Document:

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                                                                   EXHIBIT 10.31

                     DRUG DISCOVERY COLLABORATION AGREEMENT

                                     BETWEEN

                           ARRAY BIOPHARMA CORPORATION

                                       AND

                                ICOS CORPORATION

                                  JULY 31, 2000

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   2

                  THIS DRUG DISCOVERY COLLABORATION AGREEMENT (the "Agreement")
is entered into and made effective as of July 31, 2000 (the "Effective Date"),
by and between ARRAY BIOPHARMA INC, a Delaware corporation having its principal
offices located at 1885 33rd Street, Boulder, CO 80301 ("Array") and ICOS
CORPORATION, a Delaware corporation having its principal offices located at
22021 20th Avenue S.E., Bothell, Washington 98021 ("ICOS").

                  WHEREAS, Array has skills, expertise and experience in
multi-parallel synthesis and purification methods, developing and preparing
chemical libraries suitable for high throughput biological screening assays and
medicinal chemistry;

                  WHEREAS, as of the Effective Date, ICOS and its Affiliates
have developed and own, among other things, certain know how and intellectual
property rights, assays, methods and lead compounds that may be potential drug
candidates directed to PDE4, [ * ] and the Optimization Targets, (as defined
below) (collectively "ICOS Technology");

                  WHEREAS, ARRAY and ICOS have entered that certain Lead
Optimization Agreement ("LO Agreement") dated December 22, 1998, for the
optimization of, among other things, such lead compounds directed against PDE4;

                  WHEREAS, ARRAY and ICOS have entered into that certain Cell
Cycle Checkpoint Optimization Agreement ("C3 Agreement) dated April 6, 1999, for
the optimization of, among other things, such lead compounds directed against
[ * ];

                  WHEREAS, ARRAY and ICOS desire to consolidate the optimization
programs initiated pursuant to the LO and C3 Agreements with an optimization
program against the Optimization Targets;

                  WHEREAS, ARRAY and ICOS have mutually agreed to cancel and
terminate the LO Agreement and the C3 Agreement in their entirety and to release
each other from all obligations, accrued or outstanding, under the LO Agreement
and the C3 Agreement, all under the terms and conditions as set forth herein
below;

                  NOW, THEREFORE, the Parties agree as follows:

                  1. DEFINITIONS

                  1.1 "Active Target" means an Optimization Target for which
ICOS has provided reasonable written notice to Array as de scribed in Section
3.1 of this Agreement, that such Optimization Target shall be included in the
Optimization Program and for which an Optimization Plan shall be produced. For
the purpose of this definition reasonable notice shall be [ * ] days

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.
<PAGE>   3

unless the parties have agreed to a shorter period of notice either by written
agreement or by the Parties' performance.

                  1.2 "Affiliate" of a Party means any corporation or other
business entity controlled by, controlling or under common control with, such
Party. For this purpose "control" shall mean direct or indirect beneficial
ownership of more than fifty percent (50%) of the voting securities or income
interest in such corporation or other business, or if not meeting the preceding
requirements, any company owned or controlled by or owning or controlling such
Party at the maximum control or ownership right permitted in the country where
such company exists.

                  1.3 "Array Compound" means a chemical compound that is
proprietary to Array, or whose use or manufacture is proprietary to Array.

                  1.4 "Array Patents" means all Patents which claim any Array
Technology and that are Controlled by Array during the Exclusivity Period, but
shall exclude any claims of an Optimization Patent. For purposes of this
definition, "controlled" shall mean the ability to grant a license or sublicense
as provided for in Section 8.1 below.

                  1.5 "Array Technology" means certain know-how, intellectual
property or patents (i) developed, licensed and/or owned by Array, prior to the
Effective Date or (ii) developed licensed and/or owned by Array outside of the
Optimization Program and used by Array in the Optimization Program, or (iii)
developed during the Optimization Program and not having solely specific or
novel application to the Optimization Program (i.e. such know-how, intellectual
property, or patents having application outside of the development, manufacture,
use, sale, or importation of Optimization Compounds or Products). Array
Technology shall not include Daughter Libraries or Optimization Compounds.

                  1.6 "Confidential Information" shall mean:

                           (a)      all information and materials received by
                                    either Party from the other Party pursuant
                                    to this Agreement which is confidential
                                    under Section 10;

                           (b)      all information and materials received by
                                    either Party from the other Party in
                                    connection with the Optimization Program
                                    during the Optimization Period, including,
                                    without limitation, structures of lead
                                    compounds provided by ICOS to Array, to the
                                    extent the same is confidential under
                                    Section 10; and

                           (c)      the financial terms of this Agreement and
                                    the identity of the Optimization Targets, to
                                    the extent the same are confidential under
                                    Section 10.

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

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                  1.7 "Daughter Libraries" shall mean the compound libraries
which are designed and synthesized as a part of the Optimization Program by
Array.

                  1.8 "Derivative" shall mean a compound (or compounds) which
has resulted from chemical synthesis by ICOS in connection with the Optimization
Program or which is derived from an Optimization Compound.

                  1.9 "Exclusivity Period" means the Optimization Period for any
Active Target plus [ * ].

                  1.10 "Field" means all indications for any Optimization Target
against which an Optimization Compound or Products may be directed.

                  1.11 "FTE" shall mean a full-time equivalent employee of Array
having the skills, support, services and resources to fulfill Array's
obligations under this Agreement. For purposes of this Agreement, the FTEs shall
include synthetic and analytical chemists and upon approval by ICOS may also
include Array employees with the skills required to facilitate a structure based
drug design program.

                  1.12 "Milestone Compound" shall have the meaning set forth in
Section 7.2.

                  1.13 "Optimization Compound(s)" means a compound (or
compounds) which is (i) synthesized by Array following the Effective Date in the
course of performing the Optimization Program for the purpose of screening
against an Active Target, (ii) was synthesized by Array, for the purpose of
screening against an Active Target, in the course of performing lead compound
optimization under the LO agreement, or (iii) was synthesized by Array, for the
purpose of screening against an Active Target, in the course of performing lead
compound optimization under the C3 Agreement.

                  1.14 "Optimization Patent" means a Patent claiming and
disclosing the composition of an Optimization Compound or the manufacture
thereof, for which Array has made an inventive contribution to the subject
invention in the course of performing the Optimization Program, as determined
under U.S. Patent law. Notwithstanding the foregoing, Optimization Patents shall
only include Patents to the extent the same (i) is entitled to a first effective
filing date for priority purposes (i.e., for priority purposes under 35 USC, or
the corresponding laws of the country in which such Patent is filed) after the
Effective Date and (ii) claims subject matter reduced to practice (either actual
or constructive) prior to the date [ * ] after the end of the Optimization
Period.

                  1.15 "Optimization Period" means the term of the Optimization
Program as provided in Section 9 of this Agreement.

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

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                  1.16 "Optimization Plan" means the Optimization Plan for each
Optimization Target to be prepared by Array approved and accepted by ICOS, which
describes in agreed detail the research activities to be performed by Array for
each Active Target.

                  1.17 "Optimization Program" means the research and activities
for each Optimization Target to be conducted under this Agreement as described
in the Optimization Plan and as set forth in Sections 3.1 and 3.2 of this
Agreement.

                  1.18 "Optimization Target" means any [ * ] biomolecular
entities described in Appendix B, at execution of this Agreement, or as
substituted by mutual written agreement of the Parties, and unless otherwise
specified may include Active Targets, and shall in each case be selected from
Appendix B.

                  1.19 "Project Team" shall have the meaning set forth in
Section 3.1(c).

                  1.20 "Party" means Array or ICOS, as the case may be,
including their respective permitted assigns of this Agreement under Section 13
below.

                  1.21 "Patent" means (a) valid and enforceable U.S. or non U.S.
Patent, and any non-U.S. equivalent, including any extension (including
Supplemental Protection Certificates), registration, confirmation, reissue,
continuation, divisionals, continuation-in-part, reexamination or renewal
thereof, or (b) pending applications for any of the foregoing.

                  1.22 "Product(s)" means any product containing an Optimization
Compound or Derivative with such compound as the active ingredient or one of the
active ingredients, which is the subject of one or more claims under an
Optimization Patent and which is granted regulatory approval by the governing
health regulatory authority of the applicable country for marketing in the
Field.
                  1.23 "Restored Active Target" means an Active Target which has
ceased to be an Active Target either by Agreement of the Parties or by operation
of the Optimization Program, and which, by reasonable written notice has been
again designated as an Active Target. For the purposes of this definition
reasonable notice shall be [ * ] unless the Parties have agreed to a shorter
period of notice either by written Agreement or by parties performance.

                  1.24 "Territory" means the entire world.

                  1.25 "Third Party" means an entity other than Array or ICOS or
their respective Affiliates.

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   6
                  2. CANCELLATION AND TERMINATION

                  2.1 Cancellation and Termination. As of the Effective Date of
this Agreement, Array and ICOS hereby irrevocably cancel and terminate the LO
Agreement in its entirety. Array and ICOS also hereby irrevocably cancel and
terminate the C3 Agreement in its entirety Except as expressly set forth herein,
(i) all rights and obligations of Array and ICOS under the LO Agreement and
under the C3 Agreement are hereby canceled and terminated, (ii) all rights and
licenses granted under the LO Agreement or the C3 Agreement shall revert to the
party granting such right or license, and (iii) no terms and conditions of the
LO Agreement or the C3 Agreement shall survive. For the avoidance of doubt, it
is however intended by the parties that this consolidated Agreement shall give
the same rights, obligations and duties to the parties for PDE4 and [ * ] as
under the Lead Optimization Agreement and C3 Agreement respectively.

