Exhibit 10.1

EXECUTION COPY

LICENSE AGREEMENT

This License Agreement (the “Agreement”) is made effective as of April 27, 2005
(the “Effective Date”) by and between GENENTECH, INC., a Delaware corporation
having its principal business office at 1 DNA Way, South San Francisco,
California 94080 (“GENENTECH”), and IMMUNOGEN, INC., a Massachusetts corporation
with its principal place of business at 128 Sidney Street, Cambridge,
Massachusetts 02139 (“IMMUNOGEN”).  GENENTECH and IMMUNOGEN are each hereafter
referred to individually as a “Party” and together as the “Parties”.

WHEREAS, the Parties entered into the Heads of Agreement (defined below)
pursuant to which IMMUNOGEN granted GENENTECH the right to obtain up to [***]
exclusive options at any given time to obtain an exclusive license to use
IMMUNOGEN’s proprietary maytansinoid conjugation technology with certain
proprietary antibodies of GENENTECH and other binding proteins relating thereto
that bind to any antigen target selected by GENENTECH and determined by
IMMUNOGEN to be available for licensing as described more fully in the Heads of
Agreement; and

WHEREAS, pursuant to the Heads of Agreement, GENENTECH was granted an Exclusive
Target Option (as defined in the Heads of Agreement) with respect to [***] and
has exercised such Exclusive Target Option pursuant to the terms set forth in
the Heads of Agreement, resulting in the grant of an exclusive license from
IMMUNOGEN to GENENTECH on the terms set forth in the Heads of Agreement; and

WHEREAS, pursuant to the Heads of Agreement, the Parties have agreed to enter
into an agreement setting forth the detailed terms of the exclusive license from
IMMUNOGEN to GENENTECH.

NOW, THEREFORE, in consideration of the mutual covenants contained herein, and
for other good and valuable consideration, the receipt and adequacy of which are
hereby acknowledged, the Parties hereby agree as follows:

1.  DEFINITIONS

Whenever used in the Agreement with an initial capital letter, the terms defined
in this Section 1 shall have the meanings specified.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

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1.1.                              “Adverse Event” shall mean any untoward
medical occurrence in a patient or subject who is administered a Licensed
Product, whether or not considered related to the Licensed Product, including,
without limitation, any undesirable sign (including abnormal laboratory findings
of clinical concern), symptom or disease temporally associated with the use of
such Licensed Product.

1.2.                              “Affiliate” shall mean any corporation, firm,
limited liability company, partnership or other entity which directly or
indirectly controls or is controlled by or is under common control with a Party
to this Agreement.  For purposes of this Section 1.2, “control” means ownership,
directly or indirectly through one or more Affiliates, of fifty percent (50%) or
more of the shares of stock entitled to vote for the election of directors, in
the case of a corporation, or fifty percent (50%) or more of the equity
interests in the case of any other type of legal entity, or status as a general
partner in the case of any partnership, or any other arrangement whereby a Party
controls or has the right to control the Board of Directors or equivalent
governing body or management of a corporation or other entity.

1.3.                              “Agreement” shall mean this Agreement between
the Parties, dated as of the Effective Date, including any exhibits, schedules
or other attachments hereto and incorporated herein, as any of the foregoing may
be validly amended from time to time.  In the event of any inconsistency between
the terms of this Agreement and the terms of any exhibits, schedules or other
attachments incorporated herein, the terms of this Agreement shall govern unless
the Parties expressly agree otherwise in writing.

1.4.                              “Allocable Overhead” shall mean overhead costs
incurred by IMMUNOGEN attributable to IMMUNOGEN’s supervisory services,
occupancy costs, and its payroll, information systems, human relations,
purchasing, accounts receivable or accounts payable functions which are
allocated to company departments based on space occupied or headcount or another
activity-based method, and shall include the “General Administrative Fee” as
defined hereinbelow.  For purposes of any given calculation of “Allocable
Overhead” hereunder, the “General and Administrative Fee” shall equal [***]
percent ([***]%) of the total amount of Allocable Overhead (as calculated before
the inclusion of any such fee).  However, “Allocable Overhead” shall not include
any costs attributable to general corporate activities, executive management,
investor relations, corporate communications, business development, legal
affairs or finance.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

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1.5.                              “Clinical Materials” shall mean (a) supplies
of ansamitocin P-3, and/or any other MAY Compound as manufactured in accordance
with all applicable GMPs and other legal requirements and all applicable
Specifications for such MAY Compound for use in human clinical testing, and (b)
supplies of any Licensed Product as manufactured in accordance with all
applicable GMPs and other legal requirements and all applicable Specifications
for such Licensed Product for use in human clinical testing of any Licensed
Product.

1.6.                              “Collaboration Committee” shall mean the
committee with representatives of each Party established as set forth in Section
3.4.

1.7.                              “Combination Product” shall mean any Licensed
Product that contains, in addition to any conjugate of a [***] Antibody with any
MAY Compound, one or more other ingredients that has biologic activity as a
therapeutic agent when present alone.

1.8.                              “Confidential Information” shall have the
meaning set forth in Section 5.1.

1.9.                              “Control” or “Controlled” shall mean, with
respect to any Patent Rights or Technology (including, without limitation, any
MAY Compound, [***] Antibody or other proprietary biologic material covered
under this Agreement), the possession by a Party of the ability to grant a
license or sublicense of such patent rights, know-how or other intellectual
property and the rights thereto or to supply such compounds or materials as
provided for in this Agreement without violating the terms of any arrangement or
agreement between such Party and any Third Party.

1.10.                        “Development” and “Develop” shall mean, with
respect to any Licensed Product, all activities with respect to such Licensed
Product relating to research and development in connection with seeking,
obtaining and/or maintaining any Regulatory Approval for such Licensed Product
in the Field in the Territory, including without limitation, all pre-clinical
research and development activities, all human clinical studies, all activities
relating to developing the ability to manufacture any Licensed Product or any
component thereof (including, without limitation, process development work), and
all other activities relating to seeking, obtaining and/or maintaining any
Regulatory Approvals from the FDA and/or any Foreign Regulatory Authority.

1.11.                        “Drug Approval Application” shall mean any
application for Regulatory Approval (including pricing and reimbursement
approvals) required prior to any commercial sale or use of a Licensed Product in
any country or jurisdiction in the Territory, including, without

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

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limitation, (a) any NDA or MAA filed with the FDA or any Foreign Regulatory
Authority, and (b) any equivalent application filed with any Foreign Regulatory
Authority for Regulatory Approval (including pricing and reimbursement
approvals) required prior to any commercial sale or use of a Licensed Product in
any country or jurisdiction in the Territory.

1.12.                        “Effective Date” shall mean the date first written
above in the introductory paragraph to this Agreement.

1.13.                        “FDA” shall mean the United States Food and Drug
Administration and any successor agency or authority thereto.

1.14.                        “Field” shall mean any and all human uses.

1.15.                        “First Commercial Sale” shall mean the date of the
first commercial sale (other than for purposes of obtaining Regulatory Approval)
of a Licensed Product by or on behalf of GENENTECH or any Sublicensee.

1.16.                        “[***] Indication” shall mean the [***] use
permitted by the FDA or any Foreign Regulatory Authority in any Regulatory
Approval of a given Licensed Product.

1.17.                        “Foreign Regulatory Authority” shall mean any
applicable supranational, national, federal, state or local regulatory agency,
department, bureau or other governmental entity of any country or jurisdiction
in the Territory (other than the FDA in the United States), having
responsibility in such country or jurisdiction for any Regulatory Approvals of
any kind in such country or jurisdiction, and any successor agency or authority
thereto.

1.18.                        “Fully Burdened Manufacturing Cost” shall mean,
with respect to any Preclinical Materials or Clinical Materials produced by
IMMUNOGEN for GENENTECH under this Agreement, the sum of the following
components: (a) the costs of goods produced, as determined by IMMUNOGEN in
accordance with generally accepted accounting principles in the United States,
consistently applied, including, without limitation, direct labor, material and
product testing costs of such Preclinical Materials or Clinical Materials; (b)
any Third Party royalty costs directly allocable to the manufacture or use of
such Preclinical Materials or Clinical Materials; (c) all Allocable Overhead on
the cost of goods under clause (a) above; and (d) any other costs borne by
IMMUNOGEN, for the transport, customs clearance, duty, insurance and/or storage
of such Preclinical Materials or Clinical Materials.

1.19.                        “GENENTECH” shall mean Genentech, Inc., a Delaware
corporation, and its successors and permitted assigns under this Agreement.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

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1.20.                        “GLPs” shall mean all good laboratory practices
under Title 21 of the United States Code of Federal Regulations, as amended from
time to time.

1.21.                        “GMPs” shall mean all good manufacturing practices
under Title 21 of the United States Code of Federal Regulations, as amended from
time to time.

1.22.                        “Heads of Agreement” shall mean the Heads of
Agreement, dated May 2, 2000, as amended, whereunder the Parties agreed upon the
terms and conditions for a broader arrangement relating to the conjugation of a
larger array of antibodies and binding proteins to maytansine derivatives such
as DM1.

1.23.                        “HER2 License Agreement” shall mean that certain
License Agreement dated as of May 2, 2000, as amended May 3, 2006, by and
between the Parties with respect to the use of IMMUNOGEN’s proprietary
maytansinoid conjugation technology with GENENTECH’s Anti-HER2 antibodies and
other HER-2 binding proteins.

1.24.                        “IMMUNOGEN” shall mean ImmunoGen, Inc., a
Massachusetts corporation, and its successors and permitted assigns under this
Agreement.

1.25.                        “IMMUNOGEN Field” shall mean any and all uses other
than any use that involves an antibody that binds to an antigen that is subject
to an exclusive license from IMMUNOGEN under, or arising from, the Heads of
Agreement or an antigen that is subject to an Exclusive Target Option under the
Heads of Agreement, during the period that such exclusive license or Exclusive
Target Option remains in effect.

1.26.                        “Improvement” shall mean: (a) improvements to any
MAY Compound, (b) improvements to methods of making any MAY Compound, and
(c) improvements to the conjugation process for making antibody-drug conjugates
that include any MAY Compound (including, for example, reaction conditions or
changes in process that create improvements in the yield of such conjugate). 
“Improvement” excludes any and all of the following items (“GNE Exclusions”):
(w) any improvement that is specific to any antibody-drug conjugates that bind
to an antigen that is subject to an exclusive license from IMMUNOGEN under, or
arising from, the Heads of Agreement or is subject to an Exclusive Target Option
under the Heads of Agreement during the period that such exclusive license or
Exclusive Target Option remains in effect; (x) improvements to [***] or [***],
or the [***] of [***] or [***] of the foregoing; (y) improvements arising out of
GENENTECH [***] or [***] activities (whether or not the associated [***] is the
subject of a license or option to GENENTECH by IMMUNOGEN); or

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

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(z) the [***] or [***] of any [***] (i.e., the [***] or [***] of such [***]
(e.g., the [***] of [***] or the [***] of [***] to [***]) and [***] the manner
of [***] such [***]) that binds to an antigen that is subject to an exclusive
license from IMMUNOGEN under, or arising from, the Heads of Agreement or an
antigen that is subject to an Exclusive Target Option under the Heads of
Agreement, during the period that such exclusive license or Exclusive Target
Option remains in effect.

1.27.                        “IND” shall mean an investigational new drug
application (as defined in Title 21 of the United States Code of Federal
Regulations, as amended from time to time) filed or to be filed with the FDA
with regard to any Licensed Product.

1.28.                        “Indemnitees” and “Indemnifying Party” shall have
the meanings set forth in Section 9.

1.29.                        “Licensed Patent Rights” shall mean any and all
Patent Rights in the Field in the Territory which are Controlled by IMMUNOGEN as
of the Effective Date or become Controlled by IMMUNOGEN during the Term, to the
extent that any of the foregoing is necessary or useful for the Development,
manufacture, use, import, export or sale of any Licensed Product (or any
component thereof) in the Field in the Territory.  The Licensed Patent Rights as
of the Effective Date include, without limitation, the patents and patent
applications set forth in the Existing License Agreement, as updated from time
to time.

1.30.                        “Licensed Product” shall mean any product
containing any conjugate of a [***] Antibody with any MAY Compound, and shall
include, without limitation, any formulation thereof (including, without
limitation, any lyophilized, liquid, sustained release or aerosolized
formulation).  “Licensed Product” shall also include any and all Combination
Products (if any).

