $2.7 million in  the year
ended June 30, 2012 compared to $5.7 million in  the year ended June 30, 2011. We earned clinical
materials revenue of $2.9 million during  the year ended  June 30, 2010. During the years ended  June  30,
2012, 2011 and 2010, we shipped clinical materials  in support of  a  number of our collaborators’ clinical
trials, as well as preclinical materials in support of certain  collaborators’ development efforts and DMx
shipments to certain collaborators in  support of development and manufacturing efforts. The  decrease
in clinical materials revenue in fiscal  year  2012 as compared to fiscal year  2011 is primarily related to
less  clinical material shipped in support of one of our collaborator’s trials due to larger scale material
requirements being provided by another  vendor, as well as less preclinical  materials  shipped during the
year. The increase in clinical materials  revenue in  fiscal year 2011 as  compared to fiscal year 2010 is
primarily due to greater clinical material shipped in support of one  of  our  collaborator’s  trials due to
advancement of the trial, as well as shipments of preclinical  and clinical material to a  certain
collaborator for future, planned clinical  testing. We are compensated at negotiated prices  which are
generally consistent with what other  third-parties would  charge. The  amount  of  clinical materials
revenue we earn, and the related cost of clinical materials charged to research and development
expense, is directly related to the number of clinical  trials our collaborators are preparing or have
underway, the speed of enrollment in  those trials, the  dosage schedule of each clinical trial and the
time period, if any, during which patients in the trial  receive clinical  benefit from  the clinical  materials,
and the supply of clinical-grade material  to our collaborators for process  development and analytical
purposes. As  such, the amount of clinical materials revenue  and  the  related cost of clinical materials
charged to research and development  expense may vary significantly  from quarter to quarter and year
to year.

52

Research and Development Expenses

Our net  research and development expenses relate  to  (i) research to evaluate new  targets and  to

develop and evaluate new antibodies, linkers and cytotoxic  agents,  (ii) preclinical testing  of our  own
and, in certain instances, our collaborators’  product candidates, and the cost of  our own clinical  trials,
(iii) development related to clinical and commercial manufacturing processes  and (iv)  manufacturing
operations. Our research and development efforts have been  primarily  focused in the  following areas:

(cid:129) activities pursuant to our development  and license agreements with various  collaborators;

(cid:129) activities related to the process, preclinical  and clinical development of  our internal product

candidates;

(cid:129) process improvements related to the production of DM1,  DM4 and  strain  development of their

precursor, ansamitocin P3;

(cid:129) development activities with contract manufacturers for the antibody component of  our internal

product candidates, linkers, and DM1, DM4 and their precursor,  ansamitocin P3;

(cid:129) production costs for the supply of antibody for  our internal product candidates,  including

fill/finish services;

(cid:129) production costs for the supply of DMx  for  our  and our partners’ preclinical  and clinical

activities;

(cid:129) operation and maintenance of our conjugate manufacturing facility, including production of our

own and our collaborators’ clinical materials;

(cid:129) process improvements to our TAP  technology;

(cid:129) evaluation of potential antigen targets;

(cid:129) evaluation of internally developed and/or  in-licensed  product candidates  and technologies; and

(cid:129) development and evaluation of additional cytotoxic agents and  linkers.

Research and development expense for the  year  ended June  30, 2012 increased $5.7  million  to
$69.2 million from $63.5 million for the  year ended June 30, 2011.  Research and  development expense
was $50.3 million for the year ended June 30,  2010. Research and development salaries and related
expenses increased by $5.4 million in  the year ended June 30, 2012 compared to the year ended
June 30, 2010 and increased by $3.6  million in the  year ended June 30, 2011  compared to the year
ended June 30, 2010. The average number of our research personnel increased to 207 for the year
ended June 30, 2012 compared to 192 for the  year  ended June  30, 2011. We had an average of 176 for
the year ended June 30, 2010. Included in salaries  and  related expenses for  the year  ended June 30,
2012 is $5.3 million of stock compensation costs compared to $3.3 million and $2.7  million of  stock
compensation costs for fiscal years 2011 and 2010, respectively.  The higher stock compensation  costs in
fiscal years 2012 and 2011 are driven by  higher stock prices and increases in the number of annual
options granted. Clinical trial costs increased $845,000 during fiscal year 2012 compared to fiscal year
2011 and increased $2.1 million in fiscal  year 2011 compared to fiscal year 2010  due  primarily  to  new
trials initiated, increased site management  costs driven from expanded sites and higher  patient
enrollment. Additionally, antibody development and supply  expense  increased $1.2  million  during  fiscal
year 2012 compared to fiscal year 2011 and  increased  $2.6 million in fiscal year 2011  compared to fiscal
year 2010 due to the advancement of our internal programs and timing of  supply requirements.

We  are unable to accurately estimate which  potential  product candidates, if  any, will eventually
move into our internal preclinical research program. We are unable  to  reliably  estimate the  costs to
develop these products as a result of  the uncertainties related to discovery research efforts as  well as
preclinical and clinical testing. Our decision to move a  product candidate into the  clinical development

53

phase is  predicated upon the results  of  preclinical  tests.  We  cannot accurately predict  which, if any, of
the discovery stage product candidates will  advance from preclinical testing and move into our internal
clinical development program. The clinical  trial  and  regulatory approval processes for our product
candidates that have advanced or that  we  intend to advance to clinical  testing  are lengthy,  expensive
and uncertain in both timing and outcome. As  a result,  the pace and timing of  the clinical  development
of our product candidates is highly uncertain and  may not ever  result in approved products.
Completion dates and development costs will vary significantly  for each product  candidate and  are
difficult to predict. A variety of factors,  many  of  which are outside our  control,  could  cause or
contribute to the prevention or delay of  the successful completion of  our clinical trials, or  delay or
prevent our obtaining necessary regulatory approvals. The  costs to take a product through clinical trials
are dependent upon, among other factors, the  clinical indications, the  timing, size and design  of each
clinical trial, the number of patients enrolled in each trial, and the speed at which patients are enrolled
and treated. Product candidates may be found to be ineffective or to cause unacceptable side  effects
during clinical trials, may take longer  to  progress through clinical  trials than anticipated,  may fail to
receive necessary regulatory approvals  or  may  prove  impractical  to  manufacture  in commercial
quantities at reasonable cost or with  acceptable quality.

The lengthy process of securing FDA  approvals for new drugs requires the  expenditure of

substantial resources. Any failure by us  to  obtain, or any delay  in obtaining, regulatory approvals, would
materially adversely affect our product development  efforts and  our business overall.  Accordingly, we
cannot currently estimate, with any degree of certainty, the amount of time or  money  that  we will be
required to expend in the future on our product  candidates prior  to  their regulatory approval, if such
approval is ever granted. As a result of  these uncertainties  surrounding  the timing and outcome of our
clinical trials, we are currently unable to estimate  when, if  ever, our product  candidates that have
advanced into clinical testing will generate  revenues and cash flows.

We  do not track our research and development  costs by project. Since we use our research and
development resources across multiple research and development  projects,  we manage our research and
development expenses within each of the categories listed in the following table and described in more
detail below (in thousands):

Research and Development Expense

Year Ended June 30,

2012

2011

2010

Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preclinical and Clinical Testing . . . . . . . . . . . . . . . . . .
Process and Product Development . . . . . . . . . . . . . . .
Manufacturing Operations . . . . . . . . . . . . . . . . . . . . .

$16,827
21,143
7,203
24,019

$15,208
16,884
7,238
24,123

$14,200
12,892
5,959
17,229

Total Research and Development Expense . . . . . . . . .

$69,192

$63,453

$50,280

Research—Research includes expenses associated with  activities to evaluate new targets and  to

develop and evaluate new antibodies, linkers and cytotoxic  agents  for our  products and in  support of
our  collaborators. Such expenses primarily include personnel, fees to in-license certain technology,
facilities and lab supplies. Research expenses increased $1.6 million to $16.8 million in  fiscal year  2012
from fiscal year 2011 and $1.0 million to $15.2  million  in fiscal year 2011 from  fiscal year  2010. The
increase in fiscal 2012 was principally  due  to  an increase in  salaries and  related  expenses. The increase
in fiscal 2011 was principally due to an increase in salaries  and related expenses and  an increase in
contract service expense related to various research studies conducted  during  the year  for our
IMGN901, IMGN529 and IMGN853 internal programs, as well as efficacy  studies for potential new
targets.

Preclinical and Clinical Testing—Preclinical and clinical testing includes expenses  related to

preclinical testing of our own and, in  certain instances,  our collaborators’ product candidates,  regulatory

54

activities, and the cost of our own clinical  trials.  Such expenses include personnel, patient enrollment at
our  clinical testing sites, consultant fees, contract  services,  and facility expenses. Preclinical and  clinical
testing expenses increased $4.2 million  to  $21.1 million in  fiscal  year 2012 from fiscal  year 2011 and
$4.0 million to $16.9 million in fiscal  year 2011 from fiscal year 2010. The increases in fiscal years 2012
and 2011 were principally due to increases  in salaries and related expenses and increases  in clinical trial
costs. The increase in clinical trial costs  for fiscal 2012 was  primarily the  result of advancing  two new
wholly owned product candidates, IMGN529  and  IMGN853, into  clinical testing during the  year.  The
increase was partially offset by lower  costs  incurred  related to our IMGN901 and IMGN388 clinical
programs due to completion of earlier-stage IMGN901 clinical trials and  our  returning the rights  to
IMGN388 to its originator. The increase in clinical trial costs for fiscal year  2011 was primarily the
result of initiating a new IMGN901 study during the year, as well as increased site  management costs
driven from expanded sites and higher  patient enrollment across  IMGN901 studies.

Process and Product Development—Process and product development expenses include costs  for

development of clinical and commercial manufacturing processes for our own and collaborator
compounds. Such expenses include the costs of personnel, contract services and facility expenses.  Total
development expenses decreased $35,000  to  $7.2 million in fiscal year 2012 from fiscal year 2011 and
expenses increased $1.2 million to $7.2 million  in fiscal year 2011  from  fiscal year 2010. The decrease in
fiscal year 2012 was primarily due to  a decrease  in contract service expense  due  to  transferring
responsibility for certain outsourced costs to the Manufacturing Operations segment, partially offset  by
an increase in salaries and related expenses. The increase  in fiscal  year 2011  was primarily  the result of
an increase in salaries and related expenses, as  well as an  increase in  contract service expense due to
increased outsourcing of certain release and stability testing of  internal antibodies, particularly for
IMGN529 and IMGN901.

Manufacturing Operations—Manufacturing operations expense  includes costs to manufacture
preclinical and clinical materials for our  own and  our  collaborators’ product candidates, quality control
and quality assurance activities and costs to support  the operation  and maintenance of our conjugate
manufacturing facility. Such expenses include personnel, raw materials for  our  and our collaborators’
preclinical studies and clinical trials, development  costs with  contract manufacturing organizations,
manufacturing supplies, and facilities  expense. Manufacturing operations expense  decreased $104,000 to
$24.0 million in fiscal year 2012 from fiscal year 2011 and  increased $6.9  million  to  $24.1 million in
fiscal year 2011 from fiscal year 2010. The decrease in fiscal year 2012 was  primarily the  result of (i)  a
decrease in cost of clinical materials revenue due  to  decreased  orders  of such clinical materials from
our  partners and lower amounts of DMx  written off as excess; (ii) a decrease in  raw materials and
disposables used in production due to timing and mix of manufacturing requirements; and (iii) a
decrease in quality-related consultant fees due to internal resources being added to perform this work.
Partially offsetting these decreases, (i) overhead utilization absorbed by  the manufacture of  clinical
materials on behalf of our collaborators decreased; (ii) antibody development and supply expense
increased, driven primarily by IMGN853 and  an earlier-stage program; (iii) contract service expense
increased due to increased fill/finish  costs  for IMGN901 and IMGN853, greater linker development
costs and increased release and stability  testing of our internal antibodies (the cost  of  which was
recorded  in previous years within the  Process and Product  Development segment). The increase in
fiscal year 2011 was primarily the result of (i) an increase in cost of  clinical materials  shipped to
partners and greater amounts of DMx written off  as excess;  (ii) an increase in antibody development
and supply expense driven primarily by  our  IMGN529 and  IMGN853 programs; (iii) an  increase in raw
materials used in production due to increased manufacturing activity; (iv) an increase in contract
service expense driven by increased master cell bank testing costs incurred for IMGN529 and
IMGN853, as well as increased fill/finish costs incurred for IMGN901 and IMGN529; and (v) an
increase in salaries and related expenses. Partially offsetting these increases, overhead  utilization
absorbed by the manufacture of clinical materials on  behalf of our collaborators increased.

55

Antibody expense in anticipation of potential future clinical  trials, as  well as our ongoing trials, was
$4.9 million in fiscal year 2012, $3.7 million in fiscal  year 2011, and $1.1 million in fiscal year 2010.  The
process of antibody production is lengthy due  in part  to  the lead time  to  establish a satisfactory
production process at a vendor. Accordingly,  costs incurred related to antibody  production and
development have fluctuated from period  to period and  we expect these cost  fluctuations to continue in
the future.

We  expect that future research and development  expenses will increase due  to  our  continuing
advancement of our internal product  candidates through clinical trials,  as well as  expected increases in
salaries and related expenses.

General and Administrative Expenses

General and administrative expenses  for the  year ended June 30, 2012  increased $4.4 million  to
$20.4 million from $16.0 million for the  year ended June 30, 2011.  General and administrative expenses
for the year ended June 30, 2010 were  $14.9 million.  The increase in  fiscal year  2012 as compared to
fiscal year 2011 was primarily due to  an increase in salaries and related expenses, particularly stock
compensation costs, an increase in patent  expenses and an increase in professional service fees,
including increased accounting, legal and public  reporting fees. The increase  in fiscal year 2011 as
compared to fiscal year 2010 was primarily due  to  an increase  in patent expenses  and an  increase in
salaries and related expenses driven by  higher stock compensation costs, partially  offset by a  decrease
in other general corporate expenses.

Investment Income, net

Investment income for the years ended June 30, 2012,  2011and  2010 was $66,000, $218,000  and

$176,000, respectively.

Other (Expense) Income, net

Other (expense) income, net for the  years ended June 30,  2012, 2011 and 2010  was  $(128,000),
$1.7 million and ($118,000), respectively.  Net realized gains on investments were  $341,000 for  the year
ended June 30, 2011. There were no  gains or losses recognized during the  years  ended June 30, 2012
and 2010. During the years ended June  30,  2012, 2011 and 2010, we recorded  net (losses) gains on
foreign currency forward contracts of $(173,000),  $189,000 and $(219,000), respectively. We incurred
$17,000, $(57,000), and $104,000 in foreign  currency  exchange  gains and  (losses)  related to obligations
with non-U.S. dollar-based suppliers during the  years  ended June  30, 2012, 2011 and  2010, respectively.
In addition, during fiscal year 2011, we  recognized  $1.2 million  of  federal  grant funding awarded under
the Patient Protection and Affordable Care Act of 2010  to  develop new anticancer  therapies.

Liquidity and Capital Resources

Cash and cash equivalents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Working capital
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shareholders’ equity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cash used for operating activities . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cash used for investing activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cash provided by financing activities . . . . . . . . . . . . . . . . . . . . . . . . . .

$160,938
150,016
83,890
(34,288)
(2,968)
6,988

$191,206
186,959
139,969
(7,989)
(660)
90,699

June 30,

2012

2011

(In thousands)

56

Cash Flows

We  require cash to fund our operating  expenses, including the advancement  of our  own clinical

programs, and to make capital expenditures. Historically,  we  have funded our  cash requirements
primarily through equity financings in public  markets and payments from  our collaborators, including
equity investments, license fees, milestones  and research funding.  As of June 30,  2012, we  had
approximately $160.9 million in cash  and cash equivalents. Net cash used for operations was
$34.3 million, $8.0 million and $40.6  million during the years ended  June  30, 2012, 2011  and 2010,
respectively. The principal use of cash  in  operating activities for all  periods  presented  was  to  fund  our
net loss. Cash used in operations in fiscal  2012 benefited from the $20 million upfront payment
received from Lilly in January 2012 with  the execution of a right-to-test  agreement between the
companies and cash used in operations  in fiscal 2011 benefited from the $45 million upfront  payment
received from Novartis in October 2010  with the  execution  of  a right-to-test agreement between  the
companies.

Net cash used for investing activities  was $3.0  million,  $660,000 and $882,000 for the years ended

June 30, 2012, 2011 and 2010, respectively,  and substantially represents cash outflows from  capital
expenditures partially offset by cash inflows from the sales and maturities of marketable  securities.
Capital expenditures were $2.9 million,  $2.0 million and  $1.5 million for the fiscal years ended  June 30,
2012, 2011 and 2010, respectively. Capital expenditures for the year  ended  June  30, 2012 consisted
primarily of leasehold improvements  to  the laboratory and office space at our corporate headquarters,
laboratory equipment and computer  software applications. Capital  expenditures for the years ended
June 30, 2011 and 2010 consisted primarily of laboratory equipment and computer software
applications.

Net cash provided by financing activities was  $7.0 million,  $90.7 million and  $81.0 million for  the
years ended June 30, 2012, 2011 and  2010, respectively, which includes  the proceeds  from the exercise
of 1.4  million, 550,000 and 634,000 stock  options,  respectively. Also,  pursuant to public offerings,  in
fiscal 2011, we issued and sold 7,800,000  shares  of our common stock resulting  in net proceeds of
$88.0 million and in fiscal 2010, we issued and sold 10,350,000 shares of our common stock  resulting in
net proceeds of $77.5 million.

We  anticipate that our current capital resources, including $94  million in net proceeds resulting

from a public stock offering completed  in  July 2012, and expected future  collaborator payments under
existing collaborations will enable us  to  meet our operational expenses and capital expenditures through
fiscal year 2015. However, we cannot  provide assurance that such collaborative agreement  funding  will,
in fact, be received. Should we or our  partners  not  meet some or all  of the terms and  conditions of our
various collaboration agreements, we may  be  required to pursue additional strategic partners, secure
alternative financing arrangements, and/or  defer or limit  some or all of  our  research,  development
and/or clinical projects.

57

Contractual Obligations

Below is a table that presents our contractual  obligations  and commercial  commitments  as of

June 30, 2012 (in thousands):

Payments Due by Period

Total

Less than
One Year

1-3
Years

4-5
Years

More than
5 Years

Waltham lease obligations(1) . . . . . . . . . . .
Other operating lease obligations . . . . . . .

$43,183
5,565

$5,477
898

$11,203
1,841

$10,889
1,884

$15,614
942

Total

. . . . . . . . . . . . . . . . . . . . . . . . . . .

$48,748

$6,375

$13,044

$12,773

$16,556

(1) Lease agreements were signed in July 2007  and April 2012.  In December 2009, we entered

into a sublease for 14,100 square feet  of our office and laboratory space  at  830 Winter Street,
Waltham, MA through January 2015. We will  receive approximately  $1.7 million in  minimum
rental payments over the remaining term of the sublease,  which is not  included in  the table
above.

In addition to the above table, we are  contractually obligated to make future success-based
regulatory milestone payments in conjunction  with certain collaborative  agreements. These  payments
are contingent upon the occurrence of certain  future events  and, given the nature  of these  events, it is
unclear when, if ever, we may be required to pay such amounts. Therefore, the timing of any future
payment is not reasonably estimable.  As a result, these contingent  payments have not been included  in
the table above or recorded in our consolidated  financial statements.  As of  June 30, 2012, the
maximum amount that may be payable in the  future under such arrangement is $43.0 million.

Recent  Accounting Pronouncements

In May 2011, the FASB issued ASU  No. 2011-04, ‘‘Fair Value  Measurement.’’  This ASU  clarifies

the concepts related to highest and best  use and valuation premise, blockage factors and  other
premiums and discounts, the fair value measurement of financial instruments  held in a  portfolio  and  of
those instruments classified as a component of shareholders’  equity. The guidance includes enhanced
disclosure requirements about recurring  Level  3 fair  value  measurements, the use of nonfinancial
assets, and the level in the fair value hierarchy of assets and liabilities  not recorded  at fair  value. The
provisions of this ASU are effective prospectively for annual periods,  and interim  periods within those
years, beginning on or after December 15, 2011. Early application is prohibited. We do not expect the
adoption of these provisions to have  a  significant impact on our financial  statements.

In June 2011, the FASB issued ASU No. 2011-05, ‘‘Comprehensive Income.’’  This ASU intends to

enhance comparability and transparency of other  comprehensive income components. The  guidance
provides an option to present total comprehensive income, the components of  net income and  the
components of other comprehensive income in  a single  continuous statement  or two  separate but
consecutive statements. This ASU eliminates the option to present other comprehensive income
components as part of the statement  of  changes in  shareholders’ equity. The provisions of this ASU
will be applied retrospectively for annual  periods, and  interim periods within  those years, beginning
after December 15, 2011. Early application is permitted. We do not  expect the  adoption  of these
provisions to have a significant impact on  our  financial statements.

