Document:

<PAGE>   1
                                                                   EXHIBIT 10.50

                                  PROVANT, INC.
                        67 BATTERYMARCH STREET, SUITE 400
                           BOSTON, MASSACHUSETTS 02110

                                  June 9, 2000
A. Carl von Sternberg
415 1/2 Prince Street
Alexandria, VA 22314

Dear Carl:

         This letter agreement (the "Agreement") among you (the "Employee"),
PROVANT, Inc. ("PROVANT") and PROVANT's subsidiary, Star Mountain, Inc. (the
"Company"), is intended to set forth the arrangements with respect to the
termination of the Employee's employment with the Company.

        1. Effective March 29, 2000 the Employee resigned from the Executive
Committee of the Board of Directors of PROVANT, and effective May 4, 2000 the
Employee resigned as a member of the Board of Directors of PROVANT. Effective on
the date hereof, the Employee hereby resigns as an officer and director of the
Company and as an officer and director of any of PROVANT's other subsidiaries
for which he serves in such capacities. The Employee hereby resigns effective
July 31, 2000 (the "Termination Date") as an employee of the Company and from
any other position that the Employee may hold with PROVANT or any of its
subsidiaries (PROVANT and its subsidiaries, including the Company, are
collectively referred to herein as the "PROVANT Group"). The Employee and the
PROVANT Group acknowledge and agree that, although the Employee shall remain an
employee of the Company until the Termination Date, he shall not, nor be
required to, take any action on behalf of or have any duties to, any member of
the PROVANT Group or provide any services to any member of the PROVANT Group
(unless requested to do so in writing by an officer of a member of the PROVANT
Group and then, only for such additional compensation as the Employee and such
member may agree). The Employee further acknowledges and agrees that he is not
authorized to incur any expenses on behalf of the Company and shall not be
reimbursed for any such expenses unless such expenses are approved in advance
and in writing by an officer of the Company.

         2. The Employee, the Company and PROVANT (collectively referred to as
the "Parties") agree that the Employment Agreement dated as of May 4, 1998
between the Employee and the Company (the "Employment Agreement") is hereby
terminated as of the Termination Date, except for the provisions of Sections 7
through 23, inclusive, of the Employment Agreement which shall remain in full
force and effect. The Employee

<PAGE>   2

A. Carl von Sternberg
June 9, 2000
Page 2

acknowledges and agrees that he has received payment in full of all amounts due
to the Employee from the PROVANT Group for accrued wages, benefits that are paid
to him (including, without limitation, accrued, unused vacation leave, earned
commissions, and scheduled advances) and any other payments, all as accrued
through May 31, 2000, to which the Employee is entitled in connection with the
Employee's employment with the Company, except for (i) salary for the pay period
ended May 31, 2000 in the amount of $8,076.54 that will be paid on June 15, 2000
and (ii) accrued vacation leave through May 31, 2000 in the amount of $1,262.10.

        3. In consideration for the Employee's execution of and compliance with
this Agreement, the Company agrees to continue to provide the Employee with the
benefits described in the following subparagraphs (a), (b), (c) and (d):

         (a) From the date hereof through the Termination Date, the Company
shall pay the Employee installments of the Employee's base salary at the rate
currently in effect ($175,000 per year) on the same schedule as executives of
the Company then receive regular salary payments.

         (b) The Employee shall continue to receive the benefits that he is
currently entitled to receive under the Employment Agreement through the
Termination Date, on which date all such benefits shall cease. These benefits
will, as of July 31, 2000 include:

         (i)    vacation pay - $1,824.41;
         (ii)   holiday (7/4/00) - $673.12;
         (iii)  deferred compensation - 10% of salary;
         (iv)   car lease - $1,399.03 and use of the leased car;
         (v)    car insurance (2 cars) - $208.33;
         (vi)   recreational expenses (hunting, fishing, etc.) - $4,166.67; and
         (vii)  premiums on all life insurance policies referred in Schedule 2
                of the Employment Agreement (as already paid).

         PROVANT and the Company represent and warrant that life insurance
premiums covering a period ending no earlier than the Termination Date have
already been paid with respect to all insurance policies referred to in Schedule
2 to the Employment Agreement. All benefits described in this paragraph (b)
shall be paid in accordance with the Company's normal procedures, but in no
event later than ten (10) business days after the Termination Date.

         (c) After the Termination Date, the Company will offer the Employee the
opportunity to continue to participate in its group medical insurance program
(the "Health Plan") pursuant

                                       -2-
<PAGE>   3

A. Carl von Sternberg
June 9, 2000
Page 3

to the health care continuation provisions of the federal COBRA law. The
Employee's eligibility to participate in and receive benefits under the Health
Plan shall remain subject to the terms and conditions of the Health Plan.

         (d) PROVANT and the Company represent, warrant and covenant that the
Employee is covered by the PROVANT's directors and officers liability insurance
policy to the same extent as other directors of PROVANT who were or are officers
of subsidiaries and that he will remain so covered as long as such insurance is
maintained by PROVANT.