1.31.                        “Licensed Technology” shall mean any and all
Technology which relates to the use of any Licensed Product in the Field in the
Territory which is Controlled by IMMUNOGEN as of the Effective Date or becomes
Controlled by IMMUNOGEN during the Term, to the extent that any of the foregoing
relates to any Licensed Patent Rights or is necessary or useful for the
Development, manufacture, use, import, export or sale of any Licensed Product in
the Field in the Territory.

1.32.                        “MAA” shall mean an application filed with the
relevant Foreign Regulatory Authority in Europe seeking Regulatory Approval to
market and sell any Licensed Product in Europe or any country or territory
therein for a particular indication within the Field.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

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1.33.                        “MAY Compound” shall mean any and all maytansinoid
compounds (including, without limitation, maytansine, ansamitocin P-3 and DM1),
whether produced by a botanical source, natural fermentation or chemical
synthesis, and shall include, without limitation, all variants, fragments or
derivatives of any of the foregoing, in each case owned or otherwise Controlled
by IMMUNOGEN.  MAY shall include, without limitation, that certain maytansine
derivative known as “DM1” whose more specific chemical name is
N2’-deacetyl-N2’-(3-mercapto-1-oxopropyl)-maytansine.

1.34.                        “NDA” shall mean a new drug application (as defined
in Title 21 of the United States Code of Federal Regulations, as amended from
time to time) filed with the FDA seeking Regulatory Approval to market and sell
any Licensed Product in the United States for a particular indication within the
Field.

1.35.                        “Net Sales” shall mean, as to each calendar quarter
during the Term, the gross invoiced sales prices charged for all Licensed
Products sold by GENENTECH or its Sublicensees to Third Parties throughout the
Territory during such calendar quarter, less the following amounts incurred or
paid by GENENTECH or its Sublicensees during such calendar quarter with respect
to sales of Licensed Products regardless of the calendar quarter in which such
sales were made:

(a)                                  trade, cash and quantity discounts or
rebates actually allowed or taken, including discounts or rebates to
governmental or managed care organizations;

(b)                                 credits or allowances actually given or made
for rejection of or return of, and for uncollectible amounts on, previously sold
Licensed Products or for retroactive price reductions (including Medicare and
similar types of rebates);

(c)                                  any charges for insurance, freight, and
other transportation costs directly related to the delivery of Licensed Product
to the extent included in the gross invoiced sales price;

(d)                                 any tax, tariff, duty or governmental charge
levied on the sales, transfer, transportation or delivery of a Licensed Product
(including any tax such as a value added or similar tax or government charge)
borne by the seller thereof, other than franchise or income tax of any kind
whatsoever; and

(e)                                  any import or export duties or their
equivalent borne by the seller.  “Net Sales” shall not include sales or
transfers between GENENTECH and its Sublicensees, unless the

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

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Licensed Product is consumed by the Sublicensee.

1.36.                        “Patent Rights” shall mean the rights and interests
in and to any and all issued patents and pending patent applications (including
inventor’s certificates and utility models) in any country or jurisdiction in
the Territory, including any and all provisionals, non-provisionals,
substitutions, continuations, continuations-in-part, divisionals and other
continuing applications, supplementary protection certificates, renewals, and
all letters patent on any of the foregoing, and any and all reissues,
reexaminations, extensions, confirmations, registrations and patents of addition
on any of the foregoing.

1.37.                        “Phase II Clinical Study” shall mean, as to a
particular Licensed Product for a particular indication, a controlled and lawful
study in humans of the safety, dose ranging and efficacy of such Licensed
Product for such indication, which is prospectively designed to generate
sufficient data (if successful) to commence a Phase III Clinical Trial of such
Licensed Product for such indication.

1.38.                        “Phase III Clinical Trial” shall mean, as to a
particular Licensed Product for a particular indication, a controlled and lawful
study in humans of the safety and efficacy of such Licensed Product for such
indication, which is prospectively designed to demonstrate statistically whether
such Licensed Product is safe and effective for use in such indication in a
manner sufficient to file an NDA to obtain Regulatory Approval to market and
sell that Licensed Product in the United States for the indication under
investigation in such study.

1.39.                        “Phase III Equivalent Decision” shall mean the date
(if any) on which GENENTECH (or its Sublicensee) decides, based on notification
and input from the FDA, that the data and results generated from the Phase II
Clinical Studies of a Licensed Product for a particular indication are
sufficient, without any Phase III Clinical Trial of such Licensed Product for
such indication, to support the filing of an NDA to obtain Regulatory Approval
to market and sell that Licensed Product in the United States for the indication
under investigation.

1.40.                        “Preclinical Materials” shall mean (a) supplies of
ansamitocin P-3, DM1 and/or any other MAY Compound as manufactured in accordance
with all applicable legal requirements and all applicable Specifications for
such MAY Compound for use in preclinical testing, and (b) supplies of any
Licensed Product as manufactured in accordance with all applicable legal
requirements and all applicable Specifications for such Licensed Product for use
in preclinical testing of any Licensed Product.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

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1.41.                        “Regulatory Approval” shall mean any and all
approvals (including pricing and reimbursement approvals), product and
establishment licenses, registrations or authorizations of any kind of the FDA
or any Foreign Regulatory Authority necessary for the development, pre-clinical
and/or human clinical testing, manufacture, quality testing, supply, use,
storage, importation, export, transport, marketing and sale of a Licensed
Product (or any component thereof) for use in the Field in any country or other
jurisdiction in the Territory.  “Regulatory Approval” shall include, without
limitation, any NDA, MAA or other Drug Approval Application.

1.42.                        “[***] Indication” shall mean the [***] use
permitted by the FDA or any Foreign Regulatory Authority in any Regulatory
Approval of a given Licensed Product and with respect to which GENENTECH has
made a [***] based on [***] that such indication will [***] at least a $[***] in
[***] in the [***].

1.43.                        “Specifications” shall mean any specifications
agreed upon in writing by the Parties relating to the manufacturing and supply
of any MAY Compound and/or Licensed Product hereunder.

1.44.                        “Sublicensee” shall have the meaning set forth in
Section 2.2, and “Material Sublicensee” shall have the meaning set forth in
Section 3.3.

1.45.                        “Technology” shall mean and include any and all
unpatented proprietary ideas, inventions, discoveries, Confidential Information,
biologic materials, data, results, formulae, designs, specifications, methods,
processes, formulations, techniques, ideas, know-how, technical information
(including, without limitation, structural and functional information), process
information, pre-clinical information, clinical information, and any and all
proprietary biological, chemical, pharmacological, toxicological, pre-clinical,
clinical, assay, control and manufacturing data and materials.

1.46.                        “[***]” shall mean a protein that corresponds to
Swiss-Prot Primary accession number [***], or any variant or fragments thereof.

1.47.                        “[***] Antibody” shall mean any monoclonal
antibodies Controlled by GENENTECH that bind to [***] and any other proteins
binding to [***], and shall include, without limitation, any variants
(including, without limitation, humanized versions), fragments (including,
without limitation, single-chain versions) or derivatives of any of the
foregoing.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

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1.48.                        “[***] Product” shall mean any product containing
an anti-[***] monoclonal antibody conjugated to a MAY Compound.

1.49.                        “Term” shall mean the period commencing on the
Effective Date and continuing until the expiration or termination of this
Agreement in accordance with the terms hereof (including Section 7).

1.50.                        “Territory” shall mean all countries and
jurisdictions of the world.

1.51.                        “[***] Indication” shall mean the [***] use
permitted by the FDA or any Foreign Regulatory Authority in any Regulatory
Approval of a given Licensed Product and with respect to which GENENTECH has
made a [***] based on [***] that such indication will [***] at least $[***] in
[***] in the [***].

1.52.                        “Third Party” shall mean any entity other than
GENENTECH, IMMUNOGEN and their respective Affiliates.

1.53.                        “Third Party Payments” shall have the meaning set
forth in Section 4.2.2.

1.54.                        “Valid Claim” shall mean a claim in an issued,
unexpired patent within the Licensed Patent Rights that (i) has not been finally
cancelled, withdrawn, abandoned or rejected by any administrative agency or
other body of competent jurisdiction, and (ii) has not been revoked, held
invalid, or declared unpatentable or unenforceable in a decision of a court or
other body of competent jurisdiction that is unappealable or unappealed within
the time allowed for appeal, and (iii) has not been rendered unenforceable
through disclaimer or otherwise, and (iv) is not lost through an interference
proceeding.

2.  GRANT OF RIGHTS

2.1.                              License Grants.

(a)                                  License to GENENTECH.  IMMUNOGEN hereby
grants to GENENTECH an exclusive (even as to IMMUNOGEN) royalty-bearing license
within the Territory, including the right to grant sublicenses as described in
Section 2.2 below, under the Licensed Patent Rights and Licensed Technology, to
Develop, have Developed, make, have made, use, have used, sell, have sold, offer
for sale, import, have imported, export and have exported Licensed Products in
the Field in the Territory, subject to the other terms and conditions of this
Agreement.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

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(b)                                 License to IMMUNOGEN.  GENENTECH hereby
grants to IMMUNOGEN a non-exclusive, royalty-free license (i) under GENENTECH’s
intellectual property interest in Improvements, to develop, make, use, sell,
offer for sale, import, and export any product that is not a Licensed Product or
a [***] Product, only within the IMMUNOGEN Field and subject to Section 2.3(b)
below and the remaining terms of this Section 2.1(b); and (ii) also under
GENENTECH’s intellectual property interest in Improvements, to otherwise exploit
Improvements for all uses within the IMMUNOGEN Field, subject to Section 2.3(b)
below and the remaining terms of this Section 2.1(b).  The foregoing license
includes the right to sublicense the rights granted under this Section 2.1(b)
only if all of the following three conditions (i), (ii) and (iii) are met:

 (i)                                  the sublicense is limited to the IMMUNOGEN
Field;

 (ii)                               the sublicense is granted only in connection
with a license to IMMUNOGEN MAY Technology (where “IMMUNOGEN MAY Technology”
means Technology Controlled by IMMUNOGEN and used in the conjugation of MAY
Compounds to binding proteins), and the rights granted for IMMUNOGEN MAY
Technology are of the same scope (e.g., for the same product or technology and
within the same field and the same territory) as the rights granted for
GENENTECH’s Improvements; and

 (iii)                            GENENTECH obtains Substantially Similar Grant
Back Rights without incurring an obligation to pay any additional consideration
(either to IMMUNOGEN or to IMMUNOGEN’s sublicensee).  “Substantially Similar
Grant Back Rights” means non-exclusive rights in and to that sublicensee’s
“improvements” (improvements to MAY Compounds, methods of making MAY Compounds,
and methods of making antibody-drug conjugates) that are of substantially the
same scope (e.g., within the same field and the same territory) as the rights
granted in and to Improvements under this Agreement.  (GENENTECH may obtain such
rights directly from IMMUNOGEN’s sublicensee or indirectly through IMMUNOGEN; if
GENENTECH obtains such rights from IMMUNOGEN, IMMUNOGEN may have obtained such
rights under license or by transfer of ownership).

Nothing in this Agreement or the course of dealings between the Parties or usage
or custom in the industry or trade shall be construed to confer any other rights
or licenses to any other intellectual property Controlled by either Party or its
Affiliates by implication, estoppel or

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

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otherwise.  GENENTECH has no obligation to [***] in any [***] or [***] of [***]
to [***] or a [***] of [***] with respect to [***].

2.2                                 Sublicenses.  GENENTECH shall have the right
freely to grant sublicenses to all or any portion of its rights under the
license rights granted pursuant to Section 2.1(a) hereof to any Affiliate or
Third Party (in any case, a “Sublicensee”); provided, however, that (a) each
such sublicense shall be consistent with the terms and conditions of this
Agreement, and (b) GENENTECH shall remain obligated to ensure payment of all of
its milestone and royalty obligations as set forth in Section 4 hereof.

2.3                                 IMMUNOGEN Retained Rights and Covenants;
GENENTECH Technology or Patent Rights.

(a)                                  Retained Rights.  Subject to the other
terms of this Agreement, including, without limitation, Section 2.3(b) hereof,
IMMUNOGEN retains the right to use the Licensed Technology and practice the
Licensed Patent Rights (i) to perform its work under Sections 3.3, 3.4, 3.5 and
3.6 hereof relating to the Collaboration Committee and to manufacture and supply
Preclinical Materials and Clinical Materials for GENENTECH (and its
Sublicensees), and (ii) to develop, have developed, make, have made, use, have
used, sell have sold, offer for sale, import, have imported, export and have
exported any product that is not a Licensed Product or a [***] Product, subject
to Section 2.3(b) below.

