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ImmunoGen
Annual Report 2009

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FY2009 Annual Report · ImmunoGen
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ImmunoGen’s 2009 Annual Report

Teamwork for Our Futures

 
 
 
 
ImmunoGen has advanced to a different stage today. We are building and strengthening our management team as 

part of our greater focus on execution. We are making visible progress with our clinical-stage compounds, successfully 
expanding our preclinical pipeline and pursuing a wide range of collaboration opportunities. Our pipeline progress 
complements that of our partners. The most advanced TAP compound, trastuzumab-DM1 (T-DM1), potentially could 
be launched in the US by Genentech by late 2010.

Our Highlights
Promotion	of	Daniel	Junius	to	President	and	Chief	Executive	Officer	

•	

Collaborator Highlights

•	 Disclosure	by	Genentech	and	by	Roche	that	T-DM1	could	potentially	

and	of	John	Lambert,	Ph.D.,	to	Executive	Vice	President	and		

be	launched	in	the	US	in	2010.	

Chief	Scientific	Officer.

•	 Expansion	by	Genentech	and	Roche	of	the	aggressive	T-DM1	clinical	

•	 Hiring	of	James	O’Leary,	M.D.,	as	Vice	President	and	Chief	Medical	

program	being	implemented.

Officer,	Gregory	Perry	as	Senior	Vice	President	and	Chief	Financial	

•	

Presentation	of	encouraging	non-pivotal	clinical	data	with	T-DM1		

Officer	and	Peter	Williams	as	Vice	President,	Business	Development.

for	the	treatment	of	patients	with	HER2+	metastatic	breast	cancer	

•	

Presentation	of	encouraging	clinical	data	with	our	IMGN901		

product	candidate	in	the	treatment	of	CD56+	solid	tumors		

and	multiple	myeloma,	and	submission	of	abstracts	for	additional	

presentations	in	late	2009.

that	progressed	on	treatment	with	previous	HER2-directed	therapies,	
trastuzumab	(Herceptin®)	and	lapatinib	(Tykerb®).
Submission	by	sanofi-aventis	of	an	abstract	to	achieve	presentation		

•	

of	the	first	clinical	data	for	SAR3419	at	a	medical	conference		

•	 Attainment	of	the	clinical	data	needed	to	expand	our	IMGN901	

in	late	2009.

multiple	myeloma	monotherapy	trial	and	to	initiate	our		

•	

Submission	by	Biotest	of	an	abstract	to	achieve	presentation	of	the	first	

combination	trial	this	fall.

clinical	data	for	BT-062	at	the	same	conference.	

•	 Reprioritization	of	our	IMGN242	compound	into	our		

•	

Licensing	of	rights	to	use	our	TAP	technology	by	Bayer	HealthCare	

outlicensing	portfolio.

and	by	Amgen	–	the	first	licenses	taken	by	these	major	companies.	

•	 Enrollment	of	multiple	patients	into	our	IMGN388	Phase	I	trial.

•	 Receipt	of	$20	million	in	upfront	and	milestone	payments	from	our	

•	

Significant	progress	in	our	development	of	a	robust	pipeline	of		

partners	in	our	2009	fiscal	year.	

earlier-stage	compounds.

Our TAP Technology

Our Targeted Antibody Payload (TAP) technology was developed to achieve more effective, better tolerated  
anticancer therapies.

A TAP compound consists of a manufactured antibody (shown in purple) that binds specifically to a target found 

on cancer cells. 

Attached to the antibody is an ImmunoGen cancer-cell killing payload (shown in orange). Our scientists developed 

our proprietary payload agents for the purpose of being delivered to cancer cells using antibodies. Our agents are  
1,000 – 10,000 more potent than standard chemotherapy drugs.  

Our payload agents are attached to the antibody using one of our engineered linkers. Our linkers keep the agent 

firmly attached to the antibody while the TAP compound is traveling through the bloodstream. 

Once a TAP compound has bound to and entered a cancer cell, the payload agent is freed and able to kill the cell. 

We have developed alternative linkers that play a key role in determining how the payload is freed and its behavior 
after release, as the needs vary depending on the cancer target.

Letter to Our Shareholders

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This	past	year	has	been	one	of	both	change	and	considerable	progress	for	ImmunoGen.	In	writing	my	inaugural	letter	to	you	as	ImmunoGen’s	CEO,	
I	want	to	clearly	convey	that	our	Company	is	at	a	very	different	stage	today	than	we	were	just	a	short	time	ago,	that	I	believe	we’ve	put	together	the	
right	team	to	take	ImmunoGen	to	a	new	level,	and	that	I’m	very	excited	about	our	future.	

ImmunoGen Today
Today,	we	are	potentially	within	fifteen	months	or	so	of	the	first	TAP	compound	being	commercialized	in	the	US.	This	would	be	a	threshold	event	
for	the	Company	–	in	significantly	expanding	the	number	of	patients	who	can	benefit	from	our	technology,	in	changing	our	financial	profile		
through	our	realizing	royalties	on	partner	product	sales	and	in	validating	the	support	of	the	many	people	who	believe	our	technology	can	make	a	real	
difference	for	cancer	patients.	TAP	compounds	are	being	evaluated	in	numerous	clinical	trials	–	ones	assessing	the	product	candidate	used	alone	and	
ones	testing	it	as	part	of	a	combination	regimen;	trials	evaluating	the	compound	for	a	cancer	that	has	progressed	on	all	approved	therapies	and	ones	
for	earlier-stage	cancers;	multi-national	randomized	trials	and	smaller,	exploratory	studies.	

At	the	same	time,	our	research	team	has	returned	to	creating	novel	therapeutics	for	our	own	product	pipeline	after	years	of	working	on	programs	
included	in	our	collaboration	with	sanofi-aventis.	Our	scientists	are	using	the	array	of	clinical	data	that	have	been	generated	with	TAP	compounds	to	
further	refine	our	product	standards	and	advancement	criteria.	Findings	in	the	clinic	also	have	opened	up	potential	new	areas	of	opportunity	that	we	
are	now	exploring.	We	expect	to	start	reporting	preclinical	findings	with	some	of	our	research-stage	compounds	in	the	coming	year.

Our	scientists	have	continued	to	expand	our	technology	portfolio	to	enable	the	development	of	TAP	compounds	for	cancers	that	had	been	
outside	of	our	reach.	We’ve	presented	data	on	our	new	family	of	linkers	that	enables	the	creation	of	TAP	compounds	with	pronounced	activity	
against	multi-drug	resistant	cancers	–	cancers	which	are	particularly	hard	to	treat	today.	We’re	developing	a	second	family	of	potent	payload	agents	
for	targeted	delivery	to	tumors.	These	agents	–	our	IGNs	–	kill	cancer	cells	by	a	different	mechanism	than	that	of	our	DM1/DM4	maytansinoid	
agents.	Cancers	differ	in	their	sensitivity	to	these	alternative	killing	mechanisms,	so	having	both	types	of	agents	in	our	portfolio	enables	the		
development	of	TAP	compounds	for	an	expanded	range	of	cancers.	

T-DM1	is	well	on	its	way	to	making	a	real	difference	for	patients,	and	numerous	TAP	compounds	are	progressing	behind	it.	We’re	focused	
on	creating	and	advancing	significant	new	anticancer	therapeutics	and	proving	the	value	of	our	pipeline.	The	leadership	team	we	have	in	place	is	
committed	to	that	mission.	

Our Leadership Team
Our	people	are	essential	to	our	success,	and	our	employees	are	a	group	of	highly	intelligent,	experienced		
and	motivated	individuals.	As	ImmunoGen	has	progressed,	our	leadership	needs	have	changed.	In	the	past	
ten	months,	we’ve	significantly	strengthened	our	senior	team	to	reflect	the	evolving	requirements	of	our		
organization	and	the	greater	emphasis	on	execution.

 
 
 
 
 
 
We	hired	Jim	O’Leary,	M.D.,	in	the	newly	created	position	of	Chief	Medical	Officer	in	November	2008.	Jim	immediately	set	to	work	estab-
lishing	a	success-based	development	plan	for	IMGN901	and	refining	our	clinical	programs.	I	think	you’ll	agree	that	there’s	already	been	a	tangible	
impact	from	Jim	joining	our	team,	such	as	greater	progress	in	the	advancement	of	IMGN901	and	the	discontinuation	of	IMGN242,	a	difficult	but		
appropriate	decision.	We	intend	to	also	add	a	Vice	President,	Regulatory	Affairs,	to	further	enhance	our	support	for	our	clinical-stage	compounds.
Jim’s	expertise	complements	that	of	John	Lambert,	Ph.D.,	who	was	promoted	to	Executive	Vice	President	and	Chief	Scientific	Officer	in	2008.	
John,	along	with	other	members	of	our	research	team,	has	a	unique	depth	of	expertise	–	and	experience	–	in	our	field.	In	the	past	year,	John’s	been	
leading	our	initiative	to	set	even	higher	bars	for	the	product	candidates	we	develop	and	to	promptly	advance	these	compounds	to	key	decision	points.	
We	hired	Greg	Perry	in	January	2009	to	fill	the	Chief	Financial	Officer	position	that	opened	with	my	promotion.	Additionally,	Peter	Williams	
joined	our	team	last	month	as	Vice	President,	Business	Development.	Peter,	Greg	and	Craig	Barrows,	our	General	Counsel,	have	highly	complemen-
tary	experience	in	areas	central	to	building	our	business,	such	as	leveraging	our	pipeline	and	technology	through	win-win	collaborations	with	other	
companies.	One	of	Peter’s	near-term	objectives	is	to	organize	and	prioritize	our	business	development	opportunities.	I’m	confident	that	this	will	lead	
to	a	number	of	attractive	alternatives	for	us	to	consider.

In	January	2009,	we	transitioned	the	CEO	position	from	Mitchel	Sayare,	Ph.D.,	to	me,	with	Mitch	now	serving	the	Company	as	Chairman	of	
the	Board.	Mitch	joined	ImmunoGen	in	1986	and	led	the	Company	through	both	exuberant	and	lean	years,	bringing	ImmunoGen	to	the	doorstep	
of	commercial	validation.	Among	his	many	contributions	was	ensuring	that	resources	were	available	to	ImmunoGen	over	the	years	needed	for		
our	technology	to	be	validated	in	the	clinic.	The	opportunity	for	ImmunoGen’s	technology	to	improve	the	lives	of	patients	diagnosed	with	cancer	
would	not	exist	but	for	Mitch.	I’m	sure	I	speak	for	all	of	us	in	thanking	Mitch	for	his	many,	many	contributions	and	his	dedication	to	the		
Company	and	its	mission.

Looking forward
As	it	has	been,	our	strategy	continues	to	be	to	develop	novel	anticancer	compounds	that	make	a	real	difference	for	patients	with	cancer.	We	also	plan	
to	continue	to	use	corporate	collaborations	to	access	targets	that	would	not	otherwise	be	available	to	us,	to	support	the	advancement	of	numerous	
TAP	compounds	to	patients	and	to	increase	the	potential	return	to	our	shareholders.	This	has	not	changed.	

What	has	changed	is	our	focus	on	execution	–	more	expeditiously	advancing	our	product	candidates	to	value-inflection	points	and	driving	the	

formation	of	high	value	collaborations.	I	am	confident	that	the	leadership	team	in	place	can	markedly	accelerate	our	progress.	

I	thank	our	Directors	and	our	employees	for	their	support	during	this	period	of	transition.	Also,	we	should	all	thank	the	patients	who	participate	

in	clinical	trials	–	these	individuals	play	a	critical	role	in	helping	new	therapies	become	available	for	all	of	us.

And	a	special	thanks	to	you,	our	shareholders,	for	your	support	of	our	programs	and	progress.	

Sincerely,

Daniel	M.	Junius
President	and	Chief	Executive	Officer

September	18,	2009

Phase I 

Phase II 

Pivotal Ph. II/Phase III

Genentech/Roche

ImmunoGen

sanofi-aventis

Biogen Idec

Biotest

Product Pipeline

Compound 

T-DM1 

3rd-line MBC

2nd-line MBC

1st-line MBC

  Combination trials in MBC 

  Adjuvant trials under consideration 

IMGN901

  Multiple myeloma – monotherapy

  Multiple myeloma – combination

  Solid tumors  

IMGN388* – Solid tumors 

SAR3419 – Non-Hodgkin’s lymphoma 

BIIB015  – Solid tumors 

BT-062** – Multiple myeloma

  MBC = metastatic breast cancer

  *  Centocor has opt-in rights
  **  ImmunoGen has opt-in rights

The Opportunity for Our TAP Technology
Growing	excitement	around	trastuzumab-DM1	(T-DM1)	has	led	to	increasing	interest	in	ImmunoGen	and	in	our	technology.	T-DM1	has	
shown	encouraging	activity	in	patients	whose	cancer	progressed	on	treatment	with	trastuzumab	(Herceptin®),	underscoring	the	benefit	that	
can	be	achieved	with	the	addition	of	our	technology	to	an	antibody.	

Behind	T-DM1	is	a	growing	pool	of	TAP	compounds	which	contain	antibodies	that,	unlike	trastuzumab,	are	not	marketed	anticancer	
therapies	today.	The	development	path	for	these	product	candidates	tends	to	be	more	exploratory,	as	less	is	known	about	the	antibody	and	
its	target	at	the	start	of	clinical	testing.	As	a	group,	however,	these	compounds	offer	a	potentially	much	greater	opportunity	for	our	payload	
technology,	as	there	are	far	more	antibodies	that	do	not	have	significant	anticancer	activity	on	their	own	than	those	that	do.		

Our	discovery	programs	are	focused	on	further	expanding	the	application	of	our	technology	–	through	our	creation	of	significant	new	

anticancer	therapeutics	and	our	development	of	additional	linkers	and	payload	agents	that	broaden	the	reach	of	our	technology.	

 
 
 
 
 
 
 
 
 
 
T-DM1 consists of our DM1 cancer-cell killing agent linked to the HER2-binding antibody,  
trastuzumab. It is being developed by Genentech in the US and by Roche outside of the US Genentech  
became a wholly-owned member of the Roche Group in late March 2009.

T-DM1
T-DM1	is	expected	to	be	the	first	product	commercialized	that	makes	use	of	our	TAP	technology.	It	is	now	in	Phase	III	testing	for		
second-line1	treatment	of	HER2-expressing	metastatic	breast	cancer	(HER2+	MBC).	T-DM1	also	is	being	evaluated	for	third-line2	use	in	
this	cancer	in	a	Phase	II	clinical	trial	that,	if	the	findings	merit,	could	support	accelerated	approval	of	the	compound	in	the	US	in	2010.		
In	July,	Roche	noted	that	it	expects	the	findings	from	this	third-line	trial	to	be	reported	at	a	medical	conference	in	late	2009.

A	number	of	earlier-stage	clinical	trials	also	are	underway	which,	over	time,	could	pave	the	way	for	additional	uses	of	T-DM1.	The	
compound	is	being	evaluated	as	a	potential	first-line	treatment	for	HER2+	MBC	in	a	trial	that	compares	T-DM1,	given	as	a	single	agent,	
head-to-head	with	trastuzumab	used	together	with	docetaxel	(Taxotere®),	a	chemotherapy	agent.	Multiple	trials	are	underway	or	planned	
to	assess	T-DM1	when	used	as	part	of	different	combination	regimens.	And,	Genentech	has	disclosed	that	trials	are	being	considered	to	
evaluate	T-DM1	for	early-stage	HER2+	breast	cancer	(adjuvant	use).

Needless	to	say,	the	clinical	findings	that	have	been	reported	with	T-DM1	are	highly	encouraging	–	in	the	proportion	of	patients	
benefiting	from	the	compound,	the	duration	of	their	response	and	the	tolerability	reported.	We	are	delighted	that	patients	have	benefited	
from	T-DM1	in	clinical	studies	and	are	hopeful	that	this	promising	agent	will	be	available	to	increasingly	more	patients	over	time.

IMGN901 – Our Lead Product Candidate
IMGN901,	which	is	wholly-owned	by	ImmunoGen,	is	designed	to	selectively	target	and	kill	cancers	that	express	CD56.	These	include	
virtually	all	small-cell	lung	cancer	(SCLC)	and	Merkel	cell	carcinoma	(MCC)	tumors	and	most	multiple	myeloma	and	ovarian	cancers.	

Today,	CD56	is	less	well	known	to	most	practicing	physicians	than	HER2	as	currently	there	

are	no	CD56-targeting	drugs	on	the	market.	This	makes	the	development	path	for	IMGN901	
more	exploratory	than	that	of	T-DM1.	However,	it	also	means	that,	if	successful,	IMGN901	
would	be	an	entirely	new	type	of	treatment	for	CD56+	cancers.

Our	focus	with	IMGN901	is	to	demonstrate	its	clinical	value	as	quickly	as	possible	and	to	
pursue	the	best	potential	route(s)	to	marketing	approval.	Such	routes	may	include	development	to	
treat	one	or	more	types	of	CD56+	solid	tumors	and/or	as	a	treatment	for	multiple	myeloma,	either	
used	alone	or	in	combination	with	other	agents.

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IMGN901 for Multiple Myeloma
IMGN901	has	shown	encouraging	initial	findings	for	multiple	myeloma	and	could	potentially	be	
developed	for	use	alone	or	as	part	of	a	combination	regimen	for	this	cancer.

We	are	evaluating	IMGN901,	used	as	a	single	agent,	in	our	Study	003.	We	recently	obtained	

the	information	needed	to	expand	this	trial	and	treat	patients	at	the	maximum	tolerated	dose.		
We	expect	to	present	updated	clinical	data	from	Study	003	at	a	medical	conference	in		
December	2009.

The	information	obtained	also	enables	us	to	start	our	Study	005,	which	assesses	the	compound	

used	in	combination	with	lenalidomide	(Revlimid®)	plus	dexamethasone.	This	evaluation	is	
of	particular	interest	as	multiple	myeloma	typically	is	treated	with	a	combination	of	agents,	and	the	profile	of	IMGN901	is	well	suited	
to	this	use.	In	preclinical	studies,	its	addition	to	this	commonly	used	regimen	significantly	improved	its	efficacy.	And,	on	the	safety	side,	
IMGN901	is	not	associated	with	side	effects	that	would	limit	its	ability	to	be	combined	with	other	agents,	which	is	often	an	issue.		
Patient	dosing	in	Study	005	is	expected	to	begin	in	September/October	2009.	We	intend	to	report	the	first	clinical	data	from		

this	trial	in	2010.

IMGN901 for Solid Tumors
CD56	occurs	on	virtually	all	cases	of	SCLC	and	MCC	–	two	cancers	associated	with	rapid	progression	after	spread	(metastasis)	or	recur-
rence.	It	also	occurs	on	many	ovarian	cancers	as	well	as	some	other	types	of	solid	tumors.

We	recently	reported	findings	from	two	early-stage	clinical	trials	with	the	compound	which	enrolled	patients	with	CD56+	solid	tumors.	

Among	the	findings	reported	was	that	one	in	four	of	the	SCLC	patients	enrolled	had	sustained	stable	disease	and/or	tumor	shrinkage	after	
treatment	with	IMGN901.	Experts	found	these	data	to	be	encouraging	and	to	support	further	evaluation	of	the	compound	for	this	cancer.	
The	findings	reported	for	MCC	were	particularly	remarkable.	Among	the	six	MCC	patients	treated	with	IMGN901,	one	has	had	a	
complete	disappearance	of	her	disease	for	over	four	years,	one	had	marked	tumor	shrinkage	that	has	continued	for	months	after	just	one	
treatment	cycle,	and	one	had	sustained	stable	disease.	

We	are	using	the	solid	tumor	trial	underway	to	gain	experience	with	IMGN901	against	specific	types	of	tumors	and	also	important	

dosing	information.	Our	goal	is	to	establish	a	development	plan	for	IMGN901	in	solid	tumors	no	later	than	the	first	half	of	2010.

IMGN901 is the only TAP compound currently in clinical testing for the treatment of both solid and 

liquid tumors. It consists of our DM1 linked to our CD56-binding antibody, huN901.

 
 
 
 
 
 
 
 
SAR3419 is in development by sanofi-aventis for the treatment of non-Hodgkin’s lymphoma, the most 

commonly diagnosed liquid tumor in the US today.

SAR3419 and the Expanding Pipeline of Earlier-Stage Compounds 
SAR3419	was	developed	by	ImmunoGen	and	licensed	to	sanofi-aventis	as	part	of	a	broader	collaboration	between	our	companies.	This	TAP	
compound	is	of	particular	interest	because	it	has	the	potential	to	be	the	first	antibody-drug	conjugate	for	the	treatment	of	non-Hodgkin’s	
lymphoma.	Today,	this	cancer	is	frequently	treated	with	rituximab	(Rituxan®),	a	highly	successful	naked	antibody	product.	The	first	clinical	
findings	with	SAR3419	are	expected	to	be	reported	at	a	medical	conference	in	December	2009.

Our	collaborator,	Biotest,	is	making	excellent	progress	with	its	BT-062	TAP	compound	and	intends	to	report	the	first	clinical	findings	
with	it	at	the	same	medical	conference.	Looking	further	ahead,	we	expect	to	report	the	first	findings	with	our	IMGN388	compound	for	the	
treatment	of	solid	tumors	at	a	medical	conference	in	mid-2010,	and	the	first	clinical	data	for	Biogen	Idec’s	BIIB015	could	potentially	be	
reported	in	2010	as	well.

Numerous	product	candidates	are	in	earlier	stages	of	development,	and	we	expect	additional	compounds	to	advance	into	the	clinic	in	

2010	through	our	collaborations.	

We	believe	the	pool	of	compounds	in	development	will	to	continue	to	grow.	Of	particular	importance,	our	scientists	are	back	to	

creating	promising	product	candidates	for	our	own	pipeline	after	more	than	five	years	of	supporting	sanofi-aventis	programs.	

In	that	time,	a	wealth	of	new	clinical	data	has	been	generated	with	TAP	compounds	that	has	broadened	our	areas	of	exploration	and	
also	has	tightened	our	criteria	for	product	advancement.	Also,	we	have	recently	created	additional	linkers	and	cancer-cell	killing	agents	that	
we	believe	will	markedly	enhance	our	product	programs.

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Our Expanding Technology Portfolio
All	of	the	TAP	compounds	discussed	employ	one	of	our	standard	linkers	to	keep	the		
potent	cancer-cell	killing	agent	firmly	attached	to	the	antibody	while	it	is	traveling	through	the	
bloodstream	and	then	control	its	release	once	inside	a	cancer	cell.	

We	conduct	extensive	research	on	the	ways	TAP	compounds	are	processed	after	entering	
a	cancer	cell.		We	have	used	this	knowledge	–	together	with	insights	from	other	ImmunoGen	
research	–	to	further	expand	our	portfolio	of	linkers.	Our	new	POL	family	of	linkers	is	expected	to	
further	extend	the	potential	for	TAP	compounds	and	allow	us	and	our	partners	to	develop	effec-
tive	therapeutics	for	cancers	with	special	challenges,	such	as	multi-drug	resistance	or	low	levels	of	
antigen	expression.

Similarly,	all	of	our	product	candidates	and	our	partnerships	to	date	are	built	around	our	maytansinoid	cancer-cell	killing	agents		
(e.g.,	DM1,	DM4).	These	agents	can	only	kill	cells	that	are	in	the	process	of	dividing	–	a	feature	that	is	generally	advantageous.	There	are	
cancers,	however,	which	can	only	be	effectively	treated	with	agents	that	interfere	directly	with	cellular	DNA.	After	extensive	research,	our	
scientists	have	now	created	a	second	family	of	cancer-cell	killing	agents	–	our	IGNs	–	which	act	directly	on	DNA.	We	expect	to	report	
initial	preclinical	data	with	these	agents	at	a	scientific	meeting	this	fall.

We	expect	that	these	innovations	will	contribute	to	our	goal	of	developing	new	therapeutics	and	new	technologies	to	help	patients		

with	cancer.