Off-Balance Sheet Arrangements

None.

58

Item 7A. Quantitative and Qualitative Disclosure About  Market Risk

We  maintain an investment portfolio in accordance with our investment policy. The primary

objectives of our investment policy are to preserve  principal, maintain proper liquidity  to  meet
operating needs and maximize yields. Although our  investments are subject to credit  risk, our
investment policy specifies credit quality standards for our investments  and limits the  amount  of credit
exposure from any single issue, issuer or type  of investment. Our investments are  also subject  to
interest rate risk and will decrease in  value  if  market  interest rates  increase. However,  due  to  the
conservative nature of our investments and relatively  short duration, interest rate risk  is mitigated.  We
do not own derivative financial instruments in our investment  portfolio. Accordingly, we  do not believe
there is any material market risk exposure  with respect to derivative  or  other financial instruments  that
would require disclosure under this item.

Our foreign currency hedging program uses forward contracts to manage the foreign currency
exposures that exist as part of our ongoing business operations. The contracts are denominated  in
Euros and have maturities of less than  one year. Our foreign currency  risk management  strategy is
principally designed to mitigate the future  potential financial impact  of  changes in  the value  of
transactions, anticipated transactions  and balances denominated  in foreign currency, resulting from
changes in foreign currency exchange rates.

Our market risks associated with changes  in foreign currency  exchange rates are  concentrated
primarily in a portfolio of short duration  foreign currency  forward contracts. Generally, these contracts
provide that we receive certain foreign currencies and  pay U.S. dollars at specified exchange rates at
specified future dates. Although we are exposed to credit  and  market  risk in  the event of future
nonperformance by a counterparty, management  has no  reason to believe that such an  event will  occur.

59

Item 8. Financial Statements and Supplementary Data

IMMUNOGEN, INC.
INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

Report of Independent Registered Public  Accounting  Firm . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Consolidated Financial Statements:

Consolidated Balance Sheets as of June 30,  2012 and 2011 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Consolidated Statements of Operations  for the Years Ended  June  30, 2012, 2011,  and 2010 . . .
Consolidated Statements of Shareholders’ Equity for the Years Ended  June 30, 2012, 2011,

and 2010 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Consolidated Statements of Cash Flows  for  the Years  Ended June 30,  2012, 2011, and 2010 . . .
Notes to Consolidated Financial Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

61

62
63

64
65
66

60

Report of Independent Registered Public Accounting Firm

The Board of Directors and Shareholders  of ImmunoGen, Inc.

We  have audited the accompanying consolidated balance sheets of ImmunoGen, Inc.  as of June  30,

2012 and 2011, and the related consolidated  statements  of operations,  shareholders’ equity,  and cash
flows for each of the three years in the period ended June 30,  2012. Our  audits  also included the
financial statement schedule listed in the  Index at Item  15.  These financial  statements and  schedule are
the responsibility of the Company’s management. Our  responsibility is to express an opinion on these
financial statements and schedule based  on our audits.

We  conducted our audits in accordance with the standards  of  the Public Company Accounting
Oversight Board (United States). Those  standards require that we  plan and perform the audit to obtain
reasonable assurance about whether  the  financial  statements are free  of material misstatement.  An
audit includes examining, on a test basis, evidence  supporting the amounts and disclosures  in the
financial statements. An audit also includes assessing the accounting  principles used  and significant
estimates made by management, as well as  evaluating the overall financial statement presentation. We
believe that our audits provide a reasonable  basis for our opinion.

In our opinion, the financial statements referred to above present fairly, in all material respects,

the consolidated financial position of  ImmunoGen, Inc.  at June 30,  2012 and  2011, and the
consolidated results of its operations and  its cash  flows  for  each  of the three years in the period ended
June 30, 2012, in conformity with U.S. generally accepted accounting principles.  Also, in our  opinion,
the related financial statement schedule, when considered  in relation to the basic financial statements
taken as a whole, presents fairly in all material  respects the information set forth  therein.

We  also have audited, in accordance  with the standards of  the Public Company Accounting
Oversight Board (United States), ImmunoGen, Inc.’s internal control over financial  reporting as of
June 30, 2012, based on criteria established  in Internal Control—Integrated Framework  issued by the
Committee of Sponsoring Organizations  of  the Treadway Commission and our report dated  August 29,
2012 expressed an unqualified opinion thereon.

/s/ ERNST & YOUNG LLP

Boston, Massachusetts
August 29, 2012

61

IMMUNOGEN, INC.

CONSOLIDATED BALANCE SHEETS

In thousands, except per share amounts

ASSETS
Cash and cash equivalents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accounts receivable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unbilled revenue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Restricted cash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Prepaid and other current assets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Total current assets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Property and equipment, net of accumulated depreciation . . . . . . . . . . . . . . . .
Long-term restricted cash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other assets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

June 30,
2012

June 30,
2011

$ 160,938
129
1,196
1,288
319
2,400

166,270
11,633
2,231
174

$ 191,206
4,668
1,488
480
1,019
2,664

201,525
13,409
2,549
158

Total assets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 180,308

$ 217,641

LIABILITIES AND SHAREHOLDERS’ EQUITY
Accounts payable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accrued compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other accrued liabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Current portion of deferred lease incentive . . . . . . . . . . . . . . . . . . . . . . . . . . .
Current portion of deferred revenue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$

Total current liabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Deferred lease incentive, net of current  portion . . . . . . . . . . . . . . . . . . . . . . .
Deferred revenue, net of current portion . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other long-term liabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Total liabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Commitments and contingencies (Note  H)
Shareholders’ equity:
Preferred stock, $.01 par value; authorized  5,000 shares; no  shares  issued and

3,395
4,942
4,589
979
2,349

16,254
6,605
69,761
3,798

96,418

$

3,213
4,723
3,305
979
2,346

14,566
7,583
51,545
3,978

77,672

outstanding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

—

—

Common stock, $.01 par value; authorized 100,000 shares; issued and
outstanding 77,759 and 76,281 shares  as of June  30, 2012 and 2011,
respectively . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Additional paid-in capital
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accumulated deficit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

778
587,068
(503,956)

763
569,843
(430,637)

Total shareholders’ equity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

83,890

139,969

Total liabilities and shareholders’ equity . . . . . . . . . . . . . . . . . . . . . . . .

$ 180,308

$ 217,641

The accompanying notes are an integral part of the consolidated financial statements.

62

IMMUNOGEN, INC.

CONSOLIDATED STATEMENTS OF  OPERATIONS

In thousands, except per share amounts

Year Ended June 30,

2012

2011

2010

Revenues:

Research and development support . . . . . . . . . . . . . . . . . . . . . . . .
License and milestone fees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Clinical materials revenue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 4,517
9,161
2,679

$ 7,256
6,393
5,656

$ 5,365
5,698
2,880

Total revenues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

16,357

19,305

13,943

Operating Expenses:

Research and development
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General and administrative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Total operating expenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Loss from operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Investment income, net . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other (expense) income, net . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Loss before benefit for income taxes . . . . . . . . . . . . . . . . . . . . . . . . .
Benefit for income taxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

69,192
20,422

89,614

(73,257)
66
(128)

(73,319)
—

63,453
16,040

79,493

(60,188)
218
1,696

(58,274)
—

50,280
14,898

65,178

(51,235)
176
(118)

(51,177)
(265)

Net loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$(73,319) $(58,274) $(50,912)

Basic and diluted net loss per common share . . . . . . . . . . . . . . . . . . .

$

(0.95) $

(0.85) $

(0.87)

Basic and diluted weighted average common shares outstanding . . . . .

76,814

68,919

58,845

The accompanying notes are an integral part of the consolidated financial statements.

63

CONSOLIDATED STATEMENTS OF  SHAREHOLDERS’ EQUITY

IMMUNOGEN, INC.

In thousands

Common Stock

Shares Amount

Additional
Paid-In
Capital

Accumulated
Other

Total

Accumulated Comprehensive Shareholders’ Comprehensive

Deficit

Income (Loss)

Equity

(Loss)

Balance at June 30, 2009 . . . . . . . 56,947
Unrealized gains on marketable

$569

$387,947

$(321,451)

$(208)

$ 66,857

securities . . . . . . . . . . . . . . . .
Net loss . . . . . . . . . . . . . . . . . .
Stock options exercised . . . . . . . .
Stock-based compensation expense .
Issuance  of common stock in a

—
—
634
—

—
—
6
—

—
—
3,455
4,170

—
(50,912)
—
—

public offering, net of issuance
costs

. . . . . . . . . . . . . . . . . . 10,350

Directors’ deferred share unit

104

77,418

compensation . . . . . . . . . . . . .

—

—

460

—

—

490
—
—
—

—

—

490
(50,912)
3,461
4,170

77,522

460

Balance at June 30, 2010 . . . . . . . 67,931

$679

$473,450

$(372,363)

$ 282

$102,048

Comprehensive  loss

. . . . . . . . . .

Unrealized gains on marketable

securities . . . . . . . . . . . . . . . .
Net loss . . . . . . . . . . . . . . . . . .
Stock options exercised . . . . . . . .
Stock-based compensation expense .
Issuance  of common stock in a

—
—
550
—

public offering, net of issuance
costs

. . . . . . . . . . . . . . . . . .

7,800

Directors’ deferred share unit

compensation . . . . . . . . . . . . .

—

—
—
6
—

78

—

—
—
2,713
5,452

87,902

326

—
(58,274)
—
—

—

—

(282)
—
—
—

—

—

(282)
(58,274)
2,719
5,452

87,980

326

Balance at June 30, 2011 . . . . . . . 76,281

$763

$569,843

$(430,637)

$ —

$139,969

Comprehensive  loss

. . . . . . . . . .

Net loss . . . . . . . . . . . . . . . . . .
Stock options exercised . . . . . . . .
Stock-based compensation expense .
Directors’ deferred share units

converted . . . . . . . . . . . . . . .

Directors’ deferred share unit

compensation . . . . . . . . . . . . .

—
1,432
—

46

—

—
14
—

1

—

—
6,974
9,938

(1)

314

(73,319)
—
—

—

—

—
—
—

—

—

(73,319)
6,988
9,938

—

314

Balance at June 30, 2012 . . . . . . . 77,759

$778

$587,068

$(503,956)

$ —

$ 83,890

Comprehensive  loss

. . . . . . . . . .

490
(50,912)
—
—

—

—

$(50,422)

(282)
(58,274)
—
—

—

—

$(58,556)

(73,319)
—
—

—

$(73,319)

The accompanying notes are an integral part of the consolidated financial statements.

64

IMMUNOGEN, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

In thousands

Cash flows from operating activities:
Net loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adjustments to reconcile net loss to net  cash used for operating

activities:
Depreciation and amortization . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loss on sale/disposal of fixed assets . . . . . . . . . . . . . . . . . . . . . . .
Amortization of deferred lease incentive obligation . . . . . . . . . . . .
Gain on sale of marketable securities . . . . . . . . . . . . . . . . . . . . . .
Loss (gain) on forward contracts . . . . . . . . . . . . . . . . . . . . . . . . . .
Stock and deferred share unit compensation . . . . . . . . . . . . . . . . .
Deferred rent
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Change in operating assets and liabilities:

Accounts receivable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unbilled revenue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Prepaid and other current assets . . . . . . . . . . . . . . . . . . . . . . . .
Restricted cash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other assets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accounts payable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accrued compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other accrued liabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Deferred revenue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Year Ended June 30,

2012

2011

2010

$ (73,319) $ (58,274) $ (50,912)

4,633
51
(978)
—
173
10,252
(109)

4,539
292
(808)
253
1,018
(16)
182
219
1,111
18,219

4,937
9
(979)
(341)
(189)
5,778
(4)

(2,873)
107
762
(1,038)
574
38
149
522
604
42,229

4,838
41
(979)
—
219
4,640
55

(49)
(1,034)
594
(386)
366
(171)
1,820
61
1,393
(1,080)

Net cash used for operating activities . . . . . . . . . . . . . . . . . . .

(34,288)

(7,989)

(40,584)

Cash flows from investing activities:

Proceeds from maturities or sales of  marketable securities . . . . .
Purchases of property and equipment, net . . . . . . . . . . . . . . . . .
(Payments) proceeds from settlement  of forward contracts . . . . .

Net cash used for investing activities . . . . . . . . . . . . . . . . . . .

Cash flows from financing activities:

Proceeds from stock options exercised . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
Proceeds from common stock issuance,  net

Net cash provided by financing activities . . . . . . . . . . . . . . . . .

—
(2,908)
(60)

(2,968)

6,988
—

6,988

1,201
(2,029)
168

(660)

2,719
87,980

90,699

Net change in cash and cash equivalents . . . . . . . . . . . . . . . . . . . . . .
Cash and cash equivalents, beginning  of period . . . . . . . . . . . . . . . . .

(30,268)
191,206

82,050
109,156

834
(1,534)
(182)

(882)

3,462
77,521

80,983

39,517
69,639

Cash and cash equivalents, end of period . . . . . . . . . . . . . . . . . . . . .

$160,938

$191,206

$109,156

The accompanying notes are an integral part of the consolidated financial statements.

65

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

AS OF JUNE 30, 2012

A. Nature of Business and Plan of Operations

ImmunoGen, Inc. (the Company) was incorporated  in Massachusetts in 1981 and  is focused on the

development of antibody-based anticancer therapeutics.  The Company has  incurred operating losses
and negative cash flows from operations since inception, incurred a net  loss of approximately
$73.3 million during the fiscal year ended  June  30, 2012, and has  an accumulated deficit of
approximately $504.0 million as of June  30,  2012. The Company has primarily funded these  losses
through payments received from its collaborations and equity financings. To date, the Company  has no
product  revenue and management expects operating  losses to continue for the foreseeable future.

At June  30, 2012, the Company had $160.9 million of cash and cash equivalents  on hand, and  in
July, 2012 received $94 million of net proceeds from a  public  stock offering. The  Company may raise
additional funds through equity or debt  financings or generate revenues from collaborative partners
through a combination of upfront license  payments, milestone payments,  research funding, and clinical
material reimbursement. There can be  no  assurance that the  Company will be able to obtain additional
debt or equity financing or generate revenues from  collaborative partners, on  terms acceptable to the
Company, or  at all. The failure of the  Company to obtain  sufficient funds on acceptable  terms when
needed could have a material adverse  effect on the Company’s  business,  results of operations and
financial condition and require the Company to defer  or limit some  or all of its research, development
and/or clinical projects.

The Company is subject to risks common to companies in the biotechnology industry including, but
not limited to, the development by its  competitors of  new technological innovations, dependence  on key
personnel, protection of proprietary technology,  manufacturing  and  marketing limitations, collaboration
arrangements, third-party reimbursements  and  compliance with governmental regulations.

B. Summary of Significant Accounting Policies

Principles of Consolidation

The consolidated financial statements  include the accounts  of the Company  and its wholly owned

subsidiaries, ImmunoGen Securities Corp., and  ImmunoGen Europe Limited .  All intercompany
transactions and balances have been eliminated.

Use of Estimates

The preparation of financial statements  in conformity with  accounting principles generally accepted

in the United States (U.S.) requires management to make estimates and assumptions that affect the
reported amounts of assets and liabilities and disclosure  of  contingent assets and liabilities at the date
of the financial statements and the reported  amounts of revenues and  expenses during the reporting
period. Actual results could differ from  those  estimates.

Subsequent Events

The Company has evaluated all events or transactions  that  occurred after  June 30, 2012 up

through the date the Company issued  these financial  statements. In  July  2012, the Company  sold
6,250,000 shares of our common stock at  $16.00 per share in a public offering resulting in gross
proceeds of $100 million. The Company did not  have any other material recognizable subsequent
events during the period.

66

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

Revenue Recognition

The Company enters into licensing and development agreements with collaborative partners for
the development of monoclonal antibody-based anticancer therapeutics. The terms of  these agreements
contain multiple deliverables which may include (i) licenses, or options to  obtain  licenses, to the
Company’s Targeted Antibody Payload, or  TAP, technology,  (ii) rights to future technological
improvements, (iii) research activities  to  be  performed on behalf  of  the collaborative partner,
(iv) delivery of cytotoxic agents and (v) the manufacture of preclinical or  clinical materials for the
collaborative partner. Payments to the Company  under these agreements  may  include non-refundable
license fees, option fees, exercise fees, payments for  research activities, payments for the manufacture
of preclinical or clinical materials, payments based upon the achievement of certain milestones and
royalties on product sales. The Company follows the provisions  of the Financial Accounting Standards
Board (FASB) Accounting Standards Codification (ASC) Topic 605-25,  ‘‘Revenue  Recognition—
Multiple-Element Arrangements,’’ and  ASC Topic  605-28, ‘‘Revenue Recognition—Milestone  Method,’’
in accounting for these agreements. In order to account  for  these  agreements, the Company  must
identify the deliverables included within  the agreement and evaluate which deliverables represent
separate units of accounting based on  if  certain criteria  are met, including  whether the delivered
element has stand-alone value to the  collaborator. The consideration  received  is allocated among the
separate units of accounting, and the  applicable revenue recognition criteria are applied to each of  the
separate units.

At June  30, 2012, the Company had the following two types of  agreements with the  parties

identified below:

(cid:129) Exclusive development and commercialization  licenses to use the Company’s TAP  technology
and/or certain other intellectual property  to  develop compounds  to  a single target antigen
(referred to herein as single-target licenses, as distinguished from  the Company’s right-to-test
agreements described elsewhere):

Amgen (two single-target licenses)

Bayer HealthCare (one single-target license)

Biotest (one single-target license)

Roche, through its Genentech unit (five single-target licenses)

Sanofi (license to multiple individual targets)

(cid:129) Option/research agreement for a defined period of time  to  secure development and

commercialization licenses to use the Company’s TAP technology  to  develop anticancer
compounds to specified targets on established terms (referred  to  herein as right-to-test
agreements):

Amgen

Sanofi

Novartis

Eli Lilly and Company

67

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

There are no performance, cancellation,  termination  or refund provisions in any of the

arrangements that contain material financial  consequences  to  the  Company.

Exclusive Licenses

The deliverables under an exclusive license  agreement generally include the exclusive license  to  the
Company’s TAP technology with respect  to a specified antigen target, and may also  include deliverables
related to rights to future technological improvements,  research  activities to be performed on behalf of
the collaborative partner and the manufacture of  preclinical or clinical materials for the collaborative
partner.

Generally, exclusive license agreements contain non-refundable terms  for payments and, depending
on the terms of the agreement, provide  that the  Company will (i)  at  the  collaborator’s  request,  provide
research services at negotiated prices  which are generally consistent with what other  third parties would
charge, (ii) at the collaborator’s request,  manufacture  and provide to it preclinical and  clinical materials
or deliver cytotoxic agents at negotiated  prices which  are generally  consistent with what  other third
parties would charge, (iii) earn payments  upon  the achievement  of certain milestones  and (iv)  earn
royalty payments, generally until the later  of the  last applicable patent expiration  or 10 to 12  years  after
product  launch. In the case of trastuzumab emtansine  (T-DM1), however, the minimum  royalty term  is
10 years and the maximum royalty term  is  12 years on  a country-by-country basis.  Royalty rates may
vary over the royalty term depending  on the  Company’s intellectual  property rights.  The  Company may
provide technical assistance and share any technology improvements with its collaborators during the
term of the collaboration agreements. The Company  does  not directly control  when any collaborator
will request research or manufacturing services, achieve milestones  or become liable for royalty
payments. As a result, the Company cannot  predict when  it will recognize  revenues in  connection with
any of the foregoing.

In determining the units of accounting, management evaluates  whether  the exclusive license has

stand-alone value from the undelivered  elements  to  the collaborative partner based  on the
consideration of the relevant facts and  circumstances for each arrangement. Factors considered in  this
determination include the research capabilities of the  partner and the availability of TAP technology
research expertise in the general marketplace. If the  Company concludes that the license has stand
alone value and therefore will be accounted for  as a separate unit of accounting, the Company  then
determines the estimated selling prices  of  the license and all other units of accounting based  on market
conditions, similar arrangements entered  into by third parties, and entity-specific factors such as the
terms of the Company’s previous collaborative agreements, recent preclinical and clinical testing  results
of therapeutic products that use the Company’s TAP  technology, the Company’s pricing practices and
pricing objectives, the likelihood that  technological  improvements will be made, the likelihood that
technological improvements made will  be  used by the Company’s collaborators and  the nature of the
research services to be performed on behalf of its collaborators  and market  rates for similar  services.

