<PAGE>   1
                                                                   EXHIBIT 10.41

             Confidential Materials omitted and filed separately
                 with the Securities and Exchange Commission.
                       Asterisks denote such omissions.

                  LICENSE OPTION, LICENSE AND ROYALTY AGREEMENT

         This LICENSE OPTION, LICENSE AND ROYALTY AGREEMENT is entered into as
of January 1, 1995 (the "Effective Date") by and between PFIZER INC. ("Pfizer"),
a Delaware corporation, having an office at 235 East 42nd Street, New York, New
York 10017 and its Affiliates and MYCO PHARMACEUTICALS INC. ("Myco"), a Delaware
corporation, having an office at 1 Kendall Square, Building 300, Boston,
Massachusetts 02139.

         WHEREAS, Pfizer desires to obtain an option to an exclusive license to
Myco's right, title and interest in the Myco and Joint Patent Rights so that
Pfizer exclusively can manufacture, use or sell the Products; and

         WHEREAS, Myco is willing to grant such license option;
         Therefore, in consideration of the mutual covenants and promises set
forth in this Agreement, the parties agree as follows:

1.       DEFINITIONS.

         The capitalized terms used in this Agreement and not defined elsewhere
in it shall have the meanings specified for such terms in this Section 1 and in
the Research Agreement.

         1.1 "RESEARCH AGREEMENT" means the Collaborative Research Agreement
between Pfizer and Myco effective January 1, 1995.

         1.2 "NET SALES" means the gross amount invoiced by Pfizer or any
sublicensee of Pfizer for sales to a third party or parties of Products, less
normal and customary trade discounts actually allowed, rebates, returns,
credits, taxes the legal incidence of which is on the purchaser and separately
shown on Pfizer's or any sublicensee of Pfizer's invoices and transportation,
insurance and postage charges, if prepaid by Pfizer or any sublicensee of Pfizer
and billed on Pfizer's or any sublicensee of Pfizer's invoices as a separate
item.

         1.3      "MAJOR MARKET" means [***************************************
************************].
<PAGE>   2
             Confidential Materials omitted and filed separately
                 with the Securities and Exchange Commission.
                       Asterisks denote such omissions.



         1.4      "LICENSED PRODUCT" means a Product for which Pfizer has
rights under a License pursuant to this Agreement.

2.       TERM AND GRANT OF LICENSE OPTION, EXERCISE OF OPTION, TERM
         AND GRANT OF LICENSE, RIGHTS AND OBLIGATIONS.

         2.1      LICENSE OPTION GRANTED TO PFIZER UNDER THE PATENT
RIGHTS.

                  During the term of the Research Agreement and for [**********]
after its termination ("Option Term"), Myco grants to Pfizer an exclusive option
("Option") to an exclusive, worldwide license ("License") including the right to
grant sublicenses, to manufacture, use and sell each prospective Product
identified in the Research Program and each prospective Antifungal Drug
developed by Myco outside of its activities under the Research Program under
all Myco's right, title and interest in the Myco and Joint Patent Rights.
Pfizer may exercise the Option in accordance with the procedure set forth in
Section 2.2 upon notice to Myco in a manner prescribed in Section 11.

         2.2      PROCEDURE FOR EXERCISE OF OPTION.

                  2.2.1 Whenever Pfizer or Myco, individually or jointly,
identifies a compound in the course of the Research Program which it believes
may qualify as a candidate Product which satisfies a Profile of Activity, it
shall present the available information on the compound to the Research
Committee. The Research Committee shall review the data and determine whether it
believes the compound satisfies a Profile of Activity and is a bona fide
candidate for development as an Antifungal Drug and will so advise the parties
within [************] days after the presentation of the data to it.

                  2.2.2 If the Research Committee determines that a compound
should be proposed as a candidate Product which satisfies a Profile of Activity
and is a bona fide candidate for development as an Antifungal Drug, it shall so
notify the parties and shall issue a "Candidate Alert Notice," or equivalent, in
accordance with Pfizer's internal procedures. Pfizer shall then have
[*********] days to determine whether to exercise the Option

                                        2
<PAGE>   3
for such candidate Product. If Pfizer exercises the Option for such candidate
Product, it will become a "Licensed Product" hereunder. If Pfizer does not
exercise the Option for such candidate Product, it shall nevertheless have the
right to reconsider such exercise and may exercise the Option for such candidate
Product at any time during the Option Term. If Pfizer does not exercise the
Option for such candidate Product during the Option Term, Myco will be free to
develop and commercialize such candidate Product itself or with third parties
after the expiration of the Option Term, if but only if Pfizer is not developing
or selling a Product with the same Profile of Activity pursuant to this
Agreement. If Myco commercializes such candidate Product, Myco shall be
obligated to pay a royalty to Pfizer with respect to commercial sales of such
Product, as set forth in Section 3.10. In such circumstances, Pfizer shall have
no rights to such candidate Product or any resulting Product.