(b)                                 Covenants.  It is hereby further agreed that
(i) during the Term of this Agreement, IMMUNOGEN shall not Develop, have
Developed, make, have made, use, have used, sell, have sold, offer for sale,
import, have imported, export and have exported any [***] Product, which
restriction shall be [***] for [***] of this Agreement if, during a [***] prior
to expiration or termination of this Agreement, [***] is [***] or [***] with a
[***], if [***] is subject to a [***] of [***], or if this Agreement is [***]
pursuant to [***], and (ii) during the Term of this Agreement, and for [***]
(which [***] shall not apply in connection with expiration of this Agreement
under [***] below or in connection with [***] of this Agreement by [***] under
Section 7.2(a) below, but which shall apply in connection with any other [***]
of this Agreement, including by [***] under [***] below), IMMUNOGEN shall not
grant to any Third Party any license or other right under any Patent Rights or
Technology owned or Controlled by

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

12

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IMMUNOGEN to Develop, have Developed, make, have made, use, have used, sell,
have sold, offer for sale, import, have imported, export and have exported, any
[***] Product.

(c)                                  No Rights to GENENTECH Technology or Patent
Rights.  Except for the license granted to IMMUNOGEN by GENENTECH in Section
2.1(b) above, nothing in this Section 2.3 or any other provision of this
Agreement shall be construed as a grant to IMMUNOGEN of any license or other
rights with respect to any Technology (including, without limitation, any
Confidential Information) or Patent Rights owned or Controlled (in whole or in
part) by GENENTECH.

3.  DEVELOPMENT AND COMMERCIALIZATION

OF LICENSED PRODUCTS.

3.1                                 Development and Commercialization.

(a)                                  Responsibility.  On and after the Effective
Date, except as otherwise agreed in writing with respect to certain process
development and manufacturing activities, GENENTECH shall have full control and
authority over, and sole responsibility for, all Development and
commercialization of Licensed Products in the Field in the Territory, including,
without limitation, (i) all pre-clinical Development activities (including any
pharmaceutical development work on formulations or process development relating
to any Licensed Product), (ii) all activities related to human clinical trials
(including any phase I clinical studies, any Phase II Clinical Studies or any
Phase III Clinical Trials), (iii) all activities relating to manufacture and
supply of [***] Antibodies, all MAY Compounds (including ansamitocin P-3 and
DM1) and all Licensed Products, solely to the extent such activities relate to
the development and commercialization of Licensed Products (including all
required process development and scale up work with respect thereto), (iv) all
marketing, promotion, sales, distribution, import and export activities relating
to any Licensed Product (including any post-marketing trials or databases and
post-marketing safety surveillance), and (v) all activities relating to any
regulatory filings, registrations, applications and Regulatory Approvals
relating to any of the foregoing (including any INDs or foreign equivalents, any
manufacturing facility validation and/or licensure, any Drug Approval
Applications and any other Regulatory Approvals).  Except as described in the
next sentence, GENENTECH shall own all data, results

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

13

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and all other information arising from any such activities under this Agreement,
including, without limitation, all regulatory filings, registrations,
applications and Regulatory Approvals relating to Licensed Products (including
any INDs or foreign equivalents, any Drug Approval Applications and any other
Regulatory Approvals), and all of the foregoing information, documentation and
materials shall be considered Confidential Information and Technology solely
owned by GENENTECH.  IMMUNOGEN shall own all data, results and all other
information arising from IMMUNOGEN’s activities relating to the manufacture and
supply of MAY Compounds (including ansamitocin P-3 and DM1) to GENENTECH, and
all of the foregoing information, documentation and materials shall be
considered Confidential Information and Technology solely owned by IMMUNOGEN. 
All activities relating to Development and commercialization under this
Agreement shall be undertaken at GENENTECH’s sole cost and expense, except as
otherwise expressly provided in this Agreement.

(b)                                 Due Diligence.  GENENTECH will exercise its
commercially reasonable efforts and diligence in Developing and commercializing
Licensed Products in accordance with its business, legal, medical and scientific
judgment, and in undertaking investigations and actions required to obtain
appropriate Regulatory Approvals necessary to market Licensed Products in the
Field in the Territory, such reasonable efforts and diligence to be in
accordance with the efforts and resources GENENTECH would use for a compound
owned by it or to which it has rights, which is of similar market potential at a
similar stage in development as the applicable Licensed Product, taking into
account the competitiveness of the marketplace, the proprietary position of the
Licensed Product, the relative potential safety and efficacy of the Licensed
Product, the regulatory requirements involved in its Development,
commercialization and Regulatory Approval, the cost of goods and availability of
capacity to manufacture and supply the Licensed Product at commercial scale, the
profitability of the applicable Licensed Product, and other relevant factors
including, without limitation, technical, legal, scientific or medical factors. 
In the event that GENENTECH fails to use due diligence as required hereunder,
then on a Licensed Product-by-Licensed Product and country-by-country basis as
to the Licensed Product in the country in which GENENTECH has failed to use due
diligence as required hereunder, IMMUNOGEN’s exclusive remedy shall be, in its
sole discretion (i) to terminate the licenses granted under Section 2.1 this
Agreement for breach under Section 7.2(a) below

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

14

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(including the notice and cure provisions therein) or (ii) to convert the
licenses granted under Section 2.1 of this Agreement from exclusive licenses to
non-exclusive licenses, in either case only as such licenses apply to such
Licensed Product in such country, which termination or conversion, as the case
may be, shall be effective upon expiration of the cure period specified in
7.2(a) below provided that such failure remains uncured upon such expiration.

3.2                                 Updates and Reports; Exchanges of Adverse
Event Information.

(a)                                  Updates and Reports.  GENENTECH shall keep
IMMUNOGEN informed of the progress of GENENTECH’s efforts to Develop and
commercialize Licensed Products in the Field in the Territory as provided in
this Section 3.2(a).  GENENTECH (or its Sublicensee) shall provide IMMUNOGEN
with brief written reports as provided herein no less frequently than on each
anniversary of the Effective Date during the Term (commencing with the first
anniversary of the Effective Date).  Such reports shall summarize GENENTECH’s
material efforts to Develop and commercialize all Licensed Products hereunder,
identify the Drug Approval Applications with respect to any Licensed Product
that GENENTECH and its Sublicensees have filed, sought or obtained in the prior
twelve (12)-month period, and any they reasonably expect to make, seek or
attempt to obtain in the following twelve (12)-month period.  In addition,
GENENTECH (or its Sublicensee) shall provide IMMUNOGEN with prompt written
notice of the occurrence of any event giving rise to an obligation to make a
milestone payment to IMMUNOGEN under Section 4.1, and shall provide IMMUNOGEN
with prompt written notice of the occurrence of the First Commercial Sale of any
particular Licensed Product. All such reports and notices shall be sent to the
attention of IMMUNOGEN’s designated representative, who shall be its Chief
Executive Officer unless IMMUNOGEN otherwise notifies GENENTECH.

(b)                                 Adverse Events.  In addition to such
reports, GENENTECH agrees to provide IMMUNOGEN with Adverse Event information
and product complaint information relating to Licensed Products (but not
relating to any other products of GENENTECH, including any antibody that may be
included in a Licensed Product, to the extent that antibody is used in its
“naked” form or in connection with a different effector molecule) as compiled
and prepared by GENENTECH in the normal course of business in connection with
the Development, commercialization or sale of any Licensed Product, within time
frames consistent with reporting obligations under applicable laws and
regulations.  To the extent it could reasonably apply or

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

15

--------------------------------------------------------------------------------

could reasonably be relevant to a Licensed Product, IMMUNOGEN agrees to provide
GENENTECH with Adverse Event and product complaint information relating to any
product containing any MAY Compound that is compiled and prepared by IMMUNOGEN
or any Third Party in the normal course of business in connection with the
development, commercialization or sale of any such product, within time frames
consistent with reporting obligations under applicable laws and regulations;
provided, however, that the foregoing shall not require IMMUNOGEN to violate any
agreements with or confidentiality obligations owed to any Third Party. 
GENENTECH shall provide its Adverse Event and product complaint information
hereunder to IMMUNOGEN’s designated representative, who shall be its Chief
Regulatory Officer unless IMMUNOGEN otherwise notifies GENENTECH. IMMUNOGEN
shall provide its Adverse Event and product complaint information hereunder to
GENENTECH’s designated representative, who shall be the head of its Drug Safety
group in GENENTECH’S Medical Affairs Department unless GENENTECH otherwise
notifies IMMUNOGEN.

(c)                                  Confidential Information.  All reports,
updates, Adverse Event, product complaint and other information provided by one
Party to the other Party under this Agreement (including under this Section 3),
shall be considered Confidential Information of the disclosing Party, subject to
the terms of Section 5.

3.3                                 Reasonable Assistance by IMMUNOGEN.  In
connection with the exclusive grant of rights to GENENTECH under Section 2.1
above, and subject to the other terms of this Agreement, IMMUNOGEN shall provide
GENENTECH (and any Sublicensee of GENENTECH with respect to all of GENENTECH’s
license rights hereunder to make or have made all Licensed Products or any
particular Licensed Product(s) throughout the Territory or in a particular
geographic region of the Territory, and/or all of GENENTECH’s license rights
hereunder to Develop or commercialize all Licensed Products or any particular
Licensed Product(s) throughout the Territory  or in a particular geographic
region of the Territory (in any case, a “Material Sublicensee”)) such
information and materials comprising the Licensed Technology and/or Licensed
Patent Rights as GENENTECH (or its Material Sublicensee) may reasonably
request.  Without limiting the generality of the foregoing, IMMUNOGEN shall
provide all of such technical assistance within IMMUNOGEN’s area of expertise
(or its subcontractors) concerning the Development and commercialization of
Licensed Products as

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

16

--------------------------------------------------------------------------------

may be reasonably requested by GENENTECH (or its Material Sublicensee) from time
to time during the Term, provided that such technical assistance and expertise
is within the scope of the Licensed Technology and/or Licensed Patent Rights
covered under this Agreement.  Such technical assistance and expertise shall
include, but not be limited to, visits by IMMUNOGEN personnel to GENENTECH and
visits by GENENTECH to IMMUNOGEN (or its subcontractors), at GENENTECH’s
expense, at such times and for such periods of time as may be reasonably
acceptable to the Parties.   Without limiting the generality of the foregoing,
within [***] ([***]) days after GENENTECH’s reasonable written request,
IMMUNOGEN shall deliver to GENENTECH a list or description of the documents and
information that embody the Licensed Technology.  GENENTECH  will inform
IMMUNOGEN which of those identified documents and information GENENTECH believes
are reasonably related to its exercise of the license rights under this
Agreement and, within [***] ([***]) days after that identification, IMMUNOGEN
shall deliver to GENENTECH a copy of those documents and other information.

3.4                                 Collaboration Committee.

(a)                                  Mandate of Committee.  Promptly after the
Effective Date, the Parties shall form a “Collaboration Committee” to serve as a
forum for coordination and communication between the Parties with respect to
activities related to Licensed Products for which the Parties agree there is a
need for coordination and communication (including, without limitation, all
process science and process development work, formulation work, and quality
control/ assurance work hereunder), and to assist GENENTECH in its exercise of
its rights to make or have made Licensed Products under this Agreement.  Within
[***] ([***]) days after the Effective Date, the Parties shall each nominate an
equal number of representatives (which shall be no less than two (2) each) for
membership on the Collaboration Committee.  Each Party may change its
representative(s) as it deems appropriate by notice to the other Party.  The
input of the IMMUNOGEN representatives on the Collaboration Committee shall be
fully considered by the Collaboration Committee; provided, however, that all
decisions of the Collaboration Committee shall be subject to final approval by
GENENTECH.

(b)                                 Chair of Committee; Meetings.  The Parties
hereby agree that (i) the chair of the Collaboration Committee shall be one of
the GENENTECH representatives on the Collaboration Committee, as designated by
GENENTECH; provided, however, that [***] the [***] after the Effective Date, the
Collaboration Committee shall be [***] by a [***] on the

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

17

--------------------------------------------------------------------------------

Collaboration Committee (as designated by [***]) and an [***] on the
Collaboration Committee (as designated by [***]); (ii) all decisions of the
Collaboration Committee shall be subject to the approval of the GENENTECH chair
(including [***] the [***] there is a [***]); (iii) the Collaboration Committee
shall meet on a semi-annual basis or other schedule agreed upon by the Parties,
unless at least thirty (30) days in advance of any meeting the chair (or
co-chairs during the first twelve (12) months) of the Collaboration Committee
determine that there is no need for a meeting (in which instance, the next
Collaboration Committee meeting shall also be scheduled as agreed upon by the
Parties); (iv) the location of meetings of the Collaboration Committee shall
alternate between IMMUNOGEN’s offices in Massachusetts and GENENTECH’s offices
in California, unless otherwise agreed by the Parties and, as agreed upon by the
Parties, Collaboration Committee meetings may be face-to-face or may be
conducted through teleconferences and/or videoconferences.  In addition to its
Collaboration Committee representatives, each Party shall be entitled to have
other employees attend such meetings to present and participate, though not in a
decision-making capacity.  Each Party shall bear all costs and expenses,
including travel and lodging expense, that may be incurred by its Collaboration
Committee representatives or other of its attendees at Collaboration Committee
meetings, as a result of such meetings hereunder.  Minutes of each Collaboration
Committee meeting will be transcribed and issued to members of the Collaboration
Committee by the chair (or the GENENTECH co-chair, as the case may be) within
thirty (30) days after each meeting, and such minutes shall be reviewed and
modified as mutually required to obtain approval of such minutes promptly
thereafter.

