<PAGE>

                                                                    Exhibit 10.1

                           AMENDED LICENSE AGREEMENT
                           -------------------------

          THIS AGREEMENT ("Agreement") entered into as of the 20th day of
December, 1999 ("Effective Date"), by and between:

Ludwig Institute for Cancer Research, a Swiss not-for profit corporation, having
an office at 605 Third Avenue, New York, New York 10158 ("LICR"); and

Magainin Pharmaceuticals, Inc., a Delaware Corporation having an office at 5110
Campus Drive, Plymouth Meeting, PA 19462 ("MPI").

                                  WITNESSETH
                                  ----------

          WHEREAS, on December 20, 1996, LICR and MPI entered into a license
agreement in relation to the cytokine IL-9 and its receptor (the "Initial
License Agreement") and now desire to revise and amend said agreement in this
"Amended License Agreement;"

          WHEREAS, LICR has granted licenses to Peprotech Inc., Pharmingen,
Genzyme Corporation and R&D Systems to make, use, import, offer to sell and sell
IL-9 and/or its receptors and/or antibodies to IL-9 and its receptor for
research purposes only and to Innogenetics, N.V. for research and diagnostic
purposes only (the "Prior Licenses");

          WHEREAS, LICR has acquired certain IL-9 patent rights from Genetics
Institute, Inc. ("GI") and has granted GI an option to license IL-9 for
therapeutic use (the "GI Option");

          WHEREAS, on December 20, 1996, LICR and MPI entered into a
collaborative research agreement relating to the cytokine IL-9 and its receptor
(the "First Research Agreement") and are concurrently herewith entering into a
new research agreement (the "Second Research Agreement");

          NOW THEREFORE, in consideration of the mutual covenants and conditions
contained herein, and intending to be legally bound, LICR and MPI agree as
follows:

_______________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.


                                       1
<PAGE>

                             Part 1 - Definitions
                             --------------------

          1.1  "The Field" shall mean the diagnosis and treatment of atopic
allergies including asthma, bronchial hyperresponsiveness, rhinitis, eczema,
urticaria, conjunctivitis, the inflammatory bowel syndrome and HIV.

          1.2  "Affiliate" shall mean any corporation, company, partnership
and/or firm which controls or is controlled by or is under common control with
MPI. For the purposes of this definition, control shall mean: (a) in the case of
corporate entities, direct or indirect ownership of at least fifty percent (50%)
of the stock or participating shares entitled to vote for the election of
directors; and (b) in the case of non-corporate entities, direct or indirect
ownership of at least fifty percent (50%) of the equity interest or the power to
direct the management and policies of such entity.

          1.3  "LICR Patent Rights" shall mean the patents and patent
applications set forth in Amended Appendix A hereto, any division, continuation
or continuation-in-part of such applications, any patent which shall issue based
on any such application, division, continuation or continuation-in-part and any
reissue or reexamination of any such patent, and any patent applications or
patents corresponding to any such patent application or patent which has been or
hereafter is filed or issued in any country.

          1.4  "Product" shall mean any drug or other product which incorporates
or embodies IL-9 or the IL-9 receptor in any form including fragments thereof,
and/or any drug or other product which invokes, blocks, interferes with,
interacts with, binds to and/or prevents binding to IL-9 or the IL-9 receptor
and/or antibodies to IL-9 and/or the IL-9 receptor, and/or where the making,
using, importing, offering to sell or selling of such drug or other product in
the absence of a right or license, would infringe LICR Patent Rights.

          1.5  "Net Sales" shall mean, with respect to any quantity of Product
subject to royalty under this Agreement that is sold by MPI or any of its
Affiliates or sublicensees to any third party, the gross invoice selling price
for that quantity of Product, less: (a) discounts and allowances to customers,
(b) credits for returned goods, (c) prepaid freight, (d) sales taxes or other
governmental charges paid in connection with the sale; and (e) commissions and
other fees paid to distributors and

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       2
<PAGE>

other sales agencies for or in connection with the sale of Product. In the event
that a Product is sold in combination with another active ingredient or
component having independent therapeutic effect or diagnostic utility, then "Net
Sales," for purposes of determining royalty payments on the combination, shall
be calculated using one of the following methods:

     (a)  By multiplying the Net Sales of the combination by the fraction A/A+B,
          where A is the gross selling price, during the royalty paying period
          in question, of the Product sold separately, and B is the gross
          selling price, during the royalty period in question, of the other
          active ingredients or components sold separately; or

     (b)  In the event that no such separate sales are made of the Product or
          any of the other active ingredients or components in such combination
          package during the royalty paying period in question, Net Sales, for
          the purposes of determining royalty payments, shall be calculated by
          dividing the Net Sales of the combination by the number of active
          ingredients or components (including Products) contained in the
          combination.