         2.3      TERM OF LICENSE.

                  Unless terminated earlier as provided below, if Pfizer
exercises the Option, the License for the Licensed Product in question shall
commence on the date of exercise and shall terminate on the date of the last to
expire of the Patent Rights.

         2.4      PFIZER OBLIGATIONS.

                  During the term of any License:

                  2.4.1 Pfizer shall use reasonably diligent efforts to exploit
the Licensed Product to which such License applies commercially, including
conducting clinical trials and obtaining regulatory approvals. If Pfizer
determines to cease diligent efforts to exploit the Licensed Product, Pfizer
shall so notify Myco, whereupon Myco may terminate the License for such Licensed
Product in the manner (and with the consequences) set forth in Section 9 hereof.

                  2.4.2 If Pfizer grants a sublicense to a third party, Pfizer
shall guarantee that any such sublicensee fulfills all of Pfizer's obligations
under this Agreement; provided,

                                        3
<PAGE>   4
             Confidential Materials omitted and filed separately
                 with the Securities and Exchange Commission.
                       Asterisks denote such omissions.



however, that Pfizer shall not be relieved of its obligations pursuant to this
Agreement.

         2.5      TECHNICAL ASSISTANCE.

                  During the term of any License, Myco shall provide Pfizer or
any sublicensee of Pfizer, at Pfizer's request and expense, any technical
assistance reasonably necessary to enable Pfizer or such sublicensee to
manufacture, use or sell each Licensed Product and to enjoy fully all rights
granted to Pfizer pursuant to this Agreement; provided, however, that Myco is
reasonably capable of providing that assistance.

         2.6      NEGOTIATION OF MUTUAL OBLIGATIONS.
                  During the term of any License:

                  2.6.1 Section 2.4.1 to the contrary notwithstanding, if, at
any time that ************************ with resect to a Licensed Product, *****
******************************************************** for the conduct of
****************************** the parties agree to discuss in good faith the
possibility of ************************************************* in such
******************************************* may also participate in other
facets of **************** in ways that the parties agree is mutually
beneficial.  If ********************************************************* the
parties will agree on appropriate compensation to ****.  At the request of ****
the parties also agree to discuss in good faith the possibility of
*********************************** or *********************************
or******** for which *************** but **************************************

                  2.6.2 In general, Pfizer shall be responsible for the
manufacture of all Licensed Products; provided, however, that if (i) Myco
acquires the capacity or ability to manufacture or supply drug products by a
fermentation method consistent with FDA

                                        4
<PAGE>   5
             Confidential Materials omitted and filed separately
                 with the Securities and Exchange Commission.
                       Asterisks denote such omissions.


Drug Good Manufacturing Practices; and (ii) Pfizer is then manufacturing or
having manufactured a Licensed Product by a similar fermentation method, then
Pfizer will, in good faith, discuss with Myco, the manufacture by Myco of part
of Pfizer's requirements for such Product in the United Sates and elsewhere.
Pfizer shall have no obligation place an order with Myco for its US requirements
if Myco quotes a price more than [*****************] above the price Pfizer is
then paying for such Licensed Product and for its foreign requirements if Myco
quotes a price which exceeds the [*****************] price including savings for
taxes and duty. Under no circumstances shall Myco have the right to be the sole
source for any Licensed Product.

3.       PAYMENT OF ROYALTIES, ROYALTY RATES, ACCOUNTING FOR ROYALTIES, RECORDS,
         MILESTONE PAYMENTS, ADDITIONAL STOCK PURCHASE.

         3.1      PAYMENT OF ROYALTIES.

                  During the term of any License, Pfizer shall pay Myco a
royalty based on the Net Sales of each Licensed Product. Such royalty shall be
paid with respect to each country of the world from the date of the first
commercial sale (the date of the invoice of Pfizer or any sublicensee of Pfizer
with respect to such sales) of such Licensed Product in each such country until
the expiration of the last Patent Right to expire with respect to each such
country and each such Licensed Product. By way of further explanation, Pfizer
shall pay royalties pursuant to Section 3.2.3 with respect to the manufacture of
products whose manufacture would infringe or be covered by Patent Rights if it
were done by an unlicensed third party, such royalties to be paid on the Net
Sales of such Licensed Products even if the actual sale of such Licensed
Products would not alone infringe or be covered by Patent Rights if such sales
were made by an unlicensed third party.