        4. The Employee agrees that all source code, object code, memoranda,
notes, records, charts, reports, letters and other documents and software made,
compiled, received, held or used by the Employee while employed by the Company,
concerning any phase of the business of the Company or the PROVANT Group, are
the property of the Company or the PROVANT Group, as the case may be, and,
together with all reproductions or abstracts thereof and together with all
Company or PROVANT Group credit cards and keys, will be returned to the Company
on or before the Termination Date.

        5. The Employee hereby acknowledges and agrees that this Agreement is
intended to be a complete and final settlement of any and all causes of action
or claims that the Employee has had, now has or may now have, whether known or
unknown against the PROVANT Group or any of the persons or entities specified
below. Effective on the Effective Date (as defined in Section 13) and subject to
the continued effectiveness of this Agreement), the Employee hereby, on behalf
of the Employee, the Employee's executors, heirs, administrators, assigns and
anyone else claiming by, through or under the Employee, waives, releases,
covenants not to sue and forever discharges the PROVANT Group, its predecessors,
successors, related corporations, subsidiaries, divisions and affiliated
organizations, and each and all of their present and former officers, directors,
shareholders, representatives, agents, promoters, employees and attorneys
(hereinafter "PROVANT Releasees"), and each and all of them of, from and with
respect to any and all debts, demands, actions, causes of action, suits,
covenants, contracts, agreements, promises, torts, damages, claims, demands and
liabilities whatsoever of any name and nature, both in law and in equity
(hereinafter "Claims") which the Employee now has, ever had, or may in the
future have against each or any of the PROVANT Releasees by reason of any
matter, cause or thing whatsoever from the beginning of the world to the date of
this Agreement, including, but not limited to, any Claims arising out of, based
upon or connected with the Employee's engagement and/or employment by the
Company, the compensation, benefits and working conditions for that employment
and/or the termination of that employment, the acquisition by PROVANT of Star
Mountain, Inc., a Virginia corporation, pursuant to the Agreement and Plan of
Merger dated as of May 4, 1998 among PROVANT, the Company, Star Mountain, Inc.,
a Virginia corporation, the Employee and

                                       -3-
<PAGE>   4

A. Carl von Sternberg
June 9, 2000
Page 4

certain other individuals (the "Merger Agreement"), or any transactions related
thereto, and any Claims that may exist under federal, state or local laws,
including, but not limited to, any Claims based on race, disability, color,
national origin, marital status, age or sex; provided, however, that nothing
herein shall be construed as a waiver or release by the Employee of (i) any
surviving indemnity obligations of the Company or PROVANT under the Merger
Agreement or Section 10 of the Employment Agreement or (ii) any claims that the
Employee may have for breach of this Agreement by the Company or PROVANT. The
foregoing waiver and release includes, without limitation, a waiver and release
of any rights and Claims that Employee may have under Title VII of the Civil
Rights Act of 1964, the Equal Pay Act, the Americans with Disabilities Act, the
Family and Medical Leave Act, the Employee Retirement Income Security Act of
1974, the Worker Adjustment and Retraining Notification Act, the Age
Discrimination in Employment Act of 1967, as amended, 29 U.S.C. Section 621 et
seq. (the "ADEA") (except that this Agreement does not waive or release any
rights or claims under the ADEA that may arise after the execution of this
Agreement or otherwise bar the Employee from challenging this Agreement's
compliance with the provisions of 29 U.S.C. Section 627(f)(1)), the Fair Labor
Standards Act, the state and local laws of Massachusetts and Virginia.

         6. PROVANT and the Company hereby acknowledge and agree that this
Agreement is intended to be a complete and final settlement of any and all
causes of action or claims that any member of the PROVANT Group has had, now has
or may now have, whether known or unknown against the Employee or any of the
persons or entities specified below. Effective on the Effective Date (as defined
in Section 13) and subject to the continued effectiveness of the this Agreement,
each of PROVANT (on behalf of itself and the other members of the PROVANT Group)
and the Company for themselves and their past, present and future affiliates
hereby waives, releases, covenants not to sue and forever discharges the
Employee and the Employee's executors, heirs, administrators and assigns
(collectively, the "Employee Releasees"), and each and all of them of, from and
with respect to any and all Claims which any member of the PROVANT Group
(including PROVANT and the Company) now has, ever had, or may in the future have
against each or any of the Employee Releasees by reason of any matter, cause or
thing whatsoever from the beginning of the world to the date of this Agreement,
including, but not limited to, any Claims arising out of, based upon or
connected with the Employee's engagement and/or employment by the Company, the
acquisition by PROVANT of Star Mountain, Inc., a Virginia corporation, pursuant
to the Merger Agreement, any transactions related thereto or any Claims that may
exist under federal, state or local laws; provided, however, that nothing herein
shall be construed as a waiver or release by either PROVANT or the Company of
(i) any surviving indemnity obligations of the Employee Releasees under the
Merger Agreement, (ii) any claims or rights under the provisions of Sections 7,
8 or 9 of the Employment Agreement, (iii) any claims or rights under the
Employee's Non-Competition and Non-Disclosure Agreement dated May 4, 1998 (the
"Non-

                                      -4-
<PAGE>   5

A. Carl von Sternberg
June 9, 2000
Page 5

Comp. Agreement"), (iv) any claims for theft or embezzlement in connection
with the Employee's employment by the Company or (v) any claims for personal
charges made on the Employee's corporate credit card since April 1, 2000.