                  2.2 Settlement and Release. Each party hereto agrees that this
Agreement represents settlement in full of all outstanding obligations owed to
the other party under the LO Agreement and the C3 Agreement. Array and ICOS, on
behalf of themselves, and their respective heirs, executors, officers,
directors, employees, investors, shareholders, administrators, predecessor and
successor corporations, and assigns, hereby fully and forever release each other
and their respective heirs, executors, officers, directors, employees,
investors, shareholders, administrators, predecessor and successor corporations,
and assigns, of and from any claim, duty, obligation or cause of action relating
to any matters of any kind, whether presently known or unknown, suspected or
unsuspected, that any of them may possess arising from any omissions, acts or
facts that have occurred up until and including the Effective Date of this
Agreement.

                  3. OPTIMIZATION PROGRAM

                  3.1 Array Responsibilities. Array shall with due diligence
provide the following services and resources to ICOS and conduct the following
activities in accordance with the Optimization Plan:

                           (a)      During the Optimization Period, Array shall
                                    (i) review data and information regarding
                                    Active Targets and lead compounds provided
                                    by ICOS; (ii) based on such data and
                                    information design Daughter Libraries and
                                    optimize the lead compounds supplied by ICOS
                                    and (iii) synthesize compounds as provided
                                    in Section 6.3 below;

                           (b)      During the Optimization Period, Array shall
                                    keep ICOS regularly informed of its
                                    activities performed in connection with the
                                    Optimization Program, including, without
                                    limitation, providing ICOS with data and
                                    information (and, upon ICOS's written
                                    request, reasonable quantities of samples
                                    pursuant to Section 6.3) regarding the
                                    status of Array's work on Optimization
                                    Compounds under the Optimization Plan;

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.
<PAGE>   7

                           (c)      Subject to Sections 3.3, 4 and 7, and at all
                                    times during the Optimization Period, Array
                                    shall assign a project team ("Project
                                    Team"), to conduct Array's activities under
                                    the Optimization Plan. The initial Project
                                    Team shall consist of [ * ] Array FTEs,
                                    unless changed according to Section 7.1(b).

                  3.2 ICOS Responsibilities. ICOS shall provide the following
resources to Array and conduct the following activities under the Optimization
Program as more fully described in the Optimization Plan:

                           (a)      ICOS shall make payment to Array under the
                                    Optimization Program as set forth in Section
                                    7, provide screening, biological and
                                    structural data and information including
                                    leads and/or screening hits and assay
                                    methods relating to Optimization Compounds
                                    to Array necessary for Array to perform its
                                    duties under this Agreement, and will assume
                                    scientific, financial and administrative
                                    responsibility for screening and biological
                                    support activities, drug development and
                                    regulatory filings during and after the term
                                    of the Optimization Program on the terms set
                                    forth below.

                           (b)      During the Optimization Period, ICOS shall
                                    provide Array with: (i) lead compounds
                                    and/or structures of such lead compounds for
                                    Active Targets, and (ii) data and
                                    information regarding Optimization Compounds
                                    and Active Target assays developed by ICOS
                                    under the Optimization Program.

                  3.3 Conduct of Optimization Program. The Parties hereby agree
that the Optimization Program shall be carried out in accordance with the
Optimization Plan and this Agreement, as amended from time to time. ICOS shall
review the Optimization Plan on a regular and an ongoing basis and may make
written changes to the Optimization Plan so long as such changes are mutually
agreed to in writing by Array.

                  3.4 Third Party Licenses. Each Party shall be solely
responsible for any Third Party license fees required to perform its obligations
under this Agreement.

                  4. TARGETS

                  4.1 Active Target. The initial Active Targets shall be as
specified in Appendix B or as specified by reasonable written notice from ICOS
to Array. There shall be no more than [ * ] Active Targets at any one time
unless Array and ICOS mutually agree in writing to having more than [ * ]
Optimization Targets simultaneously designated as Active Targets together with
additional terms and conditions, if any.

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   8

                  4.2 Restored Active Target. Any Optimization Target which has
ceased to be an Active Target due to the later designation of another
Optimization Target as an Active Target, may always be restored to the status of
an additional Active Target at ICOS's request provided that no more than [ * ]
targets may be designated as active targets at any one time, as described in 4.1
above.

                  4.3 Disclosure of Active Target Information. ICOS agrees not
to disclose to Array any Confidential Information relating to any Optimization
Targets, or lead compounds therefor until such Optimization Targets are
designated as the Active Targets in accordance with Section 4.1 above.

                  5. EXCLUSIVITY

                  5.1 Active Target Exclusivity. During the Optimization Period,
Array shall not knowingly work on or provide information regarding any
Optimization Target with or to any Third Parties; thereafter during the
Exclusivity Period, Array shall not knowingly work on or provide information
regarding any Optimization Target which has been designated as an Active Target
during the Optimization Period with or to any Third Parties, in each case except
(a) as provided for in Section 11.2 with regard to any Public Statements, and
(b) with respect to any Third Parties who are collaborators or proposed
collaborators of Array, Array shall have the right, consistent with its
corporate policy (but without identifying any Optimization Target), to notify
any such Third Party of its decision and/or inability to work on such
Optimization Target with that Third Party. For the purposes of this Section 5.1,
"knowingly" shall mean actual knowledge or imputed knowledge that the corporate
entity or its directors and officers knew or should have known.

                  5.2 Optimization Compounds. Optimization Compounds, their
structures and best methods of synthesis and manufacture developed during the
Optimization Program shall be made available only to ICOS for research or
application to any Optimization Target, within or outside the Collaboration,
during the Optimization Period, and Array shall not work on or provide
information regarding such Optimization Compound to any Third Party, except to
take any steps necessary to protect ICOS's exclusivity hereunder.

                  5.3 Duration of Exclusivity for Optimization Targets.
Notwithstanding any other provision of this Agreement, it is understood and
agreed that once an Optimization Program has been initiated for any Active
Target Array's obligations under Section 5.1 shall continue until ICOS has
released Array from the effect of this Section 5.3 by written notice or the end
of the Exclusivity Period, whichever occurs first.

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.
<PAGE>   9

                  6. OPTIMIZATION COMPOUNDS

                  6.1 Intellectual Property Rights; Vesting and Transfer to
ICOS. Subject to Section 6.2, and except as set forth in this Section 6.1, ICOS
shall have exclusive rights in all Optimization Patents and the subject matter
contained therein and all intellectual property and know-how (whether or not
patentable) embodied in Optimization Compounds and Products and methods
specifically directed to the manufacture of Optimization Compounds and methods
of use of Products, in each case resulting from the Optimization Program; to the
extent possible such exclusive rights shall be achieved by Array assigning its
interest, if any, in such Patents and intellectual property and know-how to ICOS
and where such assignment is not legally possible ICOS shall receive an
exclusive license or sublicense to the maximum extent of Array's rights. ICOS
shall file, maintain and prosecute all Patents arising out of, or comprising,
the rights and interests granted in this Section 6.1 and Array shall do
everything reasonably necessary to assist ICOS in filing such Patents. Prior to
the filing of any such Patent applications or during the pendency of such
applications, Array shall assign to ICOS or its designee all intellectual
property rights it may have, to the extent granted in this Section 6.1, in the
Optimization Patents and the subject matter disclosed and claimed therein which
are necessary for the development and commercialization of such Optimization
Compounds by ICOS or its designee. Notwithstanding anything in this Section 6.1
to the contrary, nothing in this Section 6.1, or the operation thereof, shall be
deemed to grant to ICOS any rights in or to any Array Technology.

                  6.2 Structural Information. Array shall not disclose the
structure of any Optimization Compound, Derivative or Product (to the extent
such structure is not publicly available) to any Third Party nor identify such
structure, if publicly available, with its collaboration with ICOS without
ICOS's written permission, unless required to do so by law, in which case Array
shall promptly notify ICOS of such required disclosure and will use its
reasonable efforts to assist ICOS to secure confidential treatment of such
structure prior to any disclosure.

                  6.3 Supply of Optimization Compounds. Aliquots of at least
[ * ] of any Optimization Compound that has been synthesized will be prepared
and given to ICOS together with their structures and all known and developed
best methods of synthesis and manufacture. Array shall replenish once during the
Exclusivity Period that amount upon ICOS's reasonable request, and ICOS shall
reimburse Array for any cost thereof not otherwise reimbursed under Section 6
below for any reasonably requested replenishment in excess of a total of [ * ]
milligrams. To the extent that Optimization Compounds are not available in a
timely and sufficient quantity to allow the earliest start of necessary large
scale preclinical or other studies such unavailability of Optimization Compounds
shall not be cited as a lack of due diligence provided that the Parties have
made commercially reasonable attempts, and continue such attempts, during the
Exclusivity Period to provide such unavailable Optimization Compounds in
required quantities in an expedient manner.

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.
<PAGE>   10

                  7. CONSIDERATION

                  7.1 Optimization Program Funding.

                           (a)      Research Support for Project Team. At all
                                    times during the Optimization Period, ICOS
                                    shall make payments to Array for direct
                                    research support for its Project Team, which
                                    shall initially consist of [ * ] of Array,
                                    unless determined otherwise under Section
                                    7.1(b). The total amount payable per FTE
                                    shall be U.S. [ * ] per FTE per annum ("FTE
                                    Rate"). The FTE Rate for any Calendar Year
                                    after [ * ] shall be adjusted annually at
                                    each anniversary of this Agreement by ICOS
                                    in accordance with the annual percentage
                                    change in Consumer Price Index for all Urban
                                    Consumers as published by the United States
                                    Department of Labor, Bureau of Labor
                                    Statistics. All payments for direct research
                                    support shall be paid by ICOS to Array,
                                    quarterly in advance, and adjusted as
                                    necessary in subsequent quarters, of such
                                    amounts as are equal to the product of (i)
                                    the number of FTEs [ * ] FTEs unless
                                    determined otherwise under Section 7.1(b))
                                    allocated to the Optimization Program for
                                    the calendar quarter to which each such
                                    payment applies, multiplied by (ii) U.S. [ *
                                    ] (i.e., the quarterly amount per FTE on the
                                    basis of U.S. [ * ] per annum).