         3.2      ROYALTY RATES.

                  3.2.1 During the term of any License, Pfizer shall pay Myco a
royalty for the sale of each Licensed Product as set forth in Section 3.2.3;
provided, however, that the royalty rate

                                        5
<PAGE>   6
             Confidential Materials omitted and filed separately
                 with the Securities and Exchange Commission.
                       Asterisks denote such omissions.


otherwise applicable to Net Sales of a Licensed Product set forth below shall
be reduced by [***********] until [****************] after that Licensed
Product has been approved for sale by the US Food and Drug Administration
("FDA") and one of its regulatory counterparts in a Major Market; provided,
however, that such reduction shall in no event continue for more than [*******]
years and shall be terminated if worldwide sales of affected Licensed Product
exceed [*****************] for any year. Moreover, if [*************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
the otherwise applicable royalty rate set forth below shall be reduced by
[*********]; provided, however, that in no event shall the applicable royalty
rates after any reduction required under this Section 3.2.1 and under Section
3.2.2 be reduced to a percentage lower than that set forth in Section 3.2.3 in
the column labeled "Minimum Royalty Rates as a Percentage of net Sales."

                  3.2.2 THIRD PARTY LICENSES. If the manufacture, use or sale by
Pfizer of a Licensed Product in any country would, in the opinion of both Pfizer
and Myco infringe a patent owned by a third party, Pfizer and Myco shall attempt
to obtain a license under such patent. If Pfizer obtains a license under such
patent, [****] of any payments made by Pfizer to such third party shall be
deductible from royalty payments due from Pfizer to Myco pursuant to this
Agreement; provided, however, that in no event shall royalties payable to Myco
be reduced by more than [************] in any year as a result of all such
deductions under this Section 3.2.2. All such

                                        6
<PAGE>   7
             Confidential Materials omitted and filed separately
                 with the Securities and Exchange Commission.
                       Asterisks denote such omissions.


computations, payments and adjustments shall be on a country by
country and patent by patent basis.

                  3.2.3 The royalty paid by Pfizer to Myco shall be the sum of
the Net Sales in each Tier multiplied by the applicable royalty rate for that
Tier. Royalty rates with respect to Products are as follows:

   NET SALES IN                 ROYALTY RATES AS            MINIMUM ROYALTY
MILLIONS OF DOLLARS              A PERCENTAGE OF        RATES AS A PERCENTAGE OF
     ("TIERS")                       NET SALES                OF NET SALES

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

[*****                                  **                          **         ]
[*****                                  **                          **         ]
[*****                                  **                          **         ]
[*****                                  **                          **         ]
[*****                                  **                          **         ]

The Minimum Royalty Rate in the third column is the absolute minimum after all
offsets and deductions permitted under this Agreement, except for the credit
permitted by Section 3.8.

         3.3      RENEGOTIATION OF ROYALTY RATES.

                  The Parties acknowledge that the royalty rates set forth in
Section 3.2 are based on the premise that Licensed Products ********************
********************************************************************************
********************************************************************************
********.  If ******************************************************************
************************ with respect to a Licensed Product which represents a
commercial opportunity for Pfizer or improves the safety or efficacy of such
Licensed Product, the parties shall negotiate a new royalty rate for such
Licensed Product ***************************************************************
********************************************************************************
***************.  The foregoing provisions of this Section 3.3 regarding
renegotiation shall ************************************************************
*******************************************************************************.

         3.4      PAYMENT DATES.

                  Royalties shall be paid by Pfizer on Net Sales within sixty
(60) days after the end of each calendar quarter in which

                                        7
<PAGE>   8
             Confidential Materials omitted and filed separately
                 with the Securities and Exchange Commission.
                       Asterisks denote such omissions.


such Net Sales are made. Such payments shall be accompanied by a statement
showing the Net Sales of each Licensed Product by Pfizer or any sublicensee of
Pfizer in each country, the applicable royalty rate for such Licensed Product,
and a calculation of the amount of royalty due.

         3.5      ACCOUNTING.

                  The Net Sales used for computing the royalties payable to Myco
by Pfizer shall be computed and paid in US dollars by check or other mutually
acceptable means. For purposes of determining the amount of royalties due, the
amount of Net Sales in any foreign currency shall be computed by (a) converting
such amount into dollars at the prevailing commercial rate of exchange for
purchasing dollars with such foreign currency as quoted by Citibank in New York
on the last business day of the calendar quarter for which the relevant royalty
payment is to be made by Pfizer and (b) deducting the amount of any governmental
tax, duty, charge, or other fee actually paid in respect of such conversion
into, and remittance of dollars.

         3.6      ROYALTIES WITH RESPECT TO PRODUCTS WHICH EMPLOY MYCO OR
JOINT TECHNOLOGY BUT WHICH DO NOT INFRINGE PATENT RIGHTS.

In those countries of the world in which Pfizer sells Antifungal Drugs which
employ Myco Program Technology, Myco Non-Program Technology or Joint Technology
but which, even in the absence of a license, do not infringe an issued patent
within Patent Rights claiming Myco Program Technology, Myco Non-Program
Technology or Joint Technology, and are not covered by a claim of a pending
patent application within Patent Rights claiming Myco Program Technology, Myco
Non-Program Technology or Joint Technology and are not within the claims of any
patent or patent application owned or controlled by Pfizer, Pfizer will pay
Myco a royalty equal to [************] of Net Sales of such Antifungal Drug.
Sections 3.2.2, 3.4, 3.5, 3.7 and 3.8 shall apply to such royalties, but
[*******************************************************************************
*****************************************************************************]

                                        8
<PAGE>   9
         3.7      RECORDS.