        7. Unless previously disclosed by any member of the PROVANT Group, the
Employee hereby agrees not to disclose to any person (except the Employee's
spouse, attorney or financial advisor), organization or agency the terms of this
Agreement except as required by law and then only after notice is given by the
Employee or the Employee's attorney to the Company such that, where feasible,
the Company will have a reasonable prior opportunity to oppose such disclosure.
The Employee also acknowledges and agrees that the restrictions against
disclosure and use of confidential and/or proprietary information set forth in
Section 8 of the Employment Agreement shall survive the Termination Date and
shall remain in full force and effect. The Employee further acknowledges and
agrees that the non-competition and non-solicitation restrictions set forth in
Section 7 of the Employment Agreement shall survive the Termination Date and
remain in full force and effect until May 4, 2003. The Employee hereby reaffirms
the Employee's obligations under Sections 7 and 8 of the Employment Agreement.
The Employee further acknowledges and agrees that the non-competition,
non-solicitation and non-disclosure restrictions set forth in the Non-Comp.
Agreement remain in full force and effect until May 4, 2003. PROVANT and the
Company reaffirm the Employee's continuing right to own and manage Allen
Corporation, so long as Allen Corporation does not engage in conduct that would
violate Section 7 of the Employment Agreement or Section 1 of the Non-Comp.
Agreement.

        8. The Company and the Employee each agree with the other not to discuss
with any person or entity the circumstances surrounding the Employee's
employment with or separation from the Company, except to the extent required by
law. The Employee agrees not to make any adverse remarks whatsoever concerning
the business, operations, strategies, policies, prospects, affairs and financial
condition of the Company. The Company agrees that it will not make any adverse
remarks whatsoever concerning the Employee and that it will instruct its
officers not to make any adverse remarks whatsoever concerning the Employee. The
Company and the Employee agree that any public disclosure of this Agreement or
of the circumstances of the Employee's departure from the Company shall be
agreed upon by both parties prior to its disclosure, other than disclosure
required by law, including, without limitation, applicable securities laws.
Nothing in this Section 8 shall limit the right of the Employee to discuss any
matters mentioned in this Section 8 with his spouse or any professional advisor.

        9. It is expressly understood and agreed that by entering into this
Agreement, the Company in no way thereby admits that it unlawfully or wrongfully
discriminated against the Employee due to the Employee's age or status or
otherwise treated the Employee unlawfully.

                                       -5-
<PAGE>   6

A. Carl von Sternberg
June 9, 2000
Page 6

       10. All payments to be made to the Employee and benefits to be made
available to the Employee in accordance with the terms of this Agreement, and
the performance by the Company of its other obligations hereunder, shall be
conditioned on the Employee's continued compliance with the covenants set forth
in this Agreement and the surviving provisions of the Employment Agreement. The
performance by the Employee of his obligations hereunder shall be conditioned on
the PROVANT Group's continued compliance with the covenants set forth in this
Agreement and the surviving portions of the Employment Agreement and the Merger
Agreement. Nothing in this Section 10, however, shall affect the releases of the
parties in Sections 5 and 6 of this Agreement.

       11. The Company and the Employee agree that irreparable damages would
occur in the event that Sections 4, 5, 6, 7 and 8 of this Agreement are not
performed by the party obligated thereunder in accordance with their specific
terms. It is accordingly agreed that the other party will be entitled to an
injunction or injunctions to prevent breaches of the party obligated thereunder
and to enforce specifically the terms and provisions hereof in any court having
jurisdiction, this being in addition to any other remedy to which it is entitled
at law or in equity.

       12. If any term or provision of this Agreement or the application thereof
to any person, property or circumstance shall to any extent be invalid or
unenforceable, then at the election of the party primarily benefitted by such
term or provision, the remainder of this Agreement or the application of such
term or provision to persons, property or circumstances other than those as to
which it is invalid or unenforceable shall not be affected thereby, and each
term and provision of this Agreement shall be valid and enforced to the fullest
extent permitted by law.

       13. The Employee acknowledges that the Employee has been given a full and
fair opportunity to consider this Agreement, that he understands the provisions
of this Agreement, and that his acceptance and execution of this Agreement are
knowing and voluntary. The Employee is hereby advised to consult with an
attorney before signing this Agreement and, by the Employee's signature below,
the Employee acknowledges that the Employee has consulted with an attorney
before signing this Agreement. From the date that the Employee receives this
Agreement, the Employee has twenty-one (21) days to consider it. Should the
Employee decide to sign the Agreement, the Employee has seven (7) days following
the signing to revoke the Agreement, and the Agreement will not become effective
and enforceable until the eighth (8th) day after the Employee signs this
Agreement, provided that before such day the Employee has not revoked this
Agreement (the "Effective Date"). Should the Employee either decide not to sign
this Agreement or should the Employee sign it and elect to revoke it during the
seven (7) day revocation period, then this Agreement shall be null and void.