3.5                                 Supply of Preclinical Materials.  During the
Term of this Agreement, IMMUNOGEN shall supply to GENENTECH (or its Material
Sublicensee) with such quantities of Preclinical Materials as may be reasonably
requested by GENENTECH (or its Material Sublicensee) in order to conduct all
pre-clinical Development activities relating to Licensed Products.  GENENTECH
(or its Material Sublicensee) shall order all amounts of Preclinical Materials,
and IMMUNOGEN shall deliver all such ordered amounts, in accordance with advance
ordering timeframes and delivery timeframes to be agreed upon by the Parties
through the Collaboration Committee.  IMMUNOGEN shall use its commercially
reasonable efforts to deliver such amounts of Preclinical Materials ordered in
accordance with the foregoing (including such agreed upon timeframes) in a
timely manner.  In connection with any ordering of

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

18

--------------------------------------------------------------------------------

Preclinical Materials by GENENTECH (or its Material Sublicensee), IMMUNOGEN
shall provide GENENTECH (or its Material Sublicensee) promptly with IMMUNOGEN’s
good faith estimate of the Fully Burdened Manufacturing Cost for manufacture and
supply of such Preclinical Materials.  IMMUNOGEN’s price to supply Preclinical
Materials to GENENTECH (or its Material Sublicensee) shall equal [***]% of
IMMUNOGEN’s Fully Burdened Manufacturing Cost for such Preclinical Materials as
approved by GENENTECH (or its Material Sublicensee).  Nothing herein shall
preclude GENENTECH from making its own arrangements for manufacture and supply
of Preclinical Materials on its own or with Third Parties, in exercise of its
license rights under Section 2.1.  GENENTECH hereby agrees that (a) it shall not
use the Preclinical Materials in any human subject, (b) it shall use the
Preclinical Materials in compliance with all applicable federal, state and local
laws and regulations, and (c) it (as a matter of contract between itself and
IMMUNOGEN) shall assume all liability for damages that may arise from the use,
storage and disposal of any Preclinical Materials to the extent provided
pursuant to Section 9 below.  GENENTECH shall be entitled to transfer
Preclinical Materials to any Third Party under terms obligating such Third Party
not to transfer or use such Preclinical Materials except in compliance with the
foregoing clauses (a) and (b) of this Section 3.5.

3.6                                 Supply of Clinical Materials.  During the
Term of this Agreement, IMMUNOGEN shall supply to GENENTECH (or its Material
Sublicensee) with such quantities of Clinical Materials as may be reasonably
requested by GENENTECH (or its Material Sublicensee) in order to conduct all
human clinical trials of Licensed Products through non-pivotal Phase II Clinical
Studies.  To the extent GENENTECH requests IMMUNOGEN to manufacture Clinical
Materials as provided in the foregoing sentence, IMMUNOGEN and GENENTECH shall
enter into separate supply and quality agreements detailing the terms of supply
for any Clinical Materials that IMMUNOGEN is so requested to supply to GENENTECH
for the purpose of conducting clinical trials.  GENENTECH (or its Material
Sublicensee) shall order all amounts of Clinical Materials, and IMMUNOGEN shall
deliver all such ordered amounts, in accordance with forecasting parameters,
advance ordering timeframes and delivery timeframes to be agreed upon by the
Parties through the Collaboration Committee.  IMMUNOGEN shall use its
commercially reasonable efforts to deliver such amounts of Clinical Materials
ordered in accordance with the foregoing (including such agreed upon timeframes)
in a timely manner.  In connection with any ordering of Clinical Materials by
GENENTECH (or its

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

19

--------------------------------------------------------------------------------

Material Sublicensee), IMMUNOGEN shall provide GENENTECH (or its Material
Sublicensee) promptly with IMMUNOGEN’s good faith estimate of the Fully Burdened
Manufacturing Cost for manufacture and supply of such Clinical Materials. 
IMMUNOGEN’s price to supply Clinical Materials to GENENTECH (or its Material
Sublicensee) shall equal [***]% of IMMUNOGEN’S Fully Burdened Manufacturing Cost
for such Clinical Materials as approved by GENENTECH (or its Material
Sublicensee).  Nothing herein shall preclude GENENTECH from making its own
arrangements for manufacture and supply of Clinical Materials on its own or with
Third Parties, in exercise of its license rights under Section 2.1. GENENTECH
hereby agrees that (a) it shall use the Clinical Materials in compliance with
all applicable federal, state and local laws, and (b) it (as a matter of
contract between itself and IMMUNOGEN) shall [***] all [***] for [***] that may
arise from the [***] and [***] of such Clinical Materials to the extent provided
pursuant to Section 9 below. GENENTECH shall be entitled to transfer Clinical
Materials to any Third Party under terms obligating such Third Party not to
transfer or use such Clinical Materials except in compliance with the foregoing
clause (a) of this Section 3.6.

3.7                                 Purchase of Equipment.  If, during the Term
of this Agreement, IMMUNOGEN determines in good faith that it is necessary or
advisable to purchase equipment or instruments in order to perform any of its
obligations to manufacture Preclinical Materials and Clinical Materials under
Sections 3.5 or 3.6 of this Agreement, then IMMUNOGEN shall provide the
Collaboration Committee with written notice of such determination, along with
the estimated price for such purchase and quality parameters for the equipment
or instruments, for the Collaboration Committee’s approval of such price and
features.  Promptly after the consummation of such purchase, assuming that the
Collaboration Committee has provided its approval hereunder, IMMUNOGEN shall
provide GENENTECH with a copy of the invoice or invoices reflecting such
purchase, and GENENTECH shall reimburse IMMUNOGEN for the purchase of all such
approved equipment hereunder within [***] days of its receipt of such invoice
from IMMUNOGEN; provided, however, that no costs reimbursed by GENENTECH
hereunder (or depreciation of such purchased equipment or instruments) shall be
includible or included within the calculation of any Fully Burdened
Manufacturing Costs under this Agreement.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

20

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4.  PAYMENTS AND ROYALTIES

4.1                                 Milestone Payments for Licensed Products.

4.1.1                        Milestones.  In consideration of the grant of the
license by IMMUNOGEN hereunder, and subject to the other terms of this
Agreement, GENENTECH will make the following nonrefundable, noncreditable
(except as expressly provided in Section 4.1.2 below) payments to IMMUNOGEN, on
the payment terms in Section 4.5:

[***] Milestones

 

Milestone Payment

 

 

 

 

 

Effective Date

 

$

1 Million

 

 

 

 

 

[***] for a [***]

 

$

[***]

 

 

 

 

 

[***] of [***] in [***] for a [***]

 

$

[***]

 

 

 

 

 

[***] of [***] of [***] in [***] for a [***] or [***]

 

 

 

[***] for a [***]

 

$

[***]

 

 

 

 

 

[***] of [***] by the [***]

 

 

 

for a [***] for [***]

 

$

[***]

 

 

 

 

 

          [***] of an [***] or other [***] in the [***] for a

 

 

 

[***] for [***]

 

$

[***]

 

 

 

 

 

[***] of a [***] for a

 

 

 

[***] in [***] for [***]

 

$

[***]

 

 

 

 

 

[***] of [***] by the [***] for a [***] for [***]

 

$

[***]

 

 

 

 

 

[***] of [***] by the [***] for a [***] for a [***]

 

$

[***]

 

 

[***] Milestones

 

Milestone Payment

 

 

 

 

 

[***] of [***] greater than $[***]

 

$

[***]

 

 

 

 

 

[***] of [***] greater than $[***]

 

$

[***]

 

 

It is hereby acknowledged and agreed that any milestone payment shall be made
only once, with respect to the first achievement of the relevant milestone for
the first Licensed Product, regardless of how many times such milestones are
achieved by Licensed Products and regardless of how many times a particular
Licensed Product achieves such milestones.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

21

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GENENTECH shall notify IMMUNOGEN of the achievement of milestones hereunder as
provided in Section 3.2(a) above.

4.1.2                        [***] of [***].  GENENTECH shall be [***] to [***]
its [***] (but not any [***]) [***] to IMMUNOGEN only to the extent set forth in
this Section 4.1.2.  As to the Licensed Product with respect to which [***] are
owed to IMMUNOGEN under this Section 4.1, GENENTECH shall be [***] to [***]
[***] percent ([***]%) of each such [***] made with respect to such Licensed
Product hereunder [***][***][***] to IMMUNOGEN hereunder with respect to such
Licensed Product, but (a) only if prior to the date of such [***][***],
GENENTECH (or its Sublicensee) has modified such Licensed Product such that it
would not (even in the absence of the license under this Agreement) [***] a
[***] within the Licensed Patent Rights in the United States (excluding any
Patent Rights [***] by [***] and [***]), and (b) only if such modification was
undertaken (i) to address a [***] or [***] with respect to such Licensed Product
or its Development, manufacture, use or sale, (ii) to obtain a [***] in the
toxicity, safety or efficacy profile of such Licensed Product, or (iii) to
obtain a [***] in the ability to make or have made such Licensed Product (or any
component thereof).

4.2                                 Payment of Royalties; Royalty Rates;
Accounting for Royalties and Records.

4.2.1                        Royalty Payments.  In consideration of the grant of
the license by IMMUNOGEN hereunder, and subject to the other terms of this
Agreement (including the remainder of this Section 4), commencing on the first
date of First Commercial Sale of Licensed Products in such country or
jurisdiction in the Territory, GENENTECH shall pay to IMMUNOGEN the following
royalties based on total Net Sales of all Licensed Products sold by GENENTECH
and/or its Sublicensees, on an incremental basis in each calendar year during
the Term, at the following rates in [***] of the [***]:

For Net Sales of a Licensed Product
[***] in any Calendar Year
During the Term:

 

Royalty Rate (% of Net Sales)

 

 

 

 

 

 

 

Above $[***] and up to $[***]

 

[***]

%

 

 

 

 

 

 

Above $[***]

 

[***]

%

 

 

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

22

--------------------------------------------------------------------------------

 

For Net Sales of a Licensed Product
[***] in any Calendar Year
During the Term:

 

Royalty Rate (% of Net Sales)

 

 

 

 

 

 

 

 

Above $[***] and up to $[***]

 

[***]

%

 

 

 

 

 

 

 

 

Above $[***]

 

[***]

%

 

 

 

By way of example only, if during the Term a Licensed Product achieved total Net
Sales in a given calendar of $[***], the applicable royalty rate would be [***]%
of Net Sales for Net Sales up to $[***], and [***]% of Net Sales for Net Sales
over $[***].

4.2.2                        Third Party Royalty Offset.  Subject to the other
terms of this Agreement, on a country-by-country basis, the royalties otherwise
due and payable by GENENTECH under Section 4.2.1 above (but not the royalties
otherwise due and payable by GENENTECH under Section 4.2.3(a) or (b) below)
shall be reduced as provided in this Section 4.2.2:

(a)                                  GENENTECH Process Development.  Consistent
with GENENTECH’S due diligence obligations under this Agreement, GENENTECH
agrees to exercise due diligence to attempt to Develop a commercially viable
manufacturing process relating to the manufacture and supply of Licensed
Products.  For purposes of this Agreement, GENENTECH shall determine in good
faith the commercial viability of any such manufacturing process that is
Developed hereunder, taking into account, without limitation, the following
factors relevant thereto:  the consistency and reproducibility of the process
itself; the consistency, reproducibility, safety and efficacy of the resulting
conjugated Licensed Products; any regulatory issues; the availability of
capacity; the cost of goods and other components of Fully Burdened Manufacturing
Cost as applied to such process and to the overall manufacture and supply of
Licensed Products; the overall profitability of the Licensed Products; and the
ability to produce at commercial scale quantities.