Upfront payments on single-target licenses  are deferred if facts and circumstances  dictate that the
license does not have stand-alone value. Prior to the adoption of Accounting Standards Update (ASU)
No. 2009-13, ‘‘Revenue Arrangements with Multiple Deliverables’’ on July 1, 2010,  the Company
determined that its licenses lacked stand-alone value and were combined with other elements of the
arrangement and any amounts associated with  the license were deferred and amortized  over a certain

68

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

period, which the Company refers to  as the  Company’s period  of substantial involvement. The
determination of the length of the period over which to defer revenue is subject to judgment and
estimation and can have an impact on the  amount of revenue recognized in a  given period.  Historically
the Company’s involvement with the development of a  collaborator’s product candidate  has been
significant at the early stages of development, and  lessens as it  progresses into clinical trials. Also, as a
drug candidate gets closer to commencing pivotal testing the Company’s  collaborators  have sought  an
alternative site to manufacture the product, as  the Company’s facility  does not produce pivotal  or
commercial drug product. Accordingly, the Company generally  estimates this period of substantial
involvement to begin at the inception  of  the collaboration agreement and  conclude  at the end of
non-pivotal Phase II testing. The Company believes this period of substantial involvement is,  depending
on the nature of the license, on average six and  one-half years. Quarterly,  the Company reassesses its
periods of substantial involvement over  which the Company amortizes its  upfront license  fees  and
makes adjustments as appropriate. In  the event  a collaborator elects to discontinue development  of  a
specific  product candidate under a single  target license, but retains its right  to  use the  Company’s
technology to develop an alternative product candidate to  the  same target or a  target substitute, the
Company would cease amortization of any remaining portion  of  the upfront  fee until  there is
substantial preclinical activity on another  product  candidate and its  remaining  period of substantial
involvement can be estimated. In the  event that a  single  target license were to be terminated, the
Company would recognize as revenue any portion of the  upfront fee  that had not previously  been
recorded  as revenue, but was classified as  deferred revenue,  at  the  date of such termination.

Subsequent to the  adoption of ASU No. 2009-13, the Company determined that its research
licenses lack stand-alone value and are considered for  aggregation with the  other elements  of  the
arrangement and accounted for as one  unit of accounting.

Upfront payments on single-target licenses  may be recognized upon delivery  of the license if  facts
and circumstances dictate that the license  has stand-alone value from the undelivered elements,  which
generally include rights to future technological  improvements, research services, delivery  of cytotoxic
agents and the manufacture of preclinical  and  clinical materials.

The Company recognizes revenue related to research services that represent  separate units of
accounting as they are performed, as long as  there is  persuasive evidence  of  an arrangement, the fee is
fixed or determinable, and collection  of the related receivable is probable. The Company  recognizes
revenue related to the rights to future technological improvements over  the estimated term  of the
applicable license.

The Company may also provide cytotoxic agents  to  its collaborators  or  produce preclinical and
clinical materials at negotiated prices which are  generally  consistent with what other third parties  would
charge. The Company recognizes revenue on cytotoxic agents and  on  preclinical and  clinical materials
when the materials have passed all quality  testing required for collaborator acceptance and title and
risk of loss have transferred to the collaborator. Arrangement  consideration allocated  to  the
manufacture of preclinical and clinical  materials in a multiple-deliverable  arrangement  is below the
Company’s full cost, and the Company’s full cost is  not  expected to ever be below  its  contract selling
prices for its existing collaborations. During the fiscal years ended  June 30, 2012, 2011  and 2010,  the
difference between the Company’s full cost to manufacture preclinical and  clinical materials on behalf
of its collaborators as compared to total amounts received from collaborators for the manufacture of

69

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

preclinical and clinical materials was $85,000, $1.3  million, and $515,000,  respectively. The majority of
the Company’s costs to produce these preclinical and clinical materials are fixed and then allocated to
each  batch based on the number of batches produced during the  period. Therefore,  the Company’s
costs to produce these materials are significantly impacted by the number of batches produced during
the period. The volume of preclinical and clinical  materials the Company  produces  is directly related to
the number of clinical trials the Company and its collaborators are preparing  for or  currently  have
underway, the speed of enrollment in  those trials, the  dosage schedule of each clinical trial and the
time period such trials last. Accordingly, the volume of preclinical and clinical materials produced, and
therefore the Company’s per batch costs  to  manufacture these  preclinical and clinical materials, may
vary significantly from period to period.

The Company may also produce research material for potential collaborators under  material
transfer agreements. Additionally, the Company performs research activities,  including developing
antibody  specific conjugation processes, on  behalf of its collaborators and potential collaborators during
the early evaluation and preclinical testing stages of drug  development. The Company records amounts
received for research materials produced  or services performed as a component of research and
development support revenue. The Company  also develops conjugation processes  for materials  for later
stage testing and commercialization for  certain collaborators. The Company  is compensated at
negotiated rates and may receive milestone payments  for developing  these processes which are
recorded  as a component of research  and development support revenue.

The Company’s license agreements have milestone payments which for reporting purposes are
aggregated into three categories: (i)  development milestones, (ii) regulatory milestones, and  (iii) sales
milestones. Development milestones are typically payable when a product  candidate initiates  or
advances into different clinical trial phases. Regulatory  milestones are typically payable  upon
submission for marketing approval with  the FDA or other countries’ regulatory authorities  or on
receipt of actual marketing approvals for the compound or  for additional indications. Sales milestones
are typically payable when annual sales reach certain levels.

At the inception of each agreement that includes  milestone payments, the Company evaluates
whether each milestone is substantive  and  at risk to both parties on the  basis of the  contingent nature
of the milestone. This evaluation includes  an assessment of whether (a) the consideration is
commensurate with either (1) the entity’s performance to achieve the milestone, or (2) the
enhancement of the value of the delivered item(s)  as a result of a specific outcome resulting  from the
entity’s performance to achieve the milestone,  (b) the  consideration relates solely to past performance
and (c) the consideration is reasonable relative  to  all  of the deliverables and payment terms  within the
arrangement. The Company evaluates  factors such as  the scientific, regulatory, commercial  and other
risks that must be  overcome to achieve the respective  milestone, the level of effort and investment
required to achieve the respective milestone  and  whether  the milestone consideration  is reasonable
relative to all deliverables and payment terms in the arrangement  in making this assessment.

Non-refundable development and regulatory milestones  that are expected to be achieved as a
result of the Company’s efforts during  the period of substantial involvement are considered substantive
and are recognized as revenue upon  the achievement of the milestone, assuming all other revenue
recognition criteria are met. Milestones  that  are not considered substantive because we do not
contribute effort to the achievement  of  such milestones are generally  achieved after the  period of

70

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

substantial involvement and are recognized  as revenue upon  achievement of the  milestone, as  there are
no undelivered elements remaining and  no continuing performance  obligations, assuming  all  other
revenue recognition criteria are met.

Right-to-Test Agreements

The Company’s right-to-test agreements  provide  collaborators the right  to  (a) test the Company’s

TAP technology for a defined period of  time  through a right-to-test, or  research,  license, (b) take
options, for a defined period of time, to specified targets  and (c) upon exercise of  those options, secure
or ‘‘take’’ licenses to develop and commercialize  products for the  specified targets on  established terms.
Under these agreements, fees may be  due to the Company (i)  at the inception  of the arrangement
(referred to as ‘‘upfront’’ fees or payments),  (ii) upon taking an option  with respect to a  specific target
(referred to as option fees or payments earned, if any, when the  option is ‘‘taken’’), (iii) upon  the
exercise of a previously taken option  to  acquire a  development and commercialization license(s)
(referred to as exercise fees or payments  earned, if any, when  the development and commercialization
license is ‘‘taken’’), or (iv) some combination of all of these fees.

The accounting for right-to-test agreements is  dependent on the nature  of the options granted to

the collaborative partner. Options are considered  substantive if,  at the  inception of a right-to-test
agreement, the Company is at risk as  to  whether the  collaborative partner will  choose  to  exercise  the
options to secure development and commercialization licenses. Factors that are considered  in evaluating
whether options are substantive include the  overall  objective of the arrangement,  the benefit the
collaborator might obtain from the agreement without  exercising the  options, the  cost to exercise the
options relative to the total upfront consideration, and the  additional financial commitments or
economic penalties imposed on the collaborator as a  result of  exercising the options.

For right-to-test agreements where the options to secure a development  and commercialization
licenses to the Company’s TAP technology are considered substantive, the Company does  not  consider
the development and commercialization licenses to be a  deliverable  at  the inception of the  agreement.
For those right-to-test agreements entered into prior  to  the adoption of ASU No. 2009-13 where the
options to secure development and commercialization licenses are considered substantive, the Company
has deferred the upfront payments received and recognizes this  revenue  over the period during which
the collaborator could elect to take options for development  and  commercialization  licenses.  These
periods are specific to each collaboration  agreement. If a collaborator takes an option to acquire  a
development and commercialization license under  these agreements, any substantive  option fee is
deferred and recognized over the life  of the option, generally 12 to 18  months. If a collaborator
exercises an option and takes a development and commercialization license to a specific target, the
Company attributes the exercise fee to the development and commercialization  license. Upon exercise
of an option to acquire a development  and commercialization license, the Company would also
attribute any remaining deferred option  fee to the development  and commercialization license  and
apply  the multiple-element revenue recognition criteria to  the  development and  commercialization
license and any other deliverables to  determine the  appropriate revenue recognition, which  will  be
consistent with the Company’s accounting policy  for upfront payments  on single-target licenses. In the
event a right-to-test agreement were  to  be terminated, the Company would recognize as  revenue any
portion of the upfront fee that had not  previously  been recorded as  revenue, but was classified as

71

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

deferred revenue, at the date of such  termination. None  of the Company’s  right-to-test  agreements
entered into subsequent to the adoption  of ASU  No. 2009-13  has been determined  to  contain
substantive options.

For right-to-test agreements where the options to secure development and commercialization
licenses to the Company’s TAP technology are not considered substantive, the Company  considers  the
development and commercialization licenses to be a deliverable at the  inception of the agreement  and
applies the multiple-element revenue recognition criteria to  determine the appropriate revenue
recognition. None of the Company’s right-to-test  agreements entered  into  prior to the adoption of ASU
No. 2009-13 has been determined to  contain non-substantive options.

The Company does not directly control when any  collaborator will  exercise its  options  for
development and commercialization licenses. As  a result, the  Company cannot predict  when it will
recognize revenues in connection with any of the  foregoing.

Inventory

Inventory costs primarily relate to clinical trial materials being manufactured for sale  to  the

Company’s collaborators. Inventory is stated at the lower of cost or market  as determined on a first-in,
first-out (FIFO) basis.

Inventory at June 30, 2012 and 2011  is summarized below (in thousands):

Raw materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Work in process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 129
1,159

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$1,288

$480
—

$480

June 30,

2012

2011

Raw materials inventory consists entirely of DM1 or DM4, our proprietary cell-killing agents,
which  are included in all TAP product candidates currently in  preclinical  and clinical  testing with our
collaborators. All raw materials inventory is currently procured from a single supplier.

Work in process inventory consists of  bulk drug substance manufactured  for sale to the Company’s
collaborators to be used in preclinical and clinical studies.  All bulk drug substance is  made to order at
the request of the collaborators and  subject to the terms and conditions  of  respective supply
agreements. As such, no reserve for  work in  process inventory  is required.

Raw materials inventory cost is stated  net of write-downs of $1.3  million  and $2.0  million  as of
June 30, 2012 and June 30, 2011, respectively. The  write-downs represent the cost  of  raw materials that
the Company considers to be in excess of a twelve-month supply based on firm, fixed orders and
projections from its collaborators as  of  the respective balance  sheet date.

Due to yield fluctuations, the actual amount of  raw materials that will  be  produced in future
periods under third-party supply agreements is  highly uncertain. As such, the amount of  raw materials
produced could be more than is required to support the development  of the Company’s collaborators’

72

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

product  candidates. Such excess supply, as determined  under the Company’s inventory reserve policy, is
charged to research and development  expense.

The Company produces preclinical and clinical materials for its  collaborators either in  anticipation

of or in support of preclinical studies  and  clinical trials, or for process  development and analytical
purposes. Under the terms of supply  agreements with its collaborators, the Company generally receives
rolling six-month firm, fixed orders for  conjugate  that the Company  is required  to  manufacture, and
rolling twelve-month manufacturing projections for  the quantity  of conjugate the  collaborator expects to
need in any given twelve-month period. The amount of clinical  material produced is  directly related to
the number of collaborator anticipated or  on-going clinical trials  for which the Company is producing
clinical material, the speed of enrollment  in  those trials, the  dosage schedule of each clinical trial and
the time period, if any, during which patients in the  trial receive clinical benefit from  the clinical
materials. Because these elements are difficult to estimate  over the course of a  trial,  substantial
differences between collaborators’ actual manufacturing orders and their projections could result in
usage of raw materials varying significantly from  estimated  usage at  an earlier  reporting period.  To the
extent that a collaborator has provided the  Company with  a  firm, fixed order, the collaborator is
required by contract to reimburse the Company  the full negotiated price  of  the conjugate, even if the
collaborator subsequently cancels the manufacturing run.

The Company capitalizes raw material  as inventory upon receipt and accounts for the raw material

inventory as follows:

a)

b)

c)

to the extent that the Company  has up to twelve months  of  firm, fixed  orders  and/or
projections from its collaborators, the Company capitalizes  the  value  of raw materials  that  will
be used in the production of conjugate subject to these firm, fixed orders and/or  projections;

the Company considers more than a  twelve  month supply of  raw materials that is not
supported by firm, fixed orders and/or  projections  from its collaborators to be excess and
establishes a reserve to reduce to zero the value of any  such excess raw material inventory
with a corresponding charge to research  and  development expense; and

the Company also considers any other external factors and  information of which it  becomes
aware and assesses the impact of such factors or information on  the net realizable value of the
raw  material inventory at each reporting period.

During  fiscal years 2012, 2011 and 2010,  the Company obtained  additional amounts of DMx from
its  supplier which yielded more material  than would be required by  the Company’s collaborators  over
the next twelve months and as a result, the Company  recorded $748,000,  $1.7 million and $900,000
respectively, of charges to research and  development expense  related to raw  material  inventory
identified as excess. The Company also recorded $38,000 and $28,000 as research  and development
expense to write down certain raw material inventory to its net realizable value  in fiscal years 2012 and
2010, respectively. No similar charges  were recorded during fiscal year 2011.  Increases  in the
Company’s on-hand supply of raw materials, or  a reduction  to  the Company’s collaborators’ projections,
could result in significant changes in the  Company’s  estimate of the  net realizable value of such  raw
material inventory. Reductions in collaborators’ projections could indicate that the Company has
additional excess raw material inventory and the Company would then  evaluate the need to record
further write-downs as charges to research and  development expense.

73

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

Unbilled Revenue

The majority of the Company’s unbilled revenue at June  30, 2012 and 2011  represents research

funding earned based on actual resources  utilized  under the Company’s various collaborator
agreements.

Restricted Cash

Restricted cash at June 30, 2012 and  2011 are cash  balances  securing  irrevocable letters of credit

required for security deposits for the Company’s leased facilities.  Also  included in  restricted cash  as of
June 30, 2011 were cash balances securing  irrevocable  letters of credit for the Company to receive
value added tax reimbursements related to payments to foreign vendors  for activities  previously
performed.

Other Accrued Liabilities

Other accrued liabilities consisted of  the following at June  30, 2012 and 2011  (in  thousands):

Accrued contract payments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accrued clinical trial costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accrued professional services . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accrued employee benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accrued public reporting charges . . . . . . . . . . . . . . . . . . . . . . . . .
Other current accrued liabilities . . . . . . . . . . . . . . . . . . . . . . . . . .

June 30,

2012

2011

$1,773
865
677
351
208
715

$ 684
1,068
652
277
78
546

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$4,589

$3,305

Research and Development Expenses

The Company’s research and development expenses are  charged  to  expense as incurred and relate

to (i) research to evaluate new targets  and to develop and evaluate new antibodies, linkers and
cytotoxic agents, (ii) preclinical testing of  its own and, in  certain instances,  its collaborators’ product
candidates, and the cost of its own clinical trials, (iii) development related to clinical and  commercial
manufacturing processes and (iv) manufacturing operations. Payments made by the  Company in
advance  for research and development  services not yet  provided and/or materials not yet  delivered  and
accepted are recorded as prepaid expenses and are  included in the accompanying  Consolidated Balance
Sheets as prepaid and other current assets.

Income Taxes

The Company uses the liability method  to  account for income taxes. Deferred  tax assets and
liabilities are determined based on differences between the  financial  reporting and income tax  basis of
assets and liabilities, as well as net operating loss  carry forwards  and tax credits and are measured using
the enacted tax rates and laws that will be in effect  when the  differences  reverse. A valuation allowance

74

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

against net deferred tax assets is recorded if, based  on the available  evidence, it  is more likely than  not
that some or all of the deferred tax assets  will not be realized.

Financial Instruments and Concentration of Credit  Risk

Cash and cash equivalents are primarily maintained with  three financial institutions in the  U.S.

Deposits with banks may exceed the amount of insurance provided on such deposits.  Generally,  these
deposits may be redeemed upon demand  and,  therefore, bear minimal  risk. The  Company’s cash
equivalents consist of money market funds with underlying investments  primarily being U.S.
Government-issued securities and high  quality, short-term  commercial paper. Financial instruments that
potentially subject the Company to concentrations  of credit  risk consist principally  of  cash, cash
equivalents and marketable securities.  The Company’s  cash and cash equivalents is held  at two financial
institutions. The Company held no marketable securities as of  June 30,  2012. The Company’s
investment policy, approved by the Board  of Directors, limits the amount it may invest in  any one type
of investment, thereby reducing credit risk  concentrations.

Derivative instruments include a portfolio  of  short  duration foreign  currency  forward contracts
intended to mitigate the risk of exchange  fluctuations for existing or anticipated receivable  and payable
balances denominated in foreign currency. Derivatives are  recorded at fair value  and classified  as other
current assets or liabilities. The fair value  of these  instruments  represents  the present value  of
estimated future cash flows under the  contracts, which are a function of underlying interest rates,
currency rates, related volatility, counterparty creditworthiness and duration of  the contracts.  Changes
in these factors or a combination thereof  may affect  the fair  value of these instruments.

The Company does not designate foreign  currency  forward contracts  as hedges for  accounting
purposes, and changes in the fair value of  these instruments are recognized in  earnings during the
period of change. Because the Company  enters into forward contracts  only as an  economic hedge, any
gain or loss on the underlying foreign-denominated existing  or  anticipated  receivable or payable
balance would be offset by the loss or  gain on the forward contract.  Net (losses)  gains on  forward
contracts for the years ended June 30,  2012, 2011 and  2010 were ($173,000),  $189,000 and ($219,000),
respectively, and are included in the accompanying  Consolidated  Statement of Operations  as other
(expense) income, net. As of June 30, 2012, the  Company had outstanding forward contracts  with
notional amounts equivalent to approximately $3.3  million  (A2.5 million), all maturing on or before
October 7, 2013. As of June 30, 2011,  the Company had outstanding  forward contracts with notional
amounts equivalent to approximately  $1.6  million (A1.1 million). The Company does not anticipate
using derivative instruments for any purpose other  than hedging  exchange  rate exposure.

Cash Equivalents

All highly liquid financial instruments with maturities of three months or less when  purchased are

considered cash equivalents. As of June  30, 2012 and 2011, cash equivalents consisted  of money market
funds  with underlying investments primarily  being  U.S. Government-issued  securities and high quality,
short-term commercial paper.

75

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

Marketable Securities

The Company has invested in marketable securities of highly  rated financial institutions and
investment-grade debt instruments and limits the  amount  of  credit exposure with  any one entity.  The
Company has classified its marketable securities as ‘‘available-for-sale’’ and, accordingly, carries such
securities at aggregate fair value. Unrealized gains and losses,  if any, are reported as a  component of
other comprehensive income (loss) in  shareholders’ equity.  The amortized  cost of debt securities in this
category is adjusted for amortization of  premiums and accretion of discounts to maturity. Such
amortization and accretions are included  in investment income,  net,  as well as interest  and dividends.
Realized gains and losses on available-for-sale securities  are included  in other (expense) income, net.
The cost of securities sold is based on  the specific identification method.

Other-than-Temporary Impairments

An other-than-temporary impairment  must be recognized  through earnings if  an investor  has the
intent to sell the debt security or if it  is more likely than not that the investor will be required  to  sell
the debt security before recovery of its  amortized cost basis. In the event  of a credit loss,  only  the
amount associated with the credit loss is  recognized  in net income (loss).  The amount of loss relating
to other factors is recorded in accumulated  other  comprehensive income  (loss).

The Company conducts periodic reviews  to  identify and evaluate each investment that has an

unrealized loss, which exists when the  current  fair value of an  individual security is less than  its
amortized cost basis. Unrealized losses on available-for-sale securities that are determined to be
temporary, and not related to credit loss,  are recorded in  accumulated  other  comprehensive income
(loss).