                                       -6-
<PAGE>   7

A. Carl von Sternberg
June 9, 2000
Page 7

       14. This Agreement shall be governed by and construed in accordance with
the laws of the Commonwealth of Massachusetts without regard to conflicts of law
principles. The obligations of the Company and the Employee hereunder shall
inure to the benefit of and be binding on the respective heirs, personal
representatives, successors and assigns of the Parties. This Agreement embodies
the entire agreement and understanding between the Employee and the PROVANT
Group (including PROVANT and the Company) concerning the Employee's employment
and the termination thereof and incorporates and supersedes all other agreements
with regard to the Employee's employment and the termination thereof. This
Agreement shall not affect the Employee's or any member of the PROVANT Group's
surviving obligations under the Employment Agreement, the Merger Agreement, the
Employee's Investment Representation Letter to PROVANT dated May 4, 1998 and the
Non-Comp. Agreement.

       15. This Agreement may be amended or modified only upon the written
mutual consent of the Parties.

         If the foregoing is in accordance with your understanding, please sign
and return the enclosed copy of this letter, whereupon this letter and such copy
will constitute a binding agreement under seal between you and each member of
the PROVANT Group on the basis set forth above.

                              Very truly yours,

                              PROVANT, INC., for itself and on behalf of
                                  the PROVANT Group

                              By: /s/ Curtis M. Uehlein
                                  ---------------------------------------------
                                  Name: Curtis M. Uehlein
                                  Title:  President and Chief Executive Officer

                                       -7-
<PAGE>   8

A. Carl von Sternberg
June 9, 2000
Page 8

                              STAR MOUNTAIN, INC.

                              By: /s/ Timothy S. Schimkus
                                  ---------------------------------------------
                                  Name:  Timothy S. Schimkus
                                  Title:  Treasurer

Agreed to and accepted this
____ day of __________, 2000:

/s/ A. Carl von Sternberg
-------------------------------
A. Carl von Sternberg

                                       -8-<PAGE>   1
                                                                   Exhibit 10.51

                                                                Redacted Version

                                LICENSE AGREEMENT

     This License Agreement ("Agreement") is made effective as of May 2, 2000
(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 333 Providence Highway, Norwood,
Massachusetts 02062 ("IMMUNOGEN"). GENENTECH and IMMUNOGEN are each hereafter
referred to individually as a "Party" and together as the "Parties".

     WHEREAS, GENENTECH is the owner of or otherwise controls certain rights in
proprietary technology and know-how relating to anti-HER2 antibodies and other
HER-2 binding proteins; and

     WHEREAS, IMMUNOGEN is the owner of or otherwise controls certain rights in
proprietary technology and know-how relating to or otherwise useful in the
conjugation of maytansine derivatives such as DM1 to binding proteins;

     WHEREAS, pursuant to an MTA (as defined below), IMMUNOGEN performed certain
work using a biologic materials of GENENTECH to create a conjugated compound,
which work under the MTA is part of what is covered by this Agreement; and

     WHEREAS, on the terms and conditions set forth herein, GENENTECH desires to
obtain from IMMUNOGEN, and IMMUNOGEN desires to grant to GENENTECH, the rights
set forth herein, including a license under IMMUNOGEN'S technology and/or
intellectual property rights to develop and commercialize one or more Licensed
Products (as defined below).

     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.

     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

<PAGE>   2
                       CONFIDENTIAL TREATMENT REQUESTED.
CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

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 License 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 [*] functions which are allocated to company
departments based on [*] or [*] or another [*] method, and shall include the [*]
as defined hereinbelow. For purposes of any given calculation of "Allocable
Overhead" hereunder, the [*] of the total amount of Allocable Overhead (as
calculated before the inclusion of any such fee). However, "Allocable Overhead"
[*]

     1.5. "ANTI-HER2 ANTIBODY" shall mean [*].

     1.6. "BLA" shall mean a biologics license 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.

     1.7. "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

                                       2
<PAGE>   3

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.

     1.8. "COMBINATION PRODUCT" shall mean any Licensed Product that contains,
in addition to any conjugate of any Anti-HER2 Antibody with any MAY Compound,
one or more other ingredients that has biologic activity as a therapeutic agent
when present alone.

     1.9. "COMPETING PRODUCT" shall have the meaning set forth in Section
2.1(b).

     1.10. "CONFIDENTIAL INFORMATION" shall have the meaning set forth in
Section 5.1.

     1.11. "CONTROL" or "CONTROLLED" shall mean, with respect to any Patent
Rights or Technology (including, without limitation, any MAY Compound, Anti-HER2
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.

     1.12. "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.