(b)                                 Partial Offset.  If GENENTECH is not able to
Develop such a commercially viable manufacturing process after exercising due
diligence as required hereunder, GENENTECH may elect to license a manufacturing
process from a Third Party, and in that event GENENTECH shall be entitled to
offset up to [***] percent ([***]%) of any Third Party Payments it makes in
connection with any license providing rights to any such manufacturing

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

23

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process against the royalties due to IMMUNOGEN pursuant to Section 4.2.1 above,
subject to the clause (d) of this Section 4.2.2.  GENENTECH shall not be
entitled to the offset under this clause (b) if it fails to exercise due
diligence as required hereunder.

(c)                                  Full Offset.  If GENENTECH determines in
good faith that it is necessary, in order to exploit the license granted to it
under Section 2.1 of this Agreement in any country, to make royalty payments to
any Third Party (“Third Party Payments”) under any license agreement that
GENENTECH determines, in good faith, is necessary in connection with the
Development, manufacture, use or sale of any MAY Compound, the linker of any MAY
Compound to a [***] Antibody, and/or the conjugation of a [***] Antibody to any
MAY Compound (including, without limitation, DM1) as part of any Licensed
Product, then in any such case the royalties due to IMMUNOGEN pursuant to
Section 4.2.1 above for such Licensed Product shall be reduced by [***] of such
Third Party Payments, subject to the limitations set forth in clause (d) of this
Section 4.2.2.  If GENENTECH elects to take any such license agreement as
described herein without having first determined that it is necessary (as
determined by GENENTECH in good faith) in order to exploit the license granted
to it under Section 2.1 of this Agreement in any country, then GENENTECH shall
not be entitled to the offset under this clause (c). If IMMUNOGEN in good faith
disputes GENENTECH’s determination hereunder, the Parties shall submit the
matter promptly to IMMUNOGEN’S Chief Executive Officer and a designated officer
of GENENTECH with settlement authority.

(d)                                 Limitations on Offsets.  The royalty offset
in Section 4.2.2(c) above is separate and cumulative to the royalty offset under
Section 4.2.2(b) above, but each is subject to the limitations set forth in this
Section 4.2.2(d) as follows.  No royalty reductions under this Section 4.2.2,
alone or in the aggregate, shall reduce the royalty (if any) for any Licensed
Product in any country payable pursuant to Section 4.2.1 above by more than
[***] percent ([***]%) of the royalties otherwise owed to IMMUNOGEN thereunder,
nor reduce such royalty for such Licensed Product in any such country to less
than [***] percent ([***]%) of Net Sales of such Licensed Product in such
country.

4.2.3                        [***] and [***].

(a)                                   Notwithstanding anything set forth in
[***] above, the [***] set forth therein shall apply, on a [***] and [***]
basis, to [***] of [***] or its [***], [***] or [***] in [***] would, [***] for
the [***] under this Agreement, [***] a [***] the [***] (excluding any

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

24

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[***] by [***] and [***]).  Subject to the other terms of this Agreement (except
for Section 4.2.2 above, which shall not apply), on a [***] and [***] where and
as of when the [***] under Section 4.2.1 [***] as a [***] of this Section 4.2.3,
GENENTECH shall [***] to IMMUNOGEN a [***] to [***][***] ([***]%) of [***] of
[***] by [***] and/or its [***] in [***].

(b)                                    [***].  Notwithstanding anything set
forth in [***] above, the [***] set forth in [***] above shall no longer apply,
on a [***] basis, on and after the [***] on which any [***] to [***] and [***]
in a [***] any [***].  Subject to the other terms of this Agreement (except for
[***], which shall not apply), on a [***] basis where the [***] under [***] do
not apply as a result of this [***],  [***] on the [***] of such [***] of [***]
in such [***], [***] shall [***] and [***] to [***] a [***] equal to [***][***]
([***]%) of [***] of all [***] by [***] and/or its [***] in [***]; provided,
however, that if the [***] is [***] from the [***] in [***], then this [***]
shall no longer apply and [***] shall [***] the [***] set forth in [***] on a
[***] basis [***] on the [***] of [***] [***].

4.2.4                        Combination Products.  In determining Net Sales of
any Combination Products under this Agreement, Net Sales shall first be
calculated in accordance with the definition of “Net Sales” above, then
multiplied by the percentage value of the Licensed Product contained in the
Combination Product, such percentage value being the quotient obtained by
dividing the current market price of the Licensed Product by the sum of the
separate current market price of the Licensed Product and other ingredients
which are therapeutically active contained in the Combination Product.  The
current market price of each therapeutically active ingredient and of the
Licensed Product shall be for a quantity comparable to that contained in the
Combination Product and of the same class, purity and potency.  When no current
market price is available for any therapeutically active ingredient or for the
Licensed Product, GENENTECH shall calculate in good faith a hypothetical market
price with respect to the Combination Product, allocating the same proportions
of costs, overhead and profit as are then allocated to all similar substances
then being made and marketed by GENENTECH and having an ascertainable market
price; provided, however, that if IMMUNOGEN in good faith disputes GENENTECH’s
calculation, the Parties shall submit the matter promptly to IMMUNOGEN’S Chief
Executive Officer and a designated officer of GENENTECH with settlement
authority.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

25

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4.3                                 One Royalty.  Only one royalty, calculated
at the highest applicable royalty rate under this Section 4, shall be payable to
IMMUNOGEN hereunder for each sale of a Licensed Product.

4.4                                 Royalty Term. GENENTECH shall pay royalties
with respect to each Licensed Product on a country-by-country and Licensed
Product-by-Licensed Product basis until the later of (a) ten (10) years from the
First Commercial Sale of such Licensed Product in such country and (b) the
expiration of the last to expire Valid Claim of the Licensed Patent Rights
covering the Licensed Product in such country.  Following such royalty term,
GENENTECH shall have a fully paid-up, irrevocable, freely transferable and
sublicensable license in such country under the relevant Licensed Patent Rights
and Licensed Technology, to Develop, have Developed, make, have made, use, have
used, sell, have sold, offer for sale, import and have imported such Licensed
Product in such country.

4.5                                 Payment Terms.

(a)                                  Payment of Milestones; Payment of
Royalties; Royalty Reports.  All [***] Milestone payments shall be made within
[***] days after the first achievement of each of the [***] Milestones described
above.  All [***] Milestones payments shall be paid no later than the [***] of
the [***] of the [***] following the [***] in which the applicable [***]
Milestone is achieved, including in any circumstance in which [***] Milestones
are achieved in the [***].  Subject to the other terms of this Agreement
(including Section 4.1 above), GENENTECH shall make any milestone payments owed
to IMMUNOGEN hereunder in United States Dollars, using the wire transfer
provisions of this Section 4.4.  Subject to the other terms of this Agreement
(including Sections 4.2, 4.3 and 4.4 above), GENENTECH shall make any royalty
payments owed to IMMUNOGEN in United States Dollars, quarterly within [***] days
following the end of each calendar quarter for which such royalties are deemed
to occur (as provided in the next sentence), using the wire transfer provisions
of this Section 4.5.  For purposes of determining when a sale of any Licensed
Product occurs under this Agreement, the sale shall be deemed to occur on the
earlier of (i) the date the Licensed Product is [***] or (ii) the date of the
[***] the [***] of the Licensed Product.  Each royalty payment shall be
accompanied by a report for each country in the Territory in which sales of
Licensed Products occurred in the calendar quarter covered by such statement,
specifying:  the gross sales (if available) and Net Sales in each country’s
currency; the applicable royalty rate under this Agreement; the royalties
payable in

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

26

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each country’s currency, including an accounting of deductions taken in the
calculation of Net Sales; the applicable exchange rate to convert from each
country’s currency to United States Dollars under this Section 4.5; and the
royalties payable in United States Dollars.

(b)                                 Foreign Currency Exchange.  All royalties
shall be payable in full in the United States in United States Dollars,
regardless of the countries in which sales are made. For the purpose of
computing Net Sales for Licensed Products sold in any currency other than United
States Dollars, the quarterly royalty payment will be calculated as follows:

(A/B) x C = United States Dollars royalty payment on foreign current sales,
where

A = foreign current “Net Sales” (as defined above) per quarter;

B = foreign exchange conversion rate, expressed in local currency per United
States Dollar (using as the applicable foreign exchange rate the average of the
rate published in the [***] of the [***], for the [***] of the calendar
quarter); and

C = the royalty rate applicable to such Net Sales under this Agreement.

(c)                                  Tax Withholding; Restrictions on Payment. 
 All payments hereunder shall be made free and clear of any taxes, duties,
levies, fees or charges, except for withholding taxes (to the extent
applicable).  GENENTECH shall make any applicable withholding payments due on
behalf of IMMUNOGEN and shall promptly provide IMMUNOGEN with written
documentation of any such payment sufficient to satisfy the requirements of the
United States Internal Revenue Service relating to an application by IMMUNOGEN
for a foreign tax credit for such payment.  If by law, regulations or fiscal
policy of a particular country in the Territory, remittance of royalties in
United States Dollars is restricted or forbidden, written notice thereof shall
promptly be given to IMMUNOGEN, and payment of the royalty shall be made by the
deposit thereof in local currency to the credit of IMMUNOGEN in a recognized
banking institution designated by IMMUNOGEN by written notice to GENENTECH. 
When in any country in the Territory the law or regulations prohibit both the
transmittal and the deposit of royalties on sales in such country, royalty
payments shall be suspended for as long a such prohibition is in effect and as
soon as such prohibition ceases to be in effect, all royalties that GENENTECH
would have been under an obligation to transmit or deposit but for the
prohibition shall forthwith be deposited or transmitted, to the extent
allowable.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

27

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(d)                                 Wire Transfers.  All payments hereunder
shall be made to IMMUNOGEN by bank wire transfer in immediately available funds
to the account designated by IMMUNOGEN by written notice to GENENTECH from time
to time.

4.6                                 Overdue Royalties.  Subject to the other
terms of this Agreement, royalties not paid within the time period set forth in
this Section 4 shall bear interest at a rate of [***] percent ([***]%) per month
from the due date until paid in full.

4.7                                 Records Retention; Review.

(a)                                  Royalties.  Commencing as of the date of
First Commercial Sale of the first Licensed Product, GENENTECH and its
Sublicensees shall keep for at least [***] ([***]) years from the end of the
calendar year to which they pertain complete and accurate records of sales by
GENENTECH or its Sublicensees, as the case may be, of each Licensed Product, in
sufficient detail to allow the accuracy of the royalties to be confirmed.

(b)                                 Fully Burdened Manufacturing Costs. 
Commencing as of the Effective Date, IMMUNOGEN shall keep for at least [***]
years following the end of the calendar year to which they pertain complete and
accurate records of all of IMMUNOGEN’s Fully Burdened Manufacturing Costs for
Preclinical Materials and Clinical Materials supplied to GENENTECH (or its
Sublicensee) hereunder, in sufficient detail to allow the accuracy of the Fully
Burdened Manufacturing Costs to be confirmed.

(c)                                  Review.  Subject to the other terms of this
Section 4.7(c), at the request of either Party, upon at least [***] business
days’ prior written notice from the requesting Party, and at the expense of the
requesting Party (except as otherwise provided herein), the other Party shall
permit an independent certified public accountant reasonably selected by the
requesting Party and reasonably acceptable to the other Party to inspect (during
regular business hours) the relevant records required to be maintained by the
other Party under this Section 4.7.  At IMMUNOGEN’s request (which shall not be
made more frequently than once per year during the Term), the accountant shall
be entitled to review the then-preceding [***] years of GENENTECH’s records
under this Section 4.7 for purposes of verifying GENENTECH’s royalty
calculations. At GENENTECH’s request (which shall not be made more frequently
than once per year during the Term), the accountant shall be entitled to review
the then-preceding [***] years of IMMUNOGEN’s records under this Section 4.7 for
purposes of verifying IMMUNOGEN’s Fully Burdened Manufacturing Cost
calculations. In every case the accountant

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

28

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must have previously entered into a confidentiality agreement with both Parties
substantially similar to the provisions of Section 4 and limiting the disclosure
and use of such information by such accountant to authorized representatives of
the Parties and the purposes germane to this Section 4.7.  Results of any such
review shall be made available to both Parties and shall be binding on both
Parties.  Each Party agrees to treat the results of any such accountant’s review
of the other Party’s records under this Section 4.7 as Confidential Information
of the other Party subject to the terms of Section 5.  If any review reveals a
deficiency in the calculation of royalties resulting from any underpayment by
GENENTECH, GENENTECH shall promptly pay IMMUNOGEN the amount remaining to be
paid (plus interest thereon at the rate provided in Section 4.6 above), and if
such underpayment is by [***] percent ([***]%) or more, GENENTECH shall pay all
costs and expenses of the review.  If any review reveals a deficiency in the
calculation of Fully Burdened Manufacturing Costs resulting from any overpayment
by GENENTECH, IMMUNOGEN shall promptly refund GENENTECH the amount of any such
overpayment (plus interest thereon at the rate provided in Section 4.6 above),
and if such overpayment is by [***] percent ([***]%) or more, IMMUNOGEN shall
pay all costs and expenses of the review.