                           (b)      Expansion of Project Team. ICOS may request
                                    that Array expand its Project Team during
                                    the Optimization Period in order to match
                                    the work on Active Targets. In such event,
                                    the Parties shall promptly confer as to the
                                    appropriate number of FTEs to constitute the
                                    Project Team, as mutually agreed, to be paid
                                    as specified in Section 7.1(a).

                  7.2 Milestone Payments. Within [ * ] days of the occurrence of
a development milestone triggered by the activities of ICOS or its Affiliates,
or Third Parties acting under authority from ICOS or its Affiliates, ICOS shall
pay Array the related milestone payment in U.S. dollars as set forth in Appendix
A. Such payments shall apply once only to each milestone reached by any
Optimization Compound or Derivative for each Optimization Target. Such milestone
payments shall be due with respect to each Optimization Compound or Derivative
to meet such milestone (each a "Milestone Compound"); [ * ].

                  7.3 Taxes. All income and other taxes levied or accruing to
Array under this Agreement shall be paid by Array, including taxes levied
thereon as income to Array. If provision is made in law or regulation for
withholding, such tax shall be deducted from the payment made by ICOS to the
proper taxing authority and a receipt of payment of the tax secured and promptly
delivered to Array. Each Party agrees to assist the other Party reasonably in
claiming exemption

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.
<PAGE>   11

from such deductions or withholdings under any double taxation or similar
agreement or treaty from time to time in force.

                  7.4 Title to, and ownership of, tangible property. Without
limiting ICOS' rights under Sections 6.1 and 8 of this Agreement, it is
understood and agreed that each Party retains title to any tangible property
delivered to the other Party under this Agreement.

                  8. LICENSE GRANTS; OUTLICENSE

                  8.1 Array License Grant to ICOS. Subject to the terms and
conditions of this Agreement, Array hereby grants to ICOS a non-exclusive,
royalty-free, fully paid up except as to payment of respective milestones under
Section 7.2, worldwide license, with the right to sublicense to use Array
Technology and under the Array Patents, in each case solely to make, have made,
use, have used, sell, have sold, import and export Optimization Compounds or
Products in the Field.

                  8.2 ICOS Sublicense. ICOS shall have the right to transfer,
assign or sublicense to a Third Party ICOS's rights under Sections 6.1 and 8.1
above or Optimization Patents covering the Products.

                  8.3 No Other Licenses. No right or license is granted to ICOS
hereunder under technology or intellectual property of Array, by implication,
estoppel or otherwise, except as specifically and expressly granted under
Sections 6.1, 6.2 and 8.1 of this Agreement. No right or license is granted to
ARRAY hereunder in any Optimization Compound or Derivative, including compounds
in Daughter Libraries.

                  9. TERM AND TERMINATION OF THE AGREEMENT

                  9.1 Term, Renewals and Extensions. The term of this Agreement
and Optimization Program shall commence upon the Effective Date of this
Agreement, and unless earlier terminated as provided in this Agreement, shall
expire on the second anniversary thereafter provided, however, that the term
shall be automatically extended for a further one (1) year unless either party
provides written notice sixty (60) days or more prior to such second anniversary
canceling such extension. Unless terminated early pursuant to Section 9.2 below,
the Optimization Periods may be individually renewed for additional periods upon
mutual agreement of the Parties; provided that neither Party shall be obligated
to approve any such renewal.

                  9.2 Termination by ICOS. ICOS may terminate this Agreement
effective at any time after the first anniversary of the Effective Date, in its
sole discretion, upon ninety (90) days prior written notice.

                  9.3 Termination by ICOS or Array. If either Party materially
breaches this Agreement and fails to remedy that breach within ninety (90) days
of receiving written notice

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.
<PAGE>   12

thereof from the other Party, or makes an assignment of substantially all of its
assets for the benefit of its creditors or goes into liquidation, insolvency,
bankruptcy, receivership or reorganization proceedings, whether voluntarily or
compulsorily which is not dismissed by a court of competent jurisdiction within
ninety (90) days, then the other Party may at any time, by notice in writing or
by telefax, terminate this Agreement and/or any and/or all of the Optimization
Programs. Within ninety (90) days following termination for the Optimization
Program and/or research related to any Optimization Target under this Agreement,
Array shall prepare a detailed, final written report to ICOS, and provide any
remaining supply of Optimization Compounds in synthesis to date, for each Target
or part of the Optimization Program being terminated.

                  9.4 Effect of Termination on Licensees. In the event of any
termination of this Agreement pursuant to Section 9.2 where such termination
shall not have been caused by the action or inaction on the part of any
respective licensee of ICOS or Array, or by any breach by such licensee of its
obligations under its license from ICOS or Array, as appropriate, such
termination of this Agreement shall be without prejudice to the rights of each
non-breaching licensee and such licensee shall be deemed to be a direct licensee
hereunder; provided that such licensee agrees in writing to be bound by the
applicable provisions of this Agreement, including, without limitation, the
payment of milestone payments pursuant to Section 7.2.

                  10. CONFIDENTIAL INFORMATION

                  10.1 Nondisclosure. During the term of this Agreement and for
a period of [ * ] after termination or expiration thereof, each Party (the
"Receiving Party") will maintain all Confidential Information received from the
other Party (the "Disclosing Party") in trust and confidence and will not
disclose any such Confidential Information to any Third Party or use any such
Confidential Information for any purpose except (i) as expressly authorized by
this Agreement, (ii) as required by law or court order, after as much advance
notice as is practical to the Disclosing Party, (iii) to its consultants,
subcontractors, agents or financing sources who need to know and who are bound
by equivalent written confidentiality obligations. The Receiving Party will use
at least the same standard of care as it uses to protect proprietary or
confidential information of its own to ensure that its Affiliates, employees,
agents, consultants and other representatives do not disclose or make any
unauthorized use of the Confidential Information of the Disclosing Party. The
Receiving Party will promptly notify the Disclosing Party upon discovery of any
unauthorized use or disclosure of the Disclosing Party's Confidential
Information

                  10.2 Exceptions. Confidential Information shall not include
any information which the Receiving Party can prove by competent evidence: (a)
is now, or hereafter becomes, through no act or failure to act on the part of
the Receiving Party, generally known or available; (b) is known by the Receiving
Party at the time of receiving such information, as evidenced by its written
records; (c) is hereafter disclosed to the Receiving Party by a Third Party, as
a matter of right and without restriction on disclosure; (d) is independently
developed by the Receiving Party without the aid, application or use of
Confidential Information of the Disclosing Party; or (e) is the

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.
<PAGE>   13

subject of a written permission to disclose provided by the Disclosing Party.

                  11. PUBLICATIONS AND PUBLIC STATEMENTS

                  11.1 Publications. ICOS and Array will treat matters of
authorship of scientific abstracts, manuscripts or publications in a proper
collaborative spirit, giving credit where it is due. Without affecting
obligations under Section 10 above, Array shall not publish any information with
respect to Optimization Compounds or Derivatives during the Exclusivity Period
without the prior written permission of ICOS. ICOS agrees to provide to Array,
on a Confidential Basis, any publication, except patent prosecution documents
with respect to Optimization Compounds at least [ * ] prior to submission for
publication during the Exclusivity Period.

                  11.2 Public Statements. Except as the Parties otherwise agree
in writing, neither Array nor ICOS shall release any information to any Third
Party with respect to the existence of this Agreement. Once the Parties issue a
press release, which has been agreed to in writing before release by both
Parties, each Party may use the substance of such press release without prior
notice.

                  12. INDEMNIFICATION

                  12.1 Product Liability. ICOS hereby agrees to save, defend and
hold Array and its officers, directors, employees, consultants, and agents
harmless from and against any and all suits, claims, actions, demands,
liabilities, expenses and losses, including reasonable legal expenses and
attorneys' fees ("Losses") resulting directly or indirectly from any claim
alleging physical injury or death or otherwise arising out of the
administration, utilization and/or ingestion of Optimization Compounds or
Products manufactured, used or sold by or under the authority of ICOS, its
Affiliates or licensees except to the extent such Losses result from the
negligence (whether active, passive or imputed), breach of this Agreement or
willful misconduct of Array.

                  12.2 Procedures. If Array (the "Indemnified Party") seeks
indemnification under this Section 12, it shall inform ICOS (the "Indemnifying
Party") of a claim as soon as reasonably practicable after it receives notice of
the claim, shall permit the Indemnifying Party to assume direction and control
of the defense of the claim (including the right to settle any claim brought
against the Indemnified Party upon prior written consent, which shall not be
unreasonably withheld), and shall give reasonable cooperation (at the expense of
the Indemnifying Party) in the defense of such claim.

                  13. ASSIGNABILITY

                  13.1 Generally. This Agreement may not be assigned by either
Party without the prior written consent of the other Party, and which shall not
to be unreasonably withheld; provided, however, that either Party may assign
this Agreement, in whole or in part, to an Affiliate or to a

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.
<PAGE>   14

successor of a Party in connection with the merger, consolidation or sale of all
or substantially all of such Party's assets or that portion of its business
pertaining to the subject matter of this Agreement (and upon doing so will
promptly notify the other Party in writing) (each such transaction being
referred to as an "Acquisition"); provided that the assigning Party remains
fully liable as obligated hereunder.

                  13.2 Technology of Acquirer. In the event of an Acquisition,
it is understood and agreed that no intellectual property rights or technology
of the acquirer shall be included within the subject matter licensed hereunder,
to the extent that such intellectual property or technology was owned or
controlled by the acquirer as of the date of the Acquisition, or was created or
obtained after the date of the Acquisition other than by employees of Array in
the course of performing the Optimization Program.

                  14. DISPUTE RESOLUTION PROCEDURES

                  14.1 Senior Executives Discussions. If a dispute arises
between Array and ICOS or with respect to matters other than the management of
the Optimization Program, either during or after the Optimization Period, such
dispute will be referred to the appropriate senior management in the area of the
dispute. If such senior management are unable to resolve such dispute, such
dispute will be referred to the Executive Vice President of Operations of ICOS
and the Chief Operating Officer of Array.