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1Patients must have received prior treatment that included both a taxane (alone or in combination with another agent) and trastuzumab in the adjuvant, locally 
advanced, or metastatic setting.
2Patients must have had prior treatment with at least two lines of anti-HER2 therapy in the metastatic setting, and must have received an anthracycline, a taxane, 
trastuzumab, lapatinib and capecitabine in the neoadjuvant, adjuvant, locally-advanced or metastatic setting. 
Herceptin® is a registered trademark of Genentech, a wholly-owned member of the Roche Group.
Tykerb® is a registered trademark of GlaxoSmithKline plc.
Taxotere® is a registered trademark of sanofi-aventis.
Revlimid® is a registered trademark of Celgene Corporation.
Rituxan® is a registered trademark of Biogen Idec Inc.

 
 
 
 
 
 
 
 
 
 
 
Corporate Information

Directors

Executive Officers

Mitchel Sayare, Ph.D.
Chairman 
Former Chief Executive Officer, 
ImmunoGen, Inc. 

David W. Carter
Former Chairman and 
Chief Executive Officer,
Xenogen Corporation

Daniel M. Junius
President and Chief Executive Officer,
ImmunoGen, Inc.

Stephen C. McCluski
Former Senior Vice President 
and Chief Financial Officer, 
Baush & Lomb, Inc.

Nicole Onetto, M.D.
Former Senior Vice President,
Product Development and 
Chief Medical Officer,
ZymoGenetics, Inc.

Mark Skaletsky
Chairman and Chief Executive Officer,
Fenway Pharmaceuticals

Joseph J. Villafranca, Ph.D.
Senior Vice President, Life Sciences, 
Business Development,
Tunnell Consulting

Richard J. Wallace
Former Senior Vice President,
Research and Development,
GlaxoSmithKline plc.

Daniel M. Junius
President and Chief Executive Officer

John M. Lambert, Ph.D.
Executive Vice President, 
Research and Development
and Chief Scientific Officer

James J. O’Leary, M.D.
Vice President and Chief Medical Officer

Gregory D. Perry
Senior Vice President and  
Chief Financial Officer

Peter J. Williams
Vice President, 
Business Development

Corporate Headquarters
ImmunoGen, Inc. 
830 Winter Street
Waltham, MA 02451
781.895.0600
www.immunogen.com

Annual Meeting
11:00 AM on November 11, 2009 
At the Offices of the Company
830 Winter Street
Waltham, MA 02451

Stock Transfer Agent and Registrar
BNY Mellon Shareowner Services
Newport Office Center VII 
480 Washington Boulevard 
Jersey City, NJ 07310 
www.bnymellon.com/shareowners/isd 
Toll-Free Number: 888.810.7458 

Legal Counsel
Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
Boston, Massachusetts

Auditors
Ernst & Young LLP
Boston, Massachusetts

Shareholder Inquiries
Information about ImmunoGen can be 
found at www.immunogen.com. Inquiries 
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 Company’s and 
its collaboration partners’ clinical trial activity, progress, and presentation 
of findings. For these statements, ImmunoGen claims the protection of 
the 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 report. Factors that could cause future 
results to differ materially from such expectations include, but are not 
limited to: the outcome of ImmunoGen’s research and clinical development 
processes; the outcome of ImmunoGen’s collaboration 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 and clinical 
trials; ImmunoGen’s ability to financially support its product programs; 
ImmunoGen’s dependence on collaborative partners; and other factors 
more fully described in ImmunoGen’s Annual Report on  
Form 10-K for the fiscal year ended June 30, 2009 and other reports filed 
with the Securities and Exchange Commission.

Design: PrattDesign.net

ImmunoGen, Inc. 
830 Winter Street, Waltham, Massachusetts 02451
781.895.0600  •  www.immunogen.com

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

(cid:1) ANNUAL REPORT PURSUANT TO SECTION 13  OR  15(d) OF  THE

SECURITIES EXCHANGE ACT  OF  1934

Form 10-K

(cid:2)

For the fiscal year ended June 30, 2009
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)

(Former  address, if changed since last report)

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 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:1) 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:2) Yes (cid:1) 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:1) Yes (cid:2)  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:2) 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:2)

Accelerated  filer (cid:1)

Non-accelerated filer  (cid:2)
(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:2)  Yes (cid:1) 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,  2008: $181,094,864 (excludes shares held by executive officers, directors, and
beneficial owners of more than 10% of the  Company’s common stock). 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 25, 2009:  57,057,596 shares.

DOCUMENTS INCORPORATED BY REFERENCE

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

Shareholders  to be held on November  11, 2009  are incorporated by reference into Part III.

ImmunoGen, Inc.

Form 10-K

TABLE OF CONTENTS

Item

1.
1A.
1B.
2.
3.
4.
4.1

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
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Submission of Matters to a Vote  of  Security  Holders . . . . . . . . . . . . . . . . . . . . . . . . .
Executive Officers of the Registrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Part II
Market for the 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
23
37
38
38
38
38

40
40

41
57
59

93
93
95

96
96

96
96
96

97

98

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, 2009 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 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 be 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 a particular 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. Our TAP  technology is designed to enable  the creation of highly
effective, well-tolerated anticancer products.

We  believe that our TAP technology and our expertise in the development and humanization  of

monoclonal antibodies will enable us to become  a leader in the application of  antibody-based
anticancer compounds. We plan to achieve  this goal through the development of  our own anticancer
products and through collaborations with other companies. There  are  now six TAP compounds in
clinical trials through our own programs and those of several of our  collaborators. Our collaborators
currently include: Amgen, Bayer HealthCare, Biogen Idec, Biotest, Genentech (a wholly-owned
member of the Roche Group) and sanofi-aventis.

We  believe that the key initiatives central to our  future  success are:

(cid:127) Develop our own proprietary products. We currently have two TAP compounds in  clinical testing:
IMGN901, a potential treatment for multiple  myeloma, small-cell lung cancer or SCLC, Merkel
cell  carcinoma, ovarian cancer and other CD56-expressing cancers; and IMGN388, a potential
treatment for solid tumors including melanomas, sarcomas and  many carcinomas. We are
advancing these compounds and also  are using our scientific expertise to develop additional
antibody-based anticancer compounds. Several  of these additional compounds are in the
research assessment phase from which  we will  determine their suitability to advance to
preclinical development over the next six to 18 months.

(cid:127) Support and expand our collaborative arrangements. Part of our business model is to establish

collaborations with other companies in order to expand the application of our TAP technology
and to provide us with additional sources of cash and  revenue.  For example, Genentech created
trastuzumab-DM1, or T-DM1, under  a collaborative  arrangement  with us that enabled it to use
our  maytansinoid cell-killing agents, including DM1, with antibodies  that  bind  to  HER2, such as
its  trastuzumab (Herceptin(cid:4)) antibody. In February 2009, we earned a  $6.5 million milestone
payment with the start of T-DM1 Phase  III clinical testing. Another compound  is SAR3419,
which was initially developed by us and  was  out-licensed to sanofi-aventis (then Aventis) from
our  preclinical pipeline as part of a broader collaboration  between our  companies. We  have
entered into other types of arrangements with collaborators around our technology, expertise,
and product programs, and intend to continue to establish collaborations going forward.

3

(cid:127) Support our TAP technology to maintain our strong  position in our field. We have developed highly
potent cell-killing agents designed specifically for attachment to antibodies for targeted delivery
to cancer cells, and have a portfolio of linkers to affix our cytotoxic agents  to  antibodies. These
cell-killing agents and linkers provide  us and our  collaborators the flexibility  to  select the design
that works best for each antibody and target. More  antibody-cytotoxic agent compounds have
advanced into clinical testing using our technology than  that of any other company. We continue
to conduct research to develop additional  cell-killing agents and linkers to further strengthen our
unique position in the field. We recently reported that we have developed a new  family of
engineered linkers that we believe will extend the  utility of our technology for  the treatment of
multidrug-resistant cancers. We also recently filed a  patent on a new  family  of  cell-killing agents
which can kill cancer cells through a different mechanism than  used  by our maytansinoid agents.

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.

Our TAP  Technology

Traditional chemotherapeutic agents typically  kill any rapidly-dividing cell, including healthy cells,
which  can result in significant adverse side  effects and limit their ability to be dosed  to  full therapeutic
potential. The invention of monoclonal antibodies  enables scientists to create proteins that bind
specifically to antigen targets found on cancer  cells. This  scientific advancement led to the  development
of a few highly successful anticancer  antibody  therapeutics (CD20-binding  Rituxan(cid:4), HER2-binding
Herceptin, CD52-binding Campath(cid:4) and EGFR-binding Erbitux(cid:4) and Vectibix(cid:4)). For many of the
targets that have been identified on cancer cells, however, the binding of  a  monoclonal antibody to the
target lacks meaningful anticancer activity.

We  created our TAP technology to significantly enhance the anticancer activity  of  monoclonal
antibodies. We attach—using our engineered linkers—our highly  potent cell-killing agents  to  such
antibodies for targeted delivery to cancer  cells.  Our TAP technology  can be used with  antibodies that
have anticancer activity of their own,  such as  trastuzumab,  to achieve enhanced anticancer  activity. The
bigger opportunity, however, potentially may be use  of  our  TAP technology with antibodies  with little
anticancer activity of their own, enabling  effective  antibody-based therapies to be developed for many
more types of cancers.

We  developed our proprietary cell-killing  agents specifically for  attachment to antibodies  for
delivery to cancer cells. All TAP compounds currently in clinical or  preclinical testing  contain one of
our  maytansinoid cancer-cell killing agents  (DM1 or DM4),  which act  by interfering with the  activity of
a substance, tubulin, that is essential for  successful cell division.  Cancer cells undergo frequent  cell
division, in contrast to most normal cells. Our maytansinoid agents are:

(cid:127) Potent. Our proprietary maytansinoid agents  are 1,000- to 10,000-fold more  potent than

traditional chemotherapy agents and are thus capable of killing cancer cells when the agents are
present at low concentrations. This is  important for an  agent delivered to a cancer cell attached

4

to an antibody, as generally only a small amount of antibody,  and  therefore, the attached
cell-killing agent, will reach the cancer cells.

(cid:127) Attachable. Our proprietary maytansinoid agents  can be attached  to  an antibody using one of our

engineered ‘‘linkers.’’ Our linkers are designed to achieve  a  bond between the agent and the
antibody that remains intact while the  TAP compound  is circulating in  the bloodstream,
rendering the cytotoxic agent inactive, but then enables  the cytotoxic agent to exhibit its full
potency once inside a cancer cell.

(cid:127) Producible. Our proprietary maytansinoid agents  can be readily manufactured  and  our supplier

produces these agents for us in a manner that can be scaled-up to commercial  production
quantities.

(cid:127) Protectable. We hold issued US patents on our maytansinoid agents  and related  derivatives and

also have intellectual property related to their methods of production.

We  have developed other types of cell-killing  agents in addition to our maytansinoid agents. Most
recently disclosed is our IGN family  of highly potent cell-killing agents. Our IGNs kill  cancer cells by
attacking their DNA and thus offer potential to extend the  utility of our technology to cancers  that  are
insensitive to tubulin-acting agents. We have filed a  patent on our  IGN cell-killing  agents.

We  also have developed a portfolio of engineered linkers, which  are used to attach our cell-killing

agents to antibodies. Our linkers enable  our  cell-killing agents to remain securely attached to an
antibody  while a TAP compound is circulating in the blood stream,  and then direct its release and
activation inside a cancer cell. Our portfolio  of  linkers  enables us to create highly-hindered disulfide
bonds, less-hindered disulfide bonds and also a non-reducible or ‘‘non-cleavable’’ thioether bond. This
provides us and our collaborators with flexibility  in the  construction of TAP  compounds as the best
design for each TAP compound varies depending upon  the particular antibody and  its target.  We
recently unveiled a new family of ImmunoGen linkers  that have  been shown  in preclinical testing to
provide enhanced activity against multi-drug resistant cancers. In recent years, we  have gained
increasing recognition by our collaborative partners  for the depth of our expertise  in the design,
evaluation and development of antibody-cytotoxic  agent compounds.

Additionally, we have established capabilities and expertise with monoclonal antibodies. We have

extensive experience in cancer biology and in the evaluation  of potential targets for antibody-based
anticancer treatments. We can create monoclonal antibodies for  promising targets, and using our
patented humanization technology we can  modify these antibodies  so that the human immune  system is
unable to detect them. We also have considerable expertise in functions critical to the advancement of
an antibody-based product from the laboratory to the clinic, including cell-line development, preclinical
evaluation and process development.

Product  Candidates

The following table summarizes the antigen  target, cancer(s) expressing the target, and
development stage for compounds in development  by us  and our collaborators. The results from
preclinical testing and early clinical trials may not be predictive of results obtained in subsequent
clinical trials and there can be no assurance that  our or our collaborators’ clinical trials will

5

demonstrate the level of safety and efficacy of any product candidates necessary to obtain regulatory
approval.

Product Candidate

Antigen Target

Cancer(s) expressing target(1)

Development Stage(2)

Trastuzumab-DM1

(T-DM1) . . . . . . . . HER2

Breast cancer
Gastric cancer

For HER2+
metastatic  breast
cancer:
(cid:127) 3rd line use—

Phase II
(potentially
pivotal  trial)
(cid:127) 2nd-line use—
Phase III
(cid:127) 1st-line use—

Phase II

Collaborative
Partner, if any

Genentech/
Roche

IMGN901 . . . . . . . . . CD56

Hematological malignancies
including multiple myeloma;
small-cell lung cancer; Merkel Phase  I—SCLC
and other  solid
cell  carcinoma;  other cancers
tumors
of  neuroendocrine origin

Phase I—multiple
myeloma

Proprietary  to
ImmunoGen

SAR3419 . . . . . . . . . . CD19

B-cell malignancies including
non-Hodgkin’s lymphoma

IMGN388 . . . . . . . . . An  integrin Solid tumors

Phase I—
non-Hodgkin’s
lymphoma

Phase  I

BIIB015 . . . . . . . . . . Cripto

Solid tumors

Phase  I

BT-062 . . . . . . . . . . . CD138

Multiple myeloma,  other

Phase I—multiple
myeloma

sanofi-aventis

ImmunoGen;
Centocor has
opt-in rights

Biogen  Idec

Biotest;
ImmunoGen has
opt-in rights

SAR566658 . . . . . . . . CA6

Breast; ovarian; other solid
tumors

Preclinical

sanofi-aventis

SAR650984(3) . . . . . . . CD38

Hematological  malignancies

Preclinical

sanofi-aventis

TAP  and other

compounds . . . . . . . Undisclosed Undisclosed

Research/preclinical ImmunoGen/
collaborators

(1) Types of cancers  that express the target antigen. Not  all  tumors  of any  given type  may express the

antigen target and not all  cancers that  express the  target  may  be  listed.

(2) Compounds in clinical testing  are being  assessed in  patients whose cancer expresses the target antigen.
Compounds that are not in clinical testing and have an undisclosed  status  are listed  as research/
preclinical.

(3) Naked antibody.

Trastuzumab-DM1 (T-DM1)

T-DM1 consists of our DM1 cell-killing agent attached  to  the  HER2-binding antibody,
trastuzumab, using our thioether linker.  Trastuzumab is  the  active  component  of the marketed

6

anticancer compound, Herceptin. T-DM1 was created under a HER2-specific license agreement
established between ImmunoGen and  Genentech in  2000. Genentech and its corporate parent, Roche,
are developing T-DM1 on a worldwide basis.

To date, we have earned $13.5 million  of a potential $44  million in milestone payments  with
Genentech/Roche’s advancement of T-DM1: $2  million  when its Investigational New Drug, or IND,
became effective in January 2006, $5  million when it  entered Phase II clinical testing in July 2007, and
$6.5 million milestone when it began  Phase III  evaluation in February 2009. In May 2006, Genentech
retained us to develop a commercial-scale manufacturing process for T-DM1. We  have completed  and
transferred this process.

Multiple trials are being conducted by Genentech and/or Roche  that evaluate T-DM1 for  the

treatment of HER2-positive metastatic breast  cancer  (HER2+ MBC). In  March 2009, patient
enrollment was completed in a Phase  II trial  evaluating T-DM1 as  a  third-line treatment for HER2+
MBC. Roche has disclosed that this trial could be used to gain approval  of T-DM1  in the U.S. if the
findings are compelling and that the  findings from this trial are expected  to be available  in the fourth
quarter of 2009, which would enable potential submission to  the FDA  in 2010. In February 2009,
patient dosing began in a Phase III trial evaluating T-DM1 as a second-line  treatment for HER2+
MBC. T-DM1 also is being evaluated  as a first-line treatment  for HER2+ MBC  in a Phase II trial that
began in July 2008. Clinical trials also are underway  that evaluate T-DM1  used in combination with
other agents.

IMGN901

Our IMGN901 TAP compound targets  the antigen known as CD56.  CD56-expressing (CD56+)

cancers include multiple myeloma as  well as  other  hematological malignancies. They  also include
small-cell lung cancer, or SCLC, Merkel  cell  carcinoma, ovarian tumors and other cancers of
neuroendocrine origin. IMGN901 consists of  our  CD56-binding  antibody,  huN901,  with our DM1
cell-killing agent attached using one  of  our engineered  linkers.

We  are evaluating IMGN901 for the  treatment of CD56+ solid tumors in our Study 002  and
intend to use the expansion phase of  this Phase  I  trial to gain  additional information on the compound
for specific types of CD56+ solid tumors.  Almost 100%  of SCLC and Merkel cell carcinomas  express
CD56, and we recently reported encouraging initial clinical data with IMGN901  for the  treatment of
these cancers.

We  also are evaluating IMGN901 for  the treatment of CD56+ multiple myeloma.  Our Study 003
evaluates IMGN901 when used as a  single agent for the treatment  of this  cancer, and  our Study 005  is
designed to evaluate it when used in  combination with lenalidomide (Revlimid(cid:4)) plus dexamethasone.
We  expect to start our Study 005 later this  calendar year. Approximately 70%  of multiple myeloma
cases express CD56.

SAR3419

SAR3419 consists of our DM4 cell-killing agent  attached using one  of our  engineered linkers to a

CD19-binding antibody that was created and  humanized  by us. We licensed this compound to sanofi-
aventis in 2003 as part of a broader research  collaboration. We  earned a $1 million  milestone payment
from sanofi-aventis in October 2007 with the start of SAR3419 clinical testing. SAR3419 is being
evaluated for the treatment of non-Hodgkin’s lymphoma  in two Phase I clinical  trials that have
different dosing schedules. Data from the  first  clinical trial  are  expected to  be  reported in December
2009. Like Genentech, sanofi-aventis retained us to develop a commercial-scale  manufacturing process
for SAR3419. We have completed our process work for sanofi-aventis.

7

BIIB015

BIIB015 was created by Biogen Idec  under a 2004 license  that  grants  Biogen Idec the exclusive

right to use our maytansinoid TAP technology  with antibodies that target Cripto, an antigen found  on
solid tumors. BIIB015 consists of Biogen  Idec’s Cripto-binding antibody with our DM4 cell-killing agent
attached using one of our engineered linkers. Biogen  Idec submitted  the IND for this compound to the
FDA in February 2008, triggering a $1.5  million milestone payment to us.  BIIB015  advanced into
Phase I testing in the summer of 2008.

BT-062

BT-062 was created by Biotest under a 2006  license that grants  Biotest the exclusive right to use

our  maytansinoid TAP technology with  antibodies that target CD138, an antigen found  on multiple
myeloma and certain other cancers. BT-062 consists of Biotest’s anti-CD138  antibody  with our DM4
cell-killing agent attached using one  of  our engineered  linkers.  Biotest advanced  BT-062 into Phase I
evaluation in September 2008, triggering a $500,000 milestone payment to us.  We  have opt-in rights on
BT-062 in the U.S.

Other  Compounds

A number of product candidates using  our technology are in  various stages of  preclinical research

and development internally and at our collaborators.  Among these are the TAP compound,
SAR566658, and the naked (non-TAP) antibody, SAR650984, both of which  are in development
through our collaboration with sanofi-aventis.

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  projects  that 1.5 million  new cases  of  cancer will  be  diagnosed
in the U.S. in 2009 and that approximately 562,000 people  will die from various cancers. 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.  Additionally, patients  often receive  multiple drug
regimens sequentially, either to treat or  help  prevent recurrence of the disease.

We  are assessing our IMGN901 compound for the  treatment  of  CD56+  solid  tumors  and multiple

myeloma. According to the American  Cancer Society, approximately 21,000  new cases  of  multiple
myeloma will be diagnosed in the U.S.  in 2009,  and close to 11,000  people will die from  the disease.
Based on research conducted, we estimate that approximately  70%  of multiple  myeloma cases express
the CD56 antigen targeted by IMGN901.

IMGN901 has shown encouraging initial  clinical findings for the  treatment of SCLC and Merkel

cell  carcinoma. Close to 100% of these cancers express  CD56. It is expected  that  approximately  29,000
new cases of SCLC will be diagnosed in the  U.S. in  2009, as these cancers account for an estimated
13% of all U.S. lung cancer cases. Newly  diagnosed patients generally respond  to  their  first  treatment
regimen, but typically their SCLC then  recurs.  While  many patients  with recurrent  disease  could  be
eligible for additional treatment, survival  at  this stage is usually less than 6  months.

Merkel cell carcinoma is an aggressive  neuroendocrine cancer of the skin that typically occurs on

the head/neck, most often in individuals  of  European  ancestry. There  are approximately  800 to 1400
new cases of MCC diagnosed in the U.S.  each year, with the  incidence considered to be increasing.
Medicinal therapy is generally used with  patients  whose  cancer has recurred following  surgery and with

8

patients who have  metastases at the time of  diagnosis.  Metastatic  disease is associated with a poor
outcome, with a median survival time of  6.8 months

We  are assessing our IMGN388 compound for the  treatment  of  solid  tumors.  Cancers of particular

interest include melanoma and lung,  breast, and ovarian cancers. According to the American  Cancer
Society, approximately 504,000 new cases of these cancers are expected to be diagnosed in  the U.S.  in
2009.

In recent years, several antibody-based anticancer drugs—such as Herceptin, Rituxan and
Erbitux—have enjoyed considerable commercial success,  as  have other targeted anticancer  agents.

Out-licenses and Collaborations

As part of our business strategy to expand the  use of and financial return from our TAP
technology, we enter into license agreements with  third parties where we grant the other  party the
exclusive right to use our TAP technology with  their  antibodies to specific antigen targets. We also had
a research collaboration with sanofi-aventis  that provided  them access to compounds in our preclinical
pipeline. As part of these agreements, we are entitled  to  receive upfront fees, potential milestone
payments and royalties on the sales of  any resulting products.  Our principal out-licenses and
collaborative agreements are described below.

sanofi-aventis

In July 2003, we entered into a broad collaboration  agreement  with sanofi-aventis to discover,

develop and commercialize antibody-based anticancer  therapeutics.

The agreement provides sanofi-aventis with worldwide commercialization rights  to  new anticancer
therapeutics developed to targets that were  included in  the collaboration,  including the  right to use  our
TAP technology and our humanization technology in the creation of therapeutics  to  these  targets. The
product  candidates (targets) currently in  the collaboration include  SAR3419 (CD19), SAR566658
(CA6), SAR650984 (CD38) and additional compounds at earlier stages of development that have yet to
be disclosed.

The collaboration  agreement entitles us to receive  milestone payments potentially totaling

$21.5 million per antigen target for each therapeutic developed under the collaboration  agreement. We
have earned a $500,000 payment in September 2004 for a  preclinical milestone related  to  SAR3419, a
$1 million milestone payment in October  2007 with  the start of clinical testing of SAR3419, a $500,000
payment in December 2007 for a preclinical milestone related to SAR650984 and a $500,000 payment
in March 2008 for a preclinical milestone related to SAR566658. We also earned  an aggregate of
$8 million of milestone payments related  to two product candidates  that previously had been  in the
collaboration, AVE9633 and AVE1642.  Rights to these two product candidates  and their respective
targets have been returned to us.

The agreement also entitles us to royalties on  the commercial  sales  of  any resulting products  if  and

when such sales commence. Sanofi-aventis is  responsible for the cost of the development,
manufacturing and marketing of any products created through  the collaboration. We  are reimbursed for
any preclinical and clinical materials that we  make under 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-aventis  to  terminate our co-promotion rights if
there is a change of control of our company.