     1.13. "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 limitation, (a) any BLA, 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.

                                       3
<PAGE>   4
                       CONFIDENTIAL TREATMENT REQUESTED.
CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

     1.14. "EFFECTIVE DATE" shall mean the date first written above in the
introductory paragraph to this Agreement.

     1.15. "EXTENDED INDICATIONS" shall mean any and all human uses for the
indications of [*]. However, "Extended Indications" shall not include any human
therapeutic use for the indication of metastatic breast cancer.

     1.16. "FDA" shall mean the United States Food and Drug Administration and
any successor agency or authority thereto.

     1.17. "FIELD" shall mean any and all human uses, including, without
limitation, for the indication of metastatic breast cancer and/or any Extended
Indications.

     1.18. "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.

     1.19. "FOREIGN REGULATORY AUTHORITIES" 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.

     1.20. "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.

     1.21. "GENENTECH" shall mean Genentech, Inc., a Delaware corporation, and
its successors and permitted assigns under this Agreement.

     1.22. "GENENTECH PRODUCT" shall have the meaning set forth in Section
2.1(b).

     1.23. "GLPS" shall mean all good laboratory practices under Title 21 of the
United States Code of Federal Regulations, as amended from time to time.

                                       4
<PAGE>   5

     1.24. "GMPS" shall mean all good manufacturing practices under Title 21 of
the United States Code of Federal Regulations, as amended from time to time.

     1.25. "HER2 PRODUCT" shall have the meaning set forth in Section 2.3(b).

     1.26. "IMMUNOGEN" shall mean ImmunoGen, Inc., a Massachusetts corporation,
and its successors and permitted assigns under this Agreement.

     1.27. "IMPROVEMENT" shall mean any enhancement, improvement or modification
created or identified by GENENTECH under this Agreement or by IMMUNOGEN under
this Agreement or otherwise, to the extent covered by or under the Licensed
Patent Rights or the Licensed Technology.

     1.28. "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.

     1.29. "IND ACCEPTANCE" shall mean the expiration of thirty (30) days
following receipt by GENENTECH of a notice from the FDA to GENENTECH (or its
Sublicensee) that the FDA has received an IND for a Licensed Product filed by
GENENTECH (or its Sublicensee) for the purpose of obtaining approval or
authority to commence human clinical trials in the United States with such
Licensed Product; PROVIDED, HOWEVER, that if the FDA puts a clinical hold on the
IND during such thirty (30) day period, the term "IND Acceptance" shall mean
that date during the term of this Agreement when GENENTECH (or its Sublicensee)
receives written confirmation from the FDA that the clinical hold has been
removed and that GENENTECH (or its Sublicensee) has the approval or authority to
commence human clinical trials of such Licensed Product under such IND in the
United States. Notwithstanding anything set forth herein, "IND Acceptance" shall
not be deemed to have occurred in any circumstances where GENENTECH (or its
Sublicensee) withdraws any IND filed with the FDA for a Licensed Product at any
time prior to the commencement of human clinical trials with such Licensed
Product in the United States.

     1.30. "INDEMNITEES" and "INDEMNIFYING PARTY" shall have the meanings set
forth in Section 9.

     1.31. "JOINT PROCESS DEVELOPMENT COMMITTEE" or "JPDC" shall mean the
committee with representatives of each Party established as set forth in Section
3.4.

     1.32 "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 (including

                                       5
<PAGE>   6

IMMUNOGEN's interest in any such Patent Rights conceived or reduced to practice
or arising from any work under the MTA) 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) or any Improvement 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 SCHEDULE I attached hereto and
incorporated herein. SCHEDULE I shall be updated by IMMUNOGEN by written notice
to GENENTECH on a semi-annual basis during the term of this Agreement, beginning
six (6) months after the Effective Date, to include any Licensed Patent Rights
that have arisen in the period since the Effective Date or since the last update
to SCHEDULE I. If IMMUNOGEN fails to update SCHEDULE I on a timely basis as
provided herein, IMMUNOGEN shall update SCHEDULE I within thirty (30) days after
any written request from GENENTECH to do so.

     1.33 "LICENSED PRODUCT" shall mean any product containing any conjugate of
any Anti-HER2 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) and any
HER2 Product.

     1.34 "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 (including IMMUNOGEN's interest
in any such Technology conceived or reduced to practice or arising from any work
under the MTA) 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 (or any component thereof, including any linker) or any
unpatented Improvement in the Field in the Territory. The Licensed Technology as
of the Effective Date includes, without limitation, the materials, information
and documentation set forth in SCHEDULE II attached hereto and incorporated
herein.

     1.35 "MAA" shall mean an application filed with the relevant Foreign
Regulatory Authorities 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.

     1.36 "MAY COMPOUND" shall mean any and all maytansinoid compounds
(including, without limitation, maytansine, ansamitocin P-3 and DM1), whether
produced by a botanical

                                       6
<PAGE>   7

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.

     1.37 "MTA" shall mean that certain Material Transfer Agreement, dated as of
March 29, 1999, between the Parties.