                  Pfizer shall keep for three (3) years from the date of each
payment of royalties complete and accurate records of sales by Pfizer of each
Product in sufficient detail to allow the accruing royalties to be determined
accurately. Myco shall have the right for a period of three (3) years after
receiving any report or statement with respect to royalties due and payable to
appoint at its expense an independent certified public accountant reasonably
acceptable to Pfizer to inspect the relevant records of Pfizer to verify such
report or statement. Pfizer shall make its records available for inspection by
such independent certified public accountant during regular business hours at
such place or places where such records are customarily kept, upon reasonable
notice from Myco to verify the accuracy of the reports and payments. Such
inspection right shall not be exercised more than once in any calendar year nor
more than once with respect to sales in any given period. Myco agrees to hold in
strict confidence all information concerning royalty payments and reports, and
all information learned in the course of any audit or inspection, except to the
extent necessary for Myco to reveal such information in order to enforce its
rights under this Agreement or if disclosure is required by law. The failure of
Myco to request verification of any report or statement during said three-year
period shall be considered acceptance of the accuracy of such report, and Pfizer
shall have no obligation to maintain records pertaining to such report or
statement beyond said three-year period. The results of each inspection, if any,
shall be binding on both parties.

         3.8      MILESTONE PAYMENTS.

                  Pfizer shall pay Myco, within sixty (60) days of the
completion of each respective event set forth below ("Event"), the payment
listed opposite that Event. payments shall be made in US dollars by check or
other mutually acceptable means. Pfizer shall be obligated to make each payment
only once with respect to the first Licensed Product in each Activity Profile

                                        9
<PAGE>   10
             Confidential Materials omitted and filed separately
                 with the Securities and Exchange Commission.
                       Asterisks denote such omissions.


affected by an Event so that the occurrence of an event with respect to
additional Licensed Products contemplated in each Activity Profile will not
require Pfizer to make an additional payment with respect to that Event. All
payments made by Pfizer pursuant to this Section 3.8 shall be credited against
all sums due to Myco pursuant to Section 3.2 of this Agreement; provided,
however, that the sums due pursuant to Section 3.2 in any calendar year shall
not be reduced by virtue of this credit by more than [****************].

  EVENT                                                                 AMOUNT

[*******                                                                *****
*******
*******
*****

*******                                                                 *****
****

*******                                                                 *****
*******
*****

*******                                                                 *****
*******
****

         3.9      ADDITIONAL STOCK PURCHASE.

                  If and when an *** filed by ***** with FDA or an equivalent
agency in any major market becomes effective with respect to a product, at the
request of [***********************************], Pfizer will purchase
additional shares of Myco common stock in accordance with the terms and
conditions of the Stock Purchase Agreement. Pfizer will invest ***** at the
rate of [*****] per share (adjusted for any stock split, stock dividend or
reverse stock split) if Myco common stock is not publicly traded or at the
**************** if Myco stock is publicly traded on that date. The purchase
price will not be applied to royalties due to Myco pursuant to this

                                       10
<PAGE>   11
             Confidential Materials omitted and filed separately
                 with the Securities and Exchange Commission.
                       Asterisks denote such omissions.


Agreement and Pfizer shall be obligated to make such purchase once only during
the term of this Agreement.

         3.10     MYCO ROYALTY PAYMENTS.

                  In the event Myco shall have the right to develop and
commercialize any Product pursuant to Section 2.2, 2.4 or 9.3, Myco shall be
obligated to pay royalties to Pfizer on commercial sales of such Product for
patient treatment pursuant to an approved NDA or foreign equivalent. In the
case of such sales by Myco or its Affiliates, such royalty shall be equal to
[********] of Net Sales by Myco or its Affiliates of such Product (Net Sales
having the meaning set forth in Section 1.2 with Myco substituted for Pfizer).
In the case of such sales by a licensee of Myco, such royalty shall be the
lesser of (i) [*****] of the licensee's Net Sales of such Product (Net Sales
having the meaning set forth above) or (ii) [*****] of royalties received by
Myco from the licensee with respect to such commercial sales of the Product by
the licensee. For the avoidance of doubt, it is acknowledged that equity
investments, payments for services and payments for the purchase of goods are
not considered royalties with respect to commercial sales by the licensee.

                  In the event Myco is obligated to pay royalties to Pfizer
pursuant to this Section 3.10, Sections 3.2.1 (after the first semi-colon),
3.2.2, 3.3, 3.4, 3.5 and 3.7 shall apply, with the rights and obligations of
Pfizer and Myco thereunder being reversed.