5.  TREATMENT OF CONFIDENTIAL INFORMATION

5.1                                 Confidential Information.  During the Term,
in the course of performance of this Agreement, each Party may disclose to the
other Party proprietary technical and business information of the disclosing
Party, including techniques, data, inventions, practices, methods, knowledge,
know-how, test data and results (including from pre-clinical and/or human
clinical testing), analytical and quality control data, cost, sales,
manufacturing, patent data and any other information disclosed hereunder.  Such
information of the disclosing Party hereunder, if so identified in writing by
the disclosing Party to the receiving Party either pursuant to this Section 5.1
or otherwise upon disclosure to the receiving Party, shall be considered
“Confidential Information” of the disclosing Party.  Each Party agrees that it
will take the same commercially reasonable steps to protect the confidentiality
of other Party’s Confidential Information as it takes to protect its own
proprietary and confidential information. For a period of [***] years after the
receipt of any such Confidential Information from the disclosing Party
hereunder, subject to the terms of this Section 5, the receiving Party shall
keep confidential and not disclose (by publication or otherwise) such
Confidential Information of the other Party, and shall not use,

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

29

--------------------------------------------------------------------------------

publish or otherwise disclose Confidential Information of the other Party for
any purpose other than those contemplated by this Agreement (including as
reasonably necessary to exercise any rights or perform any obligations under
this Agreement). Notwithstanding the foregoing, it is understood and agreed that
the receiving Party’s obligations of confidentiality and non-use herein shall
not apply to the extent that it can be established by competent written records
that any such information:

(a)                                  is, at the time of disclosure by the
disclosing Party hereunder, or thereafter becomes, a part of the public domain
or publicly known or available, other than through any act or omission of the
receiving Party in breach of its obligations under this Section 5; or

(b)                                 was known to the receiving Party at the time
of disclosure to it by the disclosing Party; or

(c)                                  is, at the time of disclosure by the
disclosing Party hereunder, or thereafter becomes, known to the receiving Party
from a source that had a lawful right to disclose such information to others; or

(d)                                 was independently developed by the receiving
Party without use or reference to any Confidential Information of the disclosing
Party.

5.2                                 Permitted Disclosures; Publications.

(a)                                  Permitted Disclosures.  Each Party shall be
entitled to disclose Confidential Information of the other Party to employees of
the receiving Party, provided that such employees are already bound by
obligations of confidentiality to their employer, and also to Affiliates,
consultants, agents and Third Parties for any purpose provided for in this
Agreement, provided that any such Affiliate, consultant, agent or other Third
Party has first agreed in writing to confidentiality restrictions and
obligations at least as protective as this Section 5, in each case for any
purpose contemplated by this Agreement (including as reasonably necessary to
exercise any rights or perform any obligations under this Agreement).

(b)                               Review of Publications.  Each Party shall
consult with the other Party prior to the submission of any manuscript for
publication if the publication will contain any Confidential Information of the
other Party, unless the applicable laws and regulations prohibit such
consultation.  Such consultation shall include providing a copy of the proposed
manuscript to the other Party at least [***] days prior to the proposed date of
submission to a publisher,

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

30

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incorporating appropriate changes proposed by the other Party regarding its
Confidential Information into the manuscript submission and deleting all
Confidential Information of the other Party as it may request; provided,
however, that the other Party’s review hereunder shall be deemed completed at
the end of such [***]-day period.

(c)                                  Other Permitted Disclosures. 
Notwithstanding the foregoing, Confidential Information of either Party may be
disclosed by the other Party to the extent such disclosure is reasonably
necessary for filing or prosecuting patent applications or maintaining patents,
prosecuting or defending litigation, enforcing rights and/or obligations under
this Agreement, complying with applicable laws, regulations or court order or
conducting pre-clinical or human clinical testing of Licensed Products;
provided, that, if a Party is required by applicable law, regulation or court
order to make such disclosure of the other Party’s Confidential Information,
[***] of such other Party’s Confidential Information required to be disclosed.

5.3                                 Use of Names; Press  Releases.

(a)                                  Use of Names.  A Party may not use the name
of the other Party (or any trademarks or tradenames of the other Party) in any
press release or any other publicity or advertising without the prior written
consent of the other Party.

(b)                                 Press Releases.  Except as provided in
Sections 5.1 and 5.2 above, a Party may not issue a press release or otherwise
publicize or disclose any information related to this Agreement or the terms or
conditions hereof, without the prior written consent of the other Party.  Once
any written text is approved for disclosure by both Parties as provided herein,
either Party may make subsequent or repeated public disclosures of the contents
thereof [***] the [***] of the other Party, so long as such subsequent
disclosures continue to be correct and presented in appropriate context. 
Nothing in the foregoing, however, shall prohibit a Party from making such
disclosures regarding this Agreement or the terms thereof to the extent deemed
necessary under applicable federal or state securities laws or any rule or
regulation of any nationally recognized securities exchange, subject to the
terms of Section 5.2 above regarding disclosures required to comply with
applicable laws, regulations or court order.

5.4                                 Integration; Survival.  As to the subject
matter of this Agreement, this Section 5 supersedes any confidential disclosure
agreements between the Parties.  Section 5 shall survive termination or
expiration of this Agreement.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

31

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6.  PROVISIONS CONCERNING THE FILING, PROSECUTION AND
MAINTENANCE OF PATENT RIGHTS

6.1                                 Ownership of Intellectual Property.

(a)                                  Sole Inventions.  IMMUNOGEN shall own all
inventions (whether or not patentable) made during the course of and pursuant to
activities carried out under this Agreement solely by employees of or agents or
others obligated to assign inventions to IMMUNOGEN. GENENTECH shall own all
inventions (whether or not patentable) made during the course of and pursuant to
activities carried out under this Agreement solely by employees of or agents or
others obligated to assign inventions to GENENTECH.  The Party solely owning any
inventions hereunder shall be the sole owner of any inventorship certificate(s),
patent application(s) and patent(s) thereon. All determinations of inventive
contribution shall be as determined by United States laws of inventorship. 
Subject to the terms of Section 6.2 below relating to IMMUNOGEN sole inventions,
the Party solely owning an invention hereunder will be solely responsible, at
its own cost and expense and in its sole discretion, for the filing, prosecution
and maintenance of any inventorship certificate(s), patent application(s) and
patent(s) thereon.

(b)                                 Joint Inventions.  Inventions made during
the course of and pursuant to activities carried out under this Agreement
jointly by employees of or agents of or others obligated to assign inventions to
IMMUNOGEN and GENENTECH shall be jointly owned by IMMUNOGEN and GENENTECH. All
determinations of inventive contribution shall be as determined by United States
laws of inventorship.  The Parties shall also jointly own any inventorship
certificate(s), patent application(s) and patent(s) on any joint inventions
hereunder. The terms of Section 6.2 below relating to joint inventions shall
apply to any inventorship certificate(s), patent application(s) and patent(s)
thereon.

(c)                                  Disclosure.  As regards any IMMUNOGEN sole
or joint invention hereunder or any GENENTECH joint inventions hereunder, each
Party shall provide to the other Party any invention disclosure made during the
course of performance of this Agreement and relating to activities carried out
hereunder within [***] days after such Party receives such disclosure from its
employees, agents or others obligated to assign inventions to such Party.

(d)                                 Other Agreements.  An invention made during
the course of and pursuant to other agreements between the Parties, including
agreements related to process development or

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

32

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manufacturing, will be considered to be made under that separate agreement and
not under this Agreement.

6.2                                 Patent Filing, Prosecution and Maintenance.

(a)                                  Sole IMMUNOGEN Inventions.  Subject to the
other terms of this Section 6.2(a) and Section 6.2(b), IMMUNOGEN shall have the
right to prepare, file, prosecute, obtain and maintain, at its sole cost and
expense, all Licensed Patent Rights. IMMUNOGEN agrees that with respect to such
Licensed Patent Rights licensed exclusively to GENENTECH hereunder, (i) any such
preparation, filing, prosecution and maintenance shall be conducted with
commercially reasonable diligence by IMMUNOGEN, using patent counsel selected by
IMMUNOGEN and reasonably acceptable to GENENTECH. In any case IMMUNOGEN (i) will
provide GENENTECH with a copy of any proposed patent application covering any
such Licensed Patent Rights for review and comment reasonably in advance of
filing (which shall under no circumstances be in excess of [***] days), and (ii)
will keep GENENTECH reasonably informed of the status of such filing,
prosecution and maintenance, including, without limitation, (A) by providing
GENENTECH with copies of all communications received from or filed in patent
office(s) with respect to such filing, and (B) by providing GENENTECH, a
reasonable time prior to taking or failing to take any action that would affect
the scope or validity of any such of any such filing (including the
substantially narrowing, cancellation or abandonment of any claim(s) without
retaining the right to pursue such subject matter in a separate application, or
the failure to file or perfect the filing of any claim(s) in any country), with
prior written notice of such proposed action or inaction so that GENENTECH has a
reasonable opportunity to review and comment. Any application for extension of
Licensed Patent Rights in the Territory due to delays in regulatory review with
respect to any Licensed Product shall be filed only upon mutual written
agreement of the Parties.  If IMMUNOGEN fails to undertake the filing(s) of any
patent application with respect to any invention under such Licensed Patent
Rights within [***] days after receipt of written notice from GENENTECH that
GENENTECH believes filing of such an application by IMMUNOGEN is appropriate,
GENENTECH may undertake such filing(s) at its own expense, in which case
IMMUNOGEN will assign all of its rights to such invention to GENENTECH and any
subsequently issued patent thereon will be owned solely by GENENTECH.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

33

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(b)                                 Joint Inventions. As regards any joint
invention by the Parties hereunder, the Party from whom the majority of the data
underlying any such joint invention arose (the “controlling Party”) will have
the first right, but not the obligation, to undertake filing(s), prosecution and
maintenance of inventorship certificate(s), patent application(s) and patent(s)
thereon.  In connection with any such filing(s), the filing Party will use
patent counsel mutually acceptable to each Party (in its reasonable
determination) and the Parties will, prior to filing of the patent application,
agree on mutually acceptable sharing of the costs and expenses of such
filing(s), prosecution and maintenance.  In any case the filing Party (i) will
provide the non-controlling Party with a copy of any such proposed patent
application for review and comment reasonably in advance of filing, and (ii)
will keep the non-controlling Party reasonably informed of the status of such
filing, prosecution and maintenance, including, without limitation, (A) by
providing the non-controlling Party with copies of all communications received
from or filed in patent office(s) with respect to such filing, and (B) by
providing the non-controlling Party, a reasonable time prior to taking or
failing to take any action that would affect the scope or validity of any such
filing (including the substantially narrowing, cancellation or abandonment of
any claim(s) without retaining the right to pursue such subject matter in a
separate application, or the failure to file or perfect the filing of any
claim(s) in any country), with prior written notice of such proposed action or
inaction so that the non-controlling Party has a reasonable opportunity to
review and comment. If the Party from whom the majority of the data underlying
any such joint invention fails to undertake the filing(s) of any such patent
application with respect to any such invention within [***] days after receipt
of written notice from the other Party that the other Party believes filing(s)
of such an application by such Party is appropriate, such other Party may
undertake such filing(s) at its own expense, in which case the non-filing Party
will assign all of its rights to such joint invention to the filing Party and
any subsequently issued patent thereon will be owned solely by the filing
Party.  Either Party may assign its rights hereunder to any jointly owned
invention, inventorship certificate, patent application or patent to the other
Party, who will then have the right, in its discretion, to assume the filing,
prosecution and/or maintenance thereof as the sole owner thereof and at its sole
cost and expense.

6.3                                 Notice of Infringement.  If, during the Term
of this Agreement, either Party learns of any actual, alleged or threatened
infringement by a Third Party of any Licensed Patent Rights under this
Agreement, such Party shall promptly notify the other Party and shall provide
such other Party with available evidence of such infringement.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

34

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6.4                                 Infringement of Patent Rights.