For available-for-sale debt securities  with unrealized losses,  management performs an analysis to

assess whether it intends to sell or whether it  would more  likely than not be required  to  sell the
security before the expected recovery of  the amortized cost  basis. Where the Company  intends to sell a
security, or may be required to do so,  the  security’s decline in  fair value is  deemed to be
other-than-temporary and the full amount  of the unrealized loss  is recorded in  the statement of
operations as an other-than-temporary impairment charge. When this is not the  case, the Company
performs additional analysis on all securities with unrealized losses  to  evaluate losses  associated with
the creditworthiness of the security. Credit losses  are identified where the  Company does not expect  to
receive cash flows, based on using a single best estimate, sufficient  to  recover  the amortized cost basis
of a security and these are recognized  as other-than-temporary impairment.

Fair Value of Financial Instruments

ASC Topic 820 defines fair value, establishes  a framework for  measuring  fair value  in accordance

with accounting principles generally accepted in the U.S., and  expands disclosures about fair value
measurements. Certain provisions of  ASC Topic  820 related  to  other non-financial  assets and liabilities
were adopted by the Company on July 1,  2009 and did not have  a  material impact on  its financial
position or results of operations upon adoption; however, this standard may impact the Company in
subsequent periods and require additional disclosures.

76

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

Fair value is defined under ASC Topic  820 as the  exchange price that  would be received  for an
asset or paid to transfer a liability (an  exit price) in the  principal or most advantageous market for  the
asset or liability in an orderly transaction  between market participants on  the measurement date.
Valuation techniques used to measure fair  value must maximize the use of observable inputs and
minimize the use of unobservable inputs.  The standard  describes a fair value hierarchy to measure fair
value which is based on three levels of  inputs, of which the first two are considered observable and  the
last unobservable, as follows:

(cid:129) Level 1—Quoted prices in active markets for identical assets  or liabilities.

(cid:129) Level 2—Inputs other than Level 1  that are observable,  either  directly or  indirectly, such as
quoted prices for similar assets or liabilities;  quoted prices in  markets that  are not active; or
other inputs that are observable or can be corroborated  by observable market data for
substantially the full term of the assets or liabilities.

(cid:129) Level 3—Unobservable inputs that  are  supported by little or no  market  activity and that are

significant to the fair value of the assets  or liabilities.

As of June 30, 2012, the Company held  certain assets that are required to be measured  at fair

value on  a recurring basis. The following  table  represents the fair  value hierarchy for the Company’s
financial assets measured at fair value on a recurring basis as of  June  30, 2012 (in thousands):

Cash, cash equivalents and restricted cash .

$163,488

Total

$163,488

Fair Value Measurements at June 30, 2012 Using

Quoted Prices in
Active Markets for
Identical Assets

Significant Other
Observable Inputs

Significant
Unobservable
Inputs

(Level 1)

$163,488

$163,488

(Level 2)

(Level 3)

$—

$—

$—

$—

As of June 30, 2011, the Company held  certain assets that are required to be measured  at fair

value on  a recurring basis. The following  table  represents the fair  value hierarchy for the Company’s
financial assets measured at fair value on a recurring basis as of  June  30, 2011 (in thousands):

Cash, cash equivalents and restricted cash .

$194,774

Total

$194,774

Fair Value Measurements at June 30, 2011 Using

Quoted Prices in
Active Markets for
Identical Assets

Significant Other
Observable Inputs

Significant
Unobservable
Inputs

(Level 1)

$194,774

$194,774

(Level 2)

(Level 3)

$—

$—

$—

$—

The fair value of the Company’s cash equivalents is  based primarily on quoted  prices from active

markets.

77

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

The carrying amounts reflected in the consolidated balance sheets for accounts  receivable, unbilled
revenue, prepaid and other current assets, accounts  payable, accrued compensation,  and other accrued
liabilities approximate fair value due  to  their  short-term nature.

Property and Equipment

Property and equipment are stated at  cost. The Company  provides for depreciation  based upon

expected useful lives using the straight-line  method over the  following  estimated useful lives:

Machinery and equipment . . . . . . . . . .
Computer hardware and software . . . . .
Furniture and fixtures . . . . . . . . . . . . .
Leasehold improvements . . . . . . . . . . .

5 years
3 years
5 years
Shorter of remaining lease term or 7 years

Maintenance and repairs are charged to expense as  incurred. Upon retirement or sale, the cost  of

disposed assets and the related accumulated depreciation are  removed from  the accounts and any
resulting gain or loss is included in the statement of  operations.  The  Company recorded $51,000,  $9,000
and $41,000 of losses on the sale/disposal of certain furniture and equipment  during the years ended
June 30, 2012, 2011, and 2010, respectively.

Impairment of Long-Lived Assets

In accordance with ASC Topic 360, ‘‘Property,  Plant, and  Equipment,’’  the Company continually
evaluates whether events or circumstances have occurred that indicate  that  the estimated remaining
useful life of its long-lived assets may warrant  revision or  that the carrying value of these assets  may be
impaired. The Company evaluates the realizability  of its  long-lived assets  based on cash  flow
expectations for the related asset. Any write-downs are  treated as permanent  reductions in  the carrying
amount of the assets. Based on this evaluation, the Company believes that, as of  each  of the balance
sheet dates presented, none of the Company’s long-lived assets were impaired.

Computation of Net Loss Per Common Share

Basic and diluted net loss per common share is calculated  based upon  the weighted average
number of common shares outstanding during the period. The Company’s  common stock equivalents,
as calculated in accordance with the  treasury-stock method, are shown  in the following table (in
thousands):

Options outstanding to purchase common stock . . . . . . . . . .
Common stock equivalents under treasury stock method . . . .

6,442
2,194

6,491
1,901

6,065
1,853

The Company’s common stock equivalents  have not been included in the  net loss  per  share

calculation because their effect is anti-dilutive  due  to  the Company’s net  loss position.

June 30,

2012

2011

2010

78

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

Stock-based Compensation

As of June 30, 2012, the Company is  authorized  to  grant future awards under one employee  share-

based compensation plan, which is the  ImmunoGen, Inc. 2006 Employee, Director and Consultant
Equity Incentive Plan, or the 2006 Plan.  On  November 16, 2010,  the  Company’s shareholders  approved
an amendment to  the 2006 Plan to increase  the number of shares of common  stock  authorized for
issuance thereunder by 4,000,000. As amended, the  2006 Plan provides for  the issuance of Stock
Grants, the grant of Options and the  grant  of  Stock-Based Awards for up to 8,500,000 shares of the
Company’s common stock, as well as  any  shares of common stock  that are represented by awards
granted under the previous stock option plan, the  ImmunoGen, Inc.  Restated Stock Option Plan, or the
Former Plan, that are forfeited, expire or are cancelled without  delivery of shares  of common stock;
provided, however, that no more than 5,900,000  shares shall be added to  the Plan from the  Former
Plan, pursuant to this provision. Option awards  are granted with  an exercise price  equal to the market
price of the Company’s stock at the date of  grant. Options vest  at  various periods of up  to  four years
and may be exercised within ten years  of  the date  of grant.

The stock-based awards are accounted for under  ASC Topic  718, ‘‘Compensation—Stock

Compensation.’’ Pursuant to Topic 718, the  estimated  grant  date fair value  of  awards is charged  to  the
statement of operations over the requisite  service period,  which is the  vesting period. Such amounts
have been reduced by an estimate of  forfeitures of all unvested  awards. The fair value of each stock
option is estimated on the date of grant  using the Black- Scholes  option-pricing model with the
assumptions noted in the following table. As the  Company has not paid dividends since  inception, nor
does it expect to pay any dividends for the foreseeable future,  the expected dividend yield assumption
is zero. Expected volatility is based exclusively  on historical volatility  data  of the Company’s  stock. The
expected term of stock options granted  is  based exclusively on historical data and  represents the period
of time that stock options granted are  expected to be outstanding.  The expected  term is calculated for
and applied to one group of stock options  as the Company  does not expect  substantially different
exercise or post-vesting termination behavior amongst its employee population. The  risk-free rate of the
stock options is based on the U.S. Treasury  rate in effect at the  time of grant  for the  expected term of
the stock options.

Year Ended June 30,

2012

2011

2010

Dividend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Volatility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Risk-free interest rate . . . . . . . . . . . . . . . . . . . . . . .
Expected life (years) . . . . . . . . . . . . . . . . . . . . . . .

None
None
None
59.70% 58.81% 59.90%
3.19%
2.43%
2.16%
7.0
7.2
7.1

Using the Black-Scholes option-pricing model, the weighted average grant  date fair  values  of
options granted during fiscal 2012, 2011 and 2010  were $9.00, $5.51, and $5.83 per share, respectively.

Stock compensation expense related to stock options granted under the  2006 Plan was $9.9 million,

$5.5 million and $4.2 million during the fiscal years ended June  30, 2012, 2011, and  2010, respectively.

79

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

A summary of option activity under the  Plan  as of June 30, 2012, and changes during the twelve

month period then ended is presented below (in thousands, except weighted-average data):

Outstanding at June 30, 2011 . . . . . . . . .
Granted . . . . . . . . . . . . . . . . . . . . . . . .
Exercised . . . . . . . . . . . . . . . . . . . . . . .
Forfeited/Canceled . . . . . . . . . . . . . . . . .

Number of
Stock
Options

6,491
1,657
(1,432)
(274)

Outstanding at June 30, 2012 . . . . . . . . .

6,442

Outstanding at June 30, 2012—vested  or

unvested and expected to vest . . . . . . .

Exercisable at June 30, 2012 . . . . . . . . . .

6,135

3,416

Weighted- Weighted-
Average
Average
Remaining
Exercise
Life in Yrs
Price

Aggregate
Intrinsic
Value

$ 6.70
$14.89
$ 4.88
$12.16

$ 8.98

$ 9.21

$ 6.34

6.87

$50,001

6.79

5.48

$48,662

$35,525

As of June 30, 2012, the estimated fair value of unvested  employee awards was approximately
$11.4 million, net of estimated forfeitures. The weighted-average remaining  vesting  period for these
awards is approximately two years.

A summary of option activity for shares vested during the fiscal years ended June 30, 2012,  2011

and 2010 is presented below (in thousands):

Total fair value of shares vested . . . . . . . . . . . . . . . . . . .
Total intrinsic value of options exercised . . . . . . . . . . . . .
Cash received for exercise of stock options . . . . . . . . . . .

$ 5,647
12,476
6,988

$3,427
3,467
2,719

$2,410
1,888
3,462

Year Ended June 30,

2012

2011

2010

Comprehensive Loss

The Company presents comprehensive loss  in accordance with ASC Topic 220, Comprehensive
Income. Comprehensive loss is comprised of the  Company’s  net loss  for the  period and unrealized  gains
and losses on available-for-sale marketable securities.

Segment Information

During  the three fiscal years ended June 30, 2012,  the Company continued to operate in  one
reportable business segment under the management approach of ASC Topic 280, Segment Reporting,
which  is the business of discovery of monoclonal antibody-based anticancer therapeutics.

80

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2012

B. Summary of Significant Accounting Policies (Continued)

The percentages of revenues recognized from significant customers of  the  Company in  the years

ended June 30, 2012, 2011 and 2010  are  included  in the following table:

Collaborative Partner:

Amgen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bayer HealthCare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biogen Idec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biotest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Novartis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sanofi

Year Ended June 30,

2012

2011

2010

30% 41% 32%
15% 17% 15%
2% 1% 13%
14% 9% 9%
16% 7% —%
23% 23% 28%

There were no other customers of the  Company with  significant revenues  in the years ended

June 30, 2012, 2011 and 2010.

Recent Accounting Pronouncements

In May 2011, the FASB issued ASU  No.  2011-04, ‘‘Fair Value  Measurement.’’  This ASU  clarifies

the concepts related to highest and best  use and valuation premise, blockage factors and  other
premiums and discounts, the fair value measurement of  financial instruments  held in a  portfolio  and of
those instruments classified as a component of  shareholders’  equity. The guidance includes enhanced
disclosure requirements about recurring  Level 3 fair value measurements, the use of nonfinancial
assets, and the level in the fair value hierarchy of  assets and liabilities  not recorded  at fair  value. The
provisions of this ASU are effective prospectively for annual periods,  and interim  periods within those
years, beginning on or after December 15,  2011. Early  application is prohibited. The Company does not
expect the adoption of these provisions to have  a significant impact on  its  financial statements.

In June 2011, the FASB issued ASU No. 2011-05,  ‘‘Comprehensive Income.’’  This ASU intends to

enhance comparability and transparency of other comprehensive income components. The  guidance
provides an option to present total comprehensive  income, the components of  net income and  the
components of other comprehensive income in a single continuous statement  or two  separate but
consecutive statements. This ASU eliminates the  option to present other comprehensive income
components as part of the statement  of  changes in shareholders’ equity. The provisions of this ASU
will be applied retrospectively for annual  periods, and interim periods within  those years, beginning
after December 15, 2011. Early application is  permitted. The  Company does  not  expect the  adoption of
these provisions to have a significant impact on its  financial  statements.

C. Agreements

Significant Collaborative Agreements

Roche

In May 2000, the Company granted Roche,  through its  Genentech unit, an  exclusive  license to the

Company’s maytansinoid TAP technology  for use with  antibodies or other  proteins that target  HER2,
such as trastuzumab. Under the terms  of this  agreement, Roche  has exclusive worldwide rights  to
develop and commercialize maytansinoid  TAP compounds with  antibodies  that  target HER2.  The

81

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

C. Agreements (Continued)

product  candidate T-DM1 is currently  in development  under this agreement. Roche is responsible for
the manufacturing, product development  and marketing of any  products resulting  from the agreement.
The Company is compensated for any preclinical and clinical materials that the  Company manufactures
under the agreement. The Company received a  $2 million non-refundable  upfront payment from
Roche upon execution of the agreement.  The Company is  also entitled to  receive up  to  a total of
$44 million in milestone payments, plus  royalties on the commercial sales of any resulting  products.
Total milestones are categorized as follows: development milestones—$13.5 million; and regulatory
milestones—$30.5 million. Through June  30,  2012, the Company has received and  recognized
$13.5 million in milestone payments related to T-DM1, which were  all development milestones.  Roche
began Phase II evaluation of T-DM1  in  July 2007 and the Company received  and recognized a
$5 million milestone payment with this event.  Roche  began  Phase III evaluation  of  T-DM1 in
February 2009 and the Company received and recognized a $6.5  million milestone payment  with this
event. At the time  of execution of this  agreement, there  was  significant uncertainty as to whether  these
received and recognized milestones would  be achieved.  In  consideration of this, as well  as the
Company’s past involvement in the research and manufacturing  of  this product, these milestones were
deemed substantive. The next potential milestone the Company will  be  entitled to receive  will be a
regulatory milestone for marketing approval of T-DM1.  As this could occur  first  in either the  U.S. or
Europe, the next potential milestone due  will  be  either $10.5 million with first approval in  the U.S.  or
$5 million with first approval in Europe. Based  on an  evaluation of the  effort  contributed to the
achievement of these milestones, the Company  has determined these milestones  are not substantive.

Roche, through its Genentech unit, also  has licenses for the exclusive right  to  use the Company’s
maytansinoid TAP technology with antibodies  to  four undisclosed targets,  which were granted under  the
terms of a separate May 2000 right-to-test agreement with Genentech. For each  of  these  licenses the
Company received a $1 million license  fee and is entitled  to receive up  to  a total of $38  million in
milestone payments and also royalties on  the sales of any resulting  products. The total  milestones are
categorized as follows: development milestones—$8 million; regulatory milestones—$20 million; and
sales milestones—$10 million. The Company has not received any milestone payments  from these
agreements through June 30, 2012. Roche is responsible  for the development, manufacturing, and
marketing of any products resulting from  these licenses.  The next potential milestone the Company  will
be entitled to receive under any of these agreements  will be a development milestone for filing of an
Investigational New Drug (IND) application  which will result in a $1  million  payment being due. At the
time of execution of each of these development  and commercialization licenses,  there was significant
uncertainty as to whether this milestone would be achieved.  In consideration  of this,  as well as the
Company’s past involvement in the research and manufacturing  these products, this milestone  was
deemed substantive. Roche no longer  has the  right to take additional licenses  under the right-to-test
agreement. The Company received non-refundable technology access fees totaling $5  million  for the
eight-year term of the right-to-test agreement. The upfront  fees  were  deferred and recognized  ratably
over the period during which Genentech  could  elect  to  obtain  product licenses.

Amgen

In September 2000, the Company entered into a  ten-year right-to-test agreement  with

Abgenix, Inc., which was later acquired by Amgen. The agreement provides  Amgen with  the right to
(a) test the Company’s maytansinoid TAP  technology with Amgen’s antibodies under  a right-to-test,  or

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C. Agreements (Continued)

research, license, (b) take options, with  certain restrictions, to individual targets selected by Amgen on
either an exclusive and non-exclusive basis  for  specified option  periods and (c) upon exercise of those
options, take exclusive or non-exclusive  licenses  to  use the Company’s maytansinoid TAP technology  to
develop and commercialize products  for the specified  targets on  previously  agreed-upon terms.  The
Company received a $5 million technology access  fee in September 2000. Amgen no longer  has the
right to take additional options under the agreement, although multiple outstanding options remain in
effect for the remainder of their respective option periods.  For  each  exclusive  development and
commercialization license taken, the  Company is entitled to receive an exercise fee of $1  million and
up to a total of $34 million in milestone payments,  plus royalties  on the commercial  sales of  any
resulting products. The total milestones  per  development and commercialization license are categorized
as follows: development milestones—$9 million; regulatory  milestones—$20 million; and sales
milestones—$5 million. Amgen is responsible for  the manufacturing, product  development and
marketing of any products resulting from  the agreement.

Under the right-to-test agreement, in September 2009 and November  2009 Amgen took two
development and commercialization licenses and  the Company received an  exercise fee  of $1 million
for each  license taken. The Company has deferred each $1  million exercise  fee  and is recognizing  these
amounts as revenue ratably over the respective  estimated  periods of its substantial involvement. In
November 2011, the IND applications  to  the FDA  for two compounds developed under the September
2009 and November 2009 development and  commercialization licenses became effective, which
triggered two $1 million milestone payments to the  Company. These payments are included  in license
and milestone fees for the year ended  June 30,  2012. At the time of execution of each of these
development and commercialization licenses, there was  significant uncertainty as to whether  these
received and recognized milestones would  be achieved.  In  consideration of this, as well  as the
Company’s past involvement in the research and manufacturing  of  these product candidates, these
milestones were deemed substantive.  The next  potential milestone the  Company will be entitled to
receive under either of these development  and commercialization licenses  will be a  development
milestone for the first dosing of a patient  in  a Phase  II clinical trial, which  will result in a  $3 million
payment being due. At the time of execution of  each  of these development and  commercialization
licenses, there was significant uncertainty  as to whether this milestone would be achieved.  In
consideration of this, as well as the Company’s past involvement in the research and manufacturing of
these product candidates, this milestone was deemed substantive.

In September 2010, Amgen took a combination of  exclusive and non-exclusive options with  respect

to specific targets. For each option taken,  Amgen  paid the Company a nominal fee.

Sanofi

In July 2003, the Company entered into a broad collaboration agreement  with Sanofi  (formerly
Aventis) to discover, develop and commercialize antibody-based  products.  The  collaboration agreement
provides Sanofi with worldwide development and commercialization  rights to new antibody-based
products directed to targets that are included  in the collaboration,  including the  right to use  the
Company’s TAP technology and humanization  technology in the  creation of products developed to
these targets. The product candidates (targets) as of June 30, 2012 in the collaboration  include

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C. Agreements (Continued)

SAR3419 (CD19), SAR650984 (CD38),  SAR566658 (DS6, also known  as CA6)  and at least one earlier-
stage compound that has yet to be disclosed.

For each of the targets included in the collaboration at this time,  the Company is entitled to
receive up to a total of $21.5 million  in milestone payments,  plus royalties on the  commercial sales of
any resulting products. The total milestones are categorized as follows: development milestones—
$7.5 million; and regulatory milestones—$14 million. Through June 30,  2012, the Company  has received
and recognized an aggregate of $16 million in  milestone payments for  compounds covered under this
agreement now or in the past, including a  $3 million milestone payment related to the  initiation of a
Phase IIb clinical trial (as defined in the agreement) for SAR3419, which is  included in  license and
milestone fee revenue for the year ended June 30, 2012, as well as a $1  million  milestone payment
earned in September 2010 related to the  initiation  of  Phase I clinical testing of SAR566658 which is
included in license and milestone fee  revenue for the year  ended  June  30, 2011. At the  time of
execution of this agreement, there was significant  uncertainty as to whether these  received  and
recognized milestones would be achieved.  In consideration of  this, as well as the  Company’s past
involvement in the research and manufacturing  of these  product candidates, these milestones were
deemed substantive. The next potential milestone the Company will  be  entitled to receive  with respect
to each of SAR566658 and for SAR650984  will  be  a development milestone  for initiation  of a
Phase IIb clinical trial (as defined in the agreement), which will  result  in each case in  a $3 million
payment being due. The next potential milestone the  Company will be entitled to receive with respect
to SAR3419 will be for initiation of a Phase  III clinical trial, which will result  in a $3  million payment
being due. The next potential milestone  the Company will be entitled to receive for each of the
unidentified targets will be a development milestone  for  commencement of a  Phase I clinical trial,
which  will result in a $1 million payment  being due, or a preclinical milestone  which will result in a
$500,000 payment being due. At the  time  of execution of this agreement, there was significant
uncertainty as to whether these milestones  would be achieved.  In consideration  of  this,  as well as  the
Company’s past involvement in the research and manufacturing  of  these product candidates, these
milestones were deemed substantive.