         3.11 MYCO OBLIGATIONS TO LICENSORS. Myco shall be responsible for any
payment due as a result of this Agreement to any third party which has
heretofore licensed any Technology to Myco.

                                       11
<PAGE>   12
             Confidential Materials omitted and filed separately
                 with the Securities and Exchange Commission.
                       Asterisks denote such omissions.


4.       LEGAL ACTION.

         4.1      ACTUAL OR THREATENED INFRINGEMENT.

                  Subject to Myco's obligations to licensors, if any, of
Myco Patent Rights or Joint Patent Rights, when information comes to the
attention of Pfizer to the effect that any Myco or Joint Patent Rights relating
to a Licensed Product have been or are threatened to be unlawfully infringed
Pfizer shall have the right at its expense to take such action as it may deem
necessary to prosecute or prevent such unlawful infringement. Pfizer shall
notify Myco promptly of the receipt of any such information and of the
commencement of any such suit, action or proceeding. If Pfizer determines that
it is necessary or desirable for Myco to join any such suit, action or
proceeding, Myco shall, at Pfizer's expense, execute all papers and perform such
other acts as may be reasonably required to permit Pfizer to act in Myco's name.
If Pfizer brings a suit, it shall have the right first to reimburse itself out
of any sums recovered in such suit or in its settlement for all costs and
expenses, including attorney's fees, related to such suit or settlement, and
[***************] of any funds that shall remain from said recovery shall be
paid to Myco and the balance of such funds shall be retained by Pfizer. If
Pfizer does not, within one hundred twenty (120) days after giving notice to
Myco of the above-described information, notify Myco of Pfizer's intent to bring
suit against any infringer, Myco shall have the right to bring suit for such
alleged infringement, but it shall not be obligated to do so, and may join
Pfizer as party plaintiff, if appropriate, in which event Myco shall hold Pfizer
free, clear and harmless from any and all costs and expenses of such litigation,
including attorney's fees, and any sums recovered in any such suit or in its
settlement shall belong to Myco. However, [************************************
***] of any such sum received by Myco, after deduction of all costs and
expenses related to such suit or settlement, including attorney's fees paid,
shall be paid to Pfizer. Each party shall always have the right to be
represented by counsel of its own

                                       12
<PAGE>   13
selection and at its own expense in any suit instituted by the other for
infringement under the terms of this Section . If Pfizer lacks standing and Myco
has standing to bring any such suit, action or proceeding, then Myco shall do so
at the request of Pfizer and at Pfizer's expense.

         4.2      DEFENSE OF INFRINGEMENT CLAIMS.

                  Myco will cooperate with Pfizer at Pfizer's expense in the
defense of any suit, action or proceeding against Pfizer or any sublicensee of
Pfizer alleging the infringement of the intellectual property rights of a third
party by reason of the use of Myco, Pfizer or Joint Patent Rights in the
manufacture, use or sale of the Licensed Product. Pfizer shall give Myco prompt
written notice of the commencement of any such suit, action or proceeding or
claim of infringement and will furnish Myco a coy of each communication relating
to the alleged infringement. Myco shall give to Pfizer all authority (including
the right to exclusive control of the defense of any such suit, action or
proceeding and the exclusive right after consultation with Myco, to compromise,
litigate, settle or to otherwise dispose of any such suit, action or
proceeding), information and assistance necessary to defend or settle any such
suit, action or proceeding; provided, however, Pfizer shall obtain Myco's prior
consent to such part of any settlement which requires payment or other action by
Myco or has a material adverse effect on Myco's business. If the parties agree
that Myco should institute or join any suit, action or proceeding pursuant to
this Section , Pfizer may at Pfizer's expense, join Myco s a defendant if
necessary or desirable, and Myco shall execute all documents and take all other
actions, including giving testimony, which may reasonably be required in
connection with the prosecution of such suit, action or proceeding.

5. REPRESENTATION AND WARRANTY, HOLD HARMLESS.

         5.1 Myco represents and warrants to Pfizer that it has the right to
grant the Option and License pursuant to this Agreement and that the Option and
Licenses so granted do not conflict with

                                       13
<PAGE>   14
or violate the terms of any agreement between Myco and any third party.

         5.2 Myco agrees to defend, protect, indemnify and hold harmless Pfizer
and any sublicensee of Pfizer, from and against any loss or expense arising from
any proven claim of a third party that it has been granted rights by Myco that
Pfizer or any sublicensee of Pfizer in exercising their rights granted to Pfizer
by Myco pursuant to this Agreement, has infringed upon such rights granted to
such third party by Myco.