     1.38 "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.

     1.39 "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 Licensed Product is consumed by the Sublicensee.

                                       7
<PAGE>   8

     1.40 "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.

     1.41 "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.

     1.42 "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 a BLA or NDA to obtain Regulatory Approval to market and sell that
Licensed Product in the United States for the indication under investigation in
such study.

     1.43 "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 a BLA or NDA to obtain Regulatory Approval to market and sell that
Licensed Product in the United States for the indication under investigation.

     1.44 "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.

     1.45 "REGULATORY APPROVAL" shall mean any and all approvals (including
pricing and reimbursement approvals), product and establishment licenses,
registrations or authorizations of

                                       8
<PAGE>   9

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 BLA, NDA, MAA or other Drug Approval
Application.

     1.46 "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.

     1.47 "SUBLICENSEE" shall have the meaning set forth in Section 2.2, and
"MATERIAL SUBLICENSEE" shall have the meaning set forth in Section 3.3.

     1.48 "TARGET" shall have the meaning set forth in Section 2.1(b).

     1.49 "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.

     1.50 "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).

     1.51 "TERRITORY" shall mean all countries and jurisdictions of the world.

     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

                                       9
<PAGE>   10
                       CONFIDENTIAL TREATMENT REQUESTED.
CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

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 and IMMUNOGEN's
interest in any Improvements, 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. IMMUNOGEN and GENENTECH hereby
acknowledge and agree that this Agreement constitutes the worldwide exclusive
license relating to Licensed Products as to which IMMUNOGEN afforded GENENTECH
an exclusive option under the MTA.

          (b) LICENSE TO IMMUNOGEN. [*]

     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 GENENTECH shall remain obligated to
ensure payment of milestone and royalty obligations as set forth in Section 4.

     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 and
to use IMMUNOGEN's interest in all Improvements (i) to perform its work under
Sections 3.3, 3.4, 3.5 and 3.6 hereof relating to the Joint Process Development
Committee and to manufacture and supply of Preclinical Materials and Clinical
Materials for GENENTECH (and its Sublicensees), (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,
subject to Section 2.3(b) below,

                                       10
<PAGE>   11
                       CONFIDENTIAL TREATMENT REQUESTED.
CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

and (iii) to otherwise exploit such Improvements for any and all uses
outside of the Field, subject to Section 2.3(b) below.

          (b) COVENANTS. [*]

          (c) NO RIGHTS TO GENENTECH TECHNOLOGY OR PATENT RIGHTS. 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, GENENTECH shall
have full control and authority over 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 studies, any Phase II Clinical Studies or any Phase III Clinical
Trials), (iii) all activities relating to manufacture and supply of all
Anti-HER2 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 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

                                       11
<PAGE>   12

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 (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.

                                       12
<PAGE>   13

     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 but not limited to Herceptin(R) (trastuzumab))
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. 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

                                       13
<PAGE>   14

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 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 thirty (30) days after the Effective
Date IMMUNOGEN shall deliver to GENENTECH the materials, documentation and other
information set forth on SCHEDULE II.

     3.4  JOINT PROCESS DEVELOPMENT COMMITTEE.

                                       14
<PAGE>   15

          (a) MANDATE AND ESTABLISHMENT OF COMMITTEE. Promptly after the
Effective Date, the Parties shall form a "JOINT PROCESS DEVELOPMENT COMMITTEE"
or "JPDC" whose mandate shall be to serve as a forum for coordination and
communication between the Parties with respect to Development of manufacturing
processes applicable to any MAY Compound or Licensed Product covered by this
Agreement (including, without limitation, all process science and process
development work, formulation work, and quality control/ assurance work
hereunder), to assist GENENTECH in its exercise of its rights to make or have
made Licensed Products under this Agreement. Within thirty (30) 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
JPDC. 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
JPDC shall be fully considered by the JPDC; PROVIDED, HOWEVER, that all
decisions of the JPDC shall be subject to final approval by GENENTECH.

          (b) CHAIR OF COMMITTEE; MEETINGS. The chair of the JPDC shall be one
of the GENENTECH representatives on the JPDC, as designated by GENENTECH;
PROVIDED, HOWEVER, that during the first twelve (12) months after the Effective
Date, the JPDC shall be co-chaired by a GENENTECH representative on the JPDC (as
designated by GENENTECH) and an IMMUNOGEN representative on the JPDC (as
designated by IMMUNOGEN). All decisions of the JPDC shall be subject to the
approval of the GENENTECH chair (including during the period when there is a
co-chair from IMMUNOGEN). The JPDC 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 JPDC determine that there is no need for a meeting. In such instance, the
next JPDC meeting shall also be scheduled as agreed upon by the Parties. The
location of meetings of the JPDC shall alternate between IMMUNOGEN's offices in
Massachusetts and GENENTECH's offices in California, unless otherwise agreed by
the Parties. As agreed upon by the Parties, JPDC meetings may be face-to-face or
may be conducted through teleconferences and/or videoconferences. In addition to
its JPDC 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 JPDC representatives or other of
its attendees at JPDC meetings, as a result of such meetings hereunder. Minutes
of each JPDC meeting will be transcribed and issued to members of the