In December 2006, the Company entered into a separate right-to-test  agreement with  Sanofi. The
agreement provides Sanofi with the right  to (a) test  the Company’s maytansinoid  TAP technology with
Sanofi’s antibodies to targets that were  not  included in  the collaboration agreement  described above
under a right-to-test, or research, license, (b)  take exclusive  options, with  certain restrictions,  to
specified targets for specified option periods and (c)  upon exercise  of those options, take exclusive
licenses to use the Company’s maytansinoid TAP technology  to  develop and commercialize products
directed to the specified targets on terms agreed upon  at the  inception of the right-to-test agreement.
For each  development and commercialization license taken, the Company is entitled to receive an
exercise fee of $2 million and up to a  total of $30 million in  milestone payments, plus royalties on the
commercial sales of any resulting products. The total milestones are categorized as  follows:
development milestones—$10 million;  and  regulatory milestones—$20 million.  No development  and
commercialization license has yet been taken under this  agreement. Execution  of the first license will
entitle the Company to receive an exercise fee in  the amount of $2 million. Sanofi is responsible for
the manufacturing, product development  and marketing of any  products resulting  from the agreement.

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C. Agreements (Continued)

The Company received an aggregate of $4 million under  the right-to-test  agreement, of which
$500,000 was received in December 2006  upon execution of the agreement, and $3.5 million of which
was received in August 2008 upon Sanofi’s activation  of  its  rights under the agreement. The
right-to-test agreement had a three-year original  term from the  activation date  and was renewed by
Sanofi in August 2011for its final three-year term by  payment of a  $2 million  fee.  The  Company has
deferred the $2 million extension fee  and  is recognizing this  amount as revenue over the period during
which  Sanofi can take an option for a  development and  commercialization license.

Biotest

In July 2006, the Company granted Biotest an  exclusive  development and commercialization
license to our maytansinoid TAP technology for use  with antibodies that target  CD138. The product
candidate BT-062 is currently in development  under this agreement. Biotest is responsible for  the
manufacturing, product development and marketing of any products resulting from the  agreement. The
Company received a $1 million upfront payment upon execution of  the  agreement and  could  receive up
to $35.5 million in milestone payments, as  well as  royalties on  the commercial sales of any resulting
products. The total milestones are categorized  as follows:  development milestones—$4.5 million;  and
regulatory milestones—$31 million. The Company receives payments for manufacturing any preclinical
and clinical materials made at the request  of Biotest. In September 2008,  Biotest  began Phase I
evaluation of BT062 which triggered a  $500,000  milestone payment to the  Company. At the time of
execution of this agreement, there was significant  uncertainty as to whether this  received  and
recognized milestone would be achieved. In consideration of this, as well as the  Company’s past
involvement in the research and manufacturing  of this  product candidate, this  milestone was deemed
substantive. The next potential milestone the Company  will be entitled  to receive will be a development
milestone for commencement of a Phase IIb clinical trial (as defined in  the agreement) which will
result in a $2 million payment being due. At the time of execution of  this agreement,  there was
significant uncertainty as to whether  this milestone would be achieved. In consideration of this, as  well
as the Company’s past involvement in the  research and manufacturing of  this product, this  milestone
was deemed substantive.

The agreement also provides the Company with the right to elect at specific stages  during the
clinical evaluation of any compound  created under this  agreement, to participate in the United  States
development and commercialization of that compound in lieu of receiving  the milestone payments not
yet earned and royalties on sales in the United States. The Company can exercise this right  during  an
exercise period specified in the agreement by  notice  and  payment to Biotest of an agreed  upon opt-in
fee of $5 million or $15 million, depending on the stage of development. Upon exercise of this right,
the Company would share equally with Biotest the associated costs of product development and
commercialization in the United States along with  the profit, if any, from  product sales in the  United
States.

Bayer HealthCare

In October 2008, the Company granted Bayer HealthCare an exclusive development and

commercialization license to the Company’s  maytansinoid TAP technology  for use with  antibodies  or
other proteins that target mesothelin. Bayer HealthCare is  responsible for the  research,  development,

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AS OF JUNE 30, 2012

C. Agreements (Continued)

manufacturing and marketing of any products resulting from the license. The Company received a
$4 million upfront payment upon execution  of the agreement,  and—for  each compound developed and
marketed by Bayer HealthCare under  this collaboration—the Company is  entitled to receive  a total of
$170.5 million in milestone payments, plus  royalties on the commercial sales of any resulting  products.
The total milestones are categorized  as follows: development milestones—$16  million; regulatory
milestones—$44.5 million; and sales milestones—$110 million. Through June 30,  2012, the Company
has received and recognized an aggregate  of $3 million in milestone payments under this agreement.  At
the time of execution of this agreement, there was significant uncertainty as to whether these received
and recognized milestones would be achieved. In  consideration of this, as well as the Company’s past
involvement in the research and supply  of  cytotoxic agent for this product  candidate, these milestones
were deemed substantive. The next potential  milestone the Company will  be  entitled to receive will be
a development milestone for commencement of  a non-pivotal Phase II  clinical trial,  which will result in
a $4 million payment being due. At the time of execution of this  agreement,  there was significant
uncertainty as to whether this milestone would be achieved.  In consideration  of this,  as well as the
Company’s past involvement in the research and supply of cytotoxic agent for this product candidate,
this  milestone was deemed substantive.

The Company had previously deferred the  $4 million upfront payment received  and was

recognizing this amount as revenue ratably over  the estimated period of substantial  involvement. The
Company had previously estimated this  development period would  conclude at the  end of non-pivotal
Phase II testing. During the first quarter of fiscal 2012, Bayer HealthCare initiated Phase I clinical
testing of its product candidate. In reaching this stage of clinical testing, Bayer  HealthCare developed
its  own processes for manufacturing required clinical  material  and produced clinical  material  in its own
manufacturing facility. Considering that Bayer HealthCare was  able to accomplish  this without
significant reliance on the Company,  and  considering  that the Company’s expected future involvement
will be primarily supplying Bayer HealthCare with small quantities  of cytotoxic agents for a limited
period of time, the Company believes its  period of substantial  involvement will end  prior to the
completion of non-pivotal Phase II testing. As a result  of this determination,  beginning  in September
2011, the Company is recognizing the balance of the upfront payment as revenue ratably through
September 2012. This change in estimate results in an  increase to license  and  milestone fees of
approximately $1.2 million for the fiscal  year ending June 30,  2012 compared to amounts  that  would
have been recognized pursuant to the  Company’s previous  estimate.

Novartis

In October 2010, the Company entered  into  a three-year right-to-test agreement with  Novartis
Institutes for BioMedical Research, Inc.  (Novartis). The agreement provides  Novartis with the  right to
(a) test the Company’s TAP technology with individual  antibodies selected by Novartis under  a
right-to-test, or research, license, (b)  take exclusive options, with  certain restrictions,  to  individual
targets selected by Novartis for specified option periods and (c) upon exercise  of  those options, take
exclusive licenses to use the Company’s TAP technology to  develop and commercialize  products for a
specified number of individual targets on  terms  agreed upon  at  the  inception of the right-to-test
agreement. The initial three-year term  of the right-to-test agreement may  be  extended by Novartis for
up to two additional one-year periods by  payment of  additional consideration. The  terms of the
right-to-test agreement require Novartis to exercise  its options for the development  and

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AS OF JUNE 30, 2012

C. Agreements (Continued)

commercialization licenses by the end  of  the term of  the research license.  The  Company received a
$45 million upfront payment in connection  with the  execution  of  the right-to-test agreement, and for
each  development and commercialization license for a specific  target, the Company is entitled to
receive an exercise fee of $1 million and  up to a  total  of $199.5 million in milestone payments,  plus
royalties on the commercial sales of any  resulting products. The  total milestones are  categorized  as
follows: development milestones—$22.5 million; regulatory  milestones—$77 million;  and sales
milestones—$100 million. No development and  commercialization license has yet been taken under this
agreement. Execution of the first license  will entitle the Company to receive an exercise fee in  the
amount of $1 million. The Company  also  is entitled to receive payments for research and development
activities performed on behalf of Novartis.  Novartis is  responsible  for the  manufacturing, product
development and marketing of any products resulting from this agreement.

In accordance with ACS 605-25 (as amended  by  ASU  No. 2009-13), the  Company identified all of

the deliverables at the inception of the  right-to-test agreement. The  significant deliverables  were
determined to be the right-to-test, or research,  license, the  exclusive  development and
commercialization licenses, rights to  future technological  improvements, and the research services. The
options to obtain development and commercialization licenses in the  right-to-test  agreement were
determined not to  be substantive and, as  a  result, the exclusive development  and commercialization
licenses were considered deliverables  at the inception  of  the right-to-test agreement. Factors that were
considered in determining the options were not substantive  included (i) the overall objective of the
agreement was for Novartis to obtain development  and  commercialization licenses, (ii) the  size of the
exercise fee of $1 million for each development  and commercialization license  obtained  is not
significant relative to the $45 million  upfront payment  that was due at the  inception of the right-to-test
agreement, (iii) the limited economic  benefit that Novartis could  obtain  from the right-to-test
agreement unless it exercised its options  to  obtain  development and commercialization licenses, and
(iv) the  lack of economic penalties as  a  result  of  exercising the  options.

The Company has determined that the research license together with the development and

commercialization licenses represent  one  unit  of  accounting as the  research license  does not have
stand-alone value from the development and commercialization licenses due to the lack of
transferability of the research license and the limited economic benefit Novartis would  derive  if they
did not obtain any development and commercialization licenses. The Company  has also  determined
that this unit of accounting does have stand-alone value from  the  rights to future technological
improvements and the research services. The rights to future technological improvements and the
research services are considered separate units of  accounting as each  of these  was determined to have
stand-alone value. The rights to future technological improvements have  stand-alone value as Novartis
would be able to use those items for  their  intended purpose without  the undelivered elements. The
research services have stand-alone value  as similar services are sold separately by other vendors. The
estimated selling prices for the development and commercialization licenses are  the Company’s  best
estimate of selling price and were determined based  on market conditions,  similar arrangements
entered into by third parties, including  pricing terms offered by our competitors for single-target
development and commercialization licenses that utilize antibody-drug conjugate technology,  and entity-
specific  factors such as the pricing terms  of  the Company’s previous single-target development  and
commercialization licenses, recent preclinical and clinical testing  results of therapeutic products that use
the Company’s TAP technology, and  the Company’s pricing practices and pricing  objectives.  The

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C. Agreements (Continued)

estimated selling price of the right to  technological improvements is the Company’s best estimate of
selling price and was determined by estimating the probability that  technological improvements will  be
made and the probability that such technological  improvements  made will be used by Novartis. In
estimating these probabilities, we considered  factors such as the technology that is the  subject of the
development and commercialization licenses, our history of making technological improvements,  and
when such improvements, if any, were likely to occur  relative  to  the  stage of development of  any
product  candidates pursuant to the development and commercialization  licenses.  The  Company’s
estimate of probability considered the  likely  period of time that  any improvements would be utilized,
which  was estimated to be ten years following delivery of a  commercialization and development license.
The value of any technological improvements  made available after this ten year  period was  considered
to be de minimis due to the significant additional costs  that would be incurred to incorporate such
technology into any existing product candidates.  The estimate  of  probability was multiplied by the
estimated selling price of the development  and commercialization licenses  and the  resulting cash flow
was discounted at a rate of 16%, representing the Company’s  estimate of its cost  of capital. The
estimated selling price of the research services was based on  third-party evidence given the nature of
the research services to be performed for  Novartis and market rates for similar services. The  total
arrangement consideration of $55.1 million (which is  comprised of the  $45 million upfront payment,  the
exercise fee for each license, and the  expected fees for the research services  to  be  provided under the
arrangement) was allocated to the deliverables based on  the relative selling price  method as  follows:
$47.3 million to the development and  commercialization  licenses;  $3.9 million to the rights to future
technological improvements; and $3.9 million to the research services. The  Company will recognize as
license revenue an equal amount of the  total arrangement consideration allocated to the development
and commercialization licenses as each  individual license is  delivered to Novartis  upon Novartis’
exercise of its options to such licenses.  At the  time the  first development and commercialization license
is taken, the amount of the total arrangement consideration  allocated to future technological
improvements will commence to be recognized as  revenue  ratably over  the period  the Company is
obligated to make available any technological improvements, which  is equivalent  to  the estimated term
of the agreement. The Company estimates  the term of  a development and commercialization license to
be approximately 25 years, which reflects  management’s estimate of the time necessary to develop and
commercialize products pursuant to the  license  plus the estimated royalty term. The Company will  be
required to reassess the estimated term at  each subsequent  reporting period.  The Company does not
control when Novartis will exercise its  options  for development  and commercialization licenses.  As a
result, the Company cannot predict when  it will  recognize the related license  revenue except that it will
be within the term of the research license. The Company will recognize research services revenue as
the related services are delivered.

No license revenue has been recognized  related to the right-to-test  agreement  through June 30,

2012, as the options to take development  and  commercialization licenses  were not considered
substantive and no development and commercialization  licenses have  been taken. Accordingly, the
entire $45 million upfront payment is  included in  long-term deferred revenue at June 30, 2012.

Lilly

In December 2011, the Company entered into a three-year right-to-test  agreement with  Eli Lilly
and Company (Lilly). The agreement provides Lilly with  the right to (a) take exclusive options,  with

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C. Agreements (Continued)

certain restrictions, to individual targets selected by Lilly  for specified  option  periods, (b) test the
Company’s maytansinoid TAP technology  with  Lilly’s antibodies directed to the optioned targets under
a right-to-test, or research, license, and  (c) upon  exercise  of  those options, take exclusive licenses to use
the Company’s maytansinoid TAP technology to develop and commercialize products for a specified
number of individual targets on terms  agreed upon at the inception  of  the right-to-test agreement. The
terms of the right-to-test agreement require Lilly to exercise its  options  for the development and
commercialization licenses by the end  of  the term of  the research license.  The  Company received a
$20 million upfront payment in connection  with the  execution  of  the right-to-test agreement, and for
the first development and commercialization  license taken, the Company  is entitled to receive up  to  a
total of $200.5 million in milestone payments, plus royalties on the  commercial sales  of any  resulting
products. For each subsequent development  and commercialization license  taken, the  Company is
entitled to receive an exercise fee in  the  amount  of $2 million and  up to a  total  of $199 million in
milestone payments, plus royalties on the  commercial sales of any resulting products. The total
milestones are categorized as follows:  development milestones—$30.5 million for the first development
and commercialization license and $29  million  for each  subsequent license; regulatory  milestones—
$70 million; and sales milestones—$100 million. No development and commercialization license has  yet
been taken under this agreement. The next payment the Company could receive would either  be  a
$5 million development milestone payment with  the initiation of a Phase I clinical trial under the first
development and commercialization license taken, or a $2 million  exercise fee  for the  execution of a
second  license. At the time of execution  of  this agreement, there  was  significant uncertainty as to
whether the milestone related to initiation  of a Phase I  clinical trial under the  first  development and
commercialization license would be achieved. In  consideration of this, as  well  as the Company’s
expected involvement in the research  and manufacturing of these product candidates,  this milestone
was deemed substantive. The Company also is  entitled to receive payments for delivery of cytotoxic
agents to Lilly and research and development activities performed on behalf  of Lilly. Lilly is responsible
for the manufacturing, product development  and marketing of any  products resulting  from this
collaboration.

In accordance with ASC 605-25 (as amended by ASU No.  2009-13), the Company identified all of

the deliverables at the inception of the  right-to-test agreement. The  significant deliverables  were
determined to be the right-to-test, or research,  license, the  exclusive  development and
commercialization licenses, rights to  future technological  improvements, delivery of  cytotoxic  agents and
the research services. The options to  obtain development  and  commercialization  licenses  in the
right-to-test agreement were determined not to be substantive and, as a result, the exclusive
development and commercialization licenses were considered deliverables at  the inception of the
right-to-test agreement. Factors that  were  considered in  determining the options were not substantive
included (i) the overall objective of the agreement was for Lilly to obtain development and
commercialization licenses, (ii) the size  of  the exercise fees of  $2 million  for each development and
commercialization license taken beyond the first license is not significant relative to the $20 million
upfront payment that was due at the  inception of the  right-to-test agreement, (iii) the  limited economic
benefit that Lilly could obtain from the right-to-test agreement  unless it exercised its options to obtain
development and commercialization licenses, and  (iv) the lack  of economic penalties  as a result  of
exercising the options.

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C. Agreements (Continued)

The Company has determined that the research license together with the development and

commercialization licenses represent  one  unit  of  accounting as the  research license  does not have
stand-alone value from the development and commercialization licenses due to the lack of
transferability of the research license and the limited economic benefit Lilly  would derive if they  did
not obtain any development and commercialization licenses. The Company has also determined  that
this  unit of accounting has stand-alone value from  the rights  to  future technological improvements, the
delivery of cytotoxic agents and the research  services. The rights to future technological improvements,
delivery of cytotoxic agents and the research  services are considered separate  units of accounting as
each  of these was  determined to have  stand-alone value. The rights  to  future  technological
improvements have stand-alone value as Lilly would be able to use  those  items for  their  intended
purpose without the undelivered elements. The research  services  and cytotoxic agents  have stand-alone
value as similar services and products  are  sold separately by other vendors. The  estimated  selling prices
for the development and commercialization licenses are  the Company’s best estimate of  selling price
and were determined based on market conditions, similar arrangements  entered into by third parties,
including pricing terms offered by our  competitors  for  single-target development and commercialization
licenses that utilize antibody-drug conjugate  technology, and  entity-specific factors  such as the  pricing
terms of the Company’s previous single-target development and commercialization  licenses, recent
preclinical and clinical testing results of  therapeutic products  that use  the Company’s TAP technology,
and the Company’s pricing practices  and  pricing objectives. The estimated selling price of the  rights to
technological improvements is the Company’s best estimate of selling  price and was determined by
estimating the probability that technological improvements will  be  made, and the probability that
technological improvements made will  be  used by Lilly. In  estimating  these  probabilities, we considered
factors such as the technology that is  the subject of the  development and commercialization licenses,
our  history of making technological improvements,  and when such improvements, if any, were  likely to
occur relative to the stage of development of any product  candidates pursuant to the  development and
commercialization licenses. over the  company’s estimate  of  probability considered the likely period of
time that any improvements would be utilized, which  was estimated  to  be ten years following delivery
of a commercialization and development  license. The value of any technological improvements made
available after this ten year period was considered  to  be de minimis due to the significant additional
costs that would be incurred to incorporate such technology into any existing  product candidates.  The
estimate of probability was multiplied  by  the estimated selling price of the development and
commercialization licenses and the resulting cash flow was discounted at a  rate of  16%, representing
the Company’s estimate of its cost of capital. The estimated selling price of  the cytotoxic agent was
based on third-party evidence given market rates for the manufacture of  such cytotoxic agents. The
estimated selling price of the research services was based on  third-party evidence given,the  nature of
the research services to be performed for  Lilly  and market rates for similar services. The  total
arrangement consideration of $28.2 million (which is  comprised of the  $20 million upfront payment,  the
exercise fee, if any, for each license,  the  expected fees for the research services to be provided and the
cytotoxic agent to be delivered under the  arrangement) was allocated to the deliverables  based on the
relative selling price method as follows:  $23.5 million to the development and commercialization
licenses; $0.6 million to the rights to  future  technological improvements, $0.8 million to the sale of
cytotoxic agent; and $3.3 million to the  research services. The Company will recognize  as license
revenue an equal amount of the total arrangement consideration allocated to the  development and
commercialization licenses as each individual license  is delivered to Lilly upon Lilly’s  exercise of its

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IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

C. Agreements (Continued)

options to such licenses. At the time  the first license is taken, the amount of the  total  arrangement
consideration allocated to future technological improvements will commence  to  be  recognized as
revenue ratably over the period the Company is  obligated to make  available any technological
improvements, which is the equivalent to the  estimated  term of the license. The Company estimates  the
term of a development and commercialization license  to  be approximately  25 years, which reflects
management’s estimate of the time necessary to develop and  commercialize therapeutic products
pursuant to the license plus the estimated  royalty term. The Company  will be required  to  reassess the
estimated term at each subsequent reporting period. The Company does not control  when Lilly  will
exercise its options for development and  commercialization licenses.  As a  result, the Company cannot
predict when it will recognize the related  license revenue except that  it will  be  within the term  of the
research license. The Company will recognize research services revenue and revenue  from the delivery
of cytotoxic agents as the related services  and cytotoxic agents are delivered.