6.       TREATMENT OF CONFIDENTIAL INFORMATION.

         6.1      Pfizer and Myco each recognize that the other's
Confidential Information constitutes highly valuable, confidential information.
Subject to rights and obligations of the parties pursuant this Agreement and the
Research Agreement, Pfizer and Myco each agree that during the term of the
Research Agreement and for five (5) years thereafter, it will keep confidential,
and will cause its Affiliates to keep confidential, all Myco Confidential
Information or Pfizer Confidential Information, as the case may be, that is
disclosed to it or to any of its Affiliates pursuant to this Agreement. Neither
Pfizer nor Myco nor any of their respective Affiliates shall use such
Confidential Information of the other party except as expressly permitted in
this Agreement or the Research Agreement.

                  6.1.1 Subject to the parties' rights and obligations pursuant
to this Agreement and the License Agreement, Pfizer and Myco each agree that any
disclosure of the other's Confidential Information to any officer, employee or
agent of the other party or of any of its Affiliates shall be made only if and
to the extent necessary to carry out its responsibilities under this Agreement
and shall be limited to the maximum extent possible consistent with such
responsibilities. Subject to the parties' rights and obligations pursuant to
this Agreement and the License Agreement, Pfizer and Myco each agree not to
disclose the other's Confidential Information to any third parties under any
circumstance without written permission from the other party.

                                       14
<PAGE>   15
Each party shall take such action, and shall cause its Affiliates to take such
action, to preserve the confidentiality of each other's Confidential Information
as it would customarily take to preserve the confidentiality of its own
Confidential Information. Each party, upon the other's request, will return all
the Confidential Information disclosed to it by the other party pursuant to this
Agreement, including all copies and extracts of documents, within sixty (60)
days of the request upon the termination of this Agreement except for one (1)
copy which may be kept for the purpose of complying with continuing obligations
under this Agreement.

                  6.1.2 Myco and Pfizer each represent that all of its
employees, and any consultants to such party, who shall have access to Pfizer
Program Technology, Pfizer Non-Program Technology, Myco Program Technology, Myco
Non-Program Technology or Joint Technology and Pfizer Confidential Information
and Myco Confidential Information are bound by agreement to maintain such
information in confidence.

                  6.1.3 Notwithstanding anything to the contrary set forth
herein or in the Research Agreement, in the event Myco shall have the right to
develop and commercialize a Product pursuant to this Agreement or the Research
Agreement, Myco shall have the right to disclose and transfer (i) Confidential
Information and Materials which are part of the Myco Program Technology or Myco
Non-Program Technology with respect to such Product and (ii) Confidential
Information and Materials other than compounds which are part of the Joint
Technology with respect to such Product, to third parties who execute a
Confidentiality agreement with respect thereto.

         6.2      PUBLICITY.

                  Except as required by law, neither party may disclose the
terms of this Agreement without the written consent of the other party, which
consent shall not be unreasonably withheld; provided, however, the parties, upon
the execution of this Agreement, will agree to a news release for publication in

                                       15
<PAGE>   16
general circulation periodicals. The parties may disclose the existence of this
Agreement without the consent of the other and, once a particular item has been
generally disclosed, may further disclose such item without the consent of the
other.

         6.3      DISCLOSURE OF INVENTIONS.

                  Each party shall promptly inform the other about all
inventions in the Area that are conceived, made or developed in the course of
carrying out the Research Program by employees of, consultants to, either of
them solely, or jointly with employees of, or consultants to the other.

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

         The following provisions relate to the filing, prosecution and
maintenance of Patent Rights during the term of this Agreement:

         7.1      FILING, PROSECUTION, AND MAINTENANCE BY MYCO.

                  With respect to Myco Patent Rights, Myco shall have the
exclusive right and obligation:

                  (a) to file applications for letters patent on any patentable
invention included in Myco Program Technology and Myco Non-Program Technology;
provided, however, that Myco shall consult with Pfizer regarding countries in
which such patent applications should be filed and shall file patent
applications in those countries where Pfizer requests that Myco file such
applications; and, further provided, that Myco, at its option and expense, may
file in countries where Pfizer does not request that Myco file such
applications;

                  (b) to prosecute all pending and new patent applications
included within Myco Patent Rights;

                  (c) to respond to oppositions, nullity actions, re-
examinations, revocation actions and similar proceedings filed by third parties
against the grant of letters patent for such applications;

                  (d) to maintain in force any letters patent included in Myco
Patent Rights by duly filing all necessary papers and

                                       16
<PAGE>   17
paying any fees required by the patent laws of the particular country in which
such letters patent were granted.

                  (e) to cooperate fully with, and take all necessary actions
requested by, Pfizer in connection with the preparation, prosecution and
maintenance of any letters patent included in Myco Patent Rights.

                  Myco shall notify Pfizer in a timely manner of any decision to
abandon a pending patent application or an issued patent included in Myco Patent
Rights. Thereafter, Pfizer shall have the option, at its expense, of continuing
to prosecute any such pending patent application or of keeping the issued patent
in force.