                                       15
<PAGE>   16
                       CONFIDENTIAL TREATMENT REQUESTED.
CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

JPDC 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
JPDC. 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 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

                                       16
<PAGE>   17
                       CONFIDENTIAL TREATMENT REQUESTED.
 CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

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 Phase II Clinical Studies.
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 JPDC. 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 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 assume all liability for
damages that may arise from the use, storage and disposal 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 JPDC with written notice
of such determination, along with the estimated price for such purchase and
quality parameters for the equipment or instruments, for the JPDC's approval of
such price and features. Promptly after the consummation of such purchase,
assuming that the JPDC 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 thirty (30) days of its receipt

                                       17
<PAGE>   18
                       CONFIDENTIAL TREATMENT REQUESTED.
 CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

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.

                            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 within thirty (30) days
after the first achievement of each of the milestones set forth below:

     Milestone                         Milestone Payment
     ---------                         -----------------

     Effective Date                       $2 Million

     [*]

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

          4.1.2 [*]

     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 [*]:

                                       18
<PAGE>   19
                       CONFIDENTIAL TREATMENT REQUESTED.
 CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

FOR NET SALES OF A LICENSED PRODUCT
[*] IN ANY CALENDAR YEAR
DURING THE TERM:                              ROYALTY RATE (% OF NET SALES)

[*]

FOR NET SALES OF A LICENSED PRODUCT
[*] IN ANY CALENDAR YEAR
DURING THE TERM:                              ROYALTY RATE (% OF NET SALES)

[*]

[*].

          4.2.2 [*]. Subject to the other terms of this Agreement, on a
country-by-country basis, the [*] as provided in this Section 4.2.2:

          (a) [*].

          (b) [*]. If GENENTECH is [*].

          (c) [*]. If GENENTECH determines [*].

          (d) [*]. The [*] in Section 4.2.2(c) above is [*] under Section
4.2.2(b) above, but each is [*] set forth in this Section 4.2.2(d) as follows.
No [*] under this Section 4.2.2, [*] IMMUNOGEN thereunder,[*].

          4.2.3 [*]. In consideration of the grant of the license by IMMUNOGEN
hereunder, and subject to the other terms of this Agreement (including the other
terms of this Section 4):

          (a) [*]. Notwithstanding anything set forth in Section 4.2.1 above,
[*] set forth therein shall apply, [*] Subject to the other terms of this
Agreement (except for Section 4.2.2 above, which shall not apply), on a [*]
Section 4.2.1 [*] of this Section 4.2.3(a), GENENTECH [*].

          (b) [*]. Notwithstanding anything set forth in Section 4.2.1 above,
the [*] set forth in Section 4.2.1 above [*]. Subject to the other terms of this
Agreement (except for Section 4.2.2, which shall not apply), on a [*] under
Section 4.2.1 [*] this Section 4.2.3(b), [*]; PROVIDED, HOWEVER, [*] this
Section 4.2.3(b) [*].

          4.2.4 [*]. In determining [*] of any [*] under this Agreement, [*]
shall first [*] in accordance with the definition of "Net Sales" above, [*].

                                       19
<PAGE>   20
                       CONFIDENTIAL TREATMENT REQUESTED.
 CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

     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 [*], import and have imported such Licensed Product in such
country.

     4.5  PAYMENT TERMS.

          (a) PAYMENT OF MILESTONES; PAYMENT OF ROYALTIES; ROYALTY REPORTS.
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, [*] 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 shipped
or (ii) the date of the invoice to the purchaser 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 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

                                       20
<PAGE>   21
                       CONFIDENTIAL TREATMENT REQUESTED.
 CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

              published in the western edition of the Wall Street Journal, or
              any other mutually agreed upon source, for the last business day
              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.

          (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 one percent (1%) 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 [*] 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.

                                       21
<PAGE>   22
                       CONFIDENTIAL TREATMENT REQUESTED.
CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

          (b) FULLY BURDENED MANUFACTURING COSTS. Commencing as of the Effective
Date, IMMUNOGEN shall keep for at least [*] 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 ten (10) 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 three (3) 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 [*] 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 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 [*] 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

                                       22
<PAGE>   23
                       CONFIDENTIAL TREATMENT REQUESTED.
CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

rate provided in Section 4.6 above), and if such overpayment is by [*] or more,
IMMUNOGEN shall pay all costs and expenses of the review.

                                       23
<PAGE>   24

                    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 ten (10) 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, 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.

                                       24
<PAGE>   25

     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 thirty (30) days prior to the proposed date of submission
to a publisher, 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 thirty (30)-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, it will give reasonable advance notice of the
need for such disclosure and will use its commercially reasonable efforts to
secure confidential treatment (if available) 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.