The overall term of the agreement extends to the later of the latest patent to expire or twelve
years after the latest launch of any product discovered, developed and/or commercialized under  the
agreement. Sanofi-aventis paid us an upfront fee of $12.0  million in August 2003.  Inclusive of  its
extensions, the agreement entitled us  to  receive committed research funding totaling  $79.3 million over

9

the five years of the research collaboration. The two companies subsequently  agreed to extend the  date
of research funding through October  31, 2008 to enable completion of previously agreed-upon  research.
We  earned $81.5 million of committed  research funding for  activities performed under the completed
research term of this agreement, and are now  compensated for  research performed for  sanofi-aventis
on a mutually agreed-upon basis.

In October 2006, sanofi-aventis licensed  non-exclusive  rights to use our proprietary resurfacing
technology to humanize antibodies to targets  not  included in the collaboration,  including antibodies for
non-cancer applications. This license  provides sanofi-aventis with the non-exclusive right to use our
proprietary humanization technology  through August 31, 2011  with the  right to extend for one or more
additional periods of three years each by providing us with written notice prior  to  expiration of the
then-current license term. Under the terms of the  license, we are entitled to a  $1 million license  fee,
half of which was paid upon contract  signing and the second half  was paid in August 2008, and  in
addition, we are entitled to receive milestone  payments potentially totaling $4.5  million  for each
antibody  humanized under this agreement and also royalties on commercial sales, if any.

In August 2008, sanofi-aventis exercised  its  option under a 2006 agreement for expanded access to

our  TAP technology. The exercise of  this option enables sanofi-aventis  to evaluate, with certain
restrictions, our maytansinoid TAP technology  with antibodies  to  targets that were not included  in the
research collaboration between the companies and to license  the  exclusive  right to use  the technology
to develop products to specific targets based on the terms in  the 2006 agreement.  We  are entitled to
earn upfront and milestone payments potentially totaling  $32 million per target for each compound
developed under the 2006 agreement,  as well as  royalties on the  commercial sales of any  resulting
products. We are also entitled to manufacturing payments  for any materials  made on behalf of sanofi-
aventis. We received $3.5 million with  the exercise  of  this option in August 2008,  in addition to the
$500,000 we received in December 2006  with the signing of the option  agreement. The agreement has a
three-year term from the date of the exercise of the  option and can be renewed by sanofi-aventis for
one additional three-year term by payment of a $2 million  fee.

Genentech

In May 2000, we entered into two separate agreements with Genentech. The first agreement  grants

Genentech an exclusive license to our maytansinoid TAP technology  for use with antibodies, such as
trastuzumab, that target HER2. Under  the  terms of this agreement, Genentech  has exclusive worldwide
rights to develop and commercialize  maytansinoid TAP  compounds  with antibodies that target HER2.
Genentech is responsible for the manufacturing, product development and  marketing  of  any products
resulting from the agreement. We are reimbursed  for any preclinical  and  clinical materials that we
manufacture under the agreement. We received a $2  million non-refundable  payment from  Genentech
upon execution of the agreement. We  also are  entitled to up to $44 million in  milestone payments from
Genentech under this agreement, as amended  in May 2006, in addition to royalties  on the net  sales of
any resulting products. Genentech and  Roche began Phase III evaluation of  T-DM1 in February 2009,
which  triggered a $6.5 million milestone  payment  to  us.  Through  June 30, 2009, we have received a
total of $13.5 million in milestone payments.

In May 2000 we also entered into a ‘‘right-to-test’’ agreement with  Genentech. This agreement

provided Genentech with the right to test our  maytansinoid  TAP technology  with antibodies to a
defined number of targets on an exclusive basis for  specified option periods and to take  exclusive
licenses for individual targets on agreed-upon  terms to use our maytansinoid TAP technology to
develop products. We received non-refundable technology  access  fees  totaling  $5 million for  the
eight-year term of the agreement. Genentech  no longer has the right  to  designate new targets  under
this  ‘‘right-to-test’’ agreement, although  there are options with respect to previously  designated targets
that remain in effect for the remainder  of  the respective option  periods, which will expire during  2009.

10

Under this agreement, in April 2005, July 2005, December 2005 and  December  2008, Genentech
licensed exclusive rights to use our maytansinoid  TAP technology  with antibodies to four  undisclosed
targets. Under the terms defined in the  2000 ‘‘right-to-test’’ agreement, for  each license  we received a
$1 million license fee and may receive  up to $38 million in milestone payments. We are  also entitled  to
receive royalties on the sales of any resulting products. Genentech is responsible  for the  development,
manufacturing, and marketing of any  products resulting from these licenses.

Bayer HealthCare

In October 2008, we entered into a development and  license agreement with Bayer  HealthCare
AG.  The agreement grants Bayer HealthCare exclusive rights  to  use our maytansinoid TAP technology
to develop and commercialize therapeutic compounds  to  a specific target. Bayer HealthCare is
responsible for the research, development,  manufacturing  and  marketing of any products  resulting from
the license. We received a $4 million  upfront payment  upon execution of  the agreement,  and—for  each
compound developed and marketed by Bayer HealthCare  under this collaboration—we could
potentially receive up to $170.5 million  in milestone payments; additionally, we  are entitled to receive
royalties on the net sales of any resulting products. We also are  entitled to receive payments for
manufacturing any preclinical and clinical  materials at the request of  Bayer HealthCare as  well as for
any related process development activities.

Biogen Idec

In October 2004, we entered into a development and  license agreement with Biogen Idec MA  Inc.
The agreement grants Biogen Idec exclusive rights to use our  maytansinoid TAP technology to develop
and commercialize therapeutic compounds to the target Cripto. Biogen Idec  is responsible for the
research, development, manufacturing, and marketing of  any products  resulting from the license. We
received a $1 million upfront payment upon execution of  the agreement.  In  January 2008, Biogen Idec
submitted an IND to the FDA for BIIB015, which was created  under this agreement. This event
triggered a $1.5 million milestone payment to us.. Assuming all  benchmarks  are met,  we could receive
up to $42 million in milestone payments under this agreement.  We are also entitled to receive royalties
on net  sales of resulting products. We also receive compensation  from Biogen Idec for any product
development research done on its behalf, as well as for the production of preclinical and clinical
materials.

Biotest

In July 2006, we entered into a development and license agreement with Biotest  AG. The
agreement grants Biotest exclusive rights  to use our  maytansinoid TAP technology to develop and
commercialize therapeutic compounds  to the target  CD138. We received a $1  million upfront  payment
upon execution of the agreement. In  September 2008,  Biotest began Phase I evaluation  of  BT-062,
which  was created under this agreement. This  event triggered  a $500,000  milestone payment  to  us.
Assuming all benchmarks are met under this  agreement, we could receive  up to $35.5  million in
milestone payments. We are also entitled  to receive royalties  on net sales of any resulting  products. We
receive payments for manufacturing any preclinical and clinical materials  made at the request of
Biotest.

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

evaluation of any compound created under  this agreement, to participate  in the U.S. development and
commercialization of that compound  in  lieu of receiving royalties on U.S.  sales and the milestone
payments not yet earned. We can exercise  this right by  making  a payment  to  Biotest of  an agreed-upon
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 U.S. along with the profit, if any, from  U.S. product sales.

11

Amgen

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

was later acquired by Amgen, Inc. The  agreement provides  Amgen with the right  to  test our
maytansinoid TAP technology with antibodies to a defined number of targets on an exclusive and
non-exclusive basis for specified option  periods and to take exclusive or non-exclusive licenses  for
individual targets on agreed-upon terms  to use our  maytansinoid TAP technology to develop products.
We  received a $5 million technology  access fee in September 2000  and, with respect to each  exclusive
license taken, we are entitled to an upfront payment of $1 million and milestone  payments potentially
totaling $34 million and royalties on  net sales of resulting products, if  and when such sales commence.
In April 2007 and July 2008, we granted Amgen a non-exclusive option  and exclusive option,
respectively, to test our TAP technology with antibodies to  specific targets.  For each  option taken,
Amgen paid us a nominal fee. Under this  ‘‘right-to-test’’ agreement, there can be option periods in
effect that extend beyond the expiration of the agreement in  September 2010. As of the date of this
Annual Report on Form 10-K, Amgen  has not taken any licenses under  this 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 both TAP and naked-antibody products and  related technologies. In
exchange, we may be obligated to pay upfront fees, potential  milestone payments and royalties on any
product  sales.

Centocor, Inc.

In December 2004, we entered into a development and  license agreement with Centocor, Inc., a

wholly-owned subsidiary of Johnson &  Johnson.  Under the terms of this agreement, Centocor was
granted exclusive worldwide rights to  develop and  commercialize anticancer therapeutics that comprise
an antibody developed by Centocor that  binds to an integrin  cancer target and a maytansinoid
cell-killing agent developed by us. Under the terms of the agreement, we  received  an upfront payment
of $1  million upon execution of the agreement.

In December 2007, we licensed from Centocor the exclusive, worldwide right to develop and
commercialize a TAP compound, IMGN388, that  consists of an integrin-binding  antibody  developed by
them and one of our maytansinoid cell-killing  agents. This license  reallocates  the parties’ respective
responsibilities and financial obligations from the license referenced above. Centocor has the right to
opt-in on future development and commercialization of  IMGN388 at an agreed-upon  stage in early
clinical testing. Should Centocor not  exercise this right, Centocor would be  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 has
the right to obtain a new partner for IMGN388, with  certain restrictions.  Should Centocor exercise  its
opt-in right, ImmunoGen would receive an opt-in  fee  and be released from its obligation to pay
Centocor any milestone payments or  royalties on sales. Both companies would contribute  to  the costs
of developing the compound. The two companies would share  equally any profits on the  sales  of  the
compound in the U.S. and ImmunoGen would receive royalties on any international sales. The
companies have agreed to share certain  third-party  expenses. 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.

Other  Licenses

We  also have licenses with third parties, including other companies  and academic institutions,  to
gain access to techniques and materials  for drug discovery and product  development and  the rights to

12

use those techniques and materials to  make our product  candidates. These licenses include rights to
certain antibodies.

Patents, Trademarks and Trade Secrets

We  have a strategy of obtaining patent protection for our  proprietary technologies  and product

candidates. As of June 30, 2009, our  patent portfolio had a total of 268 worldwide  issued patents and
473 patent applications worldwide that we  own or license from third  parties.

We  have issued and pending patents  related to monoclonal antibodies.  These antibodies may  be  a

component of a TAP compound or may be developed  as a  ‘‘naked’’  antibody anticancer therapeutic.
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. This patent  covers  certain technology that we  have
licensed to sanofi-aventis on a non-exclusive basis, as  described elsewhere  in this Annual  Report on
Form 10-K under the heading ‘‘Outlicenses and Collaboration—sanofi-aventis.’’ We have received
comparable patents in other jurisdictions,  primarily in the major  countries of Europe and  in Japan.
These patents will expire between 2013  and 2014.

Of the eight product candidates named in the  table  on page  6 of this Annual Report  on

Form 10-K that are being developed  by  us  or by our collaboration partners, one  is a naked antibody
and seven are TAP compounds that contain our proprietary maytansinoid cell-killing  agents. We seek to
protect our maytansinoids and TAP compounds through  a multi-pronged approach. As of June 30,
2009, we owned 20 issued U.S. patents related to our maytansinoid technology, as follows:  claiming
composition and use of certain maytansinoids; claiming conjugates composed of maytansinoids  and
cell-binding agents; claiming a process  for the preparation  of certain maytansinoids; and  claiming
methods of preparation of conjugates  composed of maytansinoids and cell-binding  agents. In  all  cases
we have received or are applying for  comparable  patents  in other  jurisdictions,  primarily  in the major
countries of Europe and in Japan. We  also  have submitted  patent applications  in the U.S., Europe,
Japan and elsewhere covering other  aspects of  our  TAP technology, including methods of attachment of
cell-killing molecules to antibodies and the  antibody  component  of  TAP compounds as  discussed above,
as well as the use of some of these product candidates  and inventions for  certain  diseases. We expect
our  work  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.

Typically, multiple issued and pending patents can  apply for each TAP compound, and the patents

that apply can vary among the TAP compounds and over  time. For example, we have issued patents
that extend beyond 2020 that cover aspects  of  the manufacturing of the  maytansinoid cell-killing agents
used to make T-DM1, IMGN901 and  other  TAP compounds. We  have issued patents covering our
DM1 and DM4 maytansinoid cell-killing agents that  expire  in 2010 and 2024, respectively, and a
pending patent application covering conjugates  using our  SMCC thioether  linker  which, if issued as
filed, would cover antibody-maytansinoid  conjugates  using  this  linker,  such as T-DM1.

As of June 30, 2009, we also owned issued  patents  covering  proprietary  derivatives of

non-maytansinoid cell-killing molecules. These additional patent families are currently not material to
our  business.

As described elsewhere in this annual  report on  Form 10-K under the heading  ‘‘In-Licenses—

Centocor, Inc.,’’ we  have in-licensed certain technology from  Centocor in connection with the
development of our IMGN388 product candidate. In addition, 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.

13

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.

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, Wyeth, Seattle Genetics,  Inc.,
and Medarex, Inc. 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
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:127) the safety and efficacy of products;

(cid:127) the timing of regulatory approval and  commercial introduction;

(cid:127) special regulatory designation of products, such  as Orphan Drug designation; and

(cid:127) 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.

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Such new technologies include, but are not limited to:

(cid:127) the use of genomics technology to  identify  new gene-based targets for the development of

anticancer drugs;

(cid:127) the use of high-throughput screening to identify and optimize  lead compounds;

(cid:127) the use of gene therapy to deliver  genes  to  regulate gene  function; and

(cid:127) 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.

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, 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:127) completion of preclinical laboratory  tests, animal studies and formulation studies  according to

Good Laboratory Practices or other  applicable  regulations;

(cid:127) submission to the FDA of an IND  which must become  effective  before  human clinical  trials may

begin;

(cid:127) 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:127) submission to the FDA of an NDA or BLA;

(cid:127) 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:127) FDA review and approval of the NDA or  BLA.

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The testing and approval process requires substantial time, effort and financial resources,  and we
cannot be certain that any approvals  for our product candidates will  be  granted  on a  timely  basis, if at
all.

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. These regulations  include the requirement that all
research subjects provide informed consent. Further,  an institutional review board,  or IRB, must review
and approve the plan for any clinical trial  before  it commences at any institution. An IRB  considers,
among other things, whether the risks  to  individuals participating in the trials are  minimized  and are
reasonable in relation to anticipated  benefits. The IRB also approves the information regarding  the
trial and the consent form that must be provided  to  each  trial subject or his  or her legal representative
and must monitor the study until completed.

Each  new clinical protocol must be submitted  to  the IND for FDA  review, and  to  the IRBs for

approval. Protocols detail, among other  things, the objectives of the study,  dosing procedures, subject
selection and exclusion criteria, and the parameters to be used  to  monitor subject  safety.

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

combined:

(cid:127) Phase I: The drug 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:127) Phase II: 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:127) 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 and provide, if appropriate, an
adequate basis for product labeling.

Progress reports detailing the results  of  the clinical trials must  be  submitted at  least  annually  to  the

FDA and safety reports must be submitted to the  FDA and the investigators for serious and
unexpected adverse events. Phase I, Phase II, and Phase III testing may not be completed successfully
within any specified period, if at all. 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

16

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.

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
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.

In addition, under the Pediatric Research Equity  Act  of  2007, or PREA, an  NDA,  BLA and

certain types of supplements to an NDA  or BLA must contain data to assess the  safety and
effectiveness of the drug for the claimed indications in all relevant pediatric  subpopulations and to
support dosing and administration for  each pediatric  subpopulation for which the drug is  safe and
effective. The FDA may grant deferrals for submission of  data or  full  or partial  waivers. Unless
otherwise required by regulation, PREA does not apply  to  any  drug for  an indication for  which orphan
designation has been granted. PREA  sunsets on October 1, 2012.

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 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 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, 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.  In  addition,

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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
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.

Patent Term Restoration and Marketing Exclusivity

Depending upon the timing, duration and specifics of  FDA approval of the use 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,  plus the  time  between  the submission date  of an
NDA  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
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

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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  exclusivity in the  U.S. Pediatric exclusivity, if granted,
provides an additional six months to  an  existing  exclusivity or  statutory delay  in approval resulting from
a patent certification. This six-month  exclusivity, which runs from the end  of other exclusivity protection
or patent delay, may be granted based on  the voluntary completion of a pediatric study  in accordance
with an FDA-issued ‘‘Written Request’’  for such  a study. The current pediatric exclusivity provision will
sunset on October 1, 2012.

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. 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.

We  may pursue this designation with  respect to product candidates intended for qualifying  patient

populations. A drug that receives Orphan  Drug  designation and  is the  first  product of its kind to
receive FDA marketing approval for its  product claim is entitled to a  seven-year exclusive marketing
period in the U.S. for that product claim.

New Drugs for Serious or Life Threatening Illnesses

The FDA Modernization Act allows the designation of ‘‘Fast  Track’’ status to expedite

development of new drugs, including  review and approvals, and is  intended to speed the availability of
new therapies to desperately ill patients.  ‘‘Fast  Track’’ procedures  permit  early consultation and
commitment from the FDA regarding preclinical studies  and clinical  trials necessary to gain marketing
approval. We may seek ‘‘Fast Track’’  status  for some, or  all, of our product candidates.

‘‘Fast Track’’ status also incorporates initiatives  announced by the  President of  the U.S.  and the
FDA Commissioner in March 1996 intended to provide cancer patients  with faster access to new  cancer
therapies. One of these initiatives states  that the initial basis for approval of  anticancer agents to treat

19

refractory, hard-to-treat cancer may be  objective  evidence of response, rather than  statistically improved
disease-free and/or overall survival, as had been  common practice.  The  sponsor  of a product  approved
under this accelerated mechanism is required to follow up  with further studies on clinical safety and
effectiveness in larger groups of patients.

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. We rely, and expect  to  continue
to rely, on third parties for the production of clinical and commercial quantities of our products.  Future
FDA and state inspections 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. For example,  on  September 27, 2007, the  Food and Drug Administration
Amendments Act of 2007, or FDAAA, gave the FDA  enhanced postmarket authority, including the
authority to require postmarket studies and clinical  trials, labeling changes  based on new safety
information, and compliance with a risk evaluation  and mitigation  strategy approved by the FDA.
Failure to comply with any requirements under the  new law may result in significant penalties.  The  new
law also authorizes significant civil money penalties for the  dissemination of false  or misleading
direct-to-consumer advertisements. Additionally, the  new law expands  the clinical  trial registry so  that
sponsors of all clinical trials, except for  Phase I  trials, are  required to submit certain clinical  trial
information for inclusion in the clinical  trial  registry data  bank,  including summary adverse effect
information. In addition, FDA regulations and guidance are often revised or reinterpreted by the
agency in ways that may significantly  affect our business  and our products.  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 U.S., 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  of  a product by the comparable
regulatory authorities of foreign countries before we  can commence clinical trials or marketing of the
product  in those countries. The approval  process  varies from country  to  country  and the  time may  be

20

longer or shorter than that required for  FDA approval. The requirements  governing the conduct of
clinical trials, product licensing, pricing and  reimbursement  vary  greatly from country to country.

Under European Union regulatory systems,  we may submit  marketing authorization applications

either under a centralized or decentralized procedure. The  centralized  procedure, which  is compulsory
for medicines produced by certain biotechnological  processes  and  optional for  those which  are highly
innovative, provides for the grant of a  single marketing authorization that is  valid for  all  European
Union  member states. For drugs without approval in any Member State, the  decentralized procedure
provides for approval by one or more  other,  or concerned, Member States of an assessment of an
application performed by one Member State, known as the reference Member  State.  Under this
procedure, an applicant submits an application, or  dossier, and  related materials (draft summary of
product  characteristics, draft labeling  and  package  leaflet) 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 cannot approve the  assessment
report and related materials on the grounds of potential  serious risk to public health, the  disputed
points may eventually be referred to the  European Commission, whose decision is  binding  on all
Member States.

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

It  is not clear what effect the MMA  will have  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

21

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.

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. At the present time,  Medicare is prohibited from negotiating  directly with
pharmaceutical companies for drugs. However, the  administration of  President Obama  is supporting
and Congress is currently considering  major changes  to  the way  that healthcare is provided  to  U.S.
citizens. While we cannot predict whether any  legislative or regulatory  proposals will be adopted,  the
adoption of such proposals could have  an effect on the payments for our approved  products, if any,
and could have a material adverse effect on our business, financial  condition and profitability.

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.

Research and Development Spending

During  each of the three years ended  June 30, 2009, 2008  and  2007, we spent approximately

$45.9 million, $60.0 million and $49.4  million,  respectively, on research  and development activities.
During  the year ended June 30, 2009,  approximately 14% of our full-time equivalent research and
development personnel were dedicated to our sanofi-aventis collaboration  compared to 36% and 55%
during the years ended June 30, 2008  and 2007, respectively.

Raw Materials and Manufacturing

We  procure certain raw material components  of  finished  conjugate,  including antibodies,

ansamitocin P3, 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 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, 2009, we had 210 full-time employees,  of  whom 174 were  engaged  in research and
development activities. Seventy-four  research  and  development employees hold post-graduate degrees,
of which 39 hold Ph.D. degrees and  five  hold M.D.  degrees. We consider  our  relations  with our
employees to be good. None of our employees are 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.

22

Third-Party Trademarks

Herceptin is a registered trademark of  Genentech. Rituxan  is a registered trademark of Biogen

Idec. Erbitux is a registered trademark  of  ImClone Systems.

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, 2009,  we had an

accumulated deficit of $321.5 million.  For the years ended  June 30, 2009,  2008, and 2007, we generated
losses of $31.9 million, $32.0 million  and $19.0 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
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  product candidates or royalties on  revenues from  the
commercial sale of our collaborators’  product  candidates in the near future, and we may never  generate
revenues from the  commercial sale of  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 and future  payments,  if  any,  from our collaboration arrangements will  be
sufficient to meet our current and projected operating  and capital requirements for fiscal year 2010 and
at least a portion of the following fiscal year. However, we may  need additional financing sooner due to
a number of factors including:

(cid:127) if  either we or any of our collaborators  incur higher than  expected costs or experience slower
than expected progress in developing product  candidates and obtaining regulatory approvals;

(cid:127) lower revenues than expected under our collaboration  agreements; or

(cid:127) acquisition of technologies and other business opportunities that  require financial commitments.

23

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  and  the most advanced TAP product candidate is
in Phase III clinical testing. 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 one  compound that is a  conjugate of an
antibody  and a cytotoxic small molecule  that has obtained approval by the FDA and  is based  on
technology similar to our TAP technology. 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.

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. Our,  as well as  our collaborative partners’,
most advanced TAP product candidate 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:127) occurrence of unacceptable toxicities or side  effects;

(cid:127) ineffectiveness of the product candidate;

(cid:127) insufficient drug supply;

(cid:127) negative or inconclusive results from the clinical  trials, or  results that necessitate  additional

studies  or clinical trials;

(cid:127) delays in obtaining or maintaining required  approvals from institutions,  review boards  or other

reviewing entities at clinical sites;

(cid:127) delays in patient enrollment;

(cid:127) insufficient funding or a reprioritization of financial  or other resources; or

(cid:127) other reasons that are internal to the businesses of  our  collaborative partners, which  they may

not share with us.

24

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
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:127) delay marketing of potential products  for a  considerable period of time;

(cid:127) limit the indicated uses for which potential products may  be  marketed;

(cid:127) impose costly requirements on our  activities;  and

(cid:127) 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.