                  7.1.1 COPIES OF DOCUMENTS. Myco shall provide to Pfizer copies
of all patent applications that are part of Myco Patent Rights prior to filing,
for the purpose of obtaining substantive comment of Pfizer patent counsel. For
the same purpose Myco shall also provide to Pfizer copies of all documents
relating to prosecution of all such patent applications in a timely manner for
such review and shall provide to Pfizer every six (6) months a report detailing
their status.

                  7.1.2 REIMBURSEMENT OF COSTS FOR FILING, PROSECUTING AND
MAINTAINING PATENT RIGHTS. Within thirty (30) days of receipt of invoices from
Myco, Pfizer shall reimburse Myco for all the costs of filing, prosecuting,
responding to opposition and the like and maintaining patent applications and
patents (including without limitation costs incurred by Myco with respect to
Patent Rights licensed to Myco by third parties) in countries where Pfizer
requests that patent applications be filed, prosecuted and maintained. Such
reimbursement shall be in addition to Funding Payments. However, Pfizer may,
upon sixty (60) days notice, request that Myco discontinue filing or prosecution
of patent applications in any country and discontinue reimbursing Myco for the
costs of filing, prosecuting, responding to opposition and the like or
maintaining such patent application or patent in any country. Myco shall pay all
costs in those

                                       17
<PAGE>   18
countries in which Pfizer does not request that Myco file, prosecute or maintain
patent applications and patents, but in which Myco, at is option, elects to do
so.

                  7.1.3 Pfizer shall have the right to file on behalf of Myco
all applications and take all actions necessary to obtain patent extensions
pursuant to 35 USC Section 156 for Myco or Joint Patent Rights described in this
Section 7.1 licensed to Pfizer. Myco agrees to sign, at Pfizer's expense, such
further documents and take such further actions as may be requested by Pfizer in
this regard. If Pfizer determines not to apply for any such extension, Pfizer
shall so notify Myco in writing at least ninety (90) days prior to the deadline
for such application, and Myco may do so and Pfizer shall cooperate fully with
Myco and provide all necessary information within Pfizer's control to Myco for
use therein.

         7.2      FILING, PROSECUTION AND MAINTENANCE BY PFIZER.

                  With respect to Pfizer Patent Rights and Patent Rights
claiming Joint Technology, Pfizer shall have those rights and duties ascribed to
Myco in Section 7.1

         7.3      Neither party may disclaim a Patent Rights without the
consent of the other.

8.       OTHER AGREEMENTS, CONDITION PRECEDENT.

         8.1 Concurrently with the execution of this Agreement, Myco and Pfizer
shall enter into the Research Agreement and the Stock Purchase Agreement. This
Agreement, the Stock Purchase Agreement and the Research Agreement are the sole
agreements with respect to the subject matter and supersede all other agreements
and understandings between the parties with respect to the same.

9.       TERMINATION AND DISENGAGEMENT.

         9.1      EVENTS OF TERMINATION.

                  The following events shall constitute events of termination
("Events of Termination"):

                  (a)      Any written representation or warranty by Myco or
Pfizer, or any of its officers, made under or in connection with

                                       18
<PAGE>   19
this Agreement shall prove to have been incorrect in any material respect when
made.

                  (b) Myco or Pfizer shall fail in any material respect to
perform or observe any term, covenant or understanding contained in this
Agreement or in any of the other documents or instruments delivered pursuant to,
or concurrently with, this Agreement, and such failure shall remain unremedied
for thirty (30) days after written notice to the filing party.

         9.2      TERMINATION.

                  Upon the occurrence of any Event of Termination, the party not
responsible may, by notice to the other party, terminate this Agreement.

         9.3 Upon termination of this Agreement, all Licenses granted hereunder
shall terminate. In such event, all rights to Licensed Products covered by such
Licenses shall become the sole property of Myco and Myco will be free to develop
and commercialize such Products itself or with third parties after the
expiration of the Option Term, if, but only if Pfizer is not developing or
selling a Product with the same Profile of Activity pursuant to this Agreement.
Notwithstanding the foregoing, in the event Myco shall have the right to
terminate this Agreement as a result of an Event of Termination committed by
Pfizer, Myco may, in its sole discretion, terminate the License covering the
Licensed Product with respect to which the Event of Termination occurred, rather
than terminating this Agreement, in which event only Pfizer's rights to such
Licensed Product shall become the sole property of Myco and Myco shall only have
the right to develop and commercialize such Product, itself or with third
parties, after the expiration of the Option Term, if but only if Pfizer is not
developing or selling a Product with the same Profile of Activity pursuant to
this Agreement. In the event Myco shall develop and sell commercially any
Product for which Pfizer's License has terminated, or in the event Myco shall
license the rights to such Product to a third party, Myco shall be obligated to
pay royalties in accordance with Section 3.10.

                                       19
<PAGE>   20
         9.4 Termination of this Agreement by either party, with or without
cause, will not terminate the licenses granted pursuant to Section 5.2 of the
Research Agreement.