                  14.2 Injunctive Relief. Nothing contained in this Section 14
or any other provisions of this Agreement shall be construed to limit or
preclude a Party from bringing any action in any court of competent jurisdiction
for injunctive or other relief or to compel the other Party to comply with its
obligations hereunder.

                  15. NOTICES

                  Any notice required or permitted to be given hereunder shall
be deemed sufficient if sent by facsimile letter or overnight courier, or
delivered by hand to ICOS or Array at the respective addresses and facsimile
numbers as set forth below or at such other address and facsimile number as
either Party hereto may designate. If sent by facsimile letter, notice shall be
deemed given when the transmission is completed if the sender has a confirmed
transmission report. If a confirmed transmission report does not exist, then the
notice will be deemed given when the notice is actually received by the person
to whom it is sent. If delivered by overnight courier, notice shall be deemed
given when it has been signed for. If delivered by hand, notice shall be deemed
given when received.

         if to Array, to:              Array BioPharma Corporation
                                       1885 33rd Street
                                       Boulder, Colorado  80301
                                       Fax number:  (303) 381-6697

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.
<PAGE>   15

         if to ICOS, to:               ICOS Corporation
                                       22021 20th Avenue, S.E.
                                       Bothell, Washington  98021
                                       Attention: Legal Department
                                       Fax number:  (425) 398-8950

         16. SURVIVAL

         The provisions of Sections 5.1, 5.3, 6.1, 6.2, 6.3, 7.2, 7.4, 8.1, 8.2,
8.3, 9.4, 10, 11, 12, 13, and 16 shall survive the expiration and any
termination of this Agreement. In addition, Section 1 shall survive the
expiration or any termination of this Agreement to the extent necessary to
define terms in any other surviving Section. Notwithstanding the foregoing if
Array terminates this Agreement under Section 9.3 then Section 8.1 shall not
survive such termination by Array.

         17. ADDITIONAL TERMS

         17.1 Entire Agreement. This Agreement constitutes the entire
understanding between the Parties with respect to the subject matter hereto and
supersedes and replaces all previous negotiations, understandings,
representations, writings and contract provisions and rights relating hereof.

         17.2 Amendment; No Waiver. No provision of this Agreement may be
amended except to the extent expressly allowed herein, revoked or waived except
by a writing signed and delivered by an authorized officer of each Party. Any
waiver on the part of either Party of any breach or any right or interest
hereunder shall not imply the waiver of any subsequent breach or waiver of any
other right or interest.

         17.3 Validity. The invalidity or unenforceability of any provision of
this Agreement shall not affect the validity or enforceability of any other
provision of this Agreement, each of which shall remain in full force and
effect.

         17.4 Headings. The descriptive headings and numberings are inserted for
convenience of reference only and are not intended to be part of or to affect
the meaning of or interpretation of this Agreement.

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

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.
<PAGE>   16

         17.6 Governing Law. This Agreement shall be governed by and construed
and enforced in accordance with the laws of the State of Washington, without
regard to conflicts of laws and principles.

         17.7 Further Assurances. At any time and from time to time after the
Effective Date, the Parties shall each do, execute, acknowledge and deliver, and
cause to be done, executed, acknowledged or delivered, all such further acts,
transfers, conveyances, or assignments as may be reasonably required to carry
out the transactions contemplated by this Agreement.

         18. REPRESENTATIONS AND WARRANTIES

         18.1 Authorization. All action on the part of each of Array, ICOS and
their respective officers, and directors necessary for the authorization,
execution and delivery of this Agreement and the performance of all obligations
of Array and ICOS, respectively, hereunder has been taken.

         18.2 Rights to Intellectual Property. Each Party warrants that it has
the power to grant all of the rights granted and make such required assignments,
and to assume all of the obligations required, under this Agreement.

         18.3 Disclaimer of Warranties. EXCEPT AS OTHERWISE EXPLICITLY PROVIDED
IN THIS SECTION 18, ARRAY AND ICOS EXPRESSLY DISCLAIM ANY WARRANTIES OR
CONDITIONS, EXPRESS, IMPLIED, STATUTORY OR OTHERWISE, WITH RESPECT TO THE
OPTIMIZATION PROGRAM, OPTIMIZATION COMPOUNDS, DERIVATIVES, PRODUCTS, ARRAY
TECHNOLOGY, ARRAY PATENTS OR OPTIMIZATION PATENTS, INCLUDING, WITHOUT
LIMITATION, ANY WARRANTY OF MERCHANTABILITY, NON-INFRINGEMENT, OR FITNESS FOR A
PARTICULAR PURPOSE.

IN WITNESS WHEREOF, the parties have executed this Agreement to be effective as
of the Effective Date.

By:  /s/ David Snitman                       By: /s/ W. Michael Gallatin, Ph.D.
  -------------------------------               -------------------------------
David Snitman, Ph.D.                         W. Michael Gallatin, Ph.D.
V. P. of Business Development                Vice President and Scientific
and Chief Operating Officer                   Director

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.
<PAGE>   17

                                   APPENDIX A

                             Milestones and Payments
                                (in U.S. Dollars)

Milestone payments shall be due only once per Milestone Compound upon the first
occurrence of each milestone by such Milestone Compound.

Milestones related to PDE4 and DNA-PK                         Milestone Payment

                                       [ * ]

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.
<PAGE>   18

                                   APPENDIX A

                             Milestones and Payments
                                (in U.S. Dollars)

Milestone payments shall be due only once per Milestone Compound upon the first
occurrence of each milestone by such Milestone Compound.

Milestones related to all other Compounds                     Milestone Payment

                                     [ * ]

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   19

                                   APPENDIX B

                              Optimization Targets

                                     [ * ]

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.<PAGE>   1
                                                                   EXHIBIT 10.32

                           COMPOUND LIBRARY AGREEMENT

         This COMPOUND LIBRARY AGREEMENT (the "Agreement"), effective as of the
date appearing on the signature page hereof (the "Effective Date"), is made by
and between Array BioPharma Inc., a Delaware corporation, having a principal
place of business at 1885 33rd Street Building AC-1 Boulder, CO 80301-2505
("Array"), and Darwin Discovery Limited (Registration Number 3515202), a company
organized and existing under the laws of England through certain of its
affiliates Chiroscience R&D Ltd. (Registration Number 3503756), a company
organized and existing under the laws of England located at No. 283 Cambridge
Science Park, Milton Road, Cambridge, England CB4 0WE, and Chiroscience R&D,
Inc., a Delaware corporation located at 1631 220th Street, Bothell, WA 98021
(collectively, "Chiroscience"). Any other affiliate or subsidiary of
Chiroscience (including without limitation ChiroTech) shall be deemed a third
party for all purposes of this Agreement and the Exhibits hereto.

                                    RECITALS

A.       Array desires to provide to Chiroscience, and Chiroscience desires to
         obtain from Array, collections of "Diversity Library(ies)" (as defined
         below).

B.       Chiroscience desires to have the opportunity to have one or more of its
         scientists trained in high speed synthesis techniques by Array
         scientists. C. Array is willing to provide "Diversity Library(ies)" (as
         defined below) to Chiroscience and provide it the opportunity for
         training and access to Chiroscience of certain Array Synthesis
         Methodologies (as defined below), and Chiroscience is willing to obtain
         the Diversity Libraries from Array and acquire access to such Array
         Synthesis Methodologies, on the terms and conditions set forth herein.

         NOW, THEREFORE, for and in consideration of the covenants, conditions,
and undertakings hereinafter set forth, it is agreed by and between the parties
as follows:

SECTION 1. DEFINITIONS.

         1.1 "ACTIVE COMPOUND" shall mean a Library Compound to the extent the
same has been designated and maintained as an Active Compound under Section 6.3
below.

         1.2 "ARRAY HSS INFORMATION" shall mean any confidential information
directly relating to Array's high-speed synthesis.

         1.3 "ARRAY SYNTHESIS METHODOLOGIES" shall mean, collectively, (i) the
exact, detailed [ * ] the Compounds delivered to Chiroscience hereunder,
including without limitation the quality control procedures used therefor; and
(ii) [ * ] used by Array as of the time of such disclosure used in Array's high
speed

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   2

synthesis of Compounds, to the extent the same consist of (A) methods [ * ], for
[ * ] and [ * ], for quality control using [ * ] and [ * ], and for [ * ] of
samples, or (B) [*].

         1.4 "COLLABORATION" shall mean an arrangement or a contract with a
third party or a person other than a party to this Agreement focused on the
discovery, screening, testing, manufacture or development of products for
specified diseases or targets, under which Chiroscience either retains rights to
commercialize the resulting products or will receive a portion of the sales of
the resulting products from the other party (by way of royalty, profit
participation or similar mechanism, including reasonable advance, paid-up or
lump-sum royalties).

         1.5 "COLLABORATIVE MANAGEMENT TEAM" OR "CMT" shall have the meaning as
set forth in Section 4.1 below.

         1.6 "COMPOUNDS" shall mean the related but distinct chemical compounds
derived from a defined Scaffold.

         1.7 "DESIGNATION PERIOD" shall mean, for a particular Library Compound,
the period commencing upon the first delivery of such Library Compound to
Chiroscience hereunder and ending on the date [ * ] thereafter.

         1.8 "DIVERSITY LIBRARY(IES)" shall mean a collection of TA Libraries.

         1.9 "EXCLUSIVE LIBRARY" shall have the meaning as set forth in Section
2.6 below.

         1.10 "FIRST YEAR DIVERSITY LIBRARY" shall mean the Diversity Library
consisting of approximately [ * ] TA Libraries delivered by Array to
Chiroscience prior to the first anniversary of this Agreement as set forth in
more detail in Section 2.1 below.

         1.11 "FIRST YEAR SCAFFOLDS" shall mean the Scaffolds listed on Exhibit
A attached hereto.