25

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:127) restrictions on the products, manufacturers or manufacturing  processes;

(cid:127) warning letters;

(cid:127) civil or criminal penalties;

(cid:127) fines;

(cid:127) injunctions;

(cid:127) product seizures or detentions;

(cid:127) import bans;

(cid:127) voluntary or mandatory product recalls  and  publicity requirements;

(cid:127) suspension or withdrawal of regulatory approvals;

(cid:127) total or partial suspension of production; and

(cid:127) 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:127) generate cash flow and revenue;

(cid:127) fund some of the costs associated with our internal  research and development,  preclinical

testing, clinical trials and manufacturing;

26

(cid:127) seek and obtain regulatory approvals faster  than  we could  on our own;

(cid:127) successfully commercialize existing  and  future product candidates; and

(cid:127) 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:127) a change in the collaborative partner’s strategic focus as  a  result of merger, management

changes, adverse business events, or other causes;

(cid:127) a change in the priority of the product  candidate relative to other programs in the collaborator’s

pipeline;

(cid:127) a reassessment of the patent situation  related to the  compound  or  its target;

(cid:127) a change in the anticipated competition  for the  product candidate;

(cid:127) preclinical studies and clinical trial  results;  and

(cid:127) 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 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,

27

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. In July 2003, we entered
into a discovery, development and commercialization collaboration  with sanofi-aventis  that  entitled us
to receive committed research funding.  We  recorded $81.5  million  of committed research and
development support revenue under  this agreement. The committed  funding portion of this agreement
ended in October  2008 and there are no other  agreements  in place at this time  that  entitle  us to
committed research funding. As a result, we expect  a reduction in  our research  and development
revenue. To date, we have recorded $13.5  million in milestone  payments with the advancement of
T-DM1. Our agreement with Genentech entitles us to receive up to $44  million  in milestone  payments
and also royalties on commercial sales, if  any. Failure  of Genentech 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, its 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 ansamitocin  P3, DM1, DM4, and
linker, on behalf 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, we
may not be able to recover our investment in these components and we  may suffer significant losses.
Collaborators have discontinued development of 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 antibody requirements for clinical  materials to  be manufactured are significantly higher than we
estimated, the inability to procure additional antibody  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 product
candidates. 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.  For example, enrollment of
new patients into all clinical trials of IMGN901 was suspended  in late 2006 due to insufficient  supply of
IMGN901. We believe we have resolved  these supply issues and that we have sufficient  supply of
IMGN901 to complete these trials on  a  timely  basis. There  can  be  no assurance  that  we will not have

28

future 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 third-party suppliers 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 have transitioned  from our original supplier of ansamitocin  P3, as well  as our
single supplier that converts ansamitocin  P3 to DMx, to one  larger company with  more commercial
production experience. 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 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
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.

In addition to the outsourcing of manufacturing, we may develop our  manufacturing capacity  in
part by expanding our current facilities. This activity would require substantial additional funds and we
would need to hire and train significant numbers  of employees to staff  these  facilities.  We may not be
able to develop manufacturing facilities that are sufficient to produce drug materials for later-stage
clinical trials or commercial use. We  and  any  third-party manufacturers that we  may use  must
continually adhere to cGMP regulations enforced by  the FDA through its facilities inspection program.
If our facilities or the facilities of third-party manufacturers cannot pass a pre-approval plant
inspection, the FDA will not grant approval to our product candidates. In complying with  these  cGMP
regulations and foreign regulatory requirements, we and any of our third-party manufacturers will  be
obligated to expend time, money and  effort on production, record-keeping  and quality control to assure
that our potential products meet applicable specifications and other  requirements.  If we  or any  third-
party manufacturer with whom we may contract  fail to maintain regulatory  compliance, we or the third
party may be subject to fines and/or  manufacturing operations may  be  suspended.

29

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, 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
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.
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.

30

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:127) their degree of clinical efficacy and safety;

(cid:127) their advantage over alternative treatment methods;

(cid:127) 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:127) 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
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 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  Wyeth, Seattle  Genetics, Inc. and Medarex,  Inc. 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:127) develop products that are safer or  more effective than our product candidates;

31

(cid:127) 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:127) devote greater resources to market or sell their products;

(cid:127) adapt more quickly to new technologies  and scientific advances;

(cid:127) initiate or withstand substantial price  competition more  successfully than we can;

(cid:127) have greater success in recruiting skilled scientific  workers from  the  limited pool of available

talent;

(cid:127) more effectively negotiate third-party licensing and collaboration arrangements; and

(cid:127) 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, but there  currently  is  no process in the  U.S. for the submission
or approval of a biosimilar product. The U.S. Congress has been  considering the issue and legislation
has been proposed. It is not currently evident, however,  whether any of the  pending  legislative
proposals will be enacted. In Europe,  however, the  European Agency  for  the Evaluation  of Medical
Products 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 U.S. or Europe, it could have a  negative effect  on sales 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
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.

32

Also, patents and applications owned or  licensed  by us  may  become the subject  of  interference
proceedings before the U.S. Patent and Trademark  Office or a patent office  in a foreign  jurisdiction  to
determine priority of invention that could  result in  substantial cost to us. An adverse decision in  an
interference 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 challenge  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.

In recent years, policymakers have also proposed reforming U.S. patent laws and regulations. For

example, patent reform legislation was  introduced in both houses of the U.S.  Congress in 2009, and the
Senate Judiciary Committee approved a  patent reform  bill in April 2009.  In  general, the  proposed
legislation attempts to address issues surrounding the  enforceability of  patents and the increase in
patent litigation by, among other things,  changing the  way damages for patent infringement  are
calculated, establishing new procedures for  challenging  patents and  establishing different methods  for
invalidating patents. While we cannot  predict what  form any new  patent reform laws or  regulations
ultimately may take, final legislation  could introduce  new substantive rules and  procedures  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 U.S.

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

Any inability to license from third parties their  proprietary technologies or processes 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.

33

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
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:127) decreased demand for our product;

(cid:127) injury to our reputation and significant negative  media attention;

(cid:127) withdrawal of clinical trial volunteers;

34

(cid:127) costs of litigation;

(cid:127) distraction of management; and

(cid:127) 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  as a result of our  low  stock price 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.

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.

35

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

On July 11, 2007, we filed a Registration Statement on Form S-3 with the Securities and Exchange

Commission. The Securities and Exchange Commission declared the Registration Statement effective
on August 13, 2007. Subject to our ongoing  obligations under the Securities Act of  1933, as amended,
and the Securities Exchange Act of 1934,  as amended,  the Registration Statement permits us  to  offer
and sell up to an aggregate of $75 million of our common stock. Pursuant to the  shelf registration
statement, on June 20, 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.  Additionally, on June 23, 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. 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.

36

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:127) successfully finding and managing the relationships  with collaborative partners;

(cid:127) 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:127) the risk that we and/or our collaborators may not  be  able to obtain regulatory  approvals

necessary to commercialize product candidates;

(cid:127) the potential development by competitors  of  competing products and  technologies; uncertainty
whether our TAP technology will produce safe, effective  and commercially  viable products;

(cid:127) our ability to successfully protect our intellectual property;

(cid:127) our reliance on third-party manufacturers to achieve supplies of our  maytansinoid cell-killing

agents, DM1 and DM4;

(cid:127) the risk that we may be unable to  establish the  manufacturing  capabilities necessary to develop

and  commercialize our potential products;

(cid:127) the adequacy of our liquidity and capital resources;

(cid:127) government regulation of our activities,  facilities, products  and personnel; the dependence  on

key  personnel;

(cid:127) 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:127) 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.

37

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.  We  currently  are
attempting to sublease approximately 14,000 square feet of laboratory and office  space at this location.
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, 2011, with an
option for us to extend the lease for  an  additional  five-year  term.

We  also lease approximately 15,000 square  feet of laboratory and office  space  in a building  located

at 148 Sidney Street, Cambridge, MA, which  we vacated in March 2008  when we relocated all our
Cambridge operations to Waltham, MA. The 148 Sidney Street  lease expires on October  30, 2010. In
May 2008, we entered into a sub-sublease for this entire  space  for  the remainder of the  lease 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 4. Submission of Matters to a Vote of Security  Holders

No matters were submitted to a vote of our security holders through solicitation of proxies or

otherwise during the fourth quarter of the  fiscal year ended  June 30, 2009.

Item 4.1. 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 57, joined ImmunoGen  in 2005, and has served as  our  President  and Chief

Executive Officer since January 2009.  Prior to that he served  as our  President and Chief Operating
Officer and Acting Chief Financial Officer since 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, 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 is also  a  director of  ImmunoGen.

John M. Lambert, Ph.D., age 58, 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 45, 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

38

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

Gregory D. Perry, age 49, joined ImmunoGen  in January 2009, and has served  as our Senior Vice
President and Chief Financial Officer  since that date. 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 Williams, age 55, 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.

39

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 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:

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

Fiscal Year 2009

Fiscal Year 2008

High

$5.80
$4.89
$7.19
$8.83

Low

$2.95
$2.47
$3.85
$6.49

High

$5.72
$5.43
$4.18
$4.73

Low

$4.29
$3.97
$2.73
$3.01

As of August 12, 2009, the closing price per share of our common stock was $7.36,  as reported by

NASDAQ, and we had approximately 530 holders  of  record of our common stock and, according  to
our  estimates, approximately 9,331 beneficial  owners 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.

Equity Compensation Plan Information (in thousands)

(a)

(b)

(c)

Number of securities to
be issued upon exercise
of outstanding options,
warrants and rights

Weighted-average exercise
price of outstanding options,
warrants  and  rights

Number of securities
remaining available  for
future  issuance under
equity compensation plans
(excluding securities
reflected  in  column  (a))

5,529

—

5,529

$6.36

—

$6.36

2,734

—

2,734

Plan category

Equity compensation plans
approved by security
holders(1)

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

Equity compensation plans not

approved by security holders .

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

(1) These plans consist of the Restated Stock Option Plan and the 2006 Employee, Director and

Consultant Equity Incentive Plan.

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, 2009. The  information set  forth
below should be read in conjunction  with ‘‘Management’s  Discussion and Analysis of Financial

40

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,

2009

2008

2007

2006

2005

Consolidated Statement of Operations

Data:

Total revenues . . . . . . . . . . . . . . . . . .
Total operating expenses . . . . . . . . . . .
Other (expense) income, net . . . . . . . .
(Benefit) provision for income taxes . .

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

$ 40,249
74,361
2,119
27

$ 38,212
60,438
3,274
35

$ 32,088
53,474
3,569
17

$ 35,718
48,395
1,755
29

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

$ (31,937) $(32,020) $(18,987) $(17,834) $ (10,951)

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

Basic and diluted weighted average

$

(0.63) $

(0.75) $

(0.45) $

(0.43) $

(0.27)

common shares outstanding . . . . . . .

51,068

42,969

41,759

41,184

40,868

Consolidated Balance Sheet Data:
Cash, cash equivalents and marketable
securities . . . . . . . . . . . . . . . . . . . .
Total assets . . . . . . . . . . . . . . . . . . . .
Stockholders’ equity . . . . . . . . . . . . . .

$ 71,125
100,704
66,857

$ 47,871
83,338
55,299

$ 59,700
80,421
58,401

$ 75,023
94,128
72,350

$ 90,565
110,132
86,842

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
therapeutics for the treatment of cancer using our expertise  in cancer biology, monoclonal antibodies,
and small molecule cytotoxic, or cell-killing, agents.  Our  Targeted Antibody Payload, or TAP,  technology
uses antibodies to deliver a potent cytotoxic agent specifically to cancer cells, and consists of a tumor-
targeting monoclonal antibody with one of  our proprietary  cell-killing agents  attached using one of our
engineered linkers. The antibody component enables a  TAP compound to  bind  specifically to cancer
cells that express a particular target antigen, the  highly potent  cytotoxic agent serves to kill the cancer
cell, and the engineered linker controls  the release  of the  cytotoxic agent inside the cancer  cell.  Our
TAP technology is designed to enable  the creation of highly  effective, well-tolerated anticancer
products. All of our and our collaborative partners’ TAP  compounds currently in  preclinical and clinical
testing contain either DM1 or DM4  as the  cytotoxic agent. Both  DM1 and DM4 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 entered into collaborative agreements  that enable companies to  use  our TAP technology
to develop commercial product candidates to specified  targets. We have also used our proprietary TAP
technology in conjunction with our in-house antibody expertise  to  develop our  own anticancer product
candidates. 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 entitled to research and development funding based on activities  performed at our
collaborative partner’s request. We are  reimbursed for  our direct and a portion  of overhead costs to
manufacture preclinical and clinical materials and, under  certain collaborative agreements, the
reimbursement includes a profit margin.  Currently, our  collaborative partners include Amgen,  Bayer
HealthCare, Biogen Idec, Biotest , Genentech  (a  wholly-owned member of the Roche Group) and

41

sanofi-aventis. 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 follow.

sanofi-aventis—In July 2003, we entered into a discovery, development  and  commercialization

collaboration with sanofi-aventis. Under the  terms of this agreement, in consideration of  an upfront
payment of $12 million, sanofi-aventis  gained worldwide commercialization rights  to  new anticancer
therapeutics developed to targets included in  the collaboration, including  the right to use our  TAP
technology and our humanization technology  in the creation of  therapeutics to these  targets. The
agreement included a research support  funding commitment by  sanofi-aventis for $50.7 million over the
first three years of the agreement, and  then  for an additional $18.2  million when the agreement was
extended for a fourth year, and then for an  additional $10.4 million when the agreement was extended
for a fifth year. We earned $81.5 million of committed  research funding for activities  performed under
the completed research term of this agreement, of which $2.7  million,  $10.8 million, and  $18.9 million
was recognized during fiscal years 2009,  2008 and 2007, respectively, and are  now compensated for
research performed for sanofi-aventis on  a mutually agreed-upon basis.

The collaboration  agreement also provides  for  certain other payments based  on the  achievement of

product  candidate milestones and royalties on  sales of  any  resulting products, if and  when such sales
commence. For the targets included in the collaboration at this time, we are entitled to milestone
payments potentially totaling $21.5 million  for  each product  candidate developed under this  agreement.
Through the end of fiscal 2009, we have earned an  aggregate of  $10.5 million in milestone payments
under this agreement.

Additionally, in October 2006, sanofi-aventis  licensed  non-exclusive rights to use our proprietary
humanization technology, which enables antibodies of murine origin to avoid detection by the human
immune system. This license provides  sanofi-aventis with the  non-exclusive  right to use  our proprietary
humanization technology through August 31, 2011  with the right  to  extend for  one or more additional
periods of three years each by providing  us with written notice  prior to expiration of the then-current
license term. Under the terms of the license, we received  a  $1 million license  fee, half of which  was
paid upon contract signing and the second  half was  paid  in  August 2008,  and in  addition,  we are
entitled to receive milestone payments potentially  totaling $4.5  million  plus royalties on sales for  each
antibody  humanized under this agreement. We have deferred the $1  million  upfront payment and are
recognizing this amount as revenue over  the five-year term of the agreement.

In August 2008, sanofi-aventis exercised  its  option under a 2006 agreement for expanded access to

our  TAP technology. The exercise of  this option enables sanofi-aventis  to evaluate, with certain
restrictions, our maytansinoid TAP technology  with antibodies  to  targets that were not included  in the
existing research collaboration between  the companies  and to license the exclusive right to use the
technology to develop products to specific targets on the terms in  the 2006 agreement.  We are  entitled
to earn upfront and milestone payments potentially totaling $32 million per target for each compound
developed under the 2006 agreement,  as well as  royalties on the  commercial sales of any  resulting
product.  We are also entitled to manufacturing  payments for any  materials  made on behalf of sanofi-
aventis. We received $3.5 million with  the exercise  of  this option in August 2008,  in addition to the
$500,000 we received in December 2006  with the signing of the option  agreement. The agreement has a
three-year term from the date of the exercise of the  option and can be renewed by sanofi-aventis for
one additional three-year term by payment of a $2 million  fee. We  have deferred the  $3.5 million
exercise fee and are recognizing this amount as  revenue over the initial three-year  option term.

Genentech—In May 2000, we entered into a license agreement with Genentech  that  granted

Genentech exclusive rights to use our maytansinoid TAP technology with  antibodies,  such as
trastuzumab, that target HER2. We received a $2 million upfront  payment from Genentech upon
execution of the agreement. We also are entitled to up to $44 million in milestone payments  from

42

Genentech under this agreement, as amended  in May 2006, in addition to royalties  on the net  sales of
any resulting product. Through the end of fiscal 2009, we have received $13.5  million in milestone
payments.

In December 2008, Genentech licensed the exclusive right to use  our maytansinoid TAP technology

with its therapeutic antibodies to an  undisclosed target. This license  was  taken under a ‘‘right-to-test’’
agreement entered into by the companies in 2000 that  provided  Genentech with the right  to  take
exclusive licenses to use our maytansinoid  TAP technology  to develop products for  individual targets on
agreed-upon terms. While the agreement  expired in May 2008, a limited number of options to targets
remain in place for a short period of time.  This license was  taken  under one of these options. Under
the terms of the license, we received  a  $1 million upfront  payment  and  are entitled to receive  up to
$38 million in milestone payments plus  royalties  on the  sales of any resulting products. Genentech is
responsible for the development, manufacturing, and marketing of any products resulting from this
license. We have deferred the $1 million upfront payment and are recognizing this amount as  revenue
over the estimated period of substantial  involvement.

Bayer HealthCare—In October 2008, we entered into a development and license  agreement with

Bayer HealthCare AG. The agreement grants Bayer  HealthCare  exclusive  rights to use our
maytansinoid TAP technology to develop and commercialize therapeutic compounds to a specific target.
We received a $4 million upfront payment upon execution of  the  agreement, and—for each compound
developed and marketed by Bayer HealthCare under this collaboration—we could potentially receive
up to $170.5 million in milestone payments; additionally, we are entitled to receive royalties on  the
sales of any resulting products. We will be compensated by  Bayer  HealthCare at a stipulated rate for
work performed on behalf of Bayer HealthCare under a mutually agreed-upon research plan and
budget which may be amended from time  to  time  during the  term of the agreement.  We also are
entitled to receive payments for manufacturing  any  preclinical and clinical materials made at  the
request of Bayer HealthCare as well  as for any related process  development activities. We have
deferred the $4 million upfront payment  and  are  recognizing this amount  as revenue  over the estimated
period  of substantial involvement.

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, 2009,  we had approximately
$71.1 million in cash and marketable securities compared to $47.9 million in  cash and marketable
securities as of June 30, 2008.

We anticipate that future cash expenditures will be partially offset by collaboration-derived
proceeds, including milestone payments  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.

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

43

and related disclosure of contingent assets  and  liabilities. On  an on-going  basis, we evaluate our
estimates, including those related to our  collaborative agreements and inventory.  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 affect 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.  We follow the  provisions of the
Securities and Exchange Commission’s Staff Accounting Bulletin No. 104, Revenue Recognition, or
SAB 104, and Emerging Issues Task Force  Issue No. 00-21, Accounting for Revenue Arrangements with
Multiple Elements, or EITF 00-21. In accordance with SAB 104 and EITF 00-21, we recognize revenue
related to research activities 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
terms of our agreements contain multiple  elements which  typically include non-refundable  license fees,
payments based upon the achievement of  certain milestones and royalties  on product sales.  We evaluate
such arrangements to determine if the  deliverables are  separable into units  of accounting and then
apply  applicable revenue recognition  criteria to each  unit of accounting.

At June 30, 2009, we had the following three types of collaborative contracts with  the parties

identified below:

(cid:127) Exclusive license to use our TAP technology and/or certain other intellectual property to develop

compounds to a single target antigen:

Bayer HealthCare (single-target  license)

Biogen Idec (single-target license)

Biotest (single-target license)

Genentech (multiple single-target licenses)

sanofi-aventis (license to multiple individual targets)

(cid:127) Option agreement for a defined period of time to secure licenses to use  our TAP technology to

develop anticancer compounds to a limited number  of  targets on  established terms  (broad
option agreement):

Amgen

Genentech

sanofi-aventis

(cid:127) Non-exclusive license to our humanization technology:

sanofi-aventis

Generally, the foregoing collaboration agreements provide that we will  (i) at  the collaborator’s
request, manufacture and provide to them preclinical and clinical materials at our  cost, or, in some
cases, cost plus a margin, (ii) earn payments  upon the collaborators’ achievements of certain milestones
and (iii) earn royalty payments, generally  until the later of  the  last applicable patent expiration or 10 to
12 years after product launch. Royalty  rates may vary over the royalty  term depending on  certain
intellectual property rights. We are required  to  provide  technical training and to share any process

44

improvements and know-how with our  collaborators during the research term  of  the collaboration
agreements.

Generally, upfront payments on single-target licenses are  deferred  over the  period of our

substantial involvement during development.  The determination of the length of this period  is subject
to judgment and estimation and can  have an impact on the  amount  of  revenue  recognized in  a given
period. Our employees are available to assist our collaborators during the development  of  their
products. We estimate this development  phase 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 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.  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.

We  defer upfront payments received from  our  broad  option  agreements over the  period during

which  the collaborator may elect to receive a license. These  periods are specific to each collaboration
agreement, but are between three and  12 years. If  a collaborator  selects an option  to  acquire a license
under these agreements, any option fee  is deferred and is recorded  over the life of  the option,
generally 12 to 18  months. If a collaborator exercises  an option and we  grant a single-target  license to
the collaborator, we defer the license  fee and  account for the  fee as we  would an upfront  payment on a
single-target license, as discussed above. Upon exercise of an option to acquire  a license,  we would
recognize any remaining deferred option  fee over the period of  our substantial involvement  under the
license acquired. In the event a broad  option 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. 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 our  remaining  period of substantial
involvement can be estimated.

When milestone fees are specifically tied to a separate  earnings  process and are deemed to be

substantive and at risk, revenue is recognized  when such  milestones are achieved. In  addition,  we
recognize research and development  support revenue  from  certain  collaboration and  development
agreements based upon the level of research services performed during  the period  of  the research
agreement. Deferred revenue substantially  represents amounts received under collaborative agreements
and not yet earned pursuant to these policies. Where we have no  continuing  involvement, we  will
record non-refundable license fees as  revenue upon  receipt and will record revenue upon achievement
of milestones by our collaborative partners.

We  produce preclinical and clinical materials for our collaborators. We are  reimbursed for our
direct costs and a portion of our overhead  costs to produce clinical materials. We recognize revenue 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.

We  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. Generally,  we  are reimbursed  for certain  of  our  direct
and overhead costs of producing these  materials or  providing these services. We record  the amounts
received for the preclinical materials  produced or services performed as a component of  research  and
development support. We also develop conjugation processes for materials for later  stage testing  and

45

commercialization for certain collaborators.  We are  reimbursed  for  certain of our direct  and overhead
costs and may receive milestone payments for developing these  processes  which are  recorded as a
component of research and development  support.

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 is not supported by firm, fixed
collaborator orders and projections at the time of the assessment to be excess. During fiscal 2008,  we
obtained additional amounts of DMx  from a new supplier.  Due  to  the need to evaluate the  process
which  was developed to prepare such material from this new  supplier  across multiple batches,  we had
committed to a level of production which yielded more material  than  would be required by our
collaborators over the next twelve months.  As a result, during the year ended June 30,  2008, we
recorded  a $2.1 million charge to research and  development  expense related to raw material inventory
identified as excess. We also recorded  $1.6 million to write down the raw material inventory purchased
during the fiscal year 2008 to its net  realizable value,  which  is also included in  research  and
development expense for the year ended June 30,  2008. No similar  costs were recorded during the
years ended June 30, 2009 and 2007.  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.

Stock-based Compensation

As of June 30, 2009, 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 Statement  of Financial Accounting
Standards No. 123(R), Share-Based Payment, or Statement 123(R), using the modified-prospective-
transition method. Under this methodology,  the estimated 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 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. 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, 2009, 2008  and 2007  was $4.0 million,
$2.9 million and $2.4 million, respectively. During fiscal year  2009, we recorded approximately $843,000
of stock compensation cost related to the modification of certain outstanding  common stock options in
accordance with the former Chief Executive Officer’s succession  plan.