         9.5 Termination of this Agreement for any reason shall be without
prejudice to:

                  (a) the rights and obligations of the parties provided in
Sections 6 and 10;

                  (b) Myco's right to receive all royalty payments accrued
hereunder; or

                  (c) any other remedies which either party may otherwise have.

10.      INDEMNIFICATION.

         10.1     INDEMNIFICATION OF MYCO BY PFIZER.

                  Pfizer shall indemnify, defend and hold harmless Myco
and its directors, officers, employees, and agents and their respective
successors, heirs and assigns (the "Myco Indemnitees"), against any liability,
damage, loss or expense (including reasonable attorneys' fees and expenses of
litigation) incurred by or imposed upon the Myco Indemnitees, or any one of
them, in connection with any claims, suits, actions, demands or judgments,
including without limitation personal injury and product liability matters
(except in cases where such claims, suits, actions, demands or judgments result
from the material breach, negligence or willful misconduct on the part of Myco),
arising out of the production, manufacture, promotion, sale or use by any person
of any Product or Antifungal Drug which is manufactured or sold by Pfizer or by
an Affiliate, sublicensee, distributor or agent of Pfizer.

         10.2 The foregoing indemnification shall not apply if an Indemnitee
fails to give Pfizer prompt notice of any claim it receives and such failure
materially prejudices Pfizer with respect to any claim or action to which
Pfizer's obligation pursuant to this Section applies. Pfizer, in its sole
discretion, shall choose legal counsel, shall control the defense

                                       20
<PAGE>   21
of such claim or action and shall have the right to settle same on such terms
and conditions it deems advisable.

11.      NOTICES.

         All notices shall be in writing mailed via certified mail, return
receipt requested, courier, or facsimile transmission addressed as follows, or
to such other address as may be designated from time to time:

         If to Pfizer:            To Pfizer at its address as set forth at
                                  the beginning of this Agreement
                                  Attention: President, Central Research
                                  with copy to: General Counsel

         If to Myco:              To Myco at its address as set forth at
                                  the beginning of this Agreement
                                  Attention: President

Notices shall be deemed given as of the date received.

12.      GOVERNING LAW.

         This Agreement shall be governed by and construed in accordance with
the laws of the State of New York.

13.      MISCELLANEOUS.

         13.1     BINDING EFFECT.

                  This Agreement shall be binding upon and inure to the benefit
of the parties and their respective legal representatives, successors and
permitted assigns.

         13.2     HEADINGS.

                  Paragraph headings are inserted for convenience of reference
only and do not form a part of this Agreement.

         13.3     COUNTERPARTS.

                  This Agreement may be executed simultaneously in two or more
counterparts, each of which shall be deemed an original.

         13.4     AMENDMENT; WAIVER; ETC.

                  This Agreement may be amended, modified, superseded or
canceled, and any of the terms may be waived, only by a written instrument
executed by each party or, in the case of waiver, by the party or parties
waiving compliance. The delay or failure of any party at any time or times to
require performance of any

                                       21
<PAGE>   22
provisions shall in no manner affect the rights at a later time to enforce the
same. No waiver by any party of any condition or of the breach of any term
contained in this Agreement, whether by conduct, or otherwise, in any one or
more instances, shall be deemed to be, or considered as, a further or continuing
waiver of any such condition or of the breach of such term or any other term of
this Agreement.

         13.5     NO THIRD PARTY BENEFICIARIES.

                  Except as set forth in Section 10 hereof, no third party
including any employee of any party to this Agreement, shall have or acquire any
rights by reason of this Agreement. Nothing contained in this Agreement shall be
deemed to constitute the parties as agents for the other or as partners with
each other or any third party.

         13.6     ASSIGNMENT AND SUCCESSORS.

                  This Agreement may not be assigned by either party, except
that each party may assign this Agreement and the rights and interests of such
party, in whole or in part, to any of its Affiliates, any purchaser of all or
substantially all of its assets or to any successor corporation resulting from
any merger or consolidation of such party with or into such corporations.

         13.7     FORCE MAJEURE.

                  Neither Pfizer nor Myco shall be liable for failure 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 reasonably beyond the control of Pfizer or Myco.

         13.8     SEVERABILITY.

                  If any provision of this Agreement is or becomes invalid or is
ruled invalid by any court of competent jurisdiction or is deemed unenforceable,
it is the intention of the parties that the remainder of the Agreement shall not
be affected.

         IN WITNESS WHEREOF, the parties have caused this Agreement to be
executed by their duly authorized representatives.

                                       22
<PAGE>   23
PFIZER INC.                                          MYCO PHARMACEUTICALS INC.
By: ______________________                           By: _______________________
Title: ___________________                           Title: ____________________
Date: ____________________                           Date: _____________________

cc:      Pfizer Inc, Legal Division, Groton, CT  06430

                                       23