         1.12 "FIRST YEAR TA LIBRARY" shall have the meaning as set forth in
Section 2.1 below.

         1.13 "FTE" shall have the meaning as set forth in Section 5.1 below.

         1.14 "HSS EQUIPMENT" shall mean, collectively and individually, Array's
proprietary high-speed synthesis equipment.

         1.15 "INTELLECTUAL PROPERTY PROTECTION" shall mean the application,
prosecution (including, without limitation, all interference actions, term
extensions and disclaimers, reexaminations, reissues, and divisions),
maintenance, defense and enforcement of U.S. and foreign patent applications and
patents arising therefrom, and establishment and protection of trade secrets and
other forms of intellectual property rights.

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   3

         1.16 "LIBRARY COMPOUND" shall mean a Compound included in the First
Year Diversity Library or the Second Year Diversity Library delivered to
Chiroscience under this Agreement, together with all non-covalent derivatives of
such Compound, including but limited to acid addition salts, cationic salts, and
diasteromers and enantiomers thereof.

         1.17 "NON-LIBRARY COMPOUND" shall mean any composition of matter
discovered, developed or invented by Chiroscience, or that is claimed or
disclosed under patent application (including a provisional disclosure) filed by
Chiroscience or on its behalf which has a chemical structure distinct from the
Library Compounds.

         1.18 "PUBLIC DOMAIN COMPOUND" shall mean a Library Compound that cannot
be claimed as a composition of matter in a patent application because of failure
to meet the requirements for patentability under U.S. patent law (i.e., 35
U.S.C. et seq.).

         1.19 "LICENSED TECHNOLOGY" shall mean, collectively, Array patent
rights and the Array Synthesis Methodologies.

         1.20 "MAINTENANCE FEE" shall have the meaning as set forth in Section
6.3.2 below.

         1.21 "NEW FIRST YEAR TA LIBRARIES" shall mean those TA Libraries based
on Scaffolds distinct from the First Year Scaffolds, provided that New First
Year TA Libraries shall not include TA Libraries (i) that Array is prohibited or
otherwise restricted from providing Chiroscience; or (ii) that Array reasonably
believes cannot be delivered in a timely fashion to Chiroscience.

         1.22 "NEW SECOND YEAR TA LIBRARIES" shall mean the TA Libraries based
on Scaffolds distinct from the First Year Scaffolds and Second Year Scaffolds,
provided that New Second Year TA Libraries shall not include TA Libraries (i)
that Array is prohibited or otherwise restricted from providing Chiroscience; or
(ii) that Array reasonably believes cannot be delivered in a timely fashion to
Chiroscience.

         1.23 "NEW TA LIBRARIES" shall mean, collectively, the New First Year TA
Libraries and/or Second Year TA Libraries.

         1.24 "PROCESS DEVELOPMENT" shall be deemed to be initiated, with
respect to a particular TA Library, at such time as synthetic feasibility
studies used to define an efficient synthetic process for production of such TA
Library have been commenced.

         1.25 "RE-SUPPLY COMPOUNDS" shall have the meaning as set forth in
Section 2.5 below.

         1.26 "SCAFFOLD" shall mean the core chemical structure of the Compounds
of a TA Library.

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   4

         1.27 "SECOND YEAR DIVERSITY LIBRARY" shall mean the Diversity Library
consisting of approximately [ * ] TA Libraries delivered by Array to
Chiroscience prior to the second anniversary of this Agreement as set forth in
more detail in Section 2.3 below.

         1.28 "SECOND YEAR SCAFFOLDS" shall mean the Scaffolds for the Second
Year TA Libraries.

         1.29 "SECOND YEAR TA LIBRARIES" shall have the meaning as set forth in
Section 2.3 below.

         1.30 "TEMPLATE ARRAY LIBRARY" OR "TA LIBRARY" shall mean a library of
related Compounds delivered to Chiroscience by Array under this Agreement.

         1.31 "TRAINING PROGRAM" shall have the meaning as set forth in Section
5.1 below.

SECTION 2. DIVERSITY LIBRARIES.

         2.1 THE FIRST YEAR DIVERSITY LIBRARY. Subject to the terms and
conditions of this Agreement, prior to the first anniversary of this Agreement,
Array shall deliver to Chiroscience the First Year Diversity Library as set
forth in this Section 2.1. The First Year Diversity Library shall consist of
[ * ] TA Libraries (each, a "First Year TA Library") and shall contain a total
of [ * ] Compounds; provided that Chiroscience shall not be obligated to accept
or pay for more than [ * ] Compounds. Each First Year TA Library shall contain
an average of between [ * ] and [ * ] Compounds, all of which shall have the
same Scaffold. The First Year TA Libraries shall be based on, and identified by
the mutually agreed upon First Year Scaffolds, and shall be characterized in
conformance with the parameters set forth on Exhibit A, and shall meet the
quality control criteria set forth on Exhibit C hereto.

         2.2 FIRST YEAR [ * ]. As set forth in Section 2.7, during the first
year following the Effective Date, Array will disclose to Chiroscience, on at
least a [ * ] basis, the New First Year TA Libraries not previously disclosed.
Prior to the first anniversary of the Effective Date, Chiroscience shall [ * ]
New First Year TA Libraries [ * ] of the TA Libraries identified on Exhibit A
with Array's reasonable consent; provided, that written notice of the request is
received by Array no later than [ * ] after initiation of Process Development of
the TA Library that Chiroscience [ * ].

         2.3 THE SECOND YEAR DIVERSITY LIBRARY. Subject to the terms and
conditions of this Agreement, prior to the second anniversary of this Agreement,
Array shall deliver to Chiroscience the Second Year Diversity Library as set
forth in this Section 2.3. The Second Year Diversity Library shall consist of
approximately [ * ] TA Libraries (each, a "Second Year TA Library"), and shall
contain a total of [ * ] Compounds; provided that Chiroscience shall not be
obligated to accept or pay for more than [ * ] Compounds. Each Second Year TA
Library shall contain an average of between [ * ] Compounds, all of which shall
have the same Scaffold, and shall be characterized in conformance with the
parameters set forth on Exhibit B hereto, and shall comply with the quality
control criteria set forth on Exhibit C hereto. The Second Year Scaffolds shall
be [ * ]; provided, however it is understood that the

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   5

[ * ] Scaffolds set forth on Exhibit B as of the Effective Date [ * ]. [ * ]
drug-like Scaffolds of similar quality to those of the First Year Scaffolds for
the remaining [ * ] Second Year Scaffolds. If the parties cannot agree on at [ *
] Second Year Scaffolds within [ * ] from the Effective Date (i.e., for a total
of thirteen (13) Scaffolds), likewise if the parties cannot agree on a total of
[ * ] Second Year Scaffolds within [ * ] of the Effective Date; then
Chiroscience shall have the right to terminate this Agreement on [ * ] notice.
Exhibit B shall be amended by the parties to list the Second Year TA Libraries
as they are determined. Any First Year TA Library that is [ * ] under Section
2.2 shall become a Second Year TA Library, [ * ] under Section 2.4.

         2.4 SECOND YEAR [ * ]. As set forth in Section 2.7, during the second
year following the Effective Date, Array will disclose to Chiroscience, on at
least a [ * ] basis, the New Second Year TA Libraries not previously disclosed.
Prior to the second anniversary of the Effective Date, Chiroscience shall [ * ]
New Second Year TA Libraries for one or more of the TA Libraries identified on
Exhibit B with Array's reasonable consent; provided, that written notice of the
request is received by Array no later than [ * ] after initiation of Process
Development of the TA Library that Chiroscience [ * ].

         2.5 RE-SUPPLY COMPOUNDS. Chiroscience may obtain additional quantities
of Compounds already delivered ("Re-supply Compounds"), by written order to
Array specifying the Compounds desired; provided that the cumulative number of
Re-supply Compounds that Chiroscience has ordered at any given time shall in no
event [ * ] of the total number of Compounds delivered and accepted by
Chiroscience, in the aggregate, as of the date of the order, and no more than [
* ] Re-supply order may be made in any [ * ] period. Re-supply Compounds shall
be delivered in [ * ] from receipt of the order, and shall be supplied in
quantities of approximately [ * ], and shall comply with the other parameters of
Exhibit A or B, as applicable, at a charge of [ * ] provided to Chiroscience, or
[ * ] if a complete duplicate plate of [ * ] Compounds is to be provided to
Chiroscience. Unless otherwise agreed, the same Compound shall not be
re-supplied to Chiroscience more than [ * ] under this Section 2.5. In the event
that Chiroscience desires larger quantities, or higher purities of Re-supply
Compounds, the parties agree to negotiate terms for such synthesis in good
faith. Array's re-supply obligation shall continue for [ * ] following the
expiration or earlier termination (other than by Array for material breach by
Chiroscience) of this Agreement.

         2.6 THE EXCLUSIVE LIBRARY. Upon the written request of Chiroscience
given to Array prior to the first anniversary of this Agreement, the parties
agree to negotiate in good faith a separate agreement under which Chiroscience
would obtain up to [ * ] Compounds on an exclusive basis (the "Exclusive
Library") on reasonable commercial terms. The terms for the Exclusive Library
shall include: (i) Compounds for the Exclusive Library based upon Scaffolds
proposed by Chiroscience and agreed upon by Array, and the Second Year TA
Libraries for which such Scaffolds and Compounds shall be substituted; (ii) a
fully exclusive license or assignment with respect to the Exclusive Library
Compounds that [ * ]; (iii) Array will maintain the structure of such Scaffolds
as confidential until such time as the same become generally available in the
public domain, other than by breach of such provision by

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   6

Array; (iv) Array will provide Array Synthesis Methodologies for the Exclusive
Library Compounds; and (v) Array will agree not to provide Compounds within the
Exclusive Library or derivatives thereof to third parties; provided, that Array
shall have no obligation to provide any particular Scaffold to Chiroscience on
an exclusive basis and makes no representation that any particular Scaffold will
be available on such basis. The Exclusive Library shall be for a [ * ]
Compounds, and shall not include Compounds or Scaffolds contained in the First
Year Diversity Library or the Second Year Diversity Library. Without limiting
the foregoing, it is understood and agreed that the provisions of Section 6
would not apply to Exclusive Library Compounds.