(a)                                  Sole IMMUNOGEN Inventions.  IMMUNOGEN shall
have the first right (but not the obligation), at its own expense, to bring suit
(or take other appropriate legal action) against any actual, alleged or
threatened infringement of the Licensed Patent Rights solely owned by IMMUNOGEN
under this Agreement, with legal counsel of its own choice.  GENENTECH shall
have the right, at its own expense, to be represented in any such action by
IMMUNOGEN by counsel of GENENTECH’s own choice; provided, however, that under no
circumstances shall the foregoing affect the right of IMMUNOGEN to control the
suit as described in the first sentence of this Section 6.4(a).  If IMMUNOGEN
does not file any action or proceeding against such infringement within [***]
days after the later of (i) IMMUNOGEN’s notice to GENENTECH under Section 6.3
above, (ii) GENENTECH’s notice to IMMUNOGEN under Section 6.3 above, or (iii) a
written request from GENENTECH to take action with respect to such infringement,
then GENENTECH shall have the right (but not the obligation), at its own
expense, to bring suit (or take other appropriate legal action) against such
actual, alleged or threatened infringement, with legal counsel of its own
choice. IMMUNOGEN shall have the right, at its own expense, to be represented in
any such action by GENENTECH by counsel of IMMUNOGEN’s own choice.  Any damages,
monetary awards or other amounts recovered, whether by judgment or settlement,
pursuant to any suit, proceeding or other legal action taken under this Section
6.4(a), shall first be applied to reimburse the costs and expenses (including
attorneys’ fees) of the Party bringing such suit or proceeding or taking such
other legal action, then to the costs and expenses (including attorneys’ fees),
if any, of the other Party.  Any amounts remaining shall be allocated as
follows: (A) if GENENTECH is the Party bringing such suit or proceeding or
taking such other legal action, [***] percent ([***]%) to GENENTECH and [***]
percent ([***]%) to IMMUNOGEN,  (B) if IMMUNOGEN is the Party bringing such suit
or proceeding or taking such other legal action, [***] percent ([***]%) to
IMMUNOGEN and (C) if the suit is brought jointly, [***] percent ([***]%) to each
Party.  If a Party brings any such action or proceeding hereunder, the other
Party agrees to be joined as party plaintiff if necessary to prosecute such
action or proceeding, and to give the Party bringing such action or proceeding
reasonable assistance and authority to file and prosecute the suit; provided,
however,

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

35

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that neither Party shall be required to transfer any right, title or interest in
or to any property to the other Party or any Third Party to confer standing on a
Party hereunder.

(b)                               Infringement of Joint Inventions.  As to the
any actual, alleged or threatened infringement of any Patent Rights jointly
owned by IMMUNOGEN and GENENTECH under this Agreement, including actions against
any alleged infringer, the Parties hereto will consult with each other in good
faith regarding the best manner in which to proceed.  The Parties agree as a
basic principle that in the case of such actions against infringers, the
expenses incurred and damages awarded shall be for the account of the Party or
Parties who take such actions to the extent of their financial participation
therein.

6.5                                 Third Party Patents.  If any Third Party
claims that a patent it owns or controls claims any aspect of a Licensed Product
or its manufacture, use or sale, the Party with notice of such claim shall
notify the other Party promptly, and the Parties shall as soon as practicable
thereafter discuss in good faith regarding the best response.

6.6           Trademarks.  All Licensed Products shall be sold under one (1) or
more trademarks and tradenames selected and owned by GENENTECH (or its
Sublicensee) in the Territory.  GENENTECH (or its Sublicensee) shall control the
preparation, prosecution and maintenance of applications related to all such
trademarks and tradenames in the Territory, at its sole cost and expense and at
its sole discretion.  IMMUNOGEN shall notify GENENTECH promptly upon learning of
any actual, alleged or threatened infringement of a trademark or tradename
applicable to a Licensed Product in the Territory, or of any unfair trade
practices, trade dress imitation, passing off of counterfeit goods, or like
offenses in the Territory.  All of the costs, expenses and legal fees in
bringing, maintaining and prosecuting any action to maintain, protect or defend
any owned by GENENTECH (or its Sublicensee) hereunder, and any damages or other
recovery, shall be GENENTECH’s (or its Sublicensee’s) sole responsibility, and
taken in its sole discretion.

6.7           Integration; Survival.  This Section 6 supersedes any provisions
to the contrary in the HER2 License Agreement and that certain [***] Process
Development Agreement by and between the Parties dated as of [***].  This
Section 6 shall survive termination or expiration of this Agreement.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

36

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7.  TERM AND TERMINATION

7.1                                 Term; Expiration. The term of this Agreement
(“Term”) shall expire upon the expiration of the final royalty payment
obligation under Section 4.4 above.  Upon such expiration of the Term of this
Agreement, GENENTECH shall have a fully paid-up, irrevocable, freely
transferable and sublicensable license in the Territory under the Licensed
Patent Rights and Licensed Technology, to Develop, have Developed, make, have
made, use, have used, sell, have sold, offer for sale, import and have imported
any and all Licensed Products in the Territory.

7.2.                              Termination.  Subject to the other terms of
this Agreement:

(a)                                  Breach. A Party may terminate this
Agreement and the licenses granted herein, effective upon written notice to the
other Party, upon any breach by the other Party of any material obligation or
condition of this Agreement, which material breach remains uncured [***] days
after the non-breaching Party gives a first written notice to the other Party
describing such breach in reasonable detail; provided, however, that in the
event of a [***] by [***] under this Agreement, the [***] shall be [***] (in
lieu of [***]) but the other terms of this Section 7.2(a) shall apply to
termination in connection with any such payment breach.  Notwithstanding
anything set forth herein, if the asserted material breach is cured or shown to
be non-existent within the applicable cure period, the first notice of breach
hereunder shall be deemed automatically withdrawn and of no effect.

(b)                                 Bankruptcy. A Party may terminate this
Agreement, effective on written notice to the other Party, in the event the
other Party shall have become insolvent or bankrupt, or shall have made an
assignment for the benefit of its creditors, or there shall have been appointed
a trustee or receiver of the other Party or for all or a substantial part of its
property, or any case or proceeding shall have been commenced or other action
taken by or against the other Party in bankruptcy or seeking reorganization,
liquidation, dissolution, winding-up, arrangement, composition or readjustment
of its debts or any other relief under any bankruptcy, insolvency,
reorganization or other similar act or law of any jurisdiction now or hereafter
in effect, or there shall have been issued a warrant of attachment, execution,
distraint or similar process against any substantial part of the property of the
other Party, and any such foregoing events shall have continued for [***] days
undismissed, unbonded and undischarged.  Furthermore, all rights and licenses
granted under this Agreement are, and shall be deemed to be, for purposes of
Section 365(n) of the United States Bankruptcy Code, licenses of rights to
“intellectual property” as

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

37

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defined under Section 101(56) of the United States Bankruptcy Code.  The Parties
agree that in the event of the commencement of a bankruptcy proceeding by or
against one Party hereunder under the United States Bankruptcy Code, the other
Party shall be entitled to complete access to any such intellectual property,
and all embodiments of such intellectual property, pertaining to the rights
granted in the licenses hereunder of the Party by or against whom a bankruptcy
proceeding has been commenced, subject, however, to payment of the milestone
amounts and royalties set forth in this Agreement through the effective date of
any termination hereunder.

(c)                                  Unilateral Termination by GENENTECH. 
GENENTECH, in its sole discretion, at any time may terminate this Agreement, and
the rights and obligations hereunder, or may remove any Licensed Product and the
licenses related thereto from operation of this Agreement, in any case effective
[***] days after written notice thereof to IMMUNOGEN.  In the event of any
termination under this Section 7.2(c) only as to a Licensed Product, the
consequences set forth in Section 7.3 below relating to termination of the
Agreement under this Section 7.2(c) shall apply only with respect to such
terminated Licensed Product, and this Agreement and the rights and obligations
hereunder shall continue in full force and effect as to any and all other
Licensed Products.

7.3                                 Effects of Termination.  Upon any
termination of this Agreement by IMMUNOGEN under Section 7.2(a) or by GENENTECH
under Section 7.2(c), as of the effective date of such termination, all relevant
licenses and sublicenses granted by IMMUNOGEN to GENENTECH hereunder shall
terminate automatically.  Notwithstanding the foregoing, (a) no such termination
of this Agreement shall be construed as a termination of any valid sublicense of
any Sublicensee hereunder, and thereafter each such Sublicensee shall be
considered a direct licensee of IMMUNOGEN, provided that (i) such Sublicensee is
then in full compliance with all terms and conditions of its sublicense, (ii)
all accrued payments obligations to IMMUNOGEN have been paid, and (iii) such
sublicensee agrees at least ten (10) days prior to the effective date of such
termination to assume all obligations of GENENTECH under this Agreement, and (b)
GENENTECH and its Sublicensees shall have the right, for [***] ([***]) months or
such longer time period (if any) on which the Parties mutually agree in writing,
to sell or otherwise dispose of all Licensed Products then on hand, with
royalties to be paid to IMMUNOGEN on all Net Sales of such Licensed Products as
provided for in this Agreement.  Nothing set forth in this Section 7 or any
other provision of this Agreement shall entitle

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

38

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IMMUNOGEN to any ownership interest in, or to any license under or other rights
with respect to (including any rights to use or request any transfer to
IMMUNOGEN or any Third Party), any Confidential Information of GENENTECH or any
Technology or Patent Rights solely owned by GENENTECH under this Agreement.

7.4                                 Effects of Termination For IMMUNOGEN
Breach.  Upon any termination of this Agreement by GENENTECH under Section
7.2(a), as of the effective date of such termination, GENENTECH thereafter
automatically shall have a fully sublicensable and transferable, fully paid up
(subject to the remainder of this Section 7.4), exclusive license in the
Territory under the Licensed Patent Rights and Licensed Technology, to Develop,
have Developed, make, have made, use, have used, sell, have sold, offer for
sale, import and have imported any and all Licensed Products in the Territory,
provided that GENENTECH shall pay, for the remainder of the royalty term under
Section 4.4 above, [***] of any payments including milestones or royalties it
would [***] to IMMUNOGEN under this Agreement, a [***] equal to [***] of the
[***] that would [***] with respect to the Licensed Product under Sections
4.2.1, 4.2.2, 4.2.3 and 4.2.4 of this Agreement.

7.5                                 Remedies.  Except as otherwise expressly set
forth in this Agreement, the termination provisions of this Section 7 are in
addition to any other relief and remedies available to either Party at law.

7.6                                 Surviving Provisions.  Notwithstanding any
provision herein to the contrary, the rights and obligations of the Parties set
forth in Sections 4.7, 5, 6, 7.3, 7.4, 7.5, 8, 9, 10 and this Section 7.6, as
well as any rights or obligations otherwise accrued hereunder (including any
accrued payment obligations), shall survive the expiration or termination of the
Term of this Agreement. Without limiting the generality of the foregoing,
GENENTECH shall have no obligation to make any milestone or royalty payment to
IMMUNOGEN that has not accrued prior to the effective date of any termination of
this Agreement, but shall remain liable for all such payment obligations
accruing prior to the effective date of such termination.

8.  REPRESENTATIONS AND WARRANTIES

8.1                                 IMMUNOGEN Representations.  IMMUNOGEN
represents and warrants to GENENTECH that:  (a) the execution and delivery of
this Agreement and the performance of the transactions contemplated hereby have
been duly authorized by all appropriate IMMUNOGEN

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

39

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corporate action; (b) this Agreement is a legal and valid obligation binding
upon IMMUNOGEN and enforceable in accordance with its terms, and the execution,
delivery and performance of this Agreement by the Parties does not conflict with
any agreement, instrument or understanding to which IMMUNOGEN is a party or by
which it is bound; (c) IMMUNOGEN has the full right and legal capacity to grant
the licenses and rights to GENENTECH pursuant to Section 2 above without
violating the rights of any Third Party; and (d) to IMMUNOGEN’s knowledge, no
Patent Rights within the Licensed Patent Rights are invalid or unenforceable or
would infringe Patent Rights of Third Parties, and as of the Effective Date no
patents within the Licensed Patent Rights are expired.

8.2                                 GENENTECH Representations.  GENENTECH
represents and warrants to IMMUNOGEN that:  (a) the execution and delivery of
this Agreement and the performance of the transactions contemplated hereby have
been duly authorized by all appropriate GENENTECH corporate action; and (b) this
Agreement is a legal and valid obligation binding upon GENENTECH and enforceable
in accordance with its terms, and the execution, delivery and performance of
this Agreement by the Parties does not conflict with any agreement, instrument
or understanding to which GENENTECH is a party or by which it is bound.