No license revenue has been recognized  related to this agreement through  June 30, 2012 as  the
options to take development and commercialization licenses  were  not  considered to be substantive and
no development and commercialization licenses  have been delivered. Accordingly, the entire
$20 million upfront payment is included in long-term deferred revenue at  June  30, 2012.

Other Collaborative Agreements

In December 2004, the Company entered into a development and license agreement with  a

predecessor to Janssen Biotech (formerly  known as Centocor Ortho Biotech), a  wholly owned
subsidiary of Johnson & Johnson. Under  the terms  of  this agreement, Janssen was granted  exclusive
worldwide rights to develop and commercialize anticancer therapeutics that consist of the Company’s
maytansinoid cell-killing agent attached  to  an (cid:2)v  integrin-targeting antibody that was developed  by
Janssen. Under the terms of the agreement,  the Company received an  upfront payment of  $1 million
upon execution of the agreement.

In December 2007, the Company licensed  from Janssen the exclusive, worldwide  right to develop

and commercialize a TAP compound, IMGN388, that consists of an (cid:2)v  integrin-targeting antibody
developed by them and one of the Company’s maytansinoid cell-killing  agents. This  license reallocated
the parties’ respective responsibilities  and financial obligations from  the license  referenced  above.
Janssen had the right to opt-in on future  development  and  commercialization of IMGN388 at  an
agreed-upon stage in early clinical testing. Should Janssen not have  exercised this right,  Janssen would
have been entitled to receive milestone payments  potentially totaling $30  million, with the first payment
due upon the completion of a successful Phase III trial, and also royalties on IMGN388 sales, if  any. In
this  event, ImmunoGen would have had  the right to obtain a new partner for IMGN388, with  certain
restrictions. Should Janssen have exercised its opt-in right, ImmunoGen  would have received an opt-in
fee and been released from its obligation  to pay Janssen  any  milestone payments  or royalties on sales.
Both companies would have contributed to the costs  of  developing  the compound. The two companies
would have shared equally any profits on  the sales of the  compound in the U.S. and ImmunoGen
would have received royalties on any  international sales. The  companies also  agreed to share certain
third-party payments. In June 2008, the FDA approved  the IND application for IMGN388. This  event
triggered a $1 million milestone payment  to  a third-party,  half of which was paid by ImmunoGen.  As of

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NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

C. Agreements (Continued)

June 30, 2012, the  maximum amount  that may be payable in the  future to such third-parties under this
agreement is $11 million.

In November 2011, the Company announced its decision to discontinue development of IMGN388.

In connection with that decision, the  Company notified Janssen  of its  intention to terminate  the 2007
license agreement. The Company and  Janssen agreed  that such termination will become effective
30 days after  the last enrolled patient  has received his or her last  treatment.

Effective July 2011, Biogen Idec terminated its exclusive license to the Company’s TAP  technology

to develop and commercialize therapeutic compounds to the target  Cripto. This license was granted
pursuant to the Development and License  Agreement between  the Company and Biogen Idec dated
October 1, 2004. As a result of the termination, during the first  quarter of  fiscal 2012, the Company
recognized the remaining $270,000 of the  $1 million upfront fee received from Biogen Idec  upon
execution of the license which had been previously  deferred.

D. Marketable Securities

As of June 30, 2012 and 2011, $160.9  million and $191.2 million, respectively, in  cash and money
market funds consisting principally of  U.S.  Government-issued securities  and high  quality, short-term
commercial paper were classified as cash and cash equivalents.

During  fiscal year  2011, the Company  sold  the remaining marketable securities held in  its
investment portfolio at June 30, 2010, resulting in realized gains of  $347,000 and realized  losses of
$(6,000). In 2012 and 2010, the Company  had no realized losses or  gains.

E. Property and Equipment

Property and equipment consisted of  the following at June 30, 2012 and 2011 (in thousands):

June 30,

2012

2011

Leasehold improvements . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Machinery and equipment . . . . . . . . . . . . . . . . . . . . . . . . . . .
Computer hardware and software . . . . . . . . . . . . . . . . . . . . . .
Furniture and fixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assets under construction . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 25,661
13,808
4,168
1,315
660

$ 25,473
12,622
3,900
1,266
374

Less accumulated depreciation . . . . . . . . . . . . . . . . . . . . . . . .

$ 45,612
(33,979)

$ 43,635
(30,226)

Property and equipment, net

. . . . . . . . . . . . . . . . . . . . . . . . .

$ 11,633

$ 13,409

Depreciation expense was approximately $4.6 million, $4.9 million and $4.8  million for the years

ended June 30, 2012, 2011 and 2010,  respectively.

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IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

F.

Income Taxes

The difference between the Company’s expected tax benefit, as computed by applying the U.S.

federal corporate tax rate of 34% to loss  before the benefit  for income taxes, and actual tax is
reconciled in the following chart (in thousands):

Loss before income tax expense . . . . . . . . . . . . . . .

$(73,319) $(58,274) $(51,177)

Year Ended June 30,

2012

2011

2010

Expected tax benefit at 34% . . . . . . . . . . . . . . . . . .
Permanent differences . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . .
State tax benefit net of federal benefit
Increase in valuation allowance, net . . . . . . . . . . . .
Expired loss and credit carryforwards . . . . . . . . . . .
Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$(24,928) $(19,813) $(17,400)
—
(2,002)
11,991
6,858
288

—
(1,815)
16,410
5,610
(392)

1,469
(4,204)
26,574
1,089
—

Benefit for income taxes . . . . . . . . . . . . . . . . . . . .

$

— $

— $

(265)

At June  30, 2012, the Company has net operating loss carryforwards of approximately

$265.7 million available to reduce federal  taxable income, if any, that expire in 2013  through 2032 and
$156.4 million available to reduce state taxable income, if any,  that expire  in fiscal 2013 through  fiscal
2032. Included in the federal and state  carryforwards is $14.3 million  and $13.0 million,  respectively,
related to deductions from the exercise  of  stock options and  the  related  tax benefit  will result in an
increase in additional paid-in capital if  and when  realized through a  reduction of taxes paid  in cash.
The Company also has federal and state research tax credits of approximately $12.2 million available to
offset federal and state income taxes, which  expire beginning in  fiscal 2013. Due to the degree of
uncertainty related to the ultimate use of  the loss carryforwards  and tax credits, the Company  has
established a  valuation allowance to fully reserve  these tax benefits.

Deferred income taxes reflect the net  tax effects of  temporary  differences between the  carrying
amounts of assets and liabilities for financial reporting  purposes and the amounts used for income tax

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IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

F.

Income Taxes (Continued)

purposes. Significant components of the Company’s deferred tax assets as  of June  30, 2012 and 2011
are as follows (in thousands):

June 30,

2012

2011

Net operating loss carryforwards . . . . . . . . . . . . . . . . . . . . .
Research and development tax credit carryforwards . . . . . . .
Property and other intangible assets . . . . . . . . . . . . . . . . . . .
Deferred revenue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stock-based compensation . . . . . . . . . . . . . . . . . . . . . . . . . .
Deferred lease incentive . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other liabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 98,601
10,393
1,486
28,325
3,302
5,100
512

$ 82,533
9,590
807
21,168
2,308
3,363
2,676

Total deferred tax assets . . . . . . . . . . . . . . . . . . . . . . . . . . .
Valuation allowance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 147,719
(147,719)

$ 122,445
(122,445)

Net deferred tax assets . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$

— $

—

The valuation allowance increased by $25.3  million  during  2012 due primarily to the greater net

loss recognized during the year compared  to last and deferred revenue timing differences,  partially
offset by the expiration of net operating loss carryforwards.

Utilization of the NOL and R&D credit carryforwards may  be  subject to a substantial annual
limitation due to ownership change limitations that  have occurred previously or that could occur in the
future as provided by Section 382 of  the  Internal Revenue Code of  1986, as well as similar  state and
foreign provisions. These ownership changes may limit the  amount  of  NOL and R&D  credit carry
forwards that can be utilized annually  to  offset  future taxable  income and tax, respectively. In general,
an ownership change, as defined by Section 382, results from transactions  increasing  the ownership of
certain shareholders or public groups in  the stock  of  a corporation  by more than 50 percentage points
over a three-year period. Since the Company’s formation, it has raised capital through  the issuance of
capital stock on several occasions (both pre and post initial public  offering) which,  combined with the
purchasing shareholders’ subsequent  disposition of those shares, may  have resulted  in a change of
control, as defined by Section 382, or could result  in a change  of control in the  future upon subsequent
disposition. The Company has not currently completed  a study to assess  whether  a change of control
has occurred or whether there have been multiple changes of control since its  formation due to the
significant complexity and cost associated  with such study and  the  possibility that there could be
additional changes in control in the future.  If the Company  has experienced a change of control at any
time since its formation, utilization of  its  NOL  or R&D  credit carry forwards  would be subject to an
annual limitation under Section 382 which is  determined  by  first multiplying the value of the
Company’s stock at the time of the ownership  change by the applicable long-term tax-exempt rate, and
then could be subject to additional adjustments, as required. Any limitation may result  in expiration  of
a portion of the NOL or R&D credit  carry  forwards before  utilization. Further, until a study is
completed and any limitation known,  no amounts are being presented  as an  uncertain tax position. The
Company does not expect to have any  taxable income for  at least  the next several  years.

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IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

F.

Income Taxes (Continued)

Interest and penalties related to the settlement of uncertain tax positions, if any,  will  be  reflected

in income tax expense. The Company  did  not recognize  any interest and penalties associated with
unrecognized tax benefits in the accompanying consolidated  financial  statements. The Company  does
not expect any material changes to the unrecognized benefits within 12 months of  the reporting date.
Due to existence of the valuation allowance,  future changes in our unrecognized  tax benefits will  not
impact our effective tax rate. The Company’s loss  carryforwards are subject to adjustment  by  state and
federal taxing authorities, commencing when those losses are utilized to reduce  taxable income.

Included in other (expense) income,  net  for the  fiscal year ended June 30, 2011  is $1.2  million of

federal grant funding the Company was  awarded under the  Patient Protection and Affordable Care Act
of 2010 to develop new anticancer therapies.

G. Capital Stock

Sale of Common Stock

Pursuant to the shelf registration statement filed in May 2011,  in July 2012, the Company  issued
and sold a total of 6,250,000 shares of its  common stock at $16.00 per share through a public offering
resulting in gross proceeds of $100 million.

On May 19, 2011, the Company filed  a Registration Statement on Form  S-3 with the  Securities

and Exchange Commission. Pursuant  to  the shelf  registration statement, in May 2011 and June 2011,
the Company issued and sold a total  of 7,800,000 shares of its  common stock at $12.00 per share
through a public offering resulting in gross proceeds of $93.6  million.

On April 9, 2010, the Company filed  a Registration  Statement on  Form S-3  with the Securities and

Exchange Commission. Pursuant to the shelf  registration statement, in May 2010,  the Company issued
and sold 10,350,000 shares of its common  stock at  $8.00 per  share through  a public offering  resulting in
gross  proceeds of $82.8 million.

Common Stock Reserved

At June  30, 2012, the Company has reserved 9.78 million shares of authorized common stock for

the future issuance of shares under the 2006 Plan and the 2004 Director Plan. See  ‘‘Stock-Based
Compensation’’ in Note B for a description of the 2006 Plan and the Former Plan  and Note G below
for a description of the 2004 Director Plan.

Stock Options

As of June 30, 2012, the 2006 Plan was the only employee share-based compensation plan  of  the

Company. During the year ended June 30,  2012, holders of  options  issued under the 2006  Plan  and the
Former Plan exercised their rights to acquire  an aggregate  of  1.4 million shares of  common stock at
prices ranging from $2.91 to $11.18 per  share. The total proceeds to the Company  from these  option
exercises were approximately $7.0 million.

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IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

G. Capital Stock (Continued)

The Company granted options with an exercise price equal to the fair  market  value of  the common

stock on the date of such grant. The  following  options  and their respective  weighted- average  exercise
prices per share were exercisable at June  30, 2012, 2011and 2010:

June 30, 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
June 30, 2011 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
June 30, 2010 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3,416
3,834
4,011

$6.34
$5.25
$6.88

Exercisable
(in thousands)

Weighted-
Average
Exercise Price

2001 Non-Employee Director Stock Plan

In November 2001, the Company’s shareholders approved the  establishment of the  2001

Non-Employee Director Stock Plan,  or the 2001  Director Plan, and  50,000 shares of common stock to
be reserved for grant thereunder. The 2001 Director Plan provided for  the  granting of awards to
Non-Employee Directors and, at the election of Non-Employee Directors, to have all or  a portion of
their awards in the form of cash, stock,  or stock  units. All stock  or  stock units are  immediately vested.
The number of stock or stock units issued was determined by  the market value  of  the Company’s
common stock on the last date of the  Company’s fiscal quarter for  which the services are  rendered.
The 2001 Director Plan was administered  by the Board  of  Directors which was authorized to interpret
the provisions of the 2001 Director Plan,  determine which  Non-Employee  Directors would  be  granted
awards, and determine the number of  shares of  stock  for  which a stock right will be granted. The 2001
Director Plan was replaced in 2004 by  the 2004  Non-Employee  Director Compensation and Deferred
Share Unit Plan.

During  the years ended June 30, 2012, 2011 and 2010, the  Company recorded approximately
$29,000, $44,000, and $10,000 in compensation expense,  respectively, related to approximately 6,000,
15,000, 15,000 stock units outstanding,  respectively, under the 2001  Director Plan. The value of the
stock units is adjusted to market value  at each reporting  period. No stock units  have been issued  under
the 2001 Plan subsequent to June 30,  2004. Pursuant  to  the 2001 Plan, in  November 2011, the
Company paid a retiring director approximately $115,000 to settle outstanding  stock  units.

2004 Non-Employee Director Compensation  and Deferred  Share  Unit Plan

In June 2004, the Board of Directors approved the establishment of the  2004 Non-Employee
Director Compensation and Deferred Share  Unit Plan, or the 2004 Director  Plan.  The  2004 Director
Plan provided for the compensation  of  Non-Employee  Directors, awarding  their annual retainers in the
form of deferred share units, and, at their  discretion, to have  all or a  portion  of their  other
compensation such as meeting fees in the  form of cash or deferred share units. The deferred  share
units for annual retainers vested one-twelfth monthly over the  next year  after the award; other deferred
share units vested  immediately upon issuance.  The  number of deferred share units issued  was
determined by the  market value of the Company’s common stock on the last  date of the  Company’s
fiscal year prior to the fiscal year for  which services were rendered.  The  deferred share  units were to be
paid out in cash to each non-employee director based upon the market value of the  Company’s

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IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

G. Capital Stock (Continued)

common stock on the date of such director’s retirement  from the Board  of Directors  of  the Company.
The 2004 Director Plan was administered  by the Board  of  Directors.

The 2004 Director Plan was amended on September 5, 2006. Under the terms of the amended

2004 Director Plan, the redemption amount of deferred  share units will  be  paid in shares of common
stock of the Company under the 2006  Plan in lieu of cash. As  a  result of  the  change  in payout
structure, the value of the vested awards was transferred to  additional paid-in capital  as of the
modification date and the total value of  the awards, as calculated on the modification date,  was
expensed over the remainder of the vesting period. Accordingly,  the value of the share units is fixed
and will no longer be adjusted to market value at each reporting  period. In addition, the amended 2004
Director Plan changed the vesting for annual retainers to take  place quarterly  over the three years after
the award and the number of deferred  share units  awarded  for all compensation is now  based on the
market value  of the Company’s common  stock on the  date of the award.

Compensation Policy for Non-Employee Directors

On September 16, 2009, the Board adopted  a new  Compensation Policy  for  Non-Employee
Directors, which superseded the 2004 Plan and made  certain changes to the compensation  of  its
non-employee directors. The policy was  amended  on November  11, 2009  to  provide that, whenever  the
Board has a non-employee Chairman  in lieu of a Lead Director, the  cash payment for the
non-employee Chairman of the Board shall be the same  as the cash compensation that would  otherwise
have been payable to the Lead Director. Effective November 12, 2009, non-employee directors became
entitled to receive annual meeting fees  and committee fees under  the new  policy. The  new policy made
changes to the equity portion of the  non-employee director  compensation,  but left  the cash  portion
unchanged. Effective November 11, 2009,  non-employee directors became entitled to receive deferred
stock units under the new policy as follows:

(cid:129) New non-employee directors will be initially awarded a  number  of deferred stock units having  an
aggregate market value of $65,000, based on the  closing  price of our common stock on the date
of their initial election to the Board.  These awards  will vest quarterly over three years from  the
date  of grant, contingent upon the individual  remaining  a director  of ImmunoGen as of each
vesting date.

(cid:129) On the first anniversary of a non-employee  director’s initial  election to the Board, such

non-employee director will be awarded  a number  of deferred  stock  units  having an aggregate
market value of $30,000, based on the closing price  of our common stock on  such date of grant
and pro-rated based on the number of whole months remaining  between the first day of the
month in  which such grant date occurs and the  first October  31 following the grant date. These
awards will generally vest quarterly over  approximately the  period from  the grant date  to  the
first November 1 following the grant date, contingent upon the individual remaining a  director
of ImmunoGen as of each vesting date.

(cid:129) Thereafter, non-employee directors  in general will be annually awarded a  number of  deferred
stock units having an aggregate market  value of $30,000, based on the  closing  price of our
common stock on the date of our annual meeting of shareholders.  These  awards will vest

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IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

G. Capital Stock (Continued)

quarterly over approximately one year from the date  of  grant, contingent upon the individual
remaining a director of ImmunoGen  as of each vesting  date.

As with the 2004 Plan, vested deferred stock units are redeemed on the date a director  ceases  to
be a member of the Board, at which time  such director’s deferred  stock units will be settled in shares
of our common stock issued under our  2006 Plan at a rate of  one  share for each vested deferred  stock
unit then held. Any deferred stock units that remain unvested  at that time will  be  forfeited. The new
policy provides that all unvested deferred  stock units will  automatically  vest immediately prior to the
occurrence of a change of control, as defined  in the 2006 Plan. Pursuant to the  Compensation Policy
for Non-Employee Directors, in November 2011,  the Company issued two retiring  directors an
aggregate 46,298 shares of common stock  of  the Company  to  settle outstanding deferred  share units.

In connection with the adoption of the  new  compensation  policy, the  Board also  amended the

2004 Plan as follows:

(cid:129) All unvested deferred stock awards (other than any  unvested initial  awards) were  vested in full

on September 16,  2009 unless the date such deferred stock units were credited to the
non-employee director was less than  one  year prior to September 16, 2009, in  which case such
unvested deferred stock units will vest on the first anniversary of the date  such deferred  stock
units were credited to the non-employee director.

(cid:129) All unvested deferred stock awards will automatically vest immediately  prior to the  occurrence

of a change of control.

On September 22, 2010, the Board revised the Compensation  Policy for  Non-Employee Directors

to provide that, in addition to the compensation  they received previously, they would also  become
entitled to receive stock option awards  having  a grant date fair value of  $30,000, determined using  the
Black- Scholes option pricing model measured  on the date of grant,  which would  be  the date  of  the
annual meeting of shareholders. These options  will  vest  quarterly over  approximately one year from  the
date  of  grant. Any new directors will receive a pro-rated award,  depending on their date of  election to
the Board. The directors received a total of 33,187 options and 49,688  options in  fiscal  2012 and fiscal
2011, respectively, and the related compensation expense is included in the  amounts discussed in the
‘‘Stock-based Compensation’’ section of footnote B  above.

Pursuant to the Compensation Policy for Non-Employee Directors and the 2004 Director Plan,  as

amended, the Company recorded approximately:

(cid:129) $314,000 in compensation expense during the year ended  June  30, 2012 related to the issuance

of 33,000 deferred share units and 264,000 deferred  share units previously  issued under the  2004
Director Plan;

(cid:129) $326,000 in compensation expense during the year ended  June  30, 2011 related to the issuance

of 39,000 deferred share units and 225,000 deferred  share units previously  issued under the  2004
Director Plan; and

(cid:129) $460,000 in compensation expense during the year ended  June  30, 2010 related to the issuance

of 42,000 deferred share units and 183,000 deferred  share units previously  issued under the  2004
Director Plan.