                           Part 2 - Confidentiality
                           ------------------------

       2.1  Subject to Part 6.1 of the Second Research Agreement, each party
agrees that during the term of and any subsequent extension of this Agreement,
and for a period of five (5) years thereafter, a party shall not use or disclose
to any third party without the prior written consent of the other party any
Confidential Information. For purposes of this Agreement, "Confidential
Information" means any data or materials which are disclosed or furnished by one
party to the other hereunder and designated in writing as confidential. Oral
disclosures of Confidential Information must be confirmed in writing and
designated confidential within ten (10) days of disclosure.

       2.2  A receiving party shall have no obligation to the disclosing party
with respect to any portion of such Confidential Information which:

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       3
<PAGE>

       (a)   is or later becomes generally available to the public by use,
             publication or the like, through no fault of the receiving party;

       (b)   is obtained from a third party who had the legal right to disclose
             the same to the receiving party; or

       (c)   is already possessed by the receiving party, as evidenced by its
             written records, predating receipt thereof from the disclosing
             party; or

       (d)   is required to be disclosed by the receiving party to file and
             prosecute patent applications, to comply with applicable laws, to
             defend or prosecute litigation or to comply with governmental
             regulations, provided that the receiving party provides prior
             written notice of such disclosure to the other party and takes
             reasonable and lawful actions to avoid and/or minimize the degree
             of such disclosure.

                           Part 3 - Clinical Trials
                           ------------------------

       3.1   (a)  LICR will have the option to undertake the first clinical
trials for therapeutic applications of Product in the field of human cancer upon
terms, conditions (including MPI's financial support for such trials) and
protocols to be mutually agreed by LICR and MPI. Product manufactured according
to GMP for any such trial shall be furnished to LICR by MPI free of charge
provided MPI has elected for other reasons to manufacture such Product. If MPI
is not manufacturing a Product, MPI will assist LICR in having such Product
manufactured by a third party.

             (b)  MPI at its discretion may undertake clinical trials of Product
in the Field.

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       4
<PAGE>

                       Part 4 - Patents and Patent Costs
                       ---------------------------------

       4.1  LICR at its expense shall be responsible for prosecuting and
maintaining patent applications and patents included in LICR Patent Rights set
forth in Amended Appendix A. From and after December 20, 1999, MPI will
reimburse LICR for the [**] included in LICR Patent Rights. The cost of [**]
such patents will be prorated in equal portions among licensees in the event
LICR grants any new licenses for therapeutic use under LICR Patent Rights
outside the Field.

       4.2  Set forth below is an accounting of all patent costs, broken down by
[**], incurred by LICR in respect of LICR Patent Rights set forth in Amended
Appendix A during the period commencing December 20, 1996 and ending December
19, 1999. Such patent costs reimbursed by MPI [**] which LICR will pay MPI
within thirty (30) days after signing of this Amended License Agreement.

<TABLE>
<CAPTION>
                                  [**]              [**]              Other          Total
                                  USD               USD                USD            USD
----------------------------------------------------------------------------------------------
<S>                               <C>               <C>               <C>            <C>
Paid by Magainin                  [**]              [**]              [**]            [**]
(12/20/1996-12/20/1999)
----------------------------------------------------------------------------------------------
Invoiced, unpaid                  [**]              [**]              [**]            [**]
----------------------------------------------------------------------------------------------
Not yet invoiced                  [**]              [**]              [**]            [**]
----------------------------------------------------------------------------------------------
             Total                [**]              [**]              [**]            [**]
----------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------
Paid by Magainin                                    [**]
----------------------------------------------------------------------------------------------
Due to Magainin                                     [**]
----------------------------------------------------------------------------------------------
</TABLE>

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       5
<PAGE>

                            Part 5 - License Grant
                            ----------------------

       5.1  Subject to the Prior Licenses and the GI Option, LICR hereby grants
to MPI, and MPI hereby accepts, an exclusive license to make, have made, use,
sell, offer to sell, and import Product in the Field throughout the world.