46

Investment in Marketable Securities

We  invest in marketable securities of highly rated financial institutions and investment-grade  debt

instruments and limit the amount of credit exposure  with any  one  entity.  We have  classified our
marketable securities as ‘‘available-for-sale’’  and,  accordingly, carry such  securities at aggregate fair
value. In accounting for investments, we evaluate if  a decline  in the fair  value  of a marketable security
below our cost basis is other-than-temporary, and if so,  we record an  impairment  charge related to any
credit loss in our consolidated statement of operations. The  factors that we consider  in our evaluation
include the fair market value of the security, the duration and magnitude of the security’s decline, and
our  intent 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. The determination of whether a  loss is other than
temporary is highly judgmental and can have a material impact  on our results. During the fiscal years
ended June 30, 2009 and 2008, we recorded approximately $516,000 and $535,000, respectively, in
other-than-temporary impairment charges. No similar charges were recorded in the fiscal  year ended
June 30, 2007. In April 2009, the FASB issued  FSP No. FAS  115-2 and FAS  124-2, Recognition and
Presentation of Other-than-Temporary Impairments, or FSP FAS 115-2, which amended  the
other-than-temporary impairment model  for debt  securities. As a result of the  adoption  of this
standard, during fiscal year 2009 we reclassified $54,000 of previously  recognized  other-than-temporary
impairment charges to other comprehensive loss as a cumulative effect adjustment.

Fair Value of Financial Instruments

As of July 1, 2008, we partially adopted the provisions of FASB Statement No.  157, Fair Value

Measurements, or Statement 157, for financial assets and  liabilities recognized at fair  value on a
recurring basis. Statement 157 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. The provisions  of Statement 157 related to other non-financial  assets and
liabilities will be effective for us on July 1, 2009,  and will be applied prospectively.

Fair value is defined under Statement 157  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 under Statement 157 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 noted in  Note B., Summary of Significant
Accounting Policies, the fair value of our investments is generally determined from market prices  based
upon either quoted prices from active  markets or other significant  observable market transactions  at
fair value.

Effective this quarter, we implemented  FSP FAS 157-4, Determining Fair Value When the Volume
and Level of Activity for the Asset or Liability Have Significantly Decreased and Identifying  Transactions
That Are Not Orderly, or FSP FAS 157-4. FSP FAS 157-4 provides  additional guidelines for making fair
value measurements more consistent  with the  principles presented in  SFAS 157 and provides
authoritative guidance in determining whether a market is  active  or inactive, and whether a transaction
is distressed. This FSP is applicable to all assets  and liabilities (i.e. financial and non-financial)  and
requires enhanced disclosures, including interim  and annual disclosure  of  the input  and valuation
techniques (or changes in techniques) used to measure fair  value and the defining of the  major security
types comprising debt and equity securities  held  based upon the  nature and risk  of the security.  The
adoption of this FSP did not impact our  financial position  or results  of operations.

Effective this quarter, we have also implemented FSP FAS 107-1 and APB 28-1, Interim Disclosures

about Fair Value of Financial Instruments, or FSP FAS 107-1. FSP FAS 107-1  amended Statement of

47

Financial Accounting Standards No.  107, Disclosures about Fair Value of Financial Instruments, and APB
Opinion No. 28, Interim Financial Reporting, to require disclosures about the fair  value of financial
instruments in interim as well as in annual financial statements. Since this FSP addresses disclosure
requirements, the adoption of this FSP  did not impact  our financial position or results  of operations.

Derivatives

Derivative instruments include a portfolio  of  short duration foreign  currency forward contracts
intended to mitigate the risk of exchange  rate fluctuations for existing or anticipated receivable  and
payable balances denominated in foreign currency. Derivatives  are estimated at  fair value and classified
as other current assets or liabilities in  the accompanying consolidated balance sheets. The fair value of
these instruments represent 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.

We  do 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 we enter into forward contracts  only as an  economic hedge, any  gain  or loss  on the underlying
foreign-denominated balance or anticipated receivable or  payable balance would be offset by the  loss or
gain on the forward contract. Net (losses) gains recognized  on forward contracts  for the  years  ended
June 30, 2009, 2008 and 2007 were $(234,000), $699,000 and $112,000, respectively, and are included  in
the accompanying Consolidated Statement of  Operations  as other  (expense) income, net.  As of
June 30, 2009, we had outstanding forward contracts  with amounts  equivalent to approximately
$517,000 (371,000 in Euros), all maturing on or before July 24, 2009. As of June 30, 2008, we had
outstanding forward contracts with amounts equivalent to approximately $1.4 million (924,000 in
Euros), all maturing on or before August  20, 2008.  As of June 30, 2007, we had  outstanding forward
contracts with amounts equivalent to approximately $6.5 million (4.8 million in Euros). We do not
anticipate using derivative instruments  for any purpose other than hedging our exchange rate exposure.

Results of Operations

Revenues

Our total revenues for the year ended June  30, 2009 were $28.0  million compared with

$40.2 million and $38.2 million for the  years ended June  30,  2008 and 2007, respectively. The
$12.2 million decrease in revenues in fiscal year 2009 from fiscal year 2008 is primarily attributable to
lower revenues from research and development support  and  clinical materials reimbursement, partially
offset by higher revenues from license and milestone fees, as discussed  below. The $2.0 million  increase
in revenues in fiscal year 2008 from fiscal year 2007 is primarily attributable to higher revenues from
clinical materials reimbursement and license and milestone  fees,  as discussed below.

Research and development support was $7.6 million for the  year ended June 30, 2009,

$15.0 million for the year ended June 30, 2008, and $25.5  million for the year ended June 30, 2007.
These amounts primarily represent committed research funding earned based on actual resources
utilized under our discovery, development and commercialization agreement with sanofi-aventis, as well
as amounts earned for resources utilized under our  development and license agreements with other
various collaborators. Under the terms of the sanofi-aventis agreement, we were entitled to receive
committed research funding totaling not  less  than $79.3 million  over the five years of the research
collaboration, which included the initial  three-year term  of  the research program  ending August  31,
2006 plus the two 12-month extensions beginning  September  1, 2006. The two companies subsequently
agreed to extend the date of payment  through October  31,  2008 to enable completion of previously
agreed-upon research. Through the end of the  research program, we earned $81.5 million of committed

48

funding. Subsequent to October 31, 2008, we have performed,  and will continue to perform, research
on behalf of sanofi-aventis as mutually  agreed-upon. Also included in research and development
support revenue are development fees charged for reimbursement for our  direct and overhead costs
incurred in producing and delivering research-grade materials to our collaborators and 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
development fees 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  partners in  the years ended June 30, 2009, 2008
and 2007 is included in the following  table (in thousands):

Year Ended June 30,

2009

2008

2007

Collaborative Partner:

Bayer HealthCare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biogen Idec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biotest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Centocor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Genentech . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
sanofi-aventis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 227
621
1,361
—
238
4,861
258

$

88
336
1,648
466
741
11,697
59

$ —
447
1,653
418
3,487
18,916
565

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

$7,566

$15,035

$25,486

Revenue from license and milestone  fees for the year ended June 30, 2009  increased  approximately
$1.9 million to $15.1 million from $13.2 million in  the year ended  June 30, 2008. Revenue from license
and milestone fees for the year ended  June  30, 2007 was $7.6 million. Included  in license  and milestone
fees for the year ended June 30, 2009  was a  $6.5 million milestone related  to  the initiation of Phase III
clinical testing of trastuzumab-DM1,  or T-DM1, by Genentech,  a  $4 million milestone  related to the
initiation of Phase II clinical testing of  AVE1642 by sanofi-aventis and  a $500,000  milestone related  to
the initiation of Phase I clinical testing  of BT-062 by Biotest. Also during the year ended  June 30, 2009,
Millennium Pharmaceuticals and Boehringer  Ingelheim agreed to terminate their licenses with us that
were no longer being used to develop products and  as a result, we recognized as license and milestone
fees $361,000 and $486,000, respectively, of  upfront fees previously deferred. Included in license and
milestone fees for the year ended June 30, 2008  was  $5 million related to the achievement of a
milestone under the Genentech agreement  from the initiation of Phase II clinical testing of T-DM1,
$1.5 million related to the achievement of a milestone under the Biogen Idec agreement  from the
submission of the IND application for BIIB015, $2 million related to the achievement of milestones
under the sanofi-aventis agreement from  the initiation  of clinical testing of SAR3419  and certain
preclinical milestones. Included in license and milestone  fees for the year ended June 30,  2007 was
$2 million related to the achievement of a milestone under the sanofi-aventis  agreement from the
initiation of clinical testing of AVE1642.  Total revenue recognized from license and  milestone fees from

49

each  of our collaborative partners in the  years ended June 30, 2009,  2008 and  2007 is  included in  the
following table (in thousands):

Year Ended June 30,

2009

2008

2007

Collaborative Partner:

Amgen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bayer HealthCare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biogen Idec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biotest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Boehringer Ingelheim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Centocor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Genentech . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Millennium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
sanofi-aventis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$

511
410
228
669
486
138
6,651
361
5,663

$

433
—
1,684
169
—
69
5,991
—
4,810

$ 406
—
88
157
—
113
1,550
653
4,618

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

$15,117

$13,156

$7,585

Deferred revenue of $12.7 million at June 30,  2009 represents payments  received from  our
collaborators pursuant to our license and  supply agreements  with them which  we have  yet to earn
pursuant to our revenue recognition policy.

Clinical materials reimbursement decreased by approximately  $6.8 million to $5.3 million in the

year ended June 30, 2009 compared to $12.1  million  in the  year ended June 30, 2008.  We earned
clinical materials reimbursement of $5.1  million during the  year ended June 30, 2007.  During the  years
ended June 30, 2009, 2008 and 2007,  we  shipped  clinical materials in support  of a number of clinical
trials including, for certain of these years, those of T-DM1,  AVE9633, SAR3419, BIIB015, BT-062, and
of Centocor’s planned clinical testing of  their antibody-DMx  conjugate now called IMGN388, as well  as
preclinical materials in support of the development efforts  of certain  other  collaborators  and DMx
shipments to certain collaborators in  support of development and manufacturing efforts. The  decrease
in clinical materials reimbursement in fiscal  year 2009 as compared to fiscal year 2008  is primarily
related to $5.0 million in revenue recognized from supplying DMx to a collaborator in fiscal  year 2008,
along with the transfer of T-DM1 to  commercial-scale  production at a third-party contract
manufacturing organization in fiscal year  2009. The  increase in clinical materials reimbursement in
fiscal year 2008 as compared to fiscal  year 2007 is primarily related to $5.0 million  in revenue
recognized from supplying DMx to a  collaborator  in fiscal year  2008, along  with the advancement  of
the clinical trials of AVE9633 and SAR3419. During fiscal year  2009, sanofi-aventis discontinued
clinical trial activity for AVE9633. We are reimbursed for  certain of our  direct and overhead costs to
produce clinical materials plus, for certain programs, a profit  margin. The amount of clinical materials
reimbursement 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 reimbursement 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.

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

50

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:127) activities pursuant to our discovery,  development and commercialization  agreement with sanofi-

aventis;

(cid:127) activities pursuant to our development and license agreements with various  other  collaborators;

(cid:127) activities related to the preclinical  and clinical  development  of IMGN901, IMGN242 and

IMGN388;

(cid:127) process development related to production  of the huN901 antibody and  IMGN901  conjugate for

clinical materials;

(cid:127) process development related to production  of the huC242 antibody and IMGN242 conjugate for

clinical materials;

(cid:127) process development related to production  of IMGN388 conjugate for clinical  materials;

(cid:127) process improvements related to the  production of DM1,  DM4 and  strain  development of their

precursor, ansamitocin P3;

(cid:127) funded development activities with contract manufacturers  for the huN901 antibody, the huC242

antibody  and DM1, DM4 and their precursor,  ansamitocin P3;

(cid:127) production costs for the supply of the  huN901  antibody and the huC242 antibody;

(cid:127) production costs for the supply of DMx for our and  our partners’ preclinical  and clinical

activities;

(cid:127) operation and maintenance of our conjugate manufacturing facility, including production of our

own and our collaborators’ clinical materials;

(cid:127) process improvements to our TAP  technology;

(cid:127) evaluation of potential antigen targets;

(cid:127) evaluation of internally developed and/or in-licensed product candidates  and technologies; and

(cid:127) development and evaluation of additional cytotoxic agents and  linkers.

Research and development expense for  the year ended June  30, 2009 decreased $14.1  million  to

$45.9 million from $60.0 million for the  year ended June 30, 2008.  Research and development expense
was $49.4 million for the year ended June 30, 2007.  The  average  number of  our research and
development personnel increased to  175 for the  year  ended June 30,  2009 compared to 172 for  the year
ended June 30, 2008. We had an average of 167 research  and  development personnel for  the year
ended June 30, 2007. Research and development salaries  and related expenses increased by $1.4 million
in the year ended  June 30, 2009 compared to the year ended June 30, 2008 and  increased by $336,000
in the year ended  June 30, 2008 compared to the year ended June 30, 2007. Included in salaries and
related expenses for the year ended June  30, 2009 is $1.7 million  of stock compensation costs  compared
to $1.6 million and $1.4 million of stock compensation costs for  fiscal  years 2008 and 2007, respectively.
Facilities expense, including depreciation, increased $680,000  during fiscal year 2009 as  compared to
fiscal year 2008 and increased $1.2 million in fiscal year 2008 compared to fiscal year 2007.  The
increase in facilities expense in fiscal  year 2009  was  principally due  to  an increase in  depreciation  and
amortization resulting from the build  out of laboratory  and office space at our Waltham,  MA facility,
which  is partially offset by the amortization of  the lease incentive, and significant  capital improvements
made to our Norwood, MA facility. The  increase in facilities expense in fiscal year 2008 was principally
due to an increase in depreciation and  amortization and an increase  in rent  expense. The increase in

51

depreciation and amortization was due  to the acceleration of  amortization  of leasehold  improvements
for our  Cambridge, MA facilities resulting from our move to Waltham,  MA in  fiscal  year  2008, as well
as new capital purchases.

Included in research and development expenses for the  year ended June 30,  2008 is a  $2.1 million

charge  related to raw material inventory  identified as excess and a $1.6 million charge to write  down
raw  material purchased during that year  to  its net  realizable value.  No similar costs were recorded
during fiscal years 2009 and 2007. Reserve requirements for  excess  quantities  of DMx  are principally
determined based on our collaborators’ forecasted  demand compared  to  our inventory  position. The
DMx purchased during fiscal year 2008  was produced by a supplier in  conjunction with  process
scale-up, resulting in the purchase of quantities of material exceeding anticipated collaborator demand
in the next twelve  months. Due to lead  times  required to secure  material, process development and the
changing  requirements of our collaborators,  expenses to recognize excess quantities have  fluctuated
from period to period and we expect  that these period  fluctuations will  continue in the  future. See
‘‘Inventory’’ within our Critical Accounting Policies above for further discussion  of our  inventory
reserve  policy.

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
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

52

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,

2009

2008

2007

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

$13,965
9,762
6,037
16,140

$15,265
8,280
5,731
30,737

$15,647
8,072
5,599
20,091

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

$45,904

$60,013

$49,409

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  decreased  $1.3  million to $14.0  million in fiscal year 2009
from fiscal year 2008 and decreased $382,000 to $15.3 million  in fiscal year 2008 from  fiscal  year  2007.
The decrease in research expense in fiscal year 2009  was principally  the result  of a decrease in salaries
and related expenses due to a reorganization of departments in March 2008 and July 2008, resulting in
lower personnel costs included in research expense  for the current period. The decrease in  research
expenses in fiscal year 2008 was principally the  result of a  decrease in salaries and related  expenses,
partially offset by an increase in facilities expense.  Included in  salaries and related expense for the year
ended June 30, 2007 were severance costs related  to  the departure  of an executive, as  well as the
reorganization of departments mentioned previously, resulting in lower personnel costs included in
research expenses for fiscal year 2008.

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,  and the
cost of our own clinical trials, excluding  the cost of clinical materials which  is included in
manufacturing operations expense. Such expenses include personnel, patient enrollment at our clinical
testing sites, consultant fees, contract services,  and facility expenses. Preclinical and clinical testing
expenses increased $1.5 million to $9.8 million in  fiscal  year 2009  from  fiscal year 2008 and $208,000 to
$8.3 million in fiscal year 2008 from fiscal year  2007. The increase in  fiscal year  2009 was primarily due
to an increase in salaries and related  expenses  due to a reorganization of departments  in March 2008
and July 2008, as well as an increase in  clinical trials costs. The increase  in fiscal year 2008  was
primarily the result of a $500,000 milestone fee incurred  with a third party related to gaining
authorization from the FDA to begin  clinical testing  with IMGN388, as well  as increased consulting
and recruiting fees. These increases were  partially offset by a decrease in salaries and related  expense
resulting from a decrease in personnel due to turnover.

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 increased $306,000 to $6.0  million  in fiscal year  2009 from fiscal year 2008  and
increased $132,000 to $5.7 million in  fiscal year 2008  from fiscal  year 2007. The increase in  fiscal year
2009 was primarily the result of the reorganization  of  departments  in July  2008. The increase in fiscal
year 2008 was primarily the result of an  increase in  facilities expense.

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’

53

preclinical studies and clinical trials, development costs  with  contract manufacturing organizations,
manufacturing supplies, and facilities  expense.  Manufacturing operations expense  decreased
$14.6 million to $16.1 million in fiscal  year 2009  from fiscal  year 2008  and  increased  $10.6 million to
$30.7 million in fiscal year 2008 from fiscal year  2007. The decrease in  fiscal  year  2009 was primarily
the result of (i) a decrease in supply  of DMx and clinical materials  to  our collaborators;  (ii) a  decrease
in antibody supply and development expenses; (iii) a decrease in contract service expenses; and (iv) a
significant decrease in charges incurred related to the write  down of raw material inventory.  Partially
offsetting these decreases, salaries and  related expenses increased, depreciation and amortization
increased, and overhead utilization from the manufacture  of clinical materials on  behalf of our
collaborators decreased. The increase  in fiscal year 2008 was primarily the result of (i)  an increase in
supply of  DMx and clinical materials  to  our collaborators; (ii) an increase in salaries and related
expenses due to an increase in personnel,  as well  as salary  increases; (iii)  an  increase in antibody supply
and development expenses; (iv) an increase in facilities expense; and (v) an  increase in charges incurred
related to the write down of raw material inventory purchased during the  year to its net  realizable
value and raw material inventory identified as excess. Partially offsetting these increases contract service
expense decreased due primarily to lower  DMx development costs for the potential production of later-
stage materials.

Antibody expense in anticipation of potential  future  clinical  trials, as  well as our ongoing trials, was

$503,000 in fiscal year 2009, $7.4 million  in fiscal year 2008, and $6.8 million in fiscal year 2007.  The
process of antibody production is lengthy as  is 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.

General and Administrative Expenses

General and administrative expenses for the year ended June 30, 2009  decreased $448,000  to
$13.9 million from $14.3 million for the  year ended June 30, 2008.  General and administrative expenses
for the year ended June 30, 2007 were  $11.0 million. The decrease in  fiscal  year  2009 as compared to
fiscal year 2008 was primarily the result of  a decrease in  rent expense and  move-related  expenses,
partially offset by greater salaries and  related expenses. During  fiscal year  2008, the Company
recognized $1.5 million of expense related to the rental  of laboratory  and office  space in Waltham prior
to occupying the space in late March 2008, as  well as  $799,000  of  move-related  expenses, classifying
such as general and administrative expenses. During fiscal year  2009, the Company  recognized a  total
of $1.6 million in stock compensation expense and other compensation costs related  to  the former
Chief Executive Officer’s succession  plan and a termination of an executive. The increase  in fiscal year
2008 as compared to fiscal year 2007 was primarily the result of  (i) an increase in rent expense  for the
new facility for the period prior to occupancy; (ii)  an increase  in move-related expenses;  (iii) an
increase in salaries and related expenses due to an  increase in personnel,  salary increases, and higher
stock compensation costs; (iv) an increase in patent costs  resulting  from  expanded  filings; and  (v) an
increase in facilities expense.

54

Other (Expense) Income, net

Other (expense) income, net for the  years  ended June  30, 2009, 2008, and 2007  is included in the

following table (in thousands):

Other (Expense) Income, net

Year Ended June 30,

2009

2008

2007

Interest Income . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Net Realized (Losses) Gains on Investments . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . .
Other-Than-Temporary Impairment
Other (Expense) Income . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 583
(33)
(516)
(255)

$2,152
39
(535)
463

$3,265
(1)
—
10

Total Other (Expense) Income, net

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

$(221) $2,119

$3,274

Investment Income, net

Interest income for the years ended June 30, 2009,  2008 and  2007 was $583,000, $2.2  million  and
$3.3 million, respectively. The decrease  in interest income  in  fiscal  year 2009 and fiscal year 2008 from
fiscal year 2007 is  primarily the result  of lower yields on  investments tied to market rates and  lower
average investable balances.

Net Realized (Losses) Gains on Investments

Net realized (losses) gains on investments were ($33,000), $39,000  and ($1,000), for the years

ended June 30, 2009, 2008, and 2007,  respectively.

Other than Temporary Impairment

During  the years ended June 30, 2009 and 2008,  we recognized $516,000  and  $535,000,

respectively, in charges for the impairment  of  available-for-sale securities that were determined to be
other-than-temporary following a decline in  value.  No similar charges were recognized  during the year
ended June 30, 2007.

Other (Expense) Income

Other (expense) income for the years ended June 30,  2009,  2008 and 2007 was $(255,000),

$463,000 and $10,000, respectively. During the  years  ended June 30,  2009, 2008 and 2007, we recorded
net (losses) gains on forward contracts of $(234,000),  $699,000 and $112,000,  respectively. We incurred
$29,000, $243,000 and $105,000 in foreign currency translation expenses related  to  obligations with
non-U.S.  dollar-based suppliers during  the years ended  June 30, 2009, 2008 and 2007, respectively.

Liquidity and Capital Resources

Cash, cash equivalents and short-term  investments . . . . . . . . . . . . . . . .
Working capital . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stockholders’ equity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cash used for operating activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cash provided by investing activities . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cash provided by financing activities . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 71,125
65,738
66,857
(13,334)
11,995
39,359

$ 47,871
45,655
55,299
(20,149)
15,154
26,009

June 30,

2009

2008

(In thousands)

55

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,  2009, we  had
approximately $71.1 million in cash and marketable  securities. Net cash used in operations was
$13.3 million, $20.1 million and $15.8  million  during  the years ended  June  30, 2009, 2008  and 2007,
respectively. The principal use of cash  in  operating  activities for all  periods  presented  was  to  fund  our
net loss.

Net cash provided by investing activities was $12.0 million, $15.2  million  and $19.4  million  for the
years ended June 30, 2009, 2008 and  2007, respectively, and substantially  represents cash  inflows  from
the sales and maturities of marketable securities  partially offset by  capital expenditures.  Capital
expenditures were $1.9 million, $18.0  million and $2.0 million  for the  fiscal years ended June 30, 2009,
2008 and 2007, respectively. The significant capital expenditures for fiscal 2008 were primarily leasehold
improvements made to our Waltham, MA facility related  to the construction allowance received  from
the landlord to build out laboratory and  office space to our specifications, as  well as expansion and
improvements of our manufacturing plant in Norwood,  MA.  The  leasehold  improvements made to the
Waltham, MA facility were paid by the  landlord, with such reimbursement  recorded as a benefit to cash
used in operations. Capital expenditures for the  years  ended June 30,  2009 and  2007 consisted  primarily
of laboratory equipment and computer software applications.

Net cash provided by financing activities was $39.4 million,  $26.0 million and  $2.2 million for  the
years ended June 30, 2009, 2008 and  2007, respectively, which includes  the proceeds  from the exercise
of 416,000, 619,000 and 870,000 stock options, respectively. Also, in June 2009,  pursuant to a public
offering, we issued and sold 5,750,000  shares of our  common stock  resulting in net  proceeds of
$38 million. In June 2008, pursuant to  a  securities  purchase agreement with a private investor,  we
issued and sold 7,812,500 shares of our  common stock  resulting  in net proceeds of $24.9 million. The
shares of common stock offered were  registered under our  existing shelf registration statement on
Form S-3 which was filed with the Securities  and Exchange Commission  in July  2007.