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IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

H. Commitments and Contingencies

Leases

Effective July 27, 2007, the Company  entered into a lease agreement with Intercontinental Fund

III for the rental of approximately 89,000 square feet of laboratory  and office  space at 830 Winter
Street, Waltham, MA. The Company uses  this space for its corporate headquarters  and other
operations. The initial term of the lease is for  twelve  years  with an  option for the Company to extend
the lease for two additional terms of five years. The Company is required to pay certain operating
expenses for the leased premises subject to escalation charges for certain expense increases  over a base
amount. The Company entered into  a  sublease in December 2009 for 14,100 square feet of this space
in Waltham through January 2015, with  the sublessee  having a conditional  option to extend the term
for an additional two years.

Effective April 2012, the Company entered into a  sublease agreement for the rental of 7,310

square  feet of laboratory and office space  at 830 Winter Street, Waltham,  MA from Histogenics
Corporation. The initial term of the sublease is  for three years  with a conditional  option for the
Company to extend the lease through October 2017. The  Company is required to pay certain  operating
expenses for the leased premises subject to escalation charges for certain expense increases  over a base
amount.

As part of the 2007 lease agreement, the  Company received a  construction allowance of up  to

approximately $13.3 million to build out  laboratory and office space  to  the Company’s  specifications.
After completion, the Company had  recorded $12.0 million of leasehold improvements under  the
construction allowance. The Company received $10.8 million from  the  landlord  and paid  out the  same
amount towards these leasehold improvements. The remaining balance of the  improvements was  paid
directly by the landlord. The lease term  began  on October 1, 2007,  when the  Company obtained
physical control of the space in order  to  begin construction.

The Company also leases facilities in  Norwood,  MA under an agreement  through 2018 with an
option to extend the lease for an additional term of five years. The Company is required  to  pay certain
operating expenses for the leased premises  subject to escalation charges for  certain  expense increases
over a base amount.

Facilities rent expense, net of sublease income, was  approximately  $4.8 million,  $4.6 million and

$5.4 million during fiscal years 2012,  2011 and  2010, respectively.

99

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Continued)

AS OF JUNE 30, 2012

H. Commitments and Contingencies (Continued)

As of June 30, 2012, the minimum rental commitments, including real estate  taxes and  other

expenses, for the next five fiscal years  and  thereafter under the non-cancelable operating  lease
agreements discussed above are as follows  (in thousands):

2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2015 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2016 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thereafter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 6,375
6,463
6,581
6,353
6,420
16,556

Total minimum lease payments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Total minimum rental income from subleases . . . . . . . . . . . . . . . . . . . . . .

$48,748
(1,749)

Total minimum lease payments, net . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$46,999

Collaborations

The Company is contractually obligated to make potential future  success-based regulatory
milestone payments in conjunction with certain  collaborative agreements. These payments are
contingent upon the occurrence of certain future events  and, given  the nature of these events,  it is
unclear when, if ever, the Company may be required to pay such  amounts.  Further, the timing of any
future payment is not reasonably estimable. As of  June 30, 2012, the maximum amount that may be
payable in the future under such arrangements is  $43 million.

Litigation

The Company is not party to any material litigation.

I. Employee Benefit Plans

The Company has a deferred compensation  plan under Section 401(k) of the Internal Revenue
Code (the 401(k) Plan). Under the 401(k)  Plan, eligible employees are permitted to contribute, subject
to certain limitations, up to 100% of their  gross salary  and the  Company’s matching  contribution is
50% of the first 6% of the eligible employees’ contributions. In  fiscal years  2012, 2011 and 2010,  the
Company’s contributions to the 401(k)  Plan totaled  approximately  $548,000, $467,000, and $450,000,
respectively.

100

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2012

J. Quarterly Financial Information  (Unaudited)

Fiscal Year 2012

First Quarter
Ended

Second Quarter
Ended

Third Quarter
Ended

September 30, 2011 December 31, 2011 March 31, 2012

Fourth Quarter
Ended
June 30, 2012

(In thousands, except per share data)

Revenues:

Research and development support . . .
License and milestone fees . . . . . . . . .
Clinical materials revenue . . . . . . . . .

Total revenues . . . . . . . . . . . . . . . .

$ 1,068
1,187
281

2,536

Expenses:

Research and development . . . . . . . . .
General and administrative . . . . . . . .

Total expenses . . . . . . . . . . . . . . . .

Loss from operations . . . . . . . . . . . . . .
. . . . . . .

Other (expense) income, net

Loss before income tax expense . . . . . . .
Income tax expense . . . . . . . . . . . . . .

17,161
4,841

22,002

(19,466)
(17)

(19,483)
—

$

945
6,025
647

7,617

15,559
4,834

20,393

(12,776)
23

(12,753)
—

$ 1,320
999
933

3,252

16,933
5,021

21,954

(18,702)
33

(18,669)
—

$ 1,184
950
818

2,952

19,539
5,726

25,265

(22,313)
(101)

(22,414)
—

Net loss . . . . . . . . . . . . . . . . . . . . . . . .

$(19,483)

$(12,753)

$(18,669)

$(22,414)

Basic and diluted net loss per

common share . . . . . . . . . . . . . . . .

$

(0.26)

$

(0.17)

$

(0.24)

$

(0.29)

101

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2012

J. Quarterly Financial Information  (Unaudited) (Continued)

Fiscal Year 2011

First Quarter
Ended

Second Quarter
Ended

Third Quarter
Ended

September 30, 2010 December 31, 2010 March 31, 2011

Fourth Quarter
Ended
June 30, 2011

(In thousands, except per share data)

Revenues:

Research and development support . . .
License and milestone fees . . . . . . . . .
Clinical materials reimbursement . . . .

Total revenues . . . . . . . . . . . . . . . .

$ 1,495
1,810
106

3,411

Expenses:

Research and development . . . . . . . . .
General and administrative . . . . . . . .

Total expenses . . . . . . . . . . . . . . . .

Loss from operations . . . . . . . . . . . . . .
Other income, net . . . . . . . . . . . . . . .

Loss before income tax expense . . . . . . .
Income tax expense . . . . . . . . . . . . . .

13,425
3,364

16,789

(13,378)
490

(12,888)
—

$ 2,005
866
1,307

4,178

16,004
3,688

19,692

(15,514)
1,281

(14,233)
—

$ 2,190
858
2,163

5,211

15,763
4,550

20,313

(15,102)
99

(15,003)
—

$ 1,566
2,859
2,080

6,505

18,261
4,438

22,699

(16,194)
44

(16,150)
—

Net loss . . . . . . . . . . . . . . . . . . . . . . . .

$(12,888)

$(14,233)

$(15,003)

$(16,150)

Basic and diluted net loss per

common share . . . . . . . . . . . . . . . .

$

(0.19)

$

(0.21)

$

(0.22)

$

(0.23)

102

Item 9. Changes in and Disagreements with Accountants  on Accounting and Financial Disclosure

None.

Item 9A. Controls and Procedures

1. Disclosure Controls and Procedures

The Company’s management, with the  participation of its principal executive officer and principal

financial officer, has evaluated the effectiveness  of the Company’s  disclosure controls and procedures
(as defined in Rules 13a-15(e) or 15d-15(e) under the Securities Exchange  Act of 1934, as  amended) as
of the end of the period covered by this  Annual Report on Form  10-K.  Based on  such evaluation, the
Company’s principal executive officer  and  principal financial officer have concluded  that,  as of the end
of such period, the Company’s disclosure controls and procedures were adequate  and effective.

2.

Internal Control Over Financial Reporting

(a) Management’s Annual Report on  Internal  Control  Over  Financial  Reporting

Management of the Company is responsible for establishing and maintaining adequate internal

control over financial reporting. Internal control over  financial reporting is defined in  Rules  13a-15(f)
and 15d-15(f) under the Exchange Act  as a process designed by, or under the  supervision of, the
Company’s principal executive and principal financial officers and  effected  by  the Company’s board of
directors, management and other personnel  to  provide reasonable assurance  regarding the reliability  of
financial reporting and the preparation  of  financial statements  for external purposes  in accordance with
generally accepted accounting principles  in  the U.S.  and includes  those policies and procedures that:

(cid:129) pertain to the maintenance of records that in reasonable detail accurately and fairly  reflect the

transactions and dispositions of the assets of  the Company;

(cid:129) provide reasonable assurance that transactions are recorded  as necessary to permit preparation
of financial statements in accordance with generally accepted  accounting principles, and  that
receipts  and expenditures of the Company are being made only in accordance with
authorizations of management and directors of the Company; and

(cid:129) provide reasonable assurance regarding prevention or timely detection of  unauthorized

acquisition, use or  disposition of the  Company’s assets that  could have  a material effect on the
financial statements.

Because of its inherent limitations, internal control over  financial  reporting may not prevent or
detect misstatements. Projections of any  evaluation of effectiveness to future periods are subject  to  the
risks that controls may become inadequate because of changes  in conditions, or that the  degree  of
compliance with the policies or procedures may deteriorate.

Management assessed the effectiveness of the Company’s internal control over financial reporting

as of  June 30, 2012. In making this assessment,  management used the criteria established  in Internal
Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway
Commission, or COSO.

Based on this assessment, management has concluded that, as of  June  30, 2012 the  Company’s

internal control over financial reporting is  effective.

Ernst & Young LLP, the Company’s independent registered public  accounting firm, has  issued a
report on the effectiveness of the Company’s internal  control over  financial reporting  as of June 30,
2012. This report appears immediately  below.

103

(b) Attestation Report of the Independent Registered  Public  Accounting Firm

Report of Independent Registered Public Accounting Firm

The Board of Directors and Shareholders  of ImmunoGen, Inc.

We  have audited ImmunoGen, Inc.’s  internal  control  over financial reporting  as of June 30, 2012,

based on criteria established in Internal Control—Integrated  Framework  issued by the Committee of
Sponsoring Organizations of the Treadway Commission (the COSO criteria). ImmunoGen, Inc.’s
management is responsible for maintaining  effective internal  control over financial reporting,  and for its
assessment of the effectiveness of internal  control over financial reporting included  in the
accompanying Management’s Annual Report on Internal  Control Over Financial Reporting. Our
responsibility is to express an opinion  on  the company’s internal control  over  financial  reporting based
on our audit.

We  conducted our audit in accordance with the standards of  the Public Company Accounting
Oversight Board (United States). Those  standards require that we  plan and perform the audit to obtain
reasonable assurance about whether  effective  internal control over financial reporting was maintained
in all material respects. Our audit included  obtaining an understanding  of internal control  over
financial reporting, assessing the risk that a  material weakness exists, testing and evaluating the design
and operating effectiveness of internal control based  on the assessed risk, and performing such other
procedures as we considered necessary in  the circumstances. We believe that our audit provides a
reasonable basis for our opinion.

A company’s internal control over financial reporting is a process designed to provide  reasonable

assurance regarding the reliability of  financial  reporting and the preparation  of  financial  statements  for
external  purposes in accordance with  generally accepted accounting  principles. A company’s internal
control over financial reporting includes those policies and procedures that (1)  pertain to the
maintenance of records that, in reasonable  detail, accurately and fairly reflect the  transactions and
dispositions of the assets of the company; (2) provide reasonable assurance that transactions  are
recorded  as necessary to permit preparation of financial statements in  accordance with generally
accepted accounting principles, and that receipts and expenditures of the company are being made  only
in accordance with authorizations of management and directors of the company; and  (3) provide
reasonable assurance regarding prevention  or timely detection of unauthorized acquisition, use, or
disposition of the company’s assets that  could have a material effect on the financial statements.

Because of its inherent limitations, internal control over  financial  reporting may not prevent or

detect misstatements. Also, projections  of any evaluation  of  effectiveness to future periods are  subject
to the risk that controls may become inadequate  because of changes in conditions, or  that  the degree
of compliance with the policies or procedures may deteriorate.

In our opinion, ImmunoGen, Inc. maintained, in all material respects, effective internal control

over financial reporting as of June 30, 2012  based on the COSO criteria.

We  also have audited, in accordance  with the standards of  the Public Company Accounting
Oversight Board (United States), the  consolidated balance sheets of ImmunoGen, Inc.  as of June 30,
2012 and 2011, and the related consolidated  statements  of operations,  shareholders’ equity,  and cash
flows for each of the three years in the period ended June 30,  2012 and our  report dated August  29,
2012 expressed an unqualified opinion thereon.

/s/ ERNST & YOUNG LLP

Boston, Massachusetts
August 29, 2012

104

(c) Changes in Internal Control Over  Financial Reporting

There have not been any changes in the  Company’s internal control over  financial reporting  (as

such term is defined in Rules 13a-15(f) and  15d-15(f) under the Exchange  Act)  during  the quarter
ended June 30, 2012 that have materially affected, or are reasonably likely to materially affect,  the
Company’s internal control over financial reporting.

3. Limitations on the Effectiveness of  Controls

The Company’s management, including  its principal  executive officer and  principal financial  officer,

does not expect that the Company’s disclosure controls  and  procedures or  its internal control over
financial reporting will prevent all error  and all fraud. A control system,  no  matter how  well conceived
and operated, can provide only reasonable, not absolute, assurance that the objectives of the  control
system are met. Further, the design of  a control system must reflect the fact that there  are resource
constraints, and the benefits of controls must be considered relative to their  costs. Because  of  the
inherent limitations in all control systems,  no  evaluation of  controls  can provide  absolute assurance that
all control issues and instances of fraud,  if any,  within an  organization have been detected. These
inherent limitations include the realities that  judgments  in decision-making can be faulty,  and that
breakdowns can occur because of simple  error or  mistake.

Additionally, controls can be circumvented by the  individual acts of some  persons, by collusion of
two or more people, or by management override of  the control. The design  of  any system of controls
also is based in part upon certain assumptions about  the likelihood of future events,  and there  can be
no assurance that any design will succeed in achieving  our stated  goals under all potential future
conditions. Over time, controls may become inadequate  because of changes  in conditions, or  the degree
of compliance with the policies or procedures may deteriorate. Because of  the inherent limitations in a
cost-effective control system, misstatements due to error or fraud may occur and  not  be  detected.

Item 9B. Other Information

None.

105

PART III

The information called for by Part III of Form 10-K  (Item 10—Directors, Executive Officers and

Corporate Governance of the Registrant,  Item  11—Executive Compensation, Item  12—Security
Ownership of Certain Beneficial Owners  and Management  and  Related  Stockholder  Matters, Item 13—
Certain Relationships and Related Transactions, and Director Independence, and Item 14—Principal
Accounting Fees and Services) is incorporated by reference  from our proxy statement related to our
2012 annual meeting of shareholders,  which will be filed  with the  Securities  and Exchange  Commission
not later than October 28, 2012 (120 days after the  end of the fiscal year covered by this Annual
Report on Form 10-K), except that information required by Item 10  concerning our executive officers
appears  in Part I, Item 3.1 of this Annual  Report  on Form 10-K.

106

Item 15. Exhibits, Financial Statement Schedules

(a) Financial Statements:

PART IV

(1) See ‘‘Index to Consolidated Financial Statements’’  at Item  8 of this Annual  Report on

Form 10-K. Schedules not included herein are omitted  because they  are  not applicable or  the
required information appears in the accompanying Consolidated Financial  Statements or Notes
thereto.

(2) The following schedule is filed as part of this Annual Report on  Form  10-K:

Schedule II—Valuation and Qualifying  Accounts for the years ended  June 30, 2012, 2011  and 2010.

(3) See Exhibit Index following the  signature page  to  this  Annual  Report on  Form  10-K.

107

Pursuant to the requirements of Section  13 or 15(d)  of  the Securities Exchange Act  of 1934, the

Registrant has duly caused this report to be signed  on its behalf  by the undersigned,  thereunto duly
authorized.

SIGNATURES

IMMUNOGEN, INC.

By:

/s/ DANIEL M. JUNIUS

Daniel M. Junius
President and
Chief Executive Officer
(Principal Executive Officer)

Dated: August 29, 2012

Pursuant to the requirements of the Securities Exchange Act of 1934,  this report has been signed

below by the following persons on behalf of  the Registrant  in the capacities  and on the dates indicated.

Signature

Title

Date

/s/ DANIEL M. JUNIUS

Daniel M. Junius

/s/ GREGORY D. PERRY

Gregory D. Perry

/s/ STEPHEN MCCLUSKI

Stephen McCluski

/s/ MARK GOLDBERG, M.D.

Mark Goldberg

/s/ DEAN MITCHELL

Dean Mitchell

/s/ NICOLE ONETTO, M.D.

Nicole Onetto

/s/ KRISTINE PETERSON

Kristine Peterson

/s/ HOWARD PIEN

Howard Pien

/s/ MARK SKALETSKY

Mark Skaletsky

/s/ JOSEPH VILLAFRANCA PH.D.

Joseph Villafranca

/s/ RICHARD WALLACE

Richard Wallace

President, Chief Executive Officer and Director

(Principal Executive Officer)

August 29, 2012

Executive Vice President and

Chief Financial Officer
(Principal Financial and Accounting Officer)

August  29, 2012

Chairman of the Board of Directors

August  29, 2012

Director

Director

Director

Director

Director

Director

Director

Director

108

August 29, 2012

August 29, 2012

August 29, 2012

August 29, 2012

August 29, 2012

August 29, 2012

August 29, 2012

August 29, 2012

EXHIBIT INDEX

Exhibit
Number

Exhibit Description

Filed
with  this
Form 10-K Form

Incorporated by Reference

Filing  Date
with SEC

Exhibit
Number

3.1

3.2

4.1

4.2

10.1

10.1(a)

10.1(b)

10.1(c)

10.1(d)

10.1(e)

10.1(f)

10.1(g)

10.1(h)

10.1(i)

Restated Articles of Organization, as  amended

Amended and Restated By-Laws

Article 4 of Restated Articles of Organization,  as
amended (see Exhibit 3.1)

Form of Common Stock certificate

Leases dated as of December 1, 1986  and June 21,
1988 by and between James H. Mitchell, Trustee  of
New Providence Realty Trust, lessor,  and  Charles
River Biotechnical Services, Inc. (‘‘Lessee’’),
together with Assignment of Leases  dated  June  29,
1989 between Lessee and the Registrant

First Amendment to Lease dated May  9, 1991 by
and between James H. Mitchell, Trustee of New
Providence Realty Trust, lessor, and the  Registrant

Confirmatory Second Amendment to Lease dated
September 17, 1997 by and between James H.
Mitchell, Trustee of New Providence Realty Trust,
lessor, and the Registrant

Third Amendment and Partial  Termination  of  Lease
dated as of August 8, 2000 by and between
James H. Mitchell, Trustee of New Providence
Realty Trust, lessor, and the Registrant

Fourth Amendment to Lease  dated  as of  October  3,
2000 by and between James H. Mitchell, Trustee  of
New Providence Realty Trust, lessor,  and  the
Registrant

Fifth Amendment to Lease dated as of  June  7, 2001
by and between James H. Mitchell, Trustee  of New
Providence Realty Trust, lessor, and the  Registrant

Sixth  Amendment to Lease dated as  of  April 30,
2002 by and between Bobson 333 L.L.C.,  lessor,  and
the Registrant

Seventh Amendment to Lease dated  as  of
October 20, 2005 by and  between Bobson  333
L.L.C., lessor, and  the Registrant

Eighth Amendment to Lease dated as  of
February 21, 2007 by and between Bobson 333
L.L.C., lessor, and  the Registrant

Ninth Amendment to Lease dated  as  of
November 17, 2010 by and between Bobson
333 LLC and the Registrant

109

10-Q

8-K

April 30,  2010

April  6, 2007

S-1 November 15,  1989
(File No. 33-31219)

3.1

3.1

4.2

S-1 September 22,  1989
(File  No. 33-31219)

10.10

S-1 November 6,  1991 10.10a

(File No.  33-43725)

10-K September 26,  1997

10.10

10-K September  2,  2008

10.1(c)

10-K September  2,  2008 10.1(d)

10-K September  2,  2008 10.1(e)

10-K September  2,  2008

10.1(f)

10-K September  2, 2008 10.1(g)

10-K September  2, 2008 10.1(h)

8-K November  18, 2010

10.1

Exhibit
Number

10.2

10.3

Exhibit Description

Lease Agreement, dated as  of July  27,  2007, by and
between Intercontinental Fund III  830  Winter
Street LLC, landlord, and the Registrant

Research and License Agreement dated  as of
May 22, 1981 by and between the Registrant and
Sidney Farber Cancer Institute, Inc. (now
Dana-Farber Cancer Institute, Inc.),  with  addenda
dated as of August 13, 1987 and August  22,  1989

Filed
with  this
Form 10-K Form

Incorporated by Reference

Filing  Date
with SEC

Exhibit
Number

10-Q November 7,  2007

10.2

S-1 September 22,  1989
(File No.  33-31219)

10.1

10.4*

License Agreement dated  effective  May 2,  2000 by
and between the  Registrant and Genentech, Inc.

10-K September  27,  2000

10.51

10.4(a)* Amendment  to License Agreement  for Anti-HER2

10-K

August 28,  2006

10.32

Antibodies, dated as of May 3, 2006, between the
Registrant and Genentech, Inc.