       5.2  (a) MPI shall have the right to grant sublicenses to Affiliates and
others with respect to any rights conferred upon MPI under Part 5.1 hereof,
provided, however, that any such sublicense shall be subject in all respects to
the restrictions, exceptions and termination provisions contained in this
Agreement. MPI will promptly notify LICR upon the granting of any such
sublicense including the identity of the sublicensee. Notwithstanding the
foregoing, MPI shall not, without LICR's prior written approval, grant a
sublicense hereunder to any entity whose primary business is in the manufacture
and/or sale of tobacco, cigarettes, cigars, chewing tobacco or other similar
tobacco containing products.

            (b) MPI shall be responsible to LICR for all obligations of its
Affiliates and sublicensees hereunder in the same fashion and to the full extent
that MPI is obligated to LICR hereunder, including, but not limited to, the
payment of royalties due with respect to sales made by Affiliates and
sublicensees, which sales shall be treated as though they were sales by MPI.
Affiliates and sublicensees may pay royalties and provide royalty accountings to
MPI but without prejudice to the ultimate responsibility of MPI to LICR
hereunder. A breach by an Affiliate or sublicensee of MPI will be treated as a
breach by MPI. If LICR is required to bring suit against an Affiliate or a
sublicensee for breach of this Agreement, MPI will pay all costs incurred in
connection therewith, including without limitation attorneys fees and
disbursements provided any Affiliate or sublicensee is held liable for any such
breach.

       5.3  Subject to the license granted to MPI under Part 5.1 hereof, the
Prior Licenses and the GI Option, LICR agrees not to enter into any commercial
arrangement outside the Field with any third party involving LICR Materials,
LICR Technology or LICR Patent Rights without first giving MPI a first option to
same. MPI shall have [**] days from the date of written notification by LICR to
exercise such option in writing. If MPI exercises its option the parties will
negotiate in good faith to conclude a license agreement. If the parties are
unable to conclude a

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       6
<PAGE>

license within [**] of MPI exercising said option, LICR shall be free to license
outside the Field.

                              Part 6 - Royalties
                              ------------------

       6.1  For the licenses granted to MPI for Product under Part 5.1 hereof,
and Parts 2.2 and 3.1 of the Second Research Agreement, MPI shall pay LICR as
follows:

            (a) A running royalty of [**] based on the Net Sales by MPI, its
sublicensees or Affiliates of all Product manufactured, imported, offered for
sale, sold or used by MPI, its Affiliates or sublicensees.

            (b) Commencing on the termination of the Second Research Program and
any extensions thereof as defined by Part 4.1 of the Second Research Agreement
(the "Termination Date"), an annual license maintenance fee of [**], payable on
the Termination Date and each successive anniversary of the Termination Date
thereafter until MPI, an Affiliate or sublicensee commences selling a Product.
Annual license maintenance fees paid by MPI hereunder may be credited by MPI
against royalties earned hereunder in excess of the minimal annual royalty of
Part 6.1(c) hereof.

            (c) A minimum annual royalty of [**] payable on a deficiency basis
ninety (90) days after each anniversary of the Effective Date after MPI, an
Affiliate or sublicensee commences selling a Product in respect of royalties
paid hereunder during the twelve (12) month period preceding each anniversary of
the Effective Date. If royalties are paid hereunder for less than twelve (12)
months prior to the anniversary of the Effective Date, the minimum royalty for
such shortened period shall be pro rated.

            (d) [**] of all proceeds from sublicensing Product but excluding
royalties and reimbursement to MPI for research and development costs in the
Field.

       6.2  (a) Royalty payments required to be made by MPI to LICR shall be
made in U.S. Dollars within sixty (60) days following the end of each calendar

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       7
<PAGE>

quarter. Each such payment shall include the royalties which shall have accrued
during the calendar quarter immediately preceding and shall be accompanied by a
report certified by MPI's chief financial officer setting forth separately the
Net Sales of all Product sold during said calendar quarter.