We  anticipate that our current capital resources and  future collaborator payments  will  enable us to

meet our operational expenses and capital expenditures for fiscal year 2010 and at least  a portion of
the following fiscal year. However, we  cannot provide  assurance that  such collaborative agreement
funding will, in fact, be received. Should  we  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.

As mentioned above, on July 11, 2007,  we filed a Registration Statement  on Form S-3
(Registration No. 333-144488) with the Securities and Exchange Commission. The  Securities  and
Exchange Commission declared the Registration  Statement  effective  on  August 13, 2007.  Subject to our
ongoing obligations under the Securities  Act of  1933, as amended, and the  Securities  Exchange Act  of
1934, as amended, the Registration Statement permits us to offer  and sell up  to  an aggregate of
$75 million of our common stock, $65.3 million of which we sold in  the transactions discussed above.

56

Contractual Obligations

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

June 30, 2009 (in thousands):

Waltham lease obligation(1)(2) . . . . . . . . . . .
Other operating lease obligations(2)
. . . . . .
Purchase obligations . . . . . . . . . . . . . . . . .

Payments Due by Period

Total

$54,142
2,955
924

Less than
One Year

1-3
Years

4-5
Years

More than
5 Years

$4,592
1,728
924

$ 9,517
1,227
—

$9,784
—
—

$30,249
—
—

Total

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

$58,021

$7,244

$10,744

$9,784

$30,249

(1) Lease agreement was signed on July 27, 2007.

(2) The Company entered into a sub-sublease  in May  2008 for the entire space at 148 Sidney Street,

Cambridge, MA through October 2010, the remainder of the sublease. We will receive
approximately $1.0 million in minimum rental  payments over the  remaining  term of the
sub-sublease, which is not included in the table above. We intend to sublease approximately 14,000
square  feet of laboratory and office space  at 830 Winter Street, Waltham, MA. However,  we have
not included estimated sublease income in the  table  above.

Recent  Accounting Pronouncements

In March 2008, the FASB issued Statement  No. 161, Disclosures about Derivative Instruments and

Hedging Activities, or Statement 161, which is effective for fiscal years beginning  after November  15,
2008 (our fiscal year 2010). Statement  161 requires enhanced disclosures about an entity’s derivative
and  hedging activities and thereby improves the  transparency of  financial  reporting. We  do not believe
the adoption of Statement 161 will have a material impact  on our financial statements.

In December 2007, the FASB ratified EITF Issue  No. 07-1, Accounting for Collaborative

Arrangements, or EITF 07-1, which is effective for  fiscal  years  beginning after December 15,  2008 (our
fiscal year 2010). EITF 07-1 defines collaborative arrangements  and establishes reporting requirements
for transactions between participants in a collaborative arrangement and between participants in the
arrangement and third parties. EITF 07-1  also  establishes the appropriate income statement
presentation and classification for joint  operating activities and payments between participants, as well
as the sufficiency of the disclosures related to these arrangements. We  do  not  believe the adoption of
EITF 07-1 will have a material impact  on  our results  of operations or financial position.

Off-Balance Sheet Arrangements

None.

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

57

that 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.

58

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, 2009  and 2008 . . . . . . . . . . . . . . . . . . . . . . . . .
Consolidated Statements of Operations  for the  Years Ended June 30, 2009, 2008, and 2007 .
Consolidated Statements of Stockholders’ Equity for the Years Ended June 30,  2009, 2008,

and 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Consolidated Statements of Cash Flows for the Years  Ended June  30, 2009, 2008, and  2007 .
Notes to Consolidated Financial Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

60

61
62

63
64
65

59

Report of Independent Registered Public Accounting  Firm

The Board of Directors and Stockholders of ImmunoGen, Inc.

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

2009 and 2008, and the related consolidated statements of operations,  stockholders’ equity, and cash
flows for each of the three years in the period  ended June 30,  2009. 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,  2009 and  2008, and the
consolidated results of its operations and  its cash flows for  each  of the three years in the period ended
June 30, 2009, 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), the  effectiveness  of  ImmunoGen,  Inc.’s  internal control  over financial
reporting as of June 30, 2009, 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 28, 2009 expressed an unqualified opinion  thereon.

/s/ ERNST & YOUNG LLP

Boston, Massachusetts
August 28, 2009

60

IMMUNOGEN, INC.

CONSOLIDATED BALANCE SHEETS

AS OF JUNE 30, 2009 AND JUNE 30, 2008

In thousands, except per share amounts

ASSETS
Cash and cash equivalents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Marketable securities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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,
2009

June  30,
2008

$ 69,639
1,486
1,746
561
1,836
366
1,232

76,866
19,671
4,142
25

$ 31,619
16,252
396
3,472
2,116
366
1,820

56,041
22,751
4,508
38

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

$ 100,704

$ 83,338

LIABILITIES AND STOCKHOLDERS’ 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)
Stockholders’ equity:
Preferred stock, $.01 par value; authorized 5,000 shares;  no  shares  issued and

1,244
4,140
1,566
979
3,199

11,128
9,540
9,543
3,636

33,847

$

1,411
1,164
4,304
935
2,572

10,386
10,052
5,293
2,308

28,039

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

—

—

Common stock, $.01 par value; authorized  75,000 shares; issued and

outstanding 56,947 and 50,778 shares as of June  30, 2009 and 2008,
respectively . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Additional paid-in capital
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accumulated deficit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accumulated other comprehensive loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

569
387,947
(321,451)
(208)

508
344,498
(289,568)
(139)

Total stockholders’ equity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

66,857

55,299

Total liabilities and stockholders’ equity . . . . . . . . . . . . . . . . . . . . . . . .

$ 100,704

$ 83,338

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

61

IMMUNOGEN, INC.

CONSOLIDATED STATEMENTS OF  OPERATIONS

In thousands, except per share data

Year Ended June 30,

2009

2008

2007

Revenues:

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

$ 7,566
15,117
5,305

$ 15,035
13,156
12,058

$ 25,486
7,585
5,141

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

27,988

40,249

38,212

Operating Expenses:

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

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

Loss from operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Investment income, net . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other-than-temporary impairment . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other (expense) income, net . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Loss before provision for income taxes . . . . . . . . . . . . . . . . . . . . . . .
(Benefit) provision for income taxes . . . . . . . . . . . . . . . . . . . . . . . . .

45,904
13,900

59,804

(31,816)
583
(516)
(288)

(32,037)
(100)

60,013
14,348

74,361

(34,112)
2,191
(535)
463

(31,993)
27

49,409
11,029

60,438

(22,226)
3,264
—
10

(18,952)
35

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

$(31,937) $(32,020) $(18,987)

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

$

(0.63) $

(0.75) $

(0.45)

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

51,068

42,969

41,759

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

62

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY

IMMUNOGEN, INC.

In thousands

Common Stock

Shares Amount

Additional
Paid-In
Capital

Balance at June 30, 2006 . . . . . . . . . . . . . . . . . . 41,474
—
Unrealized gains on marketable securities . . . . . . . .
—
Net loss
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
870
Stock options exercised . . . . . . . . . . . . . . . . . . .
—
Stock-based compensation expense . . . . . . . . . . . .
—
Directors’ stock-based compensation . . . . . . . . . . .
2
Shares issued upon resignation of director . . . . . . . .

$414
—
—
9
—
—
—

$310,851
—
—
2,141
2,348
281
—

Deficit

$(238,561)
—
(18,987)
—
—
—
—

Balance at June 30, 2007 . . . . . . . . . . . . . . . . . . 42,346

$423

$315,621

$(257,548)

Comprehensive loss

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

. . . . . . .
Unrealized losses on marketable securities
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Net loss
Stock options exercised . . . . . . . . . . . . . . . . . . .
Stock-based compensation expense . . . . . . . . . . . .
Directors’ stock-based compensation . . . . . . . . . . .
Issuance of common stock in a private offering, net of
financing costs . . . . . . . . . . . . . . . . . . . . . . .

—
—
619
—
—

7,813

—
—
6
—
—

79

—
—
1,087
2,861
92

—
(32,020)
—
—
—

24,837

—

Accumulated
Other

Total

Accumulated Comprehensive Stockholders’ Comprehensive

(Loss)

$(354)
259
—
—
—
—
—

$ (95)

(44)
—
—
—
—

—

Equity

(Loss)

$ 72,350
259
(18,987)
2,150
2,348
281
—

$ 58,401

(44)
(32,020)
1,093
2,861
92

$

259
(18,987)
—
—
—
—

$(18,728)

(44)
(32,020)
—
—
—

24,916

—

$(32,064)

(15)

(15)

—
(31,937)
1,314
3,956
20

38,045
175

—
(31,937)
—
—
—

—
—

$(31,952)

Balance at June 30, 2008 . . . . . . . . . . . . . . . . . . 50,778

$508

$344,498

$(289,568)

$(139)

$ 55,299

Comprehensive loss

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

Unrealized losses on marketable securities
. . . . . . .
Cumulative effect adjustment relating to the adoption
of FSP FAS 115-2 and FAS 124-2 . . . . . . . . . . . .
Net loss
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stock options exercised . . . . . . . . . . . . . . . . . . .
Stock-based compensation expense . . . . . . . . . . . .
Restricted stock issued . . . . . . . . . . . . . . . . . . .
Issuance of common stock in a public offering, net of

—

—
—
416
—
3

financing costs . . . . . . . . . . . . . . . . . . . . . . .
Directors’ stock-based compensation . . . . . . . . . . .

5,750
—

—

—
—
4
—
—

57
—

—

—

—
—
1,310
3,956
20

37,988
175

54
(31,937)
—
—
—

—
—

(15)

(54)
—
—
—
—

—
—

Balance at June 30, 2009 . . . . . . . . . . . . . . . . . . 56,947

$569

$387,947

$(321,451)

$(208)

$ 66,857

Comprehensive loss

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

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

63

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 (gain) on sale/disposal of fixed  assets . . . . . . . . . . . . . . . . . .
Amortization of deferred lease incentive obligation . . . . . . . . . . . .
Loss (gain) on sale of marketable securities . . . . . . . . . . . . . . . . .
Other-than-temporary impairment of  investments . . . . . . . . . . . . .
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Proceeds from landlord for tenant improvements . . . . . . . . . . . .

Year Ended June 30,

2009

2008

2007

$(31,937) $(32,020) $ (18,987)

4,995
18
(975)
33
516
234
4,235
1,450

(1,350)
2,911
280
312
366
13
(167)
2,976
(2,871)
4,877
750

4,445
103
(512)
(39)
535
(699)
2,915
1,816

1,140
2,508
1,151
(241)
(4,511)
37
(815)
(49)
(44)
(5,910)
10,041

3,153
(1)
—
1
—
(112)
2,540
69

33
(561)
(2,032)
27
(173)
—
880
288
1,347
(2,253)
—

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

(13,334)

(20,149)

(15,781)

Cash flows from investing activities:

Proceeds from maturities or sales of  marketable securities . . . . .
Purchases of marketable securities . . . . . . . . . . . . . . . . . . . . . .
Reclassification of cash equivalent balance to marketable

securities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Purchases of property and equipment, net . . . . . . . . . . . . . . . . .
Proceeds from settlement of forward contracts . . . . . . . . . . . . . .

14,227
(25)

45,908

297,690
— (276,318)

— (13,605)
(17,995)
846

(1,896)
(311)

Net cash provided by investing activities . . . . . . . . . . . . . . . . .

11,995

15,154

Cash flows from financing activities:

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

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

Net change in cash and cash equivalents . . . . . . . . . . . . . . . . . . . . .
Cash and cash equivalents, beginning  balance . . . . . . . . . . . . . . . . . .

1,314
38,045

39,359

38,020
31,619

1,093
24,916

26,009

21,014
10,605

Cash and cash equivalents, ending balance . . . . . . . . . . . . . . . . . . . .

$ 69,639

$ 31,619

$ 10,605

Supplemental disclosure:
Cash paid for income taxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$

1

$

27

$

34

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

64

—
(1,981)
32

19,423

2,150
—

2,150

5,792
4,813

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

AS OF JUNE 30, 2009

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 continues to research and
develop its various product candidates and technologies and does not expect to derive revenue from
commercial product sales within the near future. It is anticipated that the Company’s existing capital
resources, enhanced by collaborative agreement  funding, will enable current and planned  operations to
be maintained for fiscal 2010 and at least a  portion of fiscal 2011. However, if the Company is unable
to achieve future milestones under its collaborative  agreements (see Note C) or  raise additional capital,
the Company may be required to defer or limit some or all of its research, development and/or clinical
projects. Additional funding may not  be  available on favorable terms, or at all. The Company may raise
additional funds through public or private  financings, collaborative arrangements or other
arrangements. Debt financing, if available, may involve covenants that could restrict business activities.

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.  (established  in December 1989), and ImmunoGen Europe
Limited (established in October 2005).  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

Effective June 15, 2009, the Company  adopted Statement of Financial Accounting Standards
No. 165, subsequent Events, or SFAS  165. This standard establishes general standards of accounting for
and disclosure of events that occur after  the balance sheet date but before financial statements are
issued. The adoption of SFAS 165 did not impact  the Company’s  financial position  or results of
operations. The Company has evaluated all events or transactions that occurred after  June 30, 2009 up
through August 28, 2009, the date the Company issued these financial statements. During the period
the Company did not have any material recognizable or  unrecognizable subsequent events.

65

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

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 Company follows the
provisions of the Securities and Exchange Commission’s Staff Accounting Bulletin No. 104, Revenue
Recognition, or SAB 104, and Emerging Issues Task Force Issue (EITF) Issue No.  00-21, Accounting for
Revenue Arrangements with Multiple Elements, or EITF 00-21. In accordance with SAB 104  and
EITF 00-21, the Company recognizes  revenue related to research activities 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 terms of the Company’s agreements contain multiple
elements which typically include non-refundable license fees, payments based upon  the achievement of
certain milestones and royalties on product  sales. The Company  evaluates such arrangements to
determine if the deliverables are separable  into units of accounting and then applies applicable revenue
recognition criteria to each unit of accounting.

At June  30, 2009, the Company had the  following  three types of collaborative contracts with the

parties identified below:

(cid:127) Exclusive license to use the Company’s  TAP technology and/or certain other  intellectual property

to develop compounds to a single antigen:

Bayer HealthCare (single-target license)

Biogen Idec (single-target license)

Biotest (single-target license)

Genentech (multiple single-target licenses)

sanofi-aventis (license to multiple individual targets)

(cid:127) Option agreement for a defined period  of time to secure licenses to use  the Company’s TAP

technology to develop anticancer compounds to a limited number of targets  on established  terms
(broad option agreement):

Amgen

Genentech

sanofi-aventis

(cid:127) Non-exclusive license to the Company’s  humanization technology:

sanofi-aventis

Generally, the foregoing collaboration agreements provide that the Company will (i) at  the
collaborator’s request, manufacture and provide to them preclinical  and clinical materials at the
Company’s cost, or, in some cases, cost plus a margin, (ii) earn payments upon the collaborators’
achievements of certain milestones and (iii) earn royalty payments,  generally  until the later of the last
applicable patent expiration or 10 to 12 years after  product launch.  Royalty rates may vary over the
royalty term depending on certain intellectual property rights. The Company is required to provide

66

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

B. Summary of Significant Accounting Policies (Continued)

technical training and to share any process improvements and know-how with its collaborators  during
the research term of the collaboration  agreements.

Generally, upfront payments on single-target licenses are  deferred over the  period of the

Company’s substantial involvement during  development. The determination of the length of  this period
is subject to judgment and estimation and can have  an  impact on the amount of  revenue recognized in
a given period. The Company’s employees  are available to assist the Company’s  collaborators during
the development of their products. The  Company estimates this development phase 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 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. 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.

The Company defers upfront payments received from its broad option agreements over  the period

during which the collaborator may elect  to  receive a  license. These periods are specific to each
collaboration agreement, but are between three  and 12 years. If a collaborator selects an option to
acquire a license under these agreements, any option fee is deferred  and recorded over  the life of the
option, generally 12 to 18 months. If a  collaborator  exercises an option and the Company grants a
single-target license to the collaborator, the  Company defers the license fee and accounts for  the fee as
it would an upfront payment on a single-target license, as discussed above. Upon exercise of an option
to acquire a license, the Company would recognize any remaining deferred option fee  over the period
of the Company’s substantial involvement under  the license acquired.  In the  event that a broad option
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  deferred revenue at the date
of such termination. 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 the Company’s  remaining  period of substantial involvement can be
estimated.

When milestone fees are specifically tied to a separate earnings process and are deemed to be

substantive and at risk, revenue is recognized  when such  milestones are achieved. In addition,  the
Company recognizes research and development  support revenue  from certain collaboration and
development agreements based upon the  level of  research services performed during the period of the
relevant research agreement. Deferred revenue substantially represents  amounts  received under
collaborative agreements and not yet  earned  pursuant  to  these policies. Where the Company has no
continuing involvement, the Company will record non-refundable license fees  as revenue  upon receipt
and will record revenue upon achievement of milestones by its collaborative partners.

The Company produces preclinical and clinical  materials  for its collaborators. The Company  is
reimbursed for its  direct costs and a  portion  of  its  overhead costs to produce clinical materials. The
Company recognizes revenue on preclinical and clinical  materials when the materials have  passed  all

67

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

B. Summary of Significant Accounting Policies (Continued)

quality testing required for collaborator acceptance and title and risk  of loss have transferred to the
collaborator.

The Company also produces 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. Generally, the Company is reimbursed
for certain of its direct and overhead costs of producing  these  materials  or providing  these services.
The Company records the amounts received  for the  preclinical materials produced or services
performed as a component of research  and development support. The Company also develops
conjugation processes for materials for later stage testing and commercialization for certain
collaborators. The Company is reimbursed for  certain of its direct and overhead costs and may receive
milestone payments for developing these  processes which are recorded as  a component of research and
development support.

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, 2009 and 2008 is summarized below (in thousands):

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

$ 952
884

$ 565
1,551

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

$1,836

$2,116

June 30,

2009

2008

Raw materials inventory consists entirely  of  DM1 or  DM4 ,  our proprietary cell-killing agents,
which  are included in all Targeted Antibody Payload, or TAP,  product candidates currently  in preclinical
and clinical testing with our collaborators.

Inventory cost is stated net of write-downs  of  $1.8 million and $2.5 million as of June 30, 2009  and

June 30, 2008, 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 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  and its collaborators’
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

68

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

B. Summary of Significant Accounting Policies (Continued)

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 Company and 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 cost of  the conjugate and any
agreed margin thereon, even if the collaborator subsequently cancels the manufacturing  run.

The Company accounts for the raw material  inventory as follows:

a)

b)

c)

d)

raw material is capitalized as inventory upon receipt of the materials. The portion  of the raw
material the Company uses in the production of its own  products is recorded  as research and
development expense as consumed;

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 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  the year ended June 30, 2008,  the Company obtained additional amounts of DM1 and

DM4 from a new supplier. Due to the  need to evaluate the  process which was developed to prepare
such material from this new supplier  across multiple batches, the Company had committed to a level of
production which yielded more material  than would  be  required by its collaborators  over the next
twelve months. As a result, the Company recorded a $2.1  million charge to research and development
expense related to excess inventory during the  year ended June 30, 2008. The  Company also  recorded
$1.6 million as research and development expense  to  write down this material  to  its net realizable
value. No similar costs were recorded  during the  years  ended June 30, 2009 and 2007.  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.

69

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

B. Summary of Significant Accounting Policies (Continued)

Unbilled Revenue

The majority of the Company’s unbilled revenue at June  30, 2009 and 2008  represents research

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

Restricted Cash

Restricted cash at June 30, 2009 and  2008 are cash balances securing  irrevocable letters of credit
required for the Company to receive value added tax reimbursements related to payments to foreign
vendors for activities performed in fiscal  2008 and 2007  and as security  deposits for the Company’s
leased facilities.

Other Accrued Liabilities

Other accrued liabilities consisted of  the following at June  30, 2009 and 2008  (in  thousands):

June 30,

2009

2008

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

$ 130
295
722
306
113

$2,335
1,004
535
305
125

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

$1,566

$4,304

Research and Development Expenses

The Company’s net 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.

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
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.

The Company adopted the provisions  of  FASB Financial Interpretation  No. 48, Accounting for
Uncertainty in Income Taxes, or FIN 48, an interpretation of FASB  Statement No 109, or Statement 109,
on July 1, 2007. FIN 48 prescribes a recognition threshold and  measurement attribute for financial

70

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

B. Summary of Significant Accounting Policies (Continued)

statement recognition and measurement  of a  tax  position taken or expected to be taken in a tax return
and also provides guidance on various related matters such  as derecognition, interest  and penalties, and
disclosure.

Financial Instruments and Concentration of Credit  Risk

Cash and cash equivalents are primarily maintained with two 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. Financial instruments  that
potentially subject  the Company to concentrations  of credit risk consist principally  of marketable
securities. Marketable securities at June 30, 2009 generally consist of high-grade corporate bonds and
asset-backed securities. 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  estimated  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,  2009, 2008  and  2007 were ($234,000), $699,000 and $112,000,
respectively, and are included in the accompanying  Consolidated  Statement of Operations  as other
(expense) income, net. As of June 30, 2009, we  had outstanding forward contracts with amounts
equivalent to approximately $517,000 (371,000 in Euros), all maturing on or before July 24, 2009. As of
June 30, 2008, we had outstanding forward contracts  with amounts  equivalent to approximately
$1.4 million (924,000 in Euros), all maturing  on  or before August  20, 2008. As of June 30, 2007, the
Company had outstanding forward contracts with amounts equivalent to approximately $6.5 million
(4.8 million in Euros). The Company does not anticipate using derivative  instruments for any purpose
other than hedging exchange rate exposure.

Cash Equivalents

Cash equivalents consist principally of money market funds  and  other investments with  original

maturities of three months or less at  the  date  of purchase.

Marketable Securities

The Company invests 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

71

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

B. Summary of Significant Accounting Policies (Continued)

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 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 other income, net, as well  as interest and dividends. Realized gains and losses on
available-for-sale securities are also included in other income, net, as well as charges for the
impairment of available-for-sale securities that  were determined to be other-than-temporary and  related
to a credit loss. The cost of securities sold is based  on the specific  identification method.

Other-than-Temporary Impairments

In April 2009, the FASB issued FSP No. FAS 115-2 and FAS  124-2, Recognition and Presentation of

Other-than-Temporary Impairments, or FSP FAS 115-2, which amended the other-than-temporary
impairment model for debt securities.

Under this FSP, 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 adopted the provisions  of  FSP FAS  115-2  on April 1,  2009. As  a result of  the

adoption, $54,000 of previously recognized other-than-temporary impairment charges was reclassified to
other comprehensive loss as a cumulative effect  adjustment.

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 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  in other income (expense), net.

Fair Value of Financial Instruments

As of July 1, 2008, the Company partially adopted  the provisions of FASB Statement  No. 157, Fair

Value Measurements, or Statement 157, for financial assets and  liabilities recognized at fair  value on a
recurring basis. Statement 157 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

72

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

B. Summary of Significant Accounting Policies (Continued)

value measurements. The provisions  of Statement 157 related to other non-financial assets and
liabilities will be effective on  July 1, 2009, and will be applied prospectively.

Fair value is defined under Statement 157 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 under  Statement 157 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:127) Level 1—Quoted prices in active markets for  identical assets or liabilities.

(cid:127) 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:127) 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.

Effective this quarter, the Company implemented  FSP FAS 157-4, Determining Fair Value When the

Volume and Level of Activity for the Asset  or Liability  Have Significantly Decreased  and Identifying
Transactions That Are Not Orderly, or FSP FAS 157-4. FSP FAS 157-4  provides additional  guidelines for
making fair value measurements more  consistent  with the  principles presented in  SFAS 157 and
provides authoritative guidance in determining whether a  market  is active or inactive, and whether a
transaction is distressed. This FSP is  applicable to all assets  and liabilities (i.e. financial  and
nonfinancial) and requires enhanced disclosures, including interim and annual disclosure of the  input
and valuation techniques (or changes in techniques) used to measure  fair value  and the  defining  of  the
major security types comprising debt  and  equity  securities held based  upon the  nature and risk  of  the
security. The adoption of this FSP did not impact the  Company’s financial position or results of
operations.