         2.7 REPORTING. During the term of this Agreement, Array will report to
Chiroscience, on a [ * ], on its progress in creating New First Year TA
Libraries and New Second Year TA Libraries to be disclosed to Chiroscience
hereunder, and will notify Chiroscience in writing of Array's initiation of
Process Development of any TA Libraries to be delivered to Chiroscience under
this Agreement, not less than [ * ] to such initiation. Furthermore, in
connection with the obligations under Section [ * ] Array [ * ].

SECTION 3. DELIVERY; PAYMENT.

         3.1 DELIVERY. The First Year Diversity Library shall be delivered to
Chiroscience as soon as reasonably practicable and in no event later than the
first anniversary of this Agreement, or such other time as the parties may
agree. The parties contemplate that the First Year Diversity Library will be
delivered in stages, consisting of one or more TA Libraries in each delivery.
Array will undertake its best efforts to deliver the First Year Diversity
Library in accordance with the delivery schedule set forth on Exhibit A, and
will update this schedule each quarter to advise Chiroscience of any changes to
the delivery schedule. The parties shall undertake best efforts to agree, within
[ * ] of the Effective Date, on a delivery schedule for the first [ * ] Second
Year TA Libraries, and shall undertake to agree, within [ * ] of the Effective
Date, on a delivery schedule for the [ * ] Second Year TA Libraries. Array will
use its best efforts to deliver the Second Year Diversity Library within [ * ]
of the Effective Date. Any [ * ] of a New First Year TA Library [ * ] a First
Year TA Library shall [ * ], or other agreed-upon [ * ] for the First Year
Diversity Library by [ * ] in this manner, up to a maximum [ * ]. Any [ * ] a
New Second Year TA Library [ * ] a Second Year TA Library shall [ * ] the Second
Year Diversity Library within [ * ] for each New Second Year TA Library
substituted in this manner, [ * ]. Delivery of the First Year and Second Year
Libraries shall be accompanied by the Array Synthesis Methodologies used to
generate the TA Libraries contained therein and the quality control methods
employed as defined in Exhibits A and B. Array shall promptly deliver to
Chiroscience each First Year TA Library and Second Year TA Library as such TA
Libraries become available, and shall make such delivery an Array priority.

         3.2 PRICE; ADVANCE PAYMENTS. Chiroscience agrees to pay Array [ * ] per
Compound for each Compound delivered to Chiroscience as part of the First Year
or Second Year Libraries, in the manner set forth in this Section 3.2 and
Section 3.3 below.

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   7

         (i) Upon execution of the Agreement, Chiroscience shall pay Array Three
Hundred Thousand Dollars ($300,000), which is [ * ] of the estimated total price
for the First Year Diversity Library, as an advance payment for the First Year
Diversity Library; and

         (ii) Upon the first anniversary of this Agreement, or within [ * ] of
the parties' agreement on [ * ] Second Year Scaffolds, whichever is later,
Chiroscience shall pay Array [ * ], which is [ * ] of the estimated total price
for the Second Year Diversity Library as an advance payment for the Second Year
Diversity Library. Notwithstanding the foregoing, if the parties agree upon a
Second Year Diversity Library of [ * ] TA Libraries prior to the first
anniversary of the Effective Date, the advance pay due under this Section
3.2(ii) shall be reduced to [ * ] of the price for such Second Year Diversity
Library, assuming an average of [ * ] Compounds per Second Year TA Library.

The payments made under this Section 3.2 shall be proportionately refunded to
Chiroscience, or at Chiroscience's election credited against any outstanding
Chiroscience balance, in the event that this Agreement is terminated, as
expressly permitted hereunder, before the full TA Libraries have been delivered.
The amounts to be refunded, or credited if so elected, shall be in an amount
that results in Chiroscience paying an amount equal to [ * ] per Compound that
was delivered and which conformed with its applicable requirements under
Exhibits A, B and C.

         3.3 PAYMENTS ON DELIVERY.

               3.3.1 Within [ * ] of receipt of each TA Library from the First
Year Diversity Library or Second Year Diversity Library, Chiroscience shall
notify Array in writing of its acceptance or rejection of such TA Library, and,
if accepted, shall pay Array the balance due for the TA Library within [ * ] of
such acceptance, until the payments made by Chiroscience under Sections 3.2 and
3.3 equal [ * ] per Compound delivered; provided, that the advance payments made
by Chiroscience under Section 3.2 shall be deemed allocated among the projected
total number of First Year TA Libraries or Second Year TA Libraries for the
purpose of determining the balance due for any particular TA Library, and
further provided that nothing in this paragraph shall change the transfer price
[ * ] per Compound. For purposes of example, Chiroscience would pay [ * ] within
[ * ] of receipt of a TA Library consisting of [ * ] Compounds (i.e [ * ] made
under Section 3.2 therefor). Under no circumstances shall Chiroscience be
obligated to pay Array for more [ * ] Compounds or [ * ] Compounds for the TA
Libraries provided for each of the First Year Diversity Library or for the
Second Year Diversity Library, respectively, (i.e[ * ] for the First Year
Diversity Library and [ * ] for the Second Year Diversity Library, and a total
of Four Million Dollars ($4,000,000) for both Diversity Libraries), unless
Chiroscience has expressly, specifically and in writing requested such
additional Compounds.

               3.3.2 In addition, payment for accepted Re-supply Compounds in
accordance with Section 2.5 above shall be within thirty (30) days of delivery
thereof.

         3.4 REJECTION FOR NON-CONFORMANCE. Chiroscience may reject the delivery
of any TA Library that fails to materially conform to the requirements of
Exhibit A, B or C, as

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   8

applicable, by written notice to Array within thirty (30) days of delivery of
such TA Library, accompanied by documentation of the non-conformance and any
original experimental data related thereto. If a delivery fails to conform to
Exhibit C, then Array shall have the option of re-purifying or resynthesizing
the nonconforming TA Library (or portion thereof), or reaching an agreement with
Chiroscience on alternative compounds to be synthesized. It being understood
that if a particular Compound fails to meet the requirements of Exhibit C, then
[ * ] If a delivery fails to conform to Exhibit A or B, as applicable, then
Chiroscience shall reach a reasonable agreement with Array on resynthesizing the
nonconforming TA Library (or portion thereof), [ * ] In the event of any
nonconformance under this paragraph, Array shall have [ * ] to cure; provided,
that Array's failure to deliver the First Year Diversity Library within [ * ] of
the Effective Date (subject to any extensions due to cure periods) shall be
deemed a material breach of this Agreement, and must be cured within [ * ] of
notice from Chiroscience. TA Libraries that are not rejected by Chiroscience in
accordance with Section 3.3 above within [ * ] after delivery shall be deemed
accepted. It is understood that Chiroscience may rely on applicable certificates
of analysis provided by Array for a particular TA Library in determining whether
to accept such TA Library.

         3.5 PAYMENT PROCEDURE. All payments due under this Agreement shall be
made by bank wire transfer in immediately available funds to an account
designated by Array. All payments hereunder shall be made in U.S. Dollars. Any
undisputed payments that are not paid on the date such payments are due under
this Agreement shall bear interest to the extent permitted by applicable law at
the prime rate as reported by Norwest Bank, Denver, Colorado, on the date such
payment is due, calculated on the number of days such payment is delinquent past
the due date for such payment.

SECTION 4. THE COLLABORATIVE MANAGEMENT TEAM.

         4.1 THE CMT. The parties hereby establish a Collaborative Management
Team (the "CMT") comprised of four (4) members, with two (2) representatives
appointed by each party, whose names shall be provided in writing. A party may
change one or more of its representatives to the CMT at any time upon notice to
the other party. Each party will designate one of its representatives as its
team leader.

         4.2 DUTIES OF THE CMT. The CMT shall administer this Agreement,
including: (i) reporting of initiation of the synthesis of TA Libraries; (ii)
reporting of the creation of New TA Libraries; (iii) monitoring and reporting of
the synthesis of the Exclusive Library; (iv) agreement on the [ * ]; (v) [ * ]
of New TA Libraries [ * ] First Year or Second Year TA Libraries; (vi) modifying
the composition of compounds, changing the number of compounds or modifying the
[ * ] (vii) informal adjudication of any dispute concerning rejection of
delivery of a TA Library; (viii) administration and implementation of the
Training Program (as defined in Section 5.1 below) and the transfer of the Array
Synthesis Methodologies to Chiroscience under Section 5.6; and (ix) the initial,
informal mediation of any other dispute that arises under this Agreement. Any
decision of the CMT regarding (iv), (v), (vi) or (vii) shall be by written
agreement of the CMT and shall be treated as an amendment to this Agreement.

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   9

         4.3 MEETINGS OF THE CMT. The CMT shall conduct monthly telephone
conferences and shall prepare and deliver a brief written report describing the
significant issues and discussions that take place during such telephone
conferences. The chairman of the CMT shall be jointly appointed by its members
and shall rotate between Array and Chiroscience every six (6) months. The
chairman shall provide each member with five (5) business days' notice of the
time of any such telephone conferences and the proposed agenda with respect
thereto, unless waived by all members. Array will prepare and deliver to the
members of the CMT a brief progress report in advance of the telephone
conference, which report may include: the status of synthesis of TA Libraries,
creation of New TA Libraries, the administration of the Training Program, or any
other pertinent matters. The CMT shall meet at least once each quarter,
alternating at locations of the facilities of Array and Chiroscience, or at such
other times and locations as the CMT determines, with each party to bear all
travel and related expenses for its members. The chairman of the CMT shall
provide each member with five (5) business days' notice of the time and location
of meetings, unless such notice is waived by all members. If a designated
representative of a party cannot attend any meeting of the CMT, such party may
designate a different representative for that meeting without notice to the
other party. Except as otherwise provided in this Section 4, all actions and
decisions of the CMT will require the unanimous consent of all of its members.
Subsequent to each quarterly meeting, the chairman shall prepare and deliver, to
both parties, a written report describing the decisions made, conclusions and
actions agreed upon.