          (b)  Royalties shall be payable only once with respect to the same
unit of Product regardless of the number of claims of LICR Patent Rights
pertaining to same. Royalties shall become payable at the time of any sale or
transfer of Product by MPI, its Affiliates and sublicensees to the user thereof.
If MPI sells Product in bulk form for repackaging and sale to the ultimate user,
royalties will become payable upon such sale to the end user and not upon the
sale of Product in bulk form.

          (c)  The remittance of royalties payable on Net Sales outside the U.S.
shall be made to LICR notwithstanding currency restrictions or regulations in
any country where Product is sold and in U.S. Dollars at the official rate of
exchange of the currency of the country from which the royalties are payable (as
quoted by Citibank N.A. for the last business day of the calendar quarter in
which the royalties are payable) less any withholding or transfer taxes which
are applicable. MPI shall supply LICR with proof of payment of such taxes paid
on LICR's behalf and shall cooperate with LICR in obtaining credit or refund of
any such taxes.

          (d)  MPI and its Affiliates and sublicensees shall keep and maintain
records of sales of Product. Such records shall be open to inspection at any
reasonable time during normal business hours not more often than once each
calendar quarter within three (3) years after the royalty period to which such
records relate by an independent Certified Public Accountant selected by LICR,
to whom MPI or its Affiliates or sublicensees have no reasonable objection, who
shall have the right to examine and make abstracts of the records kept pursuant
to this Agreement and report findings of said examination of records to LICR
insofar as it is necessary to evidence any mistake or impropriety on the part of
MPI. Said public accountant shall treat as confidential and shall not disclose
to LICR any information other than information which shall be given to LICR
pursuant to any provision of this Agreement.

          (e)  MPI's obligation to pay royalties shall continue on a country-by-
country basis for so long as LICR shall own an issued patent in any

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       8
<PAGE>

country under LICR Patent Rights or until [**] years from the first sale of
Product by MPI, its Affiliates or sublicensees, whichever shall later occur.

                         Part 7 - Patent Infringement
                         ----------------------------

       7.1  In the event that LICR or MPI determines that a third party may be
infringing a claim of a patent within LICR Patent Rights, it will so notify the
other party in writing. MPI shall have the first right as its expense to
institute and control all actions brought for infringement of any claim of any
licensed patent within LICR Patent Rights provided such infringement is within
the Field. Such actions may be brought, whenever in MPI's sole judgment such
actions may be necessary, proper or justified. MPI will give LICR sixty (60)
days prior written notice of its intent to commence such an action and identify
the potential infringer and the basis of the action. From any monetary award in
such action, MPI shall retain the balance, after MPI first recovers its
reasonable expenses in prosecuting the suit, and second, after MPI pays to LICR
a sum equal to the royalties LICR would have received had the infringing
products been subject to the terms of this Agreement. If, within the period of
one hundred and twenty days (120) following notification to MPI by LICR of a
third party infringement of LICR Patent Rights within the Field, MPI is unable
or unwilling to sue such alleged infringer and has not notified LICR in writing
of its intent to promptly commence an action to terminate the alleged
infringement, LICR shall have the right to commence such action at its own
expense, in which case LICR shall retain any monetary award in such action. LICR
shall have the sole right at its expense to institute and control all actions
brought for infringement of any claim of any patent under LICR Patent Rights,
where such infringement is outside the Field.

       7.2  In the event any party shall initiate or carry on legal proceedings
to enforce any patent within LICR Patent Rights against an alleged infringer,
the other party shall fully cooperate with, and supply all reasonable assistance
requested by the party initiating or carrying on such proceedings. Neither party
shall compromise or settle any claim or action regarding any patent under LICR
Patent Rights in any manner that would affect the rights of the other party
without the written consent of said other party, which consent shall not be
unreasonably withheld.