10.4(b)* Amendment  to License Agreements  made  effective

10-Q

May 7,  2009

10.1

10.5*

10.6*

as of March 11, 2009, between  the  Registrant and
Genentech, Inc.

Option and License Agreement dated  September  5,
2000 by and between the Registrant  and Amgen Inc.
(as successor-in-interest to Abgenix, Inc.)

Collaboration and License Agreement dated as  of
July 30, 2003 by and between the Registrant and
sanofi-aventis U.S. LLC (as successor-in-interest  to
Aventis Pharmaceuticals Inc.)

10.6(a)* Amendment  No. 1, dated as  of August  31, 2006, to
the Collaboration and License Agreement between
the Registrant and sanofi-aventis U.S. LLC

8-K/A

October  10,  2000

10.1

10-Q November  14,  2003

10.1

10-Q November 3,  2006

10.1

10.6(b)* Amendment  No. 2, dated as  of October  11, 2007,  to

10-Q

February  7, 2008

10.4

the Collaboration and License Agreement between
the Registrant and sanofi-aventis U.S. LLC

10.6(c)*

Amendment  No. 3, dated as  of August  31, 2008, to
the Collaboration and License Agreement between
the Registrant and sanofi-aventis U.S. LLC

10.7*

10.8*

Option and License Agreement dated  as of
December 21, 2006 by and between the Registrant
and sanofi-aventis U.S. LLC

Collaborative Development and License Agreement
dated as of July 7, 2006 by and between the
Registrant and Biotest AG

10-Q

February  6, 2009

10.7

10-Q

February 8,  2007

10.2

10-Q November  3,  2006

10.2

10.8(a)* Amendment  No. 1, dated August 23, 2006, to

10-Q November 3,  2006

10.3

Collaborative Development and License Agreement
by and between the Registrant and  Biotest AG

10.9*

Development and License Agreement dated  as  of
October 20, 2008 by and  between the Registrant and
Bayer HealthCare AG

10-Q

May 5,  2012

10.1

110

Exhibit
Number

10.10*

10.11*

10.12*

Exhibit Description

Multi-Target Agreement dated as  of  October 8,  2010
by and between the Registrant and  Novartis
Institutes for BioMedical Research, Inc.

Clinical Supply Agreement effective  as  of
December 12, 2010 by and between the Registrant
and Societ´a Italiana Corticosteroidi  S.r.l.  (Sicor)

Multi-Target Agreement dated as  of  December  19,
2011 by and between the Registrant  and Eli Lilly
and Company

Filed
with  this
Form 10-K Form

Incorporated by Reference

Filing  Date
with SEC

Exhibit
Number

10-Q

May 5,  2012

10.2

10-Q

February 8,  2011

10.1

10-Q

May 5,  2012

10.3

10.13†

Restated Stock Option Plan

10.13(a)† Form of Incentive Stock Option Agreement

10.13(b)† Form of Non-Qualified Stock Option  Agreement

8-K

8-K

8-K

February  7, 2006

February  7,  2006

February 7,  2006

10.1

10.2

10.3

10.14†

2006 Employee, Director  and Consultant  Equity
Incentive Plan, as amended  through  June 13, 2012

X

10.14(a)† Form of Incentive Stock Option Agreement for

S-8 November 15,  2006

99.4

Executives

10.14(b)† Form of Non-Qualified Stock Option  Agreement  for

S-8 November 15,  2006

99.5

Executives

10.14(c)† Form of Non-Qualified Stock Option  Agreement  for

10-Q

October  29,  2010

10.1

Directors

10.14(d)† Form of Restricted Stock Agreement  for Executives

S-8 November 15,  2006

10.14(e)† Form of Restricted Stock Agreement  for Directors

S-8 November 15,  2006

10.14(f)† Form of Director Deferred  Stock  Unit  Agreement

10-Q

October  29,  2010

99.9

99.8

10.1

10.14(g)† Form of Incentive Stock Option Agreement  for all

employees (including executives)

10.14(h)† Form of Non-Qualified Stock Option  Agreement  for

all employees (including executives)

10.14(i)† For of  Non-Qualified Stock Option  Agreement  for

X

X

X

Directors

10.15†

2001 Non-Employee Director Stock Plan

S-8 December  18, 2001

99

10.16†

10.17†

10.18†

10.19†

2004 Non-Employee Director Compensation and
Deferred Stock Unit Plan, as amended  through
September 16, 2009

Form of Proprietary Information, Inventions  and
Competition Agreement between the Registrant  and
each of its executive  officers

Severance Agreement dated as  of December  1,  2010
between the Registrant  and Craig Barrows

Severance Agreement dated as  of December  1,  2010
between the Registrant  and Daniel M.  Junius

10-Q November  4,  2009

10.1

10-Q

February  8,  2007

10.15

10-Q

February 8,  2011

10.2

10-Q

February 8,  2011

10.3

111

Exhibit
Number

10.20†

10.21†

10.22†

10.23†

10.24†

10.25†

Exhibit Description

Severance Agreement dated as  of December  1,  2010
between the Registrant  and John M. Lambert

Severance Agreement dated as  of December  1,  2010
between the Registrant  and James J. O’Leary

Severance Agreement dated as  of December  1,  2010
between the Registrant  and Gregory D. Perry

Severance Agreement dated as  of December  1,  2010
between the Registrant  and Peter Williams

Severance Agreement dated as  of January  18, 2011
between the Registrant  and Theresa  G. Wingrove

Compensation  Policy for  Non-Employee Directors,
as amended through September 22, 2010

Filed
with  this
Form 10-K Form

Incorporated by Reference

Filing  Date
with SEC

Exhibit
Number

10-Q

February 8,  2011

10.4

10-Q

February 8,  2011

105

10-Q

February 8,  2011

10.6

10-Q

February 8,  2011

10.7

10-Q

February 8,  2011

10.8

10-Q

October  29,  2010

10.1

10.26†

Summary of Annual Executive Bonus  Program

10-Q November  7,  2007

10.1

10-K

August 29,  2011

10.26

10-K

August  30, 2007

21

10.27†

Employment Agreement  dated  as of  July  27,  2011
between the Registrant  and Gregory D. Perry

21

23

31.1

31.2

32

Subsidiaries of the Registrant

Consent of Ernst & Young LLP

Certification of the Chief Executive  Officer  pursuant
to Section 302 of the Sarbanes-Oxley  Act  of  2002

Certification of the Chief Financial Officer pursuant
to Section 302 of the Sarbanes-Oxley  Act  of  2002

Certifications of Chief Executive Officer  and  Chief
Financial Officer pursuant to Section  906 of  the
Sarbanes-Oxley Act of 2002

X

X

X

X

101.INS

XBRL Instance Document

101.SCH XBRL Taxonomy Extension  Schema

101.CAL XBRL Taxonomy Extension  Calculation  Linkbase

101.DEF XBRL Taxonomy Extension  Definition Linkbase

101.LAB XBRL Taxonomy Extension  Label Linkbase

101.PRE XBRL Taxonomy Extension  Presentation  Linkbase

*

†

Portions of this Exhibit were omitted, as  indicated by  [***],  and have been  filed  separately  with  the Secretary
of the Commission pursuant to the Registrant’s application requesting  confidential  treatment.

Exhibit is a management contract  or compensatory  plan,  contract  or  arrangement required  to  be  filed  as  an
exhibit to the annual report on Form  10-K.

112

IMMUNOGEN, INC.

SCHEDULE II—VALUATION AND QUALIFYING ACCOUNTS

(In thousands)

COLUMN A—DESCRIPTION

Inventory Valuation Allowance

Year End June 30, 2012 . . . . . . . . . . . . . . . . . . .
Year End June 30, 2011 . . . . . . . . . . . . . . . . . . .
Year End June 30, 2010 . . . . . . . . . . . . . . . . . . .

COLUMN B

COLUMN C—
ADDITIONS

COLUMN D

COLUMN  E

Balance at
Beginning
of Period

$1,993
$ 939
$1,784

Charged
to Costs
and
Expenses

$ 786
$1,664
$ 927

Use of
Zero
Value
Inventory

$(1,488)
$ (610)
$(1,772)

Balance  at
End of
Period

$1,291
$1,993
$ 939

113

EXHIBIT 31.1

CERTIFICATIONS UNDER SECTION 302

I, Daniel M. Junius, certify that:

1.

I have reviewed this Annual Report on Form  10-K of ImmunoGen, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement  of  a material fact or

omit to state a material fact necessary  to  make the statements made,  in light  of the circumstances
under which such statements were made, not misleading  with respect to the period  covered by this
report;

3. Based on my knowledge, the financial statements, and  other financial  information included in  this
report, fairly present in all material respects  the financial condition, results of operations and  cash
flows of the registrant as of, and for, the  periods presented in  this report;

4. The registrant’s other certifying  officer(s) and I are responsible for establishing and maintaining
disclosure controls and procedures (as defined  in Exchange  Act Rules  13a-15(e) and 15d-15(e))
and internal control over financial reporting (as defined in  Exchange Act  Rules 13a-15(f) and
15d-15(f)) for the registrant and have:

a)

designed such disclosure controls and  procedures,  or caused such disclosure controls and
procedures to be designed under our  supervision, to ensure that material  information relating
to the registrant, including its consolidated  subsidiaries, is made  known to us by others within
those entities, particularly during the period in  which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over

financial reporting to be designed under our supervision,  to  provide reasonable assurance
regarding the reliability of financial reporting and the preparation of financial statements for
external  purposes in accordance with  generally accepted accounting  principles;

c)

evaluated the effectiveness of the registrant’s  disclosure controls and  procedures and
presented in this report our conclusions  about the effectiveness of the disclosure controls and
procedures, as of the end of the period covered  by this  report based on such evaluation; and

d) disclosed in this report any change  in the registrant’s internal control over  financial  reporting

that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal
quarter in the case of an annual report) that has materially  affected, or is reasonably likely to
materially affect, the registrant’s internal  control over financial reporting; and

5. The registrant’s other certifying  officer(s) and I have disclosed,  based on our  most recent

evaluation of internal control over financial reporting, to the registrant’s auditors and the audit
committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)

b)

all significant deficiencies and material weaknesses  in the design  or  operation  of internal
control over financial reporting which are  reasonably likely  to  adversely affect  the registrant’s
ability to record, process, summarize and report  financial information; and

any fraud, whether or not material,  that involves management  or other employees who have a
significant role in the registrant’s  internal control over financial  reporting.

Date: August 29, 2012

/s/ DANIEL M. JUNIUS

Daniel M. Junius
President and Chief Executive Officer
(Principal Executive Officer)

EXHIBIT 31.2

CERTIFICATIONS UNDER SECTION 302

I, Gregory D. Perry, certify that:

1.

I have reviewed this Annual Report on Form  10-K of ImmunoGen, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement  of  a material fact or

omit to state a material fact necessary  to  make the statements made,  in light  of the circumstances
under which such statements were made, not misleading  with respect to the period  covered by this
report;

3. Based on my knowledge, the financial statements, and  other financial  information included in  this
report, fairly present in all material respects  the financial condition, results of operations and  cash
flows of the registrant as of, and for, the  periods presented in  this report;

4. The registrant’s other certifying  officer(s) and I are responsible for establishing and maintaining
disclosure controls and procedures (as defined  in Exchange  Act Rules  13a-15(e) and 15d-15(e))
and internal control over financial reporting (as defined in  Exchange Act  Rules 13a-15(f) and
15d-15(f)) for the registrant and have:

a)

designed such disclosure controls and  procedures,  or caused such disclosure controls and
procedures to be designed under our  supervision, to ensure that material  information relating
to the registrant, including its consolidated  subsidiaries, is made  known to us by others within
those entities, particularly during the period in  which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over

financial reporting to be designed under our supervision,  to  provide reasonable assurance
regarding the reliability of financial reporting and the preparation of financial statements for
external  purposes in accordance with  generally accepted accounting  principles;

c)

evaluated the effectiveness of the registrant’s  disclosure controls and  procedures and
presented in this report our conclusions  about the effectiveness of the disclosure controls and
procedures, as of the end of the period covered  by this  report based on such evaluation; and

d) disclosed in this report any change  in the registrant’s internal control over  financial  reporting

that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal
quarter in the case of an annual report) that has materially  affected, or is reasonably likely to
materially affect, the registrant’s internal  control over financial reporting; and

5. The registrant’s other certifying  officer(s) and I have disclosed,  based on our  most recent

evaluation of internal control over financial reporting, to the registrant’s auditors and the audit
committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)

b)

all significant deficiencies and material weaknesses  in the design  or  operation  of internal
control over financial reporting which are  reasonably likely  to  adversely affect  the registrant’s
ability to record, process, summarize and report  financial information; and

any fraud, whether or not material,  that involves management  or other employees who have a
significant role in the registrant’s  internal control over financial  reporting.

Date: August 29, 2012

/s/ GREGORY D. PERRY

Gregory D. Perry
Executive Vice President and Chief Financial Officer
(Principal Financial and Accounting Officer)

EXHIBIT 32

CERTIFICATIONS UNDER SECTION 906

Pursuant to section 906 of the Sarbanes-Oxley  Act of 2002  (subsections (a)  and (b) of

section 1350, chapter 63 of title 18, United States Code),  each of the undersigned officers of
ImmunoGen, Inc., a Massachusetts corporation (the ‘‘Company’’), does  hereby certify,  to  such officer’s
knowledge, that:

The Annual Report for the year ended June 30, 2012  (the  ‘‘Form 10-K’’) of the Company  fully

complies with the requirements of Section 13(a) or 15(d) of  the Securities Exchange Act of  1934, and
the information contained in the Form  10-K fairly  presents, in all material respects, the financial
condition and results of operations of  the Company.

Dated: August 29, 2012

/s/ DANIEL M. JUNIUS

Daniel M. Junius
President and Chief Executive Officer
(Principal Executive Officer)

Dated: August 29, 2012

/s/ GREGORY D. PERRY

Gregory D. Perry
Executive Vice President and Chief Financial  Officer
(Principal Financial and Accounting Officer)

A signed original of this written statement required  by  Section 906 has  been provided to the

Company and will be retained by the  Company and furnished to the  Securities and Exchange
Commission or its staff upon request.

IMMUNOGEN, INC.

Stock Price Performance Graph

The graph and table below compare the  annual  percentage change in our cumulative total

shareholder return on our common stock  for the period from June 30,  2007 through June 30,  2012 (as
measured by dividing (i) the sum of (A)  the  cumulative amount of dividends for  the measurement
period, assuming dividend reinvestment,  and (B) the difference between  our share price at the end  and
the beginning of the measurement period;  by  (ii) the  share  price at the beginning of the measurement
period) with the total cumulative return of the NASDAQ Stock Market Index (U.S.) and the NASDAQ
Pharmaceutical Stocks Total Return Index during such period. We have not paid any dividends on  our
common stock, and no dividends are included in the  representation of our performance.  The  stock
price performance on the graph below  is  not necessarily indicative of future price performance. This
graph is not ‘‘soliciting material,’’ is not  deemed filed with  the Commission  and is not to be
incorporated by reference in any of our  filings under the Securities Act  of  1933, or the  Securities
Exchange Act of 1934, whether made before or after the date hereof and irrespective of any general
incorporation language in any such filing.  Information used  on the graph for  the NASDAQ
Pharmaceutical Stocks Total Return Index and the NASDAQ Stock Market Index (U.S.) was prepared
by the Center for Research in Security Prices,  a source believed to be reliable, but  we are  not
responsible for any errors or omissions  in such information.

350.00

300.00

250.00

200.00

150.00

100.00

50.00

0.00

2007

2008

2009

2010

2011

2012

ImmunoGen Inc.

NASDAQ Stock Market (US Companies)

NASDAQ Pharmaceutical Index

17AUG201211123479

IMMUNOGEN, INC.
. . . . . . . . . . . . . . . . . . . . . . . . . . $100.00 $55.13 $155.30 $167.01 $219.67 $301.66
NASDAQ STOCK MARKET  INDEX  (U.S.) . . . . . . . . . . $100.00 $87.47 $ 71.60 $ 83.11 $110.80 $120.72
NASDAQ PHARMACEUTICAL STOCKS TOTAL

RETURN INDEX * . . . . . . . . . . . . . . . . . . . . . . . . . . $100.00 $99.64 $ 97.39 $100.47 $130.48 $153.18

2007

2008

2009

2010

2011

2012

*

This index represents a group of peer issuers  compiled by the  Center  for Research  in Security Prices.

The above graph and table assume $100 invested on  June  30, 2007 with all dividends reinvested, in

each  of our common stock, the NASDAQ  Stock Market Index  (U.S.) and the NASDAQ
Pharmaceutical Stocks Total Return Index. Upon  written  request by  any shareholder,  we will promptly
provide a list of the companies comprising  the NASDAQ  Pharmaceutical  Stocks Total Return Index.

Corporate Information 

Directors 
Chairman of the Board 
Stephen C. McCluski 
Former Senior Vice President and  
Chief Financial Officer, 
Bausch & Lomb, Inc. 

Daniel M. Junius 
President and Chief Executive Officer, 
ImmunoGen, Inc. 

Mark Goldberg, M.D. 
Senior Vice President, 
Synageva BioPharma Corp. 

Dean J. Mitchell 
President and Chief Executive Officer,  
Lux Biosciences, Inc. 

Nicole Onetto, M.D. 
Deputy Director and Chief Scientific Officer,  
Ontario Institute for Cancer Research 

Kristine Peterson 
Chief Executive Officer,  
Valeritas, Inc. 

Howard H. Pien 
Former Chairman and Chief Executive Officer,  
Medarex, Inc. 

Mark Skaletsky 
Chairman and Chief Executive Officer,  
Fenway Pharmaceuticals 

Joseph J. Villafranca, Ph.D. 
President,  
BioPharmaceutical Consultants, LLC 

Richard J. Wallace 
Former Senior Vice President 
Research and Development,  
GlaxoSmithKline plc. 

Executive Officers 
Daniel M. Junius 
President and  
Chief Executive Officer 

John M. Lambert, Ph.D. 
Executive Vice President and  
Chief Scientific Officer 

Gregory D. Perry 
Executive Vice President and  
Chief Financial Officer 

Craig Barrows 
Vice President, General Counsel 
and Secretary 

James J. O’Leary, M.D. 
Vice President and  
Chief Medical Officer 

Peter J. Williams 
Vice President,  
Business Development 

Theresa G. Wingrove, Ph.D. 
Vice President,  
Regulatory Affairs 

Corporate Headquarters 
ImmunoGen, Inc. 
830 Winter Street 
Waltham, MA 02451 
781.895.0600 
www.immunogen.com 

Annual Meeting 
11:00 AM on November 13, 2012 
at the offices of the Company 
830 Winter Street 
Waltham, MA 02451 

Stock Transfer Agent and Registrar 
Broadridge Corporate Issuer  
Solutions, Inc. 
P.O. Box 1342 
Brentwood, NY 11717 
Phone: 877.830.4936 
Fax: 215.553.5402 
Email: shareholder@broadridge.com 

Auditors 
Ernst & Young LLP 
Boston, MA 

Shareholder Inquiries 
Information about ImmunoGen can be 
found at www.immunogen.com. Inquires 
related to the Company may be directed 
to the Investor Relations department at 
our headquarters. Communications 
related to stock and transfer 
requirements, including lost stock 
certificates and change of name or 
address, should be directed to the 
Transfer Agent. 

This annual report includes forward-looking statements based on management’s current expectations. These statements include, but are not limited to, ImmunoGen’s 
expectations related to the advancement of new Company and partner compounds into clinical testing, the initiation of new clinical trials, the timing of go/no go clinical 
decisions, and the timing and occurrence of the presentation of new preclinical and clinical data, of potential business development events, and of potential future 
regulatory submissions. For these statements, ImmunoGen claims the protection of safe harbor for forward-looking statements provided by the Private Securities Litigation 
Reform Act of 1995. Various factors could cause ImmunoGen’s actual results to differ materially from those discussed or implied in the forward-looking statements, and you 
are cautioned not to place undue reliance on these forward-looking statements, which are current only as of the date of this annual report. Factors that could cause future 
results to differ materially from such expectations include, but are not limited to: the timing and outcome of ImmunoGen’s and the Company’s partners’ research and 
clinical development processes; the difficulties inherent in the development of novel pharmaceuticals, including uncertainties as to the timing, expense and results of 
preclinical studies, clinical trials and regulatory processes; ImmunoGen’s ability to financially support its product programs; ImmunoGen’s dependence on collaborative 
partners; industry merger and acquisition activity; and other factors more fully described in ImmunoGen’s Annual Report on Form 10-K for the fiscal year ended June 30, 
2012 and other reports filed with the Securities and Exchange Commission. 

Herceptin® is a registered trademark of Genentech, a member of the Roche group. 

 
 
 
 
ImmunoGen, Inc. 
830 Winter Street 
Waltham, MA 02451 
781.895.0600 
www.immunogen.com