         4.4 COOPERATION. Each party agrees to provide the CMT with information
and documentation as reasonably required for the CMT to fulfill its duties under
this Agreement. In addition, each party agrees to make available its employees
and consultants as reasonably requested by the CMT. The parties anticipate that
members of the CMT will communicate informally with each other and with
employees and consultants of the parties on matters relating to this Agreement.

SECTION 5. TRAINING PROGRAM; ARRAY SYNTHESIS METHODOLOGIES TRANSFER

         5.1 THE TRAINING PROGRAM. Subject to the provisions of this Section 5,
at any time after the [ * ] month anniversary of the Effective Date during the
term of the Agreement, Chiroscience may, at its option, elect to have certain
Chiroscience employees ("FTEs") trained by Array employees in high speed
synthesis techniques [ * ] (the "Training Program"). The maximum number of FTEs
[ * ] Training Program during the term of the Agreement shall [ * ]; provided
that during the first year of this Agreement [ * ] FTEs [ * ] Training Program
at any time shall [ * ] and during the [ * ] year of the Agreement [ * ] FTEs [
* ] Training Program at any time shall [ * ]. Array shall have the right to [ *
] FTE's [ * ] that is directly related to [ * ]. A minimum [ * ] shall be
required of [ * ] FTE [ * ]. The FTEs shall remain Chiroscience [ * ] the
Training Program, and Chiroscience shall [ * ] FTE [ * ]. Notwithstanding the
foregoing, [ * ] FTEs [ * ].

         5.2 SELECTION. Chiroscience shall initiate the Training Program [ * ]
FTE through the CMT, coupled with a written request to Array [ * ] FTE's [ * ]
Array must consent

[*] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   10

[ * ] FTE, such consent not to be unreasonably withheld, it being agreed by the
parties [ * ] FTE, [ * ], should have appropriate [ * ]. At Array's request and
at its own expense, [ * ].

         5.3 LIABILITY; TERMINATION. Chiroscience shall execute an indemnity
agreement, in substantially the form attached as Exhibit D hereto, indemnifying
Array for any liability [ * ] FTE's [ * ] Training Program, as a condition [ * ]
FTE's [ * ] Training Program. If Array determines, in its reasonable discretion,
[ * ] FTE [ * ] Training Program, or is for any other reason not satisfactory to
Array, Array will notify Chiroscience of its intent [ * ] FTE's [ * ] Training
Program immediately, in which case Chiroscience shall be [ * ] , and for [ * ].

         5.4 CONFIDENTIALITY. As a condition of participating in the Training
Program, each FTE shall have executed a confidentiality and noncompete agreement
with Chiroscience substantially in the form attached hereto as Exhibit E
(Chiroscience's standard Confidentiality Agreement--U.S. version attached). In
addition, each FTE shall have executed the acknowledgement letter in the form
attached as Exhibit F hereto and provided a copy thereof to Array prior to such
FTE's participation in the Training Program. Array reserves the right, and
intends to [ * ] FTE [ * ]. Chiroscience's [ * ] the Training Program or
otherwise, shall not imply any right to [ * ] training program, except as
expressly granted herein. Array agrees that [ * ] to enable Chiroscience to
carry out and develop high speed synthesis, including [ * ].

         5.5 NON-SOLICITATION. The Parties agree that during the term of this
Agreement and for [ * ] thereafter, neither party shall encourage any employee
to leave the employ of the other Party. In addition, during the term of this
Agreement and for [ * ] thereafter the Parties agree not to employ or offer to
employ (as an employee, contractor, consultant or otherwise), any person who was
or is an employee or officer of the other Party during that same period.

         5.6 TECHNOLOGY TRANSFER. Array agrees to disclose to Chiroscience, for
use in accordance with Section 6, the Array Synthesis Methodologies.
Notwithstanding the foregoing, it is understood and agreed that Array's
disclosure obligations and the Array Synthesis Methodologies shall not include
information pertaining to Array's high speed synthesis equipment or to methods
of producing monomers. Disclosure of the information in (i) shall occur at the
time the particular TA Library is delivered to Chiroscience hereunder, and the
disclosure of the information described in (ii) shall occur within six (6)
months after the Effective Date. [ * ] In the event that Chiroscience purchases
from Array the HSS Equipment described in Section 5.7 below, Array personnel
will travel to the Chiroscience facility at which such equipment is to be
installed, as reasonably necessary to supervise the installation of such
equipment. Otherwise, Array personnel shall travel to Chiroscience's facilities
for purposes of the disclosure and assistance described in this Agreement only
as mutually agreed by Chiroscience and Array.

         5.7 OPTION TO PURCHASE EQUIPMENT. In addition to the disclosure of
information under Section 5.6 above, Array agrees to sell to Chiroscience one or
more duplicates of any or all of the HSS Equipment, at a price to be reasonably
agreed by the parties. Such sale shall be

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   11

made pursuant to a confidential sales agreement to be agreed upon, which will
include (among other provisions) a commitment by Chiroscience not to reverse
engineer such HSS Equipment and not to provide or disclose the HSS Equipment to
any third party. Chiroscience shall have the right to exercise this option at
any time during the term of this Agreement or within six (6) months thereafter;
it being understood that Chiroscience has no obligation to purchase such
equipment. Without limiting the foregoing, in the event that Array is restricted
from selling any particular piece of HSS Equipment to Chiroscience, Array agrees
to assist Chiroscience in acquiring any/or integrating such HSS Equipment on
reasonable terms and conditions to be agreed. Notwithstanding anything to the
contrary in this Agreement, its Exhibits or otherwise, Chiroscience may without
any obligation to Array or restriction obtain and use laboratory equipment,
reagents, consumables, software, know-how, and other articles available from
persons other than Array, in conjunction with Chiroscience's use of the HSS
Equipment or otherwise, provided however, for purposes of this Paragraph 5.7,
Chiroscience shall not disclose to any third party the Array Confidential
Information as defined in paragraph 2 of Exhibit G unless prior written approval
is obtained from Array.

         5.8 COSTS OF TECHNOLOGY TRANSFER. Chiroscience shall bear all its own
costs associated with implementing the Array Synthesis Methodologies and HSS
Equipment and practicing the same, and shall reimburse Array for its direct
costs and expenses incurred by Array under Section 5.6 on either [ * ].

         5.9 INVENTIONS. Notwithstanding anything herein to the contrary,
including Section 6 below, Array shall own inventions [ * ] and to the extent
such inventions directly relate to the subject matter of the [ * ]. Except as
otherwise expressly provided herein, Array hereby acknowledges that inventions
made by Chiroscience personnel [ * ] shall be solely owned by Chiroscience.

         5.10 ARRAY SYNTHESIS METHODOLOGIES. In addition to the licenses granted
under Section 6, Array hereby grants to Chiroscience a non-exclusive, worldwide,
license, without the right to sublicense, to use the Array Synthesis
Methodologies solely for Chiroscience's internal research and development
purposes. Notwithstanding the foregoing, Chiroscience shall not disclose or
otherwise transfer any Array Synthesis Methodologies to any third party except
to the extent necessary to exercise its right under Section 6.2 and only under
reasonable conditions of confidentiality; provided, however, in no event shall
Chiroscience disclose or otherwise transfer any Array Synthesis Methodologies to
ChiroTech or authorize any third party to do so.

SECTION 6. INTELLECTUAL PROPERTY

         6.1 OWNERSHIP OF RIGHTS--GENERALLY. Subject to the terms of this
Agreement, title to patents and other rights in inventions made solely by Array
personnel shall be owned by Array, title to patents and other rights in
inventions made solely by Chiroscience personnel shall be owned by Chiroscience,
and title to patents and other rights in inventions made jointly by Chiroscience
personnel and Array personnel shall be owned jointly by Chiroscience and Array.
Except as provided in this Section 6, neither party will have any obligation to

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   12

account to the other, or obtain the consent of the other, with respect to the
exploitation (directly or through licensees or third parties) of any jointly
owned patent, and each party hereby waives any right it may have under the laws
of any jurisdiction to require such an accounting or consent.

               6.1.1 LIBRARY COMPOUNDS DESIGNATED AS ACTIVE COMPOUNDS. [ * ]

               6.1.2 NON-LIBRARY COMPOUNDS. As between the parties hereto,
Chiroscience shall exclusively own all title to patent and other proprietary
rights for inventions, whether patentable or not, related to the Non-Library
Compounds, including, without limitation, all inventions for compositions of
matter, and methods of using or making such Non-Library Compounds.

         6.2 LICENSE OF RIGHTS.

               6.2.1 LIBRARY COMPOUNDS. Array hereby grants to Chiroscience a
non-exclusive, worldwide, paid-up right and license, without the right to
sublicense, to make, have made and use the Library Compounds under all U.S. and
foreign patents or other proprietary rights owned by Array to carry out
Chiroscience's own internal research [ * ] under this Agreement (e.g., screening
and identifying lead candidates for drug discovery and development). If
Chiroscience establishes a Collaboration (including contracts for screening,
production, testing and development services) with a third party, Chiroscience
may disclose a Library Compound to such third party and authorize such third
party to use the Library Compound as reasonably necessary for the purposes of
the Collaboration (whether or not such Library Compound has been designated as
an Active Compound); provided, the Collaboration must be evidenced by a written
agreement that provides, among other things, the third party agrees not to
provide the Library Compound to others (excepting those contractors that
actually perform screening, testing, production and development services under
such Collaboration and in each such event only under reasonable terms of
confidentiality and restricted use) and shall use such Library Compound for the
limited purpose of the Collaboration unless and until such Library Compound has
been designated and maintained as an Active Compound hereunder. Chiroscience may
disclose the composition of Compounds and transfer Compounds to potential
Collaboration partners, in each case subject to reasonable conditions of
confidentiality, without notifying Array. Notwithstanding the foregoing or any
other provision of this Agreement, in no event shall Chiroscience disclose any
Library Compound to ChiroTech for any reason.