       7.3  In the event that MPI, an Affiliate or a sublicensee is sued by a
third party charging infringement of a patent resulting from the manufacture,
use, or sale

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       9
<PAGE>

by MPI, or an Affiliate or sublicensee of a Product covered by LICR Patent
Rights, MPI shall promptly notify LICR. During the period in which any such suit
is pending, MPI shall have the right to apply up to fifty percent (50%) of the
royalties due LICR against MPI's litigation expenses of any such suit or against
royalties paid by MPI to a third party in settlement of such litigation.

                              Part 8 - Diligence
                              ------------------

       8.1  MPI agrees to use reasonable efforts to effect introduction of
Product in the Field into the commercial market as soon as practicable,
consistent with sound and reasonable business practices and judgment. To this
end, within ninety (90) days after MPI identifies a Commercial Product
Opportunity (as defined below) for a Product in the Field, MPI shall submit a
proposal to LICR for developing and marketing the Product. Such plan would
include development and marketing efforts no less strenuous than MPI uses for
the development and marketing of its own products.

       8.2  "Commercial Product Opportunity" shall mean demonstration of the
efficacy of a Product for a specific therapeutic application in the Field either
by data collected from an FDA Phase 1 trial or by other evidence clearly
establishing efficacy.

                    Part 9 - Indemnification and Insurance
                    --------------------------------------

       9.1  MPI agrees to defend, indemnify and hold LICR and its agents
harmless from any claims, demands, suits or causes of action, including all
judgments, damages, and costs (including reasonable attorneys' fees) resulting
therefrom, arising out of the use, manufacture, sale, storage or advertising of
any Product.

       9.2  At least sixty (60) days before MPI first begins using any Product
in humans, including in human clinical trials, MPI shall obtain and maintain
thereafter a comprehensive general liability insurance policy (to include
advertisers liability and product liability) written by a reputable insurer or
insurers and shall list LICR as an additional named insured thereunder and shall
require thirty (30) days written notice to be given to LICR prior to any
cancellation or material change thereof. The limits of such insurance for
personal injury and property damage shall not be less than [**] for any Phase I
clinical trial of any Product [**]

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       10
<PAGE>

for any later phase clinical trial of any Product and [**] upon approval to sell
Product anywhere. MPI shall provide LICR with certificates of insurance
evidencing the same.

                     Part 10 - Term and Early Termination
                     ------------------------------------

       10.1  Unless sooner terminated as herein provided, this Agreement shall
continue in full force and effect commencing with the Effective date of this
Agreement and continuing until [**] years from the first sale of Product by MPI,
its Affiliates or sublicensee or until the expiration of the last-to-expire
patent in LICR Patent Rights, whichever shall later occur.

       10.2  Either party may terminate this Agreement and the license herein
granted upon the breach of any of the terms herein contained by either party
upon sixty (60) days written notice; provided that if during said sixty (60)
days the party so notified cures the breach complained of then this Agreement
shall continue in full force and effect.

       10.3  In the event this Agreement shall be terminated as provided in Part
10.2, MPI shall promptly make an accounting to LICR of the inventory of Product
which it and its Affiliates and sublicensees have on hand as of the date of such
termination. MPI, its Affiliates and sublicensees shall then have the right, for
a period of [**] after said termination, to sell such inventory provided that
the Net Sales thereof shall be subject to the royalty rates set forth above and
so payable to LICR.

       10.4  In the event that further lawful performance of this Agreement or
any part hereof by either party shall be rendered impossible by or as a
consequence of any law, regulation, order, rule, direction, priority, seizure,
allocation, requisition, or any other official action by any department, bureau,
board, administration or other instrumentality or agency or any government or
political subdivision thereof having jurisdiction over such party, such party
shall not be considered in default hereunder by reason of any failure to perform
occasioned thereby.

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       11
<PAGE>

                         Part 11 - General Provisions
                         ----------------------------

       11.1  Except as required by law, and, in the case of LICR, except as may
be required in order to maintain its status as an exempt organization under Sec.
501(c)(3) of the U.S. Internal Revenue Code and regulations thereunder, neither
LICR nor MPI shall originate any publicity, news release, or other public
announcement, written or oral, whether to the public press, to stockholders, or
otherwise, relating to this Agreement to any amendment thereto or to performance
hereunder or the existence of an arrangement between the parties without the
prior written approval of the other party. MPI shall not use the name of the
Ludwig Institute for Cancer Research (or any variant thereof) or any related
organization in any advertising, packaging (except for customary technical
references) or other promotional material in connection with the sale of Product
pursuant to this Agreement.