                                       25
<PAGE>   26

          (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. The Parties shall mutually agree
on the text of any press release announcing the execution of this Agreement and
on any confidential treatment request(s) to be filed with the Securities and
Exchange Commission with respect to this Agreement. 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 without
the further approval of the other Party. 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, including, without limitation, the confidentiality provisions of the
MTA, of that certain Confidentiality Agreement effective November 5, 1996, and
of that certain Confidentiality Agreement effective April 8, 1998. Any
confidential information of a Party under any such agreement shall be treated as
Confidential Information of such Party hereunder, subject to the terms of this
Section 4 (including, without limitation, the data and results from the work
under the MTA, which are considered GENENTECH's Confidential Information as
provided under the MTA and under this Agreement). Section 4 shall survive
termination or expiration of this Agreement.

              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 (or under the MTA) 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 (or under the MTA) solely by
employees of or agents or others obligated to assign inventions to GENENTECH.
The

                                       26
<PAGE>   27

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 (or under the MTA)
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 thirty (30) days after such Party receives such disclosure from its
employees, agents or others obligated to assign inventions to such Party.

     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 thirty (30) days), and (ii)
will keep GENENTECH reasonably informed of the status of such filing,
prosecution and maintenance, including, without limitation,

                                       27
<PAGE>   28
                       CONFIDENTIAL TREATMENT REQUESTED.
CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

(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. [*] If IMMUNOGEN fails to
undertake the filing(s) of any patent application with respect to any invention
under such Licensed Patent Rights within ninety (90) 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.

          (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

                                       28
<PAGE>   29

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 ninety (90) 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.

     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 one hundred twenty (120) 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

                                       29
<PAGE>   30
                       CONFIDENTIAL TREATMENT REQUESTED.
CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

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, [*] to
GENENTECH and [*] to IMMUNOGEN, (B) if IMMUNOGEN is the Party bringing such suit
or proceeding or taking such other legal action, [*] to IMMUNOGEN and (C) if the
suit is brought jointly, [*] 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, 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

                                       30
<PAGE>   31
                       CONFIDENTIAL TREATMENT REQUESTED.
CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

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. This Section 6 supersedes any agreement between the
Parties as to the subject matter hereof, including, without limitation, the
provisions of MTA relating to inventions, patent applications and patents.
Section 6 shall survive termination or expiration of this Agreement.

                             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 [*] 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 payment breach by
GENENTECH under this Agreement, the applicable cure period shall be [*] 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

                                       31
<PAGE>   32
                       CONFIDENTIAL TREATMENT REQUESTED.
 CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

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 sixty (60) 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 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 [*]
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

                                       32
<PAGE>   33
                       CONFIDENTIAL TREATMENT REQUESTED.
 CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

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 [*] 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 [*] 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 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, in lieu of any
payments including milestones or royalties it would otherwise owe to IMMUNOGEN
under this Agreement, a royalty equal to [*] 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

                                       33
<PAGE>   34

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 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

                                       34
<PAGE>   35

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, 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

                                       35
<PAGE>   36
                       CONFIDENTIAL TREATMENT REQUESTED.
 CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

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 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  [*]

     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 (including,
without limitation, the MTA, that certain Confidentiality Agreement effective
November 5, 1996, and that certain Confidentiality Agreement effective April 8,
1998). 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. The failure of either Party at any time or times to
require performance of any provision hereof

                                       36
<PAGE>   37

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.
                     333 Providence Highway
                     Norwood, MA 02062
                     Attn:   Chief Executive Officer
                     Fax: (781) 255-9679

with a copy to       Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
                     One Financial Center
                     Boston, MA 02111
                     Attn: Jeffrey M. Wiesen, Esq.
                     (617) 542-2241

If to GENENTECH:     Genentech, Inc.
                     1 DNA Way 94080
                     South San Francisco, CA 94080
                     Attn: Corporate Secretary
                     Fax: (650) 952-9881

     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.

     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.

                                       37
<PAGE>   38

     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.

     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.

                                       38
<PAGE>   39

     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 Joint Process
Development Committee, the Parties' representatives on the JPDC 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.

     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.

                                       39
<PAGE>   40

     IN WITNESS WHEREOF, the Parties have caused this Agreement to be executed
by their duly authorized representative in two (2) originals.

GENENTECH, INC.                         IMMUNOGEN, INC.

By: ______________________________      By: ______________________________
Title: ___________________________      Title: ___________________________

                                       40
<PAGE>   41
                       CONFIDENTIAL TREATMENT REQUESTED.
 CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

                                   SCHEDULE I

                             LICENSED PATENT RIGHTS

[*]

                                       41

<PAGE>   42
                       CONFIDENTIAL TREATMENT REQUESTED.
 CONFIDENTIAL PORTIONS INDICATED BY "*", HAVE BEEN OMITTED AND FILED SEPARATELY
                  WITH THE SECURITIES AND EXCHANGE COMMISSION

                                   SCHEDULE II

                           CERTAIN LICENSED TECHNOLOGY

[*]

                                       42

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00015-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00015-of-00352.parquet"}]]