As of June 30, 2009, the Company held certain assets  that  are required to be measured  at fair
value on  a recurring basis, including our  cash equivalents and  marketable securities. 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, 2009 (in thousands):

Cash, cash equivalents and restricted cash . .
Available-for-sale marketable securities . . . .

Fair Value Measurements at June 30, 2009 Using

Quoted Prices in
Active Markets for
Identical Assets

Significant Other
Observable Inputs

Significant
Unobservable
Inputs

Total

$74,147
1,486

$75,633

(Level 1)

$74,147
—

$74,147

(Level 2)

(Level 3)

$ —
1,486

$1,486

$—
—

$—

73

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

B. Summary of Significant Accounting Policies (Continued)

The fair value of the Company’s investments is generally  determined from  market prices based
upon either quoted prices from active  markets or other significant  observable market transactions at
fair value.

In the fourth quarter of fiscal 2009, the Company has also implemented FSP FAS 107-1 and

APB 28-1, Interim Disclosures about Fair Value of Financial Instruments, or FSP FAS 107-1. FSP
FAS 107-1 amended Statement of Financial Accounting  Standards No. 107, Disclosures about Fair Value
of Financial Instruments, and APB Opinion No. 28,  Interim Financial Reporting, to require disclosures
about the fair value of financial instruments in  interim as well  as in annual financial statements. Since
this  FSP addresses disclosure requirements,  the adoption of  this FSP  did  not  impact  the Company’s
financial position or results of operations.

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 . . . . . . . . . . .

3-5 years
3-5 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 $18,000  and
$103,000 of losses on the sale/disposal of certain furniture and equipment during the years ended
June 30, 2009 and 2008, respectively. The Company recorded a $1,000  gain on  the sale  of  certain
equipment during the year ended June 30, 2007.

Impairment of Long-Lived Assets

In accordance with the Financial Accounting Standards  Board (FASB) SFAS No. 144, Accounting
for the Impairment or Disposal of Long-Lived Assets, 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,

74

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

B. Summary of Significant Accounting Policies (Continued)

as calculated in accordance with the  treasury-stock accounting  method, are shown in the  following table
(in thousands):

June 30,

2009

2008

2007

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

5,529
848

5,678
483

5,763
771

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.

Stock-Based Compensation

As of June 30, 2009, 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.  The 2006  Plan  was approved  by the Company’s  Board of
Directors and the shareholders of the  Company on November  14, 2006 and replaced  the previous stock
option plan, the ImmunoGen, Inc. Restated Stock  Option  Plan,  as amended, or the Former Plan. At
the annual meeting of shareholders on  November 12, 2008, an amendment to the 2006 Plan was
approved and an additional 2,000,000 shares  were authorized  for  issuance  under this plan.  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 4,500,000 shares  of  the Company’s common stock, as  well as any shares  of
common stock that are represented by awards granted  under the Former Plan that are forfeited,  expire
or are cancelled without delivery of shares of common  stock or which result  in the forfeiture of shares
of common stock back to the Company  on  or after November 13,  2006, or  the equivalent of  such
number of shares after the Administrator, in its sole discretion, has interpreted the effect of  any stock
split, stock dividend, combination, recapitalization or  similar  transaction in accordance with the 2006
Plan; 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 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

75

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

B. Summary of Significant Accounting Policies (Continued)

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,

2009

2008

2007

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

None

None

None
63.11% 66.60% 73.42%
2.40% 3.72% 5.14%
7.1
7.2

6.9

Using the Black-Scholes option-pricing model, the weighted average grant  date fair  values  of
options granted during fiscal 2009, 2008 and 2007  were $2.73, $2.38, and $3.99 per share, respectively.

A summary of option activity under the Plan as of June  30, 2009, and changes during the twelve

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

Number of
Stock
Options

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

Aggregate
Intrinsic
Value

Outstanding at June 30, 2008 . . . . . . . . .
Granted . . . . . . . . . . . . . . . . . . . . . . . .
Exercised . . . . . . . . . . . . . . . . . . . . . . .
Forfeited/Canceled . . . . . . . . . . . . . . . . .

5,678
505
(416)
(238)

Outstanding at June 30, 2009 . . . . . . . . .

5,529

Outstanding at June 30, 2009—vested  or

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

Exercisable at June 30, 2009 . . . . . . . . . .

4,998

3,906

$6.28
4.31
3.16
5.74

$6.36

$6.59

$9.00

6.14

$19,246

5.85

5.05

$17,040

$12,075

As of June 30, 2009, the estimated fair value of unvested  employee awards was $3.2  million, net of
estimated forfeitures. The weighted-average remaining vesting  period for these awards is approximately
two and one-half years.

A summary of option activity  for shares vested during  the fiscal years ended June 30, 2009, 2008

and 2007 is presented below (in thousands):

Year Ended June 30,

2009

2008

2007

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

$2,838
920
1,314

$2,817
1,749
1,093

$2,406
2,053
2,150

During  the years ended June 30, 2009 and 2007,  the Company recorded approximately $843,000
and $80,000, respectively of stock-based  compensation expense related to the modification of certain
outstanding common stock options. During the year ended June 30, 2009,  certain options  previously

76

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

B. Summary of Significant Accounting Policies (Continued)

granted to the former Chief Executive  Officer of the Company were modified in  accordance with the
succession plan approved by the Company’s Board of Directors in September 2008. No  similar charges
were recorded during the year ended June  30,  2008.

Comprehensive Loss

The Company presents comprehensive loss  in  accordance with FASB  Statement No.  130, Reporting
Comprehensive Income. Comprehensive loss is comprised of the  Company’s net loss  for the period and
unrealized gains and losses recognized on available-for-sale marketable  securities.

Segment Information

During  the three fiscal years ended June 30, 2009,  the Company continued to operate in  one
reportable business segment under the management approach of FASB Statement No.  131, Disclosures
about Segments of an Enterprise and Related Information, which is the business of discovery of
monoclonal antibody-based anticancer  therapeutics.

The percentages of revenues recognized from  significant customers of  the  Company in  the years

ended June 30, 2009, 2008 and 2007  are  included in  the following table:

Collaborative Partner:

Year Ended June 30,

2009

2008

2007

sanofi-aventis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Genentech . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Biotest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

45% 48% 64%
26% 34% 22%
13% 8% 5%

There were no other customers of the Company  with significant revenues  in the years ended

June 30, 2009, 2008 and 2007.

Recent Accounting Pronouncements

In March 2008, the FASB issued Statement  No. 161, Disclosures about Derivative Instruments and

Hedging Activities, or Statement 161, which is effective for fiscal years beginning  after November  15,
2008 (our fiscal year 2010). Statement  161 requires enhanced disclosures about an entity’s derivative
and  hedging activities and thereby improves the  transparency of  financial  reporting. The Company  does
not believe the adoption of Statement 161 will have a material impact on its  financial  statements.

In December 2007, the FASB ratified EITF Issue  No. 07-1, Accounting for Collaborative

Arrangements, or EITF 07-1, which is effective for  fiscal  years  beginning after December 15,  2008 (the
Company’s fiscal year 2010). EITF 07-1  defines collaborative arrangements and  establishes  reporting
requirements for transactions between participants in a collaborative arrangement and between
participants in the arrangement and third parties. EITF  07-1 also establishes the appropriate income
statement presentation and classification  for joint operating  activities and payments between
participants, as well as the sufficiency  of  the disclosures related to these arrangements.  The Company
does not believe the adoption of EITF 07-1 will  have a material impact on its results  of  operations  or
financial position.

77

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

C. Agreements

Significant Collaborative Agreements

sanofi-aventis

In July 2003, the Company entered into a broad collaboration agreement with sanofi-aventis to

discover, develop and commercialize antibody-based  anticancer  therapeutics.

The agreement provides sanofi-aventis with worldwide commercialization rights  to  new anticancer
therapeutics developed to targets that were  included in the collaboration, including the right to use the
Company’s TAP technology and humanization technology in  the creation of therapeutics to these
targets. The product candidates (targets)  as of June  30,  2009 in the  collaboration include SAR3419
(CD19), SAR566658 (CA6), SAR650984  (CD38)  and additional compounds  at earlier  stages of
development that have yet to be disclosed.  During  fiscal  2009, sanofi-aventis discontinued clinical trial
activity for two product candidates previously included in the collaboration, AVE9633 (CD33) and
AVE1642 (IGF-1R).

The collaboration agreement entitles the Company to receive milestone payments potentially

totaling $21.5 million, per antigen target  for each  therapeutic developed under the collaboration
agreement. The Company has earned a  $500,000 payment  in September 2004 for a preclinical milestone
related to SAR3419, a $1 million milestone payment in October 2007 with the start of  clinical testing of
SAR3419, a $500,000 payment in December 2007 for  a preclinical milestone related  to  SAR650984 and
a $500,000 payment in March 2008 for  a preclinical  milestone related to SAR566658. The Company
also earned an aggregate of $8 million of milestone payments related to two product candidates that
previously had been in the collaboration,  AVE9633  and  AVE1642. Rights to these two product
candidates and their respective targets  have been returned to us.

The agreement also entitles the Company to royalties on  the commercial sales of any resulting

products if and when such sales commence. Sanofi-aventis is  responsible for the  cost of the
development, manufacturing and marketing  of  any products created through  the collaboration. The
Company is reimbursed for any preclinical and clinical  materials that it makes under the  agreement.
The collaboration agreement also provides  the Company 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-aventis
to terminate the Company’s co-promotion  rights  if there is  a change of  control  of the company.

The overall term of the agreement extends to the  later of the latest patent to expire or twelve
years after the latest launch of any product  discovered,  developed and/or commercialized under the
agreement. Sanofi-aventis paid the Company an upfront  fee of $12 million  in August 2003. Inclusive of
its  extensions, the agreement entitled the  Company to receive committed research funding totaling
$79.3 million over the five years of the  research  collaboration.  The two companies subsequently agreed
to extend the date of research funding through October  31, 2008 to enable  completion  of previously
agreed-upon research. The Company  recorded  the research funding  as it was earned based upon its
actual resources utilized in the collaboration. The Company earned $81.5 million of committed funding
over the duration of the research program, of which  $2.7  million, $10.8 million and $18.9 million was
recognized during fiscal years 2009, 2008  and 2007,  respectively. The  Company is  now compensated for
research performed for sanofi-aventis on  a mutually agreed-upon basis.

78

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

C. Agreements (Continued)

In October 2006, sanofi-aventis licensed  non-exclusive  rights to use the  Company’s proprietary

resurfacing technology to humanize antibodies  to  targets not included  in the collaboration, including
antibodies for non-cancer applications. This license provides sanofi-aventis with the non-exclusive right
to use the Company’s proprietary humanization technology through August 31, 2011 with the right  to
extend for one or more additional periods of three years each by providing  the Company with written
notice prior to expiration of the then-current license term.  Under the terms of  the license,  the
Company is entitled to a $1 million license fee,  half of which was paid upon contract signing and the
second  half was paid in August 2008,  and  in addition, the  Company is entitled to receive milestone
payments potentially totaling $4.5 million  for each antibody humanized under this agreement and also
royalties on commercial sales, if any.

In August 2008, sanofi-aventis exercised its option under a 2006 agreement for expanded access to

ImmunoGen’s TAP technology. The exercise  of  this  option enables sanofi-aventis to evaluate, with
certain restrictions, the Company’s maytansinoid TAP technology with  antibodies to targets that were
not included in the existing research  collaboration between the  companies and to license  the exclusive
right to use the technology to develop  products  to  specific targets on the terms  in the 2006  agreement.
ImmunoGen is entitled to earn upfront  and milestone payments potentially totaling $32 million per
target for each compound developed  under the 2006 agreement, as well as royalties on the commercial
sales of any resulting products. ImmunoGen also is entitled  to  manufacturing payments for any
materials made on behalf of sanofi-aventis. The Company  received $3.5 million with the exercise of this
option in  August 2008, in addition to the  $500,000 ImmunoGen received in December 2006 with the
signing of the option agreement. The agreement has a  three-year term from  the date of  the exercise of
the option and can be renewed by sanofi-aventis for one additional three-year term by payment of a
$2 million fee.

Genentech

In May 2000, the Company entered into two  separate  agreements with  Genentech. The first
agreement grants Genentech  an exclusive license to the Company’s maytansinoid TAP technology for
use with antibodies, such as trastuzumab, that  target HER2. Under the terms of this agreement,
Genentech has exclusive worldwide rights to develop and commercialize maytansinoid TAP compounds
with antibodies that target HER2. Genentech  is responsible for  the manufacturing, product
development and marketing of any products resulting from the agreement. The Company received a
$2 million non-refundable payment from  Genentech upon execution of the agreement.  The Company is
also entitled to up to $44 million in milestone payments from Genentech under  this agreement, as
amended in May 2006, in addition to  royalties on the  net sales of any resulting products. Genentech
began Phase II evaluation of T-DM1  in July 2007  and  the Company earned a $5 million  milestone
payment with this event, which is included in  license and milestone fees for the fiscal year ended
June 30, 2008. Genentech and Roche began Phase  III evaluation of T-DM1 in February  2009 and the
company earned a $6.5 million milestone  payment with this event.  This milestone is included in license
and milestone fees for the fiscal year  ended June 30, 2009. Through June 30,  2009, the Company has
received $13.5 million in milestone payments.

In May 2000 the Company also entered into a ‘‘right-to-test’’ agreement with Genentech. This
agreement provided Genentech with the  right to test the Company’s maytansinoid  TAP technology with

79

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

C. Agreements (Continued)

Genentech antibodies to a defined number of targets on  an exclusive basis  for specified option periods
and to take exclusive licenses  for individual targets on agreed-upon terms to use the Company’s
maytansinoid TAP technology to develop  products.  The Company  received a  non-refundable technology
access fee of $3 million when the Company entered  into  this  five-year agreement in May 2000,  and an
additional technology access fee of $2  million when Genentech renewed this agreement in April 2005
for the one additional three-year period allowed.  The  upfront  fees  were deferred and recognized
ratably over the period during which Genentech  could elect to obtain product licenses. Genentech no
longer has the right to designate new targets  under this ‘‘right-to-test’’ agreement, although there are
options with respect to previously designated targets that remain in effect for the remainder of  the
respective option periods, which will expire  during 2009.

Under this agreement, in December 2008,  December  2005,  July 2005 and April 2005, Genentech

licensed exclusive rights to use the Company’s maytansinoid TAP technology with antibodies to four
undisclosed targets. Under the terms defined in the  2000  ‘‘right-to-test’’ agreement, for  each license the
Company received a $1 million license  fee and may receive  up to $38  million in  milestone payments.
The Company is also entitled to receive  royalties  on the sales of any resulting products. Genentech is
responsible for the development, manufacturing, and  marketing of any products resulting from these
licenses.

Biotest

In July 2006, the Company entered into a development and license agreement with Biotest AG.

The agreement grants Biotest exclusive rights  to  use  our maytansinoid TAP technology to develop and
commercialize therapeutic compounds  to  the target CD138. The Company received a $1 million
upfront payment upon execution of the  agreement and could potentially receive up  to  $35.5 million in
milestone payments, as well as royalties on the  sales  of  any resulting  products. 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. This milestone  is included in license  and milestone  fees  for the  fiscal year
ended June 30, 2009.

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 U.S.
development and commercialization of that compound in lieu of receiving royalties on U.S.  sales of
that product and the milestone payments not yet earned. The Company can exercise this right by
making a payment to Biotest of an agreed-upon 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 U.S. along  with the profit, if any,
from U.S. product sales.

Bayer HealthCare

In October 2008, the Company entered into a  development and license agreement with Bayer

HealthCare AG. The agreement grants  Bayer HealthCare exclusive rights  to  use the Company’s
maytansinoid TAP technology to develop  and commercialize therapeutic compounds to a specific target.
Bayer HealthCare is responsible for  the research, development, manufacturing and marketing of any

80

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

C. Agreements (Continued)

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 could  potentially receive  up to $170.5 million in  milestone
payments; additionally, the Company is  entitled to receive  royalties on the sales of any resulting
products. The Company will be compensated by Bayer HealthCare at a stipulated rate for work
performed on behalf of Bayer HealthCare under a mutually agreed-upon research plan and budget
which  may be amended from time to  time during the term of the agreement.  The Company also is
entitled to receive payments for manufacturing  any  preclinical and clinical materials at the request of
Bayer HealthCare as well as for any  related  process development activities. The  Company has deferred
the $4 million upfront payment and is  recognizing this amount as revenue ratably over the estimated
period of substantial involvement.

Other Collaborative Agreements

In July 2008, the Company received  notice of Millennium  Pharmaceuticals Inc.’s election to

terminate its exclusive license to the  Company’s  TAP technology to develop and commercialize
antibody-based cytotoxic products directed  to  the prostate specific membrane antigen (PSMA) target.
This license  was granted pursuant to  the Access, Option  and License Agreement between the Company
and Millennium dated March 30, 2001. As a  result of the  termination, the Company recognized the
remaining $361,000 of the $1 million  upfront fee  received from Millennium upon execution of the
license which had been previously deferred, and is included  in license and milestone fees for the fiscal
year ended June 30, 2009.

In August 2008, the Company received notice of  Boehringer Ingelheim’s election  to  terminate its
exclusive license to use the Company’s  technology to develop and commercialize TAP  compounds to
CD44 or the alternative target selected.  This license was granted pursuant to the Development and
License Agreement between the Company  and Boehringer Ingelheim dated November 27, 2001. As a
result of the termination, the Company recognized the remaining $486,000 of the $1  million upfront fee
received from Boehringer Ingelheim  upon execution of  the license agreement which had  been
previously deferred, and is included in license and milestone fees for the fiscal  year ended June 30,
2009.

Other  Agreements

Cytovance Biologics

In August 2007, the Company entered into an agreement  with Cytovance Biologics LLC., or
Cytovance, to develop a process for production of  our huN901 antibody in accordance  with current
Good Manufacturing Practices, or cGMP, for potential  use  in IMGN901 clinical materials for pivotal
trials and commercial applications. Under the  terms of the agreement, the Company pays  Cytovance
incremental amounts for each step in  the development  process. During the  fiscal years ended June 30,
2009 and 2008, the Company incurred  $13,000 and $1.7  million in antibody-related expenses under the
supply agreement.

81

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

C. Agreements (Continued)

Laureate  Pharma

In December 2005, the Company entered into an  antibody supply agreement with Laureate
Pharma, Inc., or Laureate. Under the terms  of  the agreement, Laureate  agreed to perform process
qualification and manufacture one of the  Company’s  antibodies pursuant to cGMP regulations.  Under
the terms of the agreement, the Company agreed to pay a stated price per manufactured batch of
antibody,  subject to adjustment as set forth in the agreement. In January  2007, the agreement was
amended to provide additional quantities of  the monoclonal antibody at a stated  price per
manufactured batch of antibody. In October 2007, the  Company entered into an additional agreement
with Laureate to develop a process for  cGMP production of the Company’s huC242 antibody for
potential use in IMGN242 clinical materials for pivotal trials and commercial applications. Under the
terms of the agreements, the Company pays Laureate  incremental amounts for each step in the
development process. During the fiscal  years ended  June 30, 2009, 2008  and 2007, the Company
recorded  $395,000, $5.5 million and $1.5  million, respectively, in  antibody-related  expenses under these
agreements.

BioInvent International

In June 2006, the Company entered into a supply agreement with BioInvent International AB to

produce quantities of a monoclonal antibody that  is  a component  of one of the Company’s internal
products pursuant to cGMP regulations. Under  the terms of the agreement, the Company agreed to
pay a stated price per manufactured batch  of  antibody, subject to adjustment as  set forth in the
agreement. During the fiscal year ended  June 30, 2007,  the Company recorded $1.3  million in antibody-
related expenses under the supply agreement. No  expenses were incurred in the fiscal years ended
June 30, 2009 and 2008.

Diosynth RTP

In August 2005, the Company entered into a  bioprocessing services agreement with Diosynth

RTP, Inc., or Diosynth. Under the terms of  the agreement, Diosynth agreed  to  perform technology
transfer, process development and scale-up of the antibody component of one of the Company’s
product  candidates pursuant to cGMP regulations. Under the terms of the agreement, the Company
agreed to pay Diosynth a stated price for  the technology transfer and process development. During the
fiscal year ended June 30, 2007, the Company recorded $3.3 million in antibody-related expenses under
the agreement. No expenses were incurred  in  the fiscal  years ended June 30,  2009 and 2008.

Societ`a Italiana Corticosteroidi S.r.l (SICOR)

Effective November 2004, the Company entered into a  technology transfer and development

agreement with SICOR. Under the terms  of  the  agreement, SICOR agreed to perform a  feasibility
study  and full process development work to produce  DM1, a component  of the Company’s  TAP
products. Under the terms of the agreement, the  Company agreed to pay SICOR a stated  price for
work performed based on achievement of certain milestone events. In June 2006, the  Company
amended the 2004 technology transfer and development agreement with  SICOR.  Under  the terms of
the amendment, SICOR also provides  preparatory activities in order  to  scale-up the  production of
ansamitocin P3, a precursor to DM1 and DM4, collectively DMx, in  anticipation  of large-scale

82

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

C. Agreements (Continued)

production of ansamitocin P3 to be used  in  TAP compounds for later-stage clinical trials and
commercialization. During the fiscal  years ended June  30, 2009, 2008 and  2007, the Company recorded
$611,000, $1 million and $2.4 million,  respectively, in expenses under  the agreement.

In April 2007, the Company entered into a  manufacturing agreement with SICOR. Under the

terms of the agreement, SICOR agreed  to  produce a  certain number of  cGMP-compliant  batches of
DMx for use in the production of TAP  compounds. Under the  terms of the agreement, the Company
agreed to pay SICOR five million Euros  for these  cGMP-compliant batches of DMx through
completion of the contract in early calendar 2008. Pursuant to a  letter agreement, the  Company
received additional quantities of DM4 from Sicor  during fiscal 2009. The Company and Sicor are
currently negotiating terms and conditions of a Clinical Supply Agreement,  pursuant to which Sicor will
manufacture and supply DMx based  on purchase orders placed by the Company.

D. Marketable Securities

As of June 30, 2009, $71.1 million in cash and money market funds were classified as cash  and

cash equivalents. The Company’s cash,  cash equivalents and marketable securities as of June 30, 2009
are as follows (in thousands):

Cash and money market funds . . . . . . . .
Asset-backed securities

. . . . . . . . . . . . . . . . . . . . . .
Current
Non-current . . . . . . . . . . . . . . . . . . .

Corporate notes

Current
. . . . . . . . . . . . . . . . . . . . . .
Non-current . . . . . . . . . . . . . . . . . . .

Total . . . . . . . . . . . . . . . . . . . . . . .
Less amounts classified as cash and cash
equivalents . . . . . . . . . . . . . . . . . . . .

Amortized
Cost

Gross
Unrealized
Gains

Gross
Unrealized
Losses

Estimated
Fair Value

$ 69,639

$ —

$ — $ 69,639

395
1,024

250
25

25
201

—
1

(25)
(410)

—
—

395
815

250
26

$ 71,333

$227

$(435)

$ 71,125

(69,639)

—

—

(69,639)

Total marketable securities . . . . . . .

$ 1,694

$227

$(435)

$ 1,486

83

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

D. Marketable Securities (Continued)

As of June 30, 2008, $31.6 million in cash and money market funds were classified as cash  and

cash equivalents. The Company’s cash,  cash equivalents and marketable securities as of June 30, 2008
are as follows (in thousands):

Cash and money market funds . . . . . . . . . . . . . .
Money market fund reclassified to marketable

Amortized
Cost

Gross
Unrealized
Gains

Gross
Unrealized
Losses

Estimated
Fair Value

$ 31,619

$—

$ — $ 31,619

securities . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6,193

Asset-backed securities

Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Non-current . . . . . . . . . . . . . . . . . . . . . . . . . .

3,070
3,558

Corporate notes

Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3,570

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

$ 48,010

Less amounts classified as cash and cash

equivalents . . . . . . . . . . . . . . . . . . . . . . . . . . .