       11.2  MPI acknowledges that it has certain duties and obligations under
Part 379 of the Export Administration Regulations of the U.S. Department of
Commerce (as presently promulgated or hereafter modified or amended) concerning
the export and reexport of technical data. MPI will be solely responsible for
any breach of such Regulations by MPI, its Affiliates or sublicensees and will
defend and hold LICR harmless in the event of a suit or action involving LICR
occasioned by any such breach.

       11.3  Neither party shall unreasonably withhold its consent or agreement
when such consent or agreement is required hereunder or is requested in good
faith by the other party hereunder.

       11.4  This Agreement is unassignable by either party except with the
prior written consent of the other and except that it may be assigned without
consent to a corporate successor of MPI or LICR or to a person or corporation
acquiring all or substantially all of the business and assets of the division or
divisions of MPI involved in the development and sale of Product.
Notwithstanding the foregoing LICR may assign its rights hereunder to a
corporate affiliate, division or successor and MPI may assign its rights
hereunder to an Affiliate which may be substituted directly for MPI hereunder.

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       12
<PAGE>

       11.5  Notice hereunder shall be deemed sufficient if given by telefax and
registered mail, postage prepaid, and addressed to the party to receive such
notice at the address given herein, or such other address as may hereinafter be
designated by notice in writing. All such notices shall be considered as given
when telefaxed and mailed as aforesaid:

To LICR:          Ludwig Institute for Cancer Research
                  605 Third Avenue
                  New York, New York 10158

                  Facsimile No. (212) 450-1555

                  Attn: Lloyd J. Old, M.D.
                  Chief Executive Officer

with copies to:   Ludwig Institute for Cancer Research
                  605 Third Avenue
                  New York, New York 10158

                  Facsimile No. (212) 450-1555

                  Attn: Edward A. McDermott, Jr.
                  President
and
                  London Office
                  Ludwig Institute for Cancer Research
                  6th Floor Glen House
                  Stag Place
                  London SW1E 5AG, England

                  Facsimile No. 44171 8285427

                  Attn: Prof. A. Munro Neville
                  Associate Director

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       13
<PAGE>

To MPI:           Magainin Pharmaceuticals, Inc.
                  5110 Campus Drive
                  Plymouth Meeting, PA 19462

                  Facsimile No. (610) 941-5399

                  Attn: Roy C. Levitt, M.D.
                  President and Chief Executive Officer

     11.6    None of the terms of this Agreement may be waived or modified
except by an express agreement in writing signed by the party against whom
enforcement of such waiver or modification is sought.

     11.7    Each party represents and warrants that it has to the best of its
knowledge and will have the full right, power and authority to enter into this
Agreement and to disclose and to deliver all of the information delivered to the
other pursuant to this Agreement and to grant the licenses and rights granted
therein.

     11.8    This Amended License Agreement replaces and supersedes the Initial
License Agreement. This Amended License Agreement thus contains the entire
understanding of the parties hereto with respect to the subject matter herein
contained and will control in the event of any conflict with the Initial License
Agreement.

     11.9    This Agreement shall be construed and enforced under the laws of
New York.

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       14
<PAGE>

       IN WITNESS WHEREOF, the parties hereto have caused this instrument to be
executed by their respective duly authorized officers or representatives on the
respective dates indicated below.

THE LUDWIG INSTITUTE FOR CANCER RESEARCH


By   /s/ Lloyd J. Old, M.D.
  -------------------------
     Lloyd J. Old, M.D.
     Chief Executive Officer

By   /s/ Edward A. McDermott, Jr.
  -------------------------------
     Edward A. McDermott, Jr.
     President


  MAGAININ PHARMACEUTICALS, INC.


  By   /s/ Roy C. Levitt, M.D.
    --------------------------
       Roy C. Levitt, M.D.
       President and Chief Executive Officer

__________________

** Certain portions of this exhibit have been omitted based upon a request for
confidential treatment that has been filed with the Commission. The omitted
portions have been filed separately with the Commission.

                                       15