8.3                                 No Warranties.

(a)                                  Nothing in this Agreement is or shall be
construed as:

(i)                                     a warranty or representation by
IMMUNOGEN as to the validity or scope of any patent application or patent within
the Licensed Patent Rights;

(ii)                                  a warranty or representation that anything
made, used, sold or otherwise disposed of under any license granted in this
Agreement is or will be free from infringement of patents, copyrights, and other
rights of third parties.

(b)                                 Except as expressly set forth in this
Agreement, NEITHER PARTY MAKES ANY REPRESENTATIONS OR EXTENDS ANY WARRANTIES OF
ANY KIND, EITHER EXPRESS OR IMPLIED.  THERE ARE NO EXPRESS OR IMPLIED WARRANTIES
OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, THAT ANY LICENSED
PRODUCT WILL BE SUCCESSFULLY DEVELOPED OR MARKETED, OR THAT THE DEVELOPMENT,
MANUFACTURE, SALE, IMPORTATION OR USE OF THE LICENSED PRODUCT(S) WILL NOT
INFRINGE ANY PATENT,

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

40

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COPYRIGHT, TRADEMARK, OR OTHER RIGHTS, OR ANY OTHER EXPRESS OR IMPLIED
WARRANTIES.

8.4                                 Survival. Section 8 shall survive
termination or expiration of this Agreement.

9.  INDEMNIFICATION; LIABILITY

9.1                                 Indemnification.

(a)                                  GENENTECH Indemnity.  Subject to Section
9.1(b) below and the remainder of this Section 9, GENENTECH shall indemnify,
defend and hold harmless IMMUNOGEN, its Affiliates and their respective
directors, officers, employees, and agents and their respective successors,
heirs and assigns (the “Indemnitees”), from and against any liability, damage,
loss or expense (including reasonable attorneys’ fees and expenses of
litigation) incurred by or imposed upon such Indemnitees, or any of them, in
connection with any Third Party claims, suits, actions, demands or judgments,
including, without limitation, personal injury and product liability matters
(but excluding any patent, trademark or tradename infringement matters, which
are governed by Section 6 above), that arise out of or relate to (i) any actions
or omissions of GENENTECH or any Sublicensee in the development, testing,
production, manufacture, supply, promotion, import, sale or use by any person of
any Licensed Product (or any component thereof) manufactured or sold by
GENENTECH or any Sublicensee under this Agreement, (ii) any material breach of
this Agreement by GENENTECH, or (iii) negligence or willful misconduct on the
part of GENENTECH, in any such case under this Section 9.1(a) except to the
extent of IMMUNOGEN’s responsibility therefor under Section 9.1(b) below.

(b)                                 IMMUNOGEN Indemnity.  Subject to Section
9.1(a) above and the remainder of this Section 9, IMMUNOGEN shall indemnify,
defend and hold harmless GENENTECH, its Affiliates and their respective
directors, officers, employees, and agents, and their respective successors,
heirs and assigns (also the “Indemnitees”), from and against any liability,
damage, loss or expense (including reasonable attorneys’ fees and expenses of
litigation) incurred by or imposed upon such Indemnitees, or any of them, in
connection with any Third Party claims, suits, actions, demands or judgments,
including, without limitation, personal injury and product liability matters
(but excluding any patent, trademark or tradename infringement matters, which
are governed by Section 6 above), that arise out of or relate to (i) any actions
or omissions of  IMMUNOGEN or subcontractor of IMMUNOGEN in the

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

41

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development, testing, production, manufacture or supply of any Licensed Product
(or any component thereof) manufactured and supplied by IMMUNOGEN or any
subcontractor of IMMUNOGEN under this Agreement, (ii) any material breach of
this Agreement by IMMUNOGEN, or (iii) negligence or willful misconduct on the
part of IMMUNOGEN, in any such case under this Section 9.1(b) except to the
extent of GENENTECH’s responsibility therefor under Section 9.1(a) above.

9.2                                 Indemnification Procedures.  In the event
that any Indemnitee is seeking indemnification under Section 9.1 above from a
Party (the “Indemnifying Party”), the other Party shall notify the Indemnifying
Party of such claim with respect to such Indemnitee as soon as reasonably
practicable after the Indemnitee receives notice of the claim, and the Party (on
behalf of itself and such Indemnitee) shall permit the Indemnifying Party to
assume direction and control of the defense of the claim (including the right to
settle the claim solely for monetary consideration) and shall cooperate as
requested (at the expense of the Indemnifying Party) in the defense of the
claim.

9.3                                 Liability.  NOTWITHSTANDING ANYTHING ELSE IN
THIS AGREEMENT OR OTHERWISE, NEITHER PARTY WILL BE LIABLE WITH RESPECT TO ANY
SUBJECT MATTER OF THIS AGREEMENT UNDER ANY CONTRACT, NEGLIGENCE, STRICT
LIABILITY OR OTHER LEGAL OR EQUITABLE THEORY FOR (a) ANY INDIRECT, INCIDENTAL,
CONSEQUENTIAL OR PUNITIVE DAMAGES OR LOST PROFITS OR (b) COST OF PROCUREMENT OF
SUBSTITUTE GOODS, TECHNOLOGY OR SERVICES.

9.4                                 Survival. Section 9 shall survive
termination or expiration of this Agreement.

10. MISCELLANEOUS

10.1                           Entire Agreement; Amendments.  This is the entire
Agreement between the Parties with respect to the subject matter herein, and
supersedes any prior agreements, understandings, negotiations or correspondence
between the Parties respecting the subject matter hereof, whether written or
verbal.  No modification or other amendment of this Agreement shall be effective
unless in writing and signed by a fully authorized representative of each Party.

10.2                           Waiver.  The terms or conditions of this
Agreement may be waived only by a written instrument executed by a duly
authorized representative of the Party waiving compliance.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

42

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The failure of either Party at any time or times to require performance of any
provision hereof shall in no manner affect its rights at a later time to enforce
the same.  No waiver by either Party of any condition or term shall be deemed as
a continuing waiver of such condition or term or of another condition or term.

10.3                           Governing Law.  This Agreement will be construed,
interpreted and applied in accordance with the laws of the State of California
applicable to contracts entered into and to be performed entirely within the
State of California.

10.4                           Notices.  Any notices, requests, deliveries,
approvals or consents required or permitted to be given under this Agreement to
GENENTECH or IMMUNOGEN shall be in writing and shall be personally delivered or
sent by telecopy (with machine confirmation of transmission) or by overnight
courier providing evidence of receipt or certified mail, return receipt
requested, postage prepaid, in each case to the respective address specified
below (or to such address as may be specified in writing to the other Party
hereto):

If to IMMUNOGEN:

 

ImmunoGen, Inc.

 

 

128 Sidney Street

 

 

Cambridge, MA 02139-4239

 

 

Attn:  Chief Executive Officer

 

 

Fax: (617) 995-2510

 

 

 

with a copy to

 

Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.

 

 

One Financial Center

 

 

Boston, MA 02111

 

 

Attn: [***], Esq.

 

 

(617) 542-2241

 

 

 

If to GENENTECH:

 

Genentech, Inc.

 

 

1 DNA Way 94080

 

 

South San Francisco, CA 94080

 

 

Attn: Corporate Secretary

 

 

Fax: (650) 467-9146

 

Such notices shall be deemed to have been sufficiently given on:  (a) the date
sent if delivered in person or transmitted by telecopy, (b) the next business
day after dispatch in the case of overnight courier or (c) five (5) business
days after deposit in the U.S. mail in the case of certified mail.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

43

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10.5                           No Implied Licenses.  Except as expressly set
forth elsewhere in this Agreement, neither Party grants to the other Party any
right or license to any of its intellectual property.

10.6                           Headings.  Section and subsection headings are
inserted for convenience of reference only and do not form part of this
Agreement.

10.7                           Assignment.  This Agreement may not be assigned
by either Party without the consent of the other, except that each Party may,
without such consent, assign this Agreement and the rights, obligations and
interests of such Party, in whole or in part, to any of its Affiliates, to any
purchaser of all or substantially all of its assets in the line of business to
which this Agreement pertains or to any successor corporation resulting from any
merger or consolidation of such Party with or into such corporations.

10.8                           Force Majeure.  Neither Party shall be liable for
failure of or delay in performing obligations set forth in this Agreement, and
neither shall be deemed in breach of its obligations, if such failure or delay
is due to natural disasters or any causes beyond the reasonable control of such
Party.  In event of such force majeure, the Party affected thereby shall use
reasonable efforts to cure or overcome the same and resume performance of its
obligations hereunder.

10.9                           Construction.  The Parties hereto acknowledge and
agree that:  (a) each Party and its counsel reviewed and negotiated the terms
and provisions of this Agreement and have contributed to its revision; (b) the
rule of construction to the effect that any ambiguities are resolved against the
drafting Party shall not be employed in the interpretation of this Agreement;
and (c) the terms and provisions of this Agreement shall be construed fairly as
to each Party hereto and not in a favor of or against any Party, regardless of
which Party was generally responsible for the preparation of this Agreement.

10.10                     Severability.  If any provision(s) of this Agreement
are or become invalid, are ruled illegal by any court of competent jurisdiction
or are deemed unenforceable under then current applicable law from time to time
in effect during the term hereof, it is the intention of the Parties that the
remainder of this Agreement shall not be affected thereby provided that a
Party’s rights under this Agreement are not materially affected.  The Parties
hereto covenant and agree to renegotiate any such term, covenant or application
thereof in good faith in order to provide a reasonably acceptable alternative to
the term, covenant or condition of this Agreement or the application thereof
that is invalid, illegal or unenforceable, it being the intent of the Parties
that the basic purposes of this Agreement are to be effectuated.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

44

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10.11                     Status.          Nothing in this Agreement is intended
or shall be deemed to constitute a partner, agency, employer-employee, or joint
venture relationship between the Parties.

10.12                     Dispute Resolution.  The Parties recognize that a bona
fide dispute as to certain matters may from time to time arise during the term
of this Agreement relating to either Party’s rights and/or obligations hereunder
or otherwise relating to the validity, enforceability or performance of this
Agreement, including disputes relating to alleged breach or termination of this
Agreement but excluding any determination of the validity of the Parties’
patents (hereinafter, a “Dispute”).  In the event of the occurrence of any such
Dispute, the Parties pledge to attempt to resolve it amicably.  Accordingly, if
any Dispute should arise, either Party may, by written notice to the other
Party, have such dispute referred to their respective senior officers designated
below (and to any designated officer of a GENENTECH Sublicensee, if such Dispute
involves such Sublicensee), for attempted resolution by good faith negotiations
commencing promptly after such notice is received; provided, however, that if
the subject matter of such Dispute is within the purview of the Collaboration
Committee, the Parties’ representatives on the Collaboration Committee shall
first attempt to resolve such Dispute before referring it to the Parties’ senior
officers hereunder.  Said designated senior officials of the Parties are as
follows:

For GENENTECH:

 

Designated officer with settlement authority; and

 

 

 

For IMMUNOGEN:

 

Chief Executive Officer.

 

In the event the designated senior officials are not able to resolve such
Dispute, the Parties may seek to mediate their Dispute, on terms and with a
mediator mutually agreeable to the Parties, or may seek to arbitrate their
Dispute, on mutually agreed upon terms and conditions, but neither Party shall
be required or obligated to mediate or arbitrate and the dispute resolution
provisions of this Section 10.12 are in addition to any other relief and
remedies available to either Party at law or in equity.

10.13                     Further Assurances.  Each Party agrees to execute,
acknowledge and deliver such further instruments, and to do all other such acts,
as may be necessary or appropriate in order to carry out the purposes and intent
of this Agreement.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

45

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10.14                     Counterparts.  This Agreement may be executed
simultaneously in one or more counterparts, each of which shall be deemed an
original, but all of which together shall constitute one and the same
instrument.

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

[Remainder of page intentionally left blank.]

46

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IN WITNESS WHEREOF, the Parties have caused this Agreement to be executed by
their duly authorized representatives, effective as of the Effective Date set
forth on the first page hereof.

GENENTECH, INC.

 

IMMUNOGEN, INC.

 

 

 

 

 

 

 

 

 

 

 

 

By:

 

 

 

By:

 

 

 

 

 

 

 

 

 

Title:

 

 

 

Title:

 

 

 

 

 

 

 

 

 

 

Date:

 

 

 

Date:

 

 

 

 

Portions of this Exhibit were omitted and have been filed separately with the
Secretary of the Commission pursuant to the Company’s application requesting
confidential treatment under Rule 24b-2 of the Securities Exchange Act of 1934.

47

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