(31,619)

Total marketable securities . . . . . . . . . . . . . .

$ 16,391

—

7
9

14

$30

—

$30

—

(147)
(4)

6,193

2,930
3,563

(18)

3,566

$(169)

$ 47,871

—

(31,619)

$(169)

$ 16,252

In 2009, the Company realized losses  of $33,000 and realized zero gains.  In  2008, the Company
realized losses of $42,000 and realized gains of  $3,000. In 2007, the Company realized  losses of $19,000
and realized gains  of $18,000.

As of June 30, 2009, the Company had  19 individual securities in its investment portfolio, of which
seven were in an unrealized loss position. The aggregate  fair value of  investments with unrealized losses
was approximately $705,000 as of June 30, 2009, of which $332,000 had been  in an unrealized  loss
position for more than a year, as of June 30,  2009. All such  other  investments as  of June  30, 2009 have
been or were in an unrealized loss position for less than  a year. As  of  June 30, 2008, the Company had
47 individual securities in its investment portfolio, of  which 19  were in an unrealized  loss position. The
aggregate fair value of investments with unrealized losses was approximately $4.4  million, of  which
$3.5 million had been in an unrealized loss position for  more than  one year,  as of June 30, 2008.  See
Note  B Other-than-Temporary Impairments. The Company reviewed its investments with  unrealized
losses and as a result recorded $516,000 and $535,000, respectively, as  an other-than-temporary
impairment charge during the years ended June 30,  2009 and  2008. No similar charges were incurred
during the fiscal year ended June 30,  2007.

84

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

E. Property and Equipment

Property and equipment consisted of  the following at June 30, 2009 and 2008 (in thousands):

June 30,

2009

2008

Leasehold improvements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Machinery and equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Computer hardware and software . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Furniture and fixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assets  under construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 25,189
11,910
1,635
1,361
766

$ 23,760
11,418
949
1,297
1,882

Less accumulated depreciation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 40,861
(21,190)

$ 39,306
(16,555)

Property and equipment, net . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 19,671

$ 22,751

During  the fiscal year ended June 30,  2008, the Company added $3.7 million in improvements to
its  capabilities at its manufacturing plant in Norwood,  MA and  $12.0 million to build  out the laboratory
and office space at the Waltham, MA facility occupied by ImmunoGen in late March 2008. The
$12.0 million of leasehold improvements  was  paid by the landlord of the Waltham, MA facility.
Depreciation expense was approximately $5.0 million, $4.4 million and $3.2  million for the years ended
June 30, 2009, 2008 and 2007, respectively.

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 provision for income taxes, and actual tax is
reconciled in the following chart (in thousands):

Loss before income tax expense . . . . . . . . . . . . . . . . . . . . . .

$(32,037) $(31,993) $(18,952)

Year Ended June 30,

2009

2008

2007

Expected tax benefit at 34% . . . . . . . . . . . . . . . . . . . . . . . .
State tax benefit net of federal benefit . . . . . . . . . . . . . . . . .
Increase in valuation allowance, net . . . . . . . . . . . . . . . . . . .
Expired loss and credit carryforwards . . . . . . . . . . . . . . . . . .
Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$(10,893) $(10,888) $ (6,444)
(718)
1,518
5,703
(24)

(394)
4,538
6,235
536

(677)
1,531
7,924
2,015

Provision for income taxes . . . . . . . . . . . . . . . . . . . . . . . . . .

$

(100) $

27

$

35

At June 30, 2009, the Company has net operating loss carryforwards of approximately

$205.3 million available to reduce federal taxable income, if any, that expire in 2010  through 2029 and
$113.4 million available to reduce state taxable Income, if  any,  that expire in fiscal  2010 through fiscal
2014. A portion of such carryforwards  related to the exercise  of stock  options  and the  related tax
benefit will result in an increase in additional  paid-in  capital if and when realized. The Company also
has federal and state research tax credits of approximately $9.4 million available to offset federal  and
state income taxes, which expire beginning in fiscal  2010. Due  to  the degree of uncertainty  related to

85

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

F.

Income Taxes (Continued)

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
purposes. Significant components of the Company’s deferred tax assets as of June 30, 2009 and 2008
are as follows (in thousands):

June 30,

2009

2008

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

$ 74,626
8,081
(745)
5,005
879
4,132
2,148

$ 75,504
9,625
(2,067)
3,167
590
4,424
1,318

Total deferred tax assets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Valuation allowance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 94,126
(94,126)

$ 92,561
(92,561)

Net deferred tax assets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$

— $

—

The valuation allowance increased by $1.6  million during  2009 due primarily to deferred revenue

and  depreciation timing differences,  partially offset by the expiration of research and development
credits.

The Company adopted the provisions of FASB Financial  Interpretation  No. 48, Accounting for
Uncertainty in Income Taxes, or FIN 48, an interpretation of FASB Statement  No. 109, or Statement
109, on July 1, 2007. The adoption of  FIN 48 did not impact  the  Company’s financial condition, results
of operations or cash flows for the years ended June 30,  2009 and  2008. 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

86

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

F.

Income Taxes (Continued)

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 under  FIN 48. The
Company does not expect to have any  taxable income for  at least  the next several  years.

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 carry forwards are subject to adjustment by state and federal taxing
authorities, commencing when those  losses are  utilized  to  reduce taxable income.

G. Capital Stock

Sale of Common Stock

On July 11, 2007, the Company filed  a Registration Statement on Form S-3 with  the Securities and

Exchange Commission. The Securities and Exchange Commission declared the  Registration Statement
effective on August 13, 2007. Subject  to  our ongoing obligations under the  Securities  Act of 1933, as
amended, and the Securities Exchange Act of 1934, as  amended, the Registration Statement permits
the Company to offer and sell up to  an  aggregate of $75 million of our common stock. Pursuant to the
shelf registration statement, in June 2009,  the Company  issued and sold 5,750,000 shares of our
common stock at $7.00 per share through a public  offering resulting in gross  proceeds of $40.3 million,
and in June 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.

Common Stock Reserved

At June  30, 2009, the Company has reserved 8.263 million shares of authorized common stock for

the future issuance of shares under the 2006 Plan. See ‘‘Stock-Based Compensation’’ in Note B for a
description of the 2006 Plan and the  Former  Plan.

Stock Options

As of June 30, 2009, the 2006 Plan was the only  employee share-based compensation plan  of the

Company. During the year ended June 30,  2009, holders of  options  issued under the 2006 Plan  and the
Former Plan exercised their rights to acquire  an aggregate  of  415,891 shares  of common stock at prices
ranging from $1.38 to $6.78 per share. The  total  proceeds  to  the Company from these option exercises
were approximately $1.3 million.

87

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

G. Capital Stock (Continued)

The Company has granted options at 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, 2009, 2008 and  2007:

June 30, 2009 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
June 30, 2008 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
June 30, 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3,906
3,430
3,623

$9.00
$7.57
$7.33

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 to  be  issued is 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, 2009, 2008  and  2007, the  Company recorded approximately
$84,000, (38,000), and $49,000 in compensation expense or (expense  reduction),  respectively, related to
stock units outstanding 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 Director Plan, during the year ended June 30, 2007,  the Company paid  a

retiring director approximately $40,000  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  to  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

88

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

G. Capital Stock (Continued)

paid out in cash to each non-employee director  based upon the market value of the Company’s
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.

Pursuant to the 2004 Director Plan, during the year ended June 30, 2007,  the Company paid  a

retiring director approximately $41,000  to settle outstanding deferred  share units.

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.

Pursuant to the 2004 Director Plan, as  amended,  the Company recorded approximately $175,000 in

compensation expense during the year  ended June 30,  2009  related to the  issuance  of 54,000 deferred
share units and 183,000 deferred share  units previously issued  under the 2004 Director Plan. The
Company recorded approximately $92,000 in compensation expense  during  the year ended June 30,
2008 related to the issuance of 49,000  deferred share units and 108,000  deferred share units previously
issued under the 2004 Director Plan. The  Company  recorded approximately $210,000 in compensation
expense during the year ended June  30,  2007 related to the issuance of 76,000 deferred share units and
32,000 deferred share units previously  issued under the  2004 Director Plan.

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.

As part of the 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.
The construction allowance is accounted  for as a lease incentive pursuant to FASB Statement No. 13,
Accounting for Leases, and FASB Technical Bulletin 88-1, Issues Relating to Accounting for Leases. 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

89

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

H. Commitments and Contingencies (Continued)

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.

Under the terms of the agreement, any remaining construction  allowance  was to be applied evenly
as a credit to rent for the first year. The  final balance  of  the construction allowance  was determined in
August 2008, resulting in a credit of  $1.3 million  to  the Company from the landlord during the current
fiscal year relating to the first year of  occupancy.

At June  30, 2009, the Company also leases  facilities in Norwood and  Cambridge, MA under
agreements through 2011. 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  sub-sublease  in  May  2008  for  the  entire  space  in  Cambridge,  MA  through  October  2010,
the remainder of the sublease.

Facilities rent expense, net of sublease income, was  approximately  $5.0 million,  $5.3 million and

$3.2 million during fiscal years 2009,  2008 and  2007, respectively. During fiscal 2008, the  Company
recorded  $1.8 million of rent expense related to the Waltham, MA facility for the period prior to
occupancy, which has been classified  as general and administrative expense in the  accompanying
Consolidated Statement of Operations for the year  ended June 30,  2008.

The minimum rental commitments, including real estate taxes and other  expenses, for the next five

fiscal years under the non-cancelable  operating lease agreements discussed above are as follows (in
thousands):

2010 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2011 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$ 6,320
5,885
4,859
4,859
4,925

Total minimum lease payments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Total minimum rental income from sub-sublease . . . . . . . . . . . . . . . . . . . .

$26,848
(1,046)

Total minimum lease payments, net . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

$25,802

Purchase Obligations

At June 30, 2009, the Company is obligated to a number of  vendors for certain contractual services

to be performed totaling $924,000 in  fiscal 2010 and fiscal  2011.

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

90

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

I.

Employee Benefit Plans (Continued)

to certain limitations, up to 100% of their  gross  salary. Effective  February 1, 2008,  the Company
increased its matching contribution to  50% of the first 6% of the eligible employees’ contributions,
compared to 20% of the first  7% of the eligible  employees’  contributions previously. In fiscal years
2009, 2008 and 2007, the Company’s contributions to the  401(k) Plan  totaled approximately  $429,000,
$268,000, and $170,000, respectively.

J. Quarterly Financial Information  (Unaudited)

Fiscal Year 2009

First Quarter
Ended
September 30, 2008

Second Quarter
Ended

Third  Quarter
Ended

December 31, 2008 March 31, 2009

Fourth Quarter
Ended
June 30, 2009

(In thousands, except per share data)

Revenues:

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

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

Expenses:

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

Total expenses . . . . . . . . . . . . .

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

Loss before income tax expense . . . .
Income tax expense . . . . . . . . . . .

$ 3,207
2,223
696

6,126

11,860
3,678

15,538

(9,412)
16

(9,396)
1

$ 2,283
4,766
2,285

9,334

12,888
3,521

16,409

(7,075)
(129)

(7,204)
(101)

$

908
7,314
4

8,226

9,493
3,243

12,736

(4,510)
(100)

(4,610)
—

$ 1,168
814
2,320

4,302

11,663
3,458

15,121

(10,819)
(8)

(10,827)
—

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

$ (9,397)

$ (7,103)

$ (4,610)

$(10,827)

Basic and diluted net loss per

common share . . . . . . . . . . . . .

$ (0.19)

$ (0.14)

$ (0.09)

$

(0.21)

91

IMMUNOGEN, INC.

NOTES TO CONSOLIDATED FINANCIAL  STATEMENTS (Continued)

AS OF JUNE 30, 2009

J. Quarterly Financial Information  (Unaudited)  (Continued)

Fiscal Year 2008

First Quarter
Ended
September 30, 2007

Second Quarter
Ended

Third  Quarter
Ended

December 31, 2007 March 31, 2008

Fourth Quarter
Ended
June 30, 2008

(In thousands except per share data)

Revenues:

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

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

Expenses:

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

Total expenses . . . . . . . . . . . . .

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

Loss before income tax expense . . . .
Income tax expense . . . . . . . . . . .

$ 4,473
4,188
2,764

11,425

10,834
2,424

13,258

(1,833)
813

(1,020)
12

$ 3,672
2,680
3,399

9,751

13,158
3,527

16,685

(6,934)
727

(6,207)
5

$ 3,516
5,228
5,846

14,590

23,282
4,675

27,957

(13,367)
524

(12,843)
5

$ 3,374
1,060
49

4,483

12,739
3,722

16,461

(11,978)
55

(11,923)
5

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

$ (1,032)

$ (6,212)

$(12,848)

$(11,928)

Basic and diluted net loss per

common share . . . . . . . . . . . . .

$ (0.02)

$ (0.15)

$

(0.30)

$

(0.27)

92

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
(the ‘‘Exchange Act’’)) 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:127) 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:127) 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:127) 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, 2009. 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, 2009 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,
2009. This report appears immediately  below.

93

(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, 2009,

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. 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, 2009 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,
2009 and 2008, and the related consolidated statements of operations,  stockholders’ equity, and cash
flows for each of the three years in the period  ended June 30,  2009 and our  report dated August 28,
2009 expressed an unqualified opinion thereon.

/s/ ERNST & YOUNG LLP

Boston, Massachusetts
August 28, 2009

94

(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, 2009 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.

95

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 2009 annual meeting of shareholders, which  will  be  filed with the Securities
and Exchange Commission not later  than October 28, 2009 (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 4.1  of this  Annual Report on  Form 10-K.

96

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, 2009, 2008  and 2007.

(3) See Exhibit Index following the signature page to this Annual Report  on Form 10-K.

97

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 28, 2009

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/ MITCHEL SAYARE

Mitchel Sayare

/s/ DAVID W. CARTER

David W. Carter

/s/ STEPHEN MCCLUSKI

Stephen McCluski

/s/ NICOLE ONETTO, M.D.

Nicole Onetto

/s/ MARK SKALETSKY

Mark Skaletsky

/s/ JOSEPH VILLAFRANCA

Joseph Villafranca

/s/ RICHARD WALLACE

Richard Wallace

President, Chief Executive Officer and Director
(Principal Executive Officer)

August 28, 2009

Senior Vice President and
Chief Financial Officer
(Principal Financial and Accounting Officer)

August 28, 2009

Chairman of the Board of Directors

August 28, 2009

Director

August  28, 2009

Director

August  28, 2009

Director

August  28, 2009

Director

August  28, 2009

Director

August  28, 2009

Director

August  28, 2009

98

EXHIBIT INDEX

Filed
with this
Form 10-K Form

Incorporated by Reference

Filing Date
with SEC

Exhibit
Number

10-Q November  8, 1996

10-Q February 14,  2002

Amended and Restated By-Laws

8-K

April  6,  2007

Exhibit
Number

3.1

3.1(a)

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)

10.2

Exhibit Description

Restated Articles  of Organization

Articles of Amendment to Restated Articles of
Organization

Article 4 of Restated Articles of Organization,  as
amended (see Exhibits 3.1 and 3.1(a))

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

Lease Agreement, dated as of July  27, 2007,  by  and
between Intercontinental Fund III 830 Winter
Street LLC, landlord, and the Registrant

99

3.1

3.1

3.1

4.2

S-1 November  15, 1989
(File No. 33-31219)

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)

10-Q November 7,  2007

10.2

Exhibit
Number

10.3

10.4*

10.4(a)

10.5*

10.6*

Exhibit Description

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

License Agreement dated  as of June  1,  1998 by
and between the  Registrant  and Pharmacia  &
Upjohn AB

Amendment to License Agreement  dated  as of
October 23, 1998 by and  between  the  Registrant and
Pharmacia & Upjohn AB

Heads of Agreement dated effective May 2, 2000  by
and between the  Registrant  and Genentech,  Inc.

License Agreement dated  effective May  2, 2000  by
and between the  Registrant  and Genentech,  Inc.

Incorporated by Reference

Filed
with this
Form 10-K Form

Filing Date
with SEC

S-1 September 22,  1989
(File  No.  33-31219)

Exhibit
Number

10.1

10-K September 29,  1998

10.48

10-K September 2,  2008 10.4(a)

10-K September  27, 2000

10.52

10-K September  27, 2000

10.51

10.6(a)* Amendment to License Agreement  for Anti-HER2

10-K

August  28,  2006

10.32

10.7*

10.8*

10.9*

10.10*

10.11*

10.12*

10.13*

Antibodies, dated as of May 3, 2006,  between  the
Registrant and Genentech, Inc.

Process Agreement, dated as  of May  3,  2006,
between the Registrant and Genentech,  Inc.

License Agreement executed November  13,  2006,
effective as of July 22, 2005, between the Registrant
and Genentech, Inc.

License Agreement executed February 21,  2007,
effective as of April 27, 2005, between the
Registrant and Genentech, Inc.

License Agreement executed February 21,  2007,
effective as of December 12, 2005, between  the
Registrant and Genentech, Inc.

Amendment to License Agreements  made  effective
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
Aventis Pharmaceuticals Inc.

10.13(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

10-K

August  28, 2006

10.31

10-Q

February  8, 2007

10.3

10-Q

May  9,  2007

10.1

10-Q

May  9,  2007

10.2

10-Q

May  7,  2009

10.1

8-K/A

October 10,  2000

10.1

10-Q November 14,  2003

10.1

10-Q November  3, 2006

10.1

10.13(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

10.13(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-Q

February 6,  2009

10.7

100

Exhibit
Number

10.14*

10.15*

10.16*

10.17*

Exhibit Description

License Agreement dated  as of October 5, 2006  by
and between the  Registrant  and sanofi-aventis
U.S. LLC

Option and License Agreement dated  as of
December 21, 2006 by and between the  Registrant
and sanofi-aventis U.S. LLC

Development and License Agreement  dated as  of
October 1, 2004 by and  between the  Registrant and
Biogen Idec MA Inc.

Collaborative Development  and License  Agreement
dated as of July 7, 2006 by and between  the
Registrant and Biotest AG

Filed
with this
Form 10-K Form

Incorporated by Reference

Filing Date
with SEC

Exhibit
Number

10-Q

February  8, 2007

10.1

10-Q

February 8,  2007

10.2

10-Q

February  9, 2005

10.1

10-Q November  3, 2006

10.2

10.17(a)* Amendment No. 1, dated August 23, 2006,  to

10-Q November 3,  2006

10.3

10.18

Collaborative Development and License  Agreement
by and between the Registrant and Biotest AG

Securities Purchase Agreement dated as  of June  20,
2008 by and between the Registrant and Ziff Asset
Management, L.P.

10.18(a) Registration Rights Agreement dated as of June  20,
2008 by and between the Registrant and Ziff Asset
Management, L.P.

10.19†

Restated Stock Option Plan

10.19(a)† Form of Incentive Stock Option Agreement

10.19(b)† Form of Non-Qualified Stock  Option Agreement

10.20†

2006 Employee, Director and Consultant Equity
Incentive Plan, as amended  and restated  through
November 12, 2008

8-K

June  23,  2008

10.1

8-K

June 23,  2008

10.2

8-K

8-K

8-K

February  7, 2006

February  7, 2006

February 7,  2006

8-K November  14, 2008

10.1

10.2

10.3

10.1

10.20(a)† Form of Incentive Stock Option Agreement  for

S-8 November 15,  2006

99.4

Executives

10.20(b)† Form of Non-Qualified Stock  Option Agreement  for

S-8 November  15, 2006

99.5

Executives

10.20(c)† Form of Non-Qualified Stock  Option Agreement  for

S-8 November  15, 2006

99.6

Directors

10.20(d)† Form of Restricted Stock Agreement  for  Executives

10.20(e)† Form of Restricted Stock Agreement  for  Directors

10.21†

10.22†

10.23†

10.24†

10.25†

2001 Non-Employee Director Stock  Plan

2004 Non-Employee Director Compensation and
Deferred Stock Unit Plan, as amended on
September 5, 2006

Form of Proprietary Information,  Inventions  and
Competition Agreement between the  Registrant  and
each of its executive  officers

Amendment to Stock Option  Agreements dated  as
of September 24, 2008 between the Registrant  and
Mitchel Sayare

Severance Agreement dated as  of December  1, 2008
between the Registrant and Mitchel Sayare

101

S-8 November 15,  2006

S-8 November 15,  2006

S-8 December  18, 2001

10-Q November 3,  2006

99.9

99.8

99

10.4

10-Q

February 8,  2007

10.15

10-Q

October 31,  2008

10.1

10-Q

February  6, 2009

10.2

Exhibit
Number

10.26†

10.27†

10.28†

10.29†

10.30†

10.31†

10.32†

10.33†

Exhibit Description

Severance Agreement dated as  of December  1, 2008
between the Registrant and Daniel  M.  Junius

Severance Agreement dated as  of December  1, 2008
between the Registrant and John M. Lambert

Severance Agreement dated as  of December  1, 2008
between the Registrant and James  J.  O’Leary

Severance Agreement dated as  of December  1, 2008
between the Registrant and Gregory D.  Perry

Severance Agreement dated as  of August 17,  2009
between the Registrant and Peter  Williams

Employment offer letter between the  Registrant  and
Gregory D. Perry

Employment offer letter between the  Registrant  and
James J. O’Leary

Employment Agreement  dated as  of November  27,
2007 between the Registrant and John A.
Tagliamonte

10.34†

Summary of Annual Executive Bonus Program

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

Filed
with this
Form 10-K Form

Incorporated by Reference

Filing Date
with SEC

Exhibit
Number

10-Q

February  6, 2009

10.1

10-Q

February  6, 2009

10.3

10-Q

February  6, 2009

10.4

10-Q

February  6, 2009

10.5

10-Q

February  6, 2009

10.6

10-Q

February  7, 2008

10.1

10-Q November  7, 2007

10-K

August 30,  2007

10.1

21

X

X

X

X

X

X

*

†

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.

102

IMMUNOGEN, INC.

SCHEDULE II—VALUATION AND QUALIFYING ACCOUNTS

(In thousands)

COLUMN A—DESCRIPTION

Inventory Write-downs

Year End June 30, 2009 . . . . . . . . . . . . . . . . . . .
Year End June 30, 2008 . . . . . . . . . . . . . . . . . . .
Year End June 30, 2007 . . . . . . . . . . . . . . . . . . .

COLUMN B

COLUMN C—
ADDITIONS

COLUMN D

COLUMN  E

Balance At
Beginning
of  Period

$2,534
$1,430
$2,922

Charged
to Costs
and
Expenses

—
3,732
—

Use of
Zero
Value
Inventory

(750)
(2,628)
(1,492)

Balance  at
End of
Period

$1,784
$2,534
$1,430

103

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 28, 2009

/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 28, 2009

/s/ GREGORY D. PERRY

Gregory D. Perry
Senior 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, 2009 (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 28, 2009

/s/ DANIEL M. JUNIUS

Daniel M. Junius
President and Chief Executive Officer
(Principal Executive Officer)

Dated: August 28, 2009

/s/ GREGORY D. PERRY

Gregory D. Perry
Senior 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,  2004 through June 30,  2009 (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, as amended, or the
Securities Exchange Act of 1934, as amended, 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.

IMMUNOGEN INC

NASDAQ STOCK MARKET INDEX (U.S.)

NASDAQ PHARMACEUTICAL STOCKS TOTAL RETURN INDEX

)
s
r
a
l
l

o
D

.

.

S
U
n
I
(

s
i
s
a
B

$160.00

$140.00

$120.00

$100.00

$80.00

$60.00

$40.00

$20.00

$0.00

2004

2005

2006

2007

2008

2009

19AUG200919292508

2004

2005

2006

2007

2008

2009

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0

IMMUNOGEN, INC.
NASDAQ STOCK MARKET INDEX (U.S.) . . . . . . . . . . . . . . 100.0 101.1 107.5 128.1 112.1
NASDAQ PHARMACEUTICAL STOCKS . . . . . . . . . . . . . . . 100.0
TOTAL RETURN INDEX*

50.4 142.0
72.2
94.9 104.4 113.6 113.2 110.6

91.4

95.4

51.6

*

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, 2004 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.