               6.2.2 ACTIVE COMPOUNDS

                  (a) License to Chiroscience. Array hereby grants to
Chiroscience an exclusive, worldwide sublicenseable right and license to make,
have made, use, sell, and import, and to authorize others to make, have made,
use, sell and import any Active Compounds designated and maintained in
accordance with Section 6.3 below under any U.S. or foreign patents owned by
Array. The exclusive license granted Chiroscience under this Section 6.2.2(a)
with respect to any Compound shall not take effect until and

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   13

unless Chiroscience has designated that Compound as an Active Compound. The
right and license granted Chiroscience under this Section 6.2.2(a) shall become
paid-up and irrevocable with respect to a particular Active Compound at such
time as Chiroscience has paid all of the Maintenance Fees with respect to such
Active Compound as required under Section 6.3.2 below. Except as provided in
this Section 6, Chiroscience shall have no obligation to account to Array, or
obtain its consent, with respect to the exploitation (directly or through
licensees or third parties) of any Chiroscience owned rights, and Array hereby
waives any right it may have under the laws of any jurisdiction to require such
an accounting or consent.

                  (b) Restriction on Supply of Active Compounds. Upon
designation of a Library Compound as an Active Compound by Chiroscience as
provided in Section 6.3, Array shall not thereafter for so long as such Library
Compound remains an Active Compound hereunder [ * ]. If another person or
entity, that is a party to an Array compound library agreement, requests to
obtain exclusive rights from Array with respect to a Library Compound, which
Chiroscience had previously designated as an Active Compound hereunder, [ * ].

         6.3 DESIGNATION AND MAINTENANCE OF COMPOUNDS AS ACTIVE COMPOUNDS

               6.3.1 DESIGNATION OF ACTIVE COMPOUNDS.

                  (a) Designation. At any time during the Designation Period for
a Library Compound, Chiroscience shall have the right to designate the same as
an Active Compound. It is understood, however, that any such designation shall
be subject to Section 6.3.5 below; and to the extent that such designation is
precluded as described in Section 6.3.5 below, such Library Compound shall not
be an Active Compound hereunder. Subject to the foregoing, Chiroscience may
designate [ * ] Library Compounds as Active Compounds. To designate a Library
Compound as an Active Compound, Chiroscience must so notify Array in writing,
with a description of the Compound (including a complete description of its
chemical structure), together with payment of the applicable Maintenance Fee for
such Active Compound (the "Active Compound Notice").

                  (b) Restriction. Chiroscience agrees that it will not, and
will not authorize any third party to, sell or otherwise commercialize any
Library Compound for any purpose unless such Library Compound has been (i)
designated and maintained as an Active Compound hereunder [ * ].

               6.3.2 MAINTENANCE FEES FOR ACTIVE COMPOUNDS. To maintain a
Library Compound as an Active Compound hereunder and Chiroscience's rights with
respect thereto, Chiroscience agrees to pay to Array an annual maintenance fee
for each such Active Compound ("Maintenance Fee"). The amount of the Maintenance
Fee for each Active Compound will be based upon the aggregate number of Active
Compounds, according to the following schedule:

<TABLE>
<CAPTION>
    NO. OF ACTIVE COMPOUNDS            ANNUAL MAINTENANCE FEE PER COMPOUND
    -----------------------            -----------------------------------
<S>                                    <C>
    First [  *  ]                      [  *  ]/Compound for these Compounds
</TABLE>

[ * ]= Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   14

<TABLE>

<S>                                    <C>
    Next [  *  ]                       [  *  ]/Compound for these Compounds
    Next [  *  ]                       [  *  ]/Compound for these Compounds
    Over [  *  ]                       [  *  ]/Compound for these Compounds
</TABLE>

               6.3.3 CALCULATION OF MAINTENANCE COMPOUNDS. The annual
Maintenance Fees will be calculated for each Active Compound on a calendar year
basis. The first annual Maintenance Fee for an Active Compound would be due upon
the designation of such Active Compound pursuant to Section 6.3.1 above;
provided that such first annual Maintenance Fee would be prorated based upon the
number of days remaining in the calendar year from the date of such designation.
Thereafter, the annual Maintenance Fees shall be due for all Active Compounds no
later than January 15 of the particular calendar year. Once paid, the
Maintenance Fee shall be nonrefundable.

               6.3.4 TERMINATION OF ACTIVE COMPOUND DESIGNATION. Chiroscience
may terminate its designation of any particular Active Compound at any time, by
so notifying Array in writing (specifying the Active Compound for which such
designation is being terminated) (the "Termination Notice"), provided that [ * ]
Library Compounds designated as Active Compound under Section 6.3.1 above may be
terminated under this Section 6.3.4. From and after the date Array receives such
Termination Notice, the specified Library Compound shall cease to be an Active
Compound for all purposes of this Agreement and shall thereafter be subject to
the provisions for Library Compounds that are not designated as Active
Compounds, and the Maintenance Fees for the remaining Active Compounds shall be
appropriately adjusted. Without limiting the foregoing, in the event
Chiroscience terminates its designation of any Active Compound, Chiroscience
hereby grants to Array an exclusive, worldwide, fully paid-up, irrevocable
license, with the right to grant and authorize sublicenses, under all patent
rights held by Chiroscience claiming composition of matter of any such Active
Compound. [ * ]. For purposes of determining the amount of the Maintenance Fee
due for a particular Active Compound, such amount shall be based upon the total
number of Active Compounds that have been designated and not so terminated at
the time the Maintenance Fee is due. For purposes of determining the initial
annual Maintenance Fee, the Active Compounds being designated shall be included
in such total. The annual Maintenance Fee for any particular Active Compound
shall be due for a period of [ * ] calculated from the date that Compound was
designated as an Active Compound, after which time it shall be fully paid-up and
no further Maintenance Fee shall be due for such Active Compound. In the event
that the first year was less than a full calendar year, the Maintenance Fee for
the [ * ] calendar year beginning after the date such Active Compound was
initially designated pursuant to Section 6.3 would be prorated from January 1 of
such year until the date that is the [ * ] of the date of such designation. If
an Active Compound is terminated, and later re-designated, as an Active
Compound, such [ * ] period would begin as of the date the subsequent
re-designation.

               6.3.5 Third Party Rights. The First Year Diversity Library and
Second Year Diversity Library are being provided to Chiroscience on a
non-exclusive basis, and nothing herein shall prevent or restrict Array from
providing some or all of the Library Compounds within the First Year Diversity
Library or Second Year Diversity Library to third

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   15

parties. It is further understood that Array may grant to third parties rights
to acquire licenses in the Library Compounds similar to those granted to
Chiroscience hereunder; accordingly, Chiroscience's right to designate any
particular Library Compound as an Active Compound, and Array's grant of rights
to Chiroscience under this Section 6, are limited to the extent that prior to
Chiroscience's designation of a Library Compound as an Active Compound, a third
party has similarly designated such Library Compound. It is understood and
agreed that so long as Array complies with this Section 6, Array shall have no
liability with respect to any conflict of Chiroscience's rights and those rights
granted to third parties by Array. For avoidance of doubt, it is understood and
acknowledged that Array shall not have the right to grant to any third party,
who is an Affiliate of Array at the time of such grant, any right that might
conflict with the rights granted to Chiroscience under Section 6.2. For purposes
of the foregoing, an "Affiliate" shall mean any entity which controls, is
controlled by or is under common control with Array and an entity shall be
regarded as in "control" of another entity for purposes of this definition if it
owns or controls more than fifty percent (50%) of the shares of the subject
entity entitled to vote in the election of directors (or, in the case of an
entity that is not a corporation, for the election of the corresponding managing
authority).

         6.4 INTELLECTUAL PROPERTY PROTECTION. Chiroscience shall have the
right, at its expense and discretion and without obligation to Array, to fully
direct and control the Intellectual Property Protection for any and all Active
Compounds, [ * ], and to abstain or withdraw from such Intellectual Property
Protection; provided, however prior to filing or otherwise initiation of the
prosecution of any Intellectual Property Protection for any Library Compound
hereunder (whether covering composition-of-matter, method of use, synthesis
process, pharmaceutical composition or otherwise), Chiroscience shall (i)
designate such Library Compound as an Active Compound as set forth in Section
6.3 above [ * ] and maintain documentation to support such determination. In the
event Chiroscience designates a [ * ] under this Section 6.4(ii), then
Chiroscience shall retain all rights to fully direct and control the
Intellectual Property Protection for such [ * ]. In the event Chiroscience files
a patent application covering the Intellectual Property Protection of the
designated [ * ] Chiroscience shall provide all written documentation to Array
supporting Chiroscience's designation as a [ * ]. Array shall reasonably
cooperate with Chiroscience, at Chiroscience's expense, in its carrying out the
Intellectual Property Protection set forth under this Section 6.4, and shall
provide such records and shall cause its employees, officers and directors to
execute such documents and provide such testimony as reasonably necessary for
Chiroscience to perfect and enforce its rights and to carry out Intellectual
Property Protection, and shall not object to being joined by Chiroscience as a
party to any action brought or defended by Chiroscience to the extent necessary
for Chiroscience to maintain such action or defense.

         6.5 CONGRUENCE OF ARRAY LIBRARY AGREEMENTS. Array represents and
warrants that it shall ensure that each agreement under which it is or may
become obligated to provide access or rights to any of the Library Compounds
that are or might be provided to Chiroscience shall: (i) contain the provisions
not inconsistent with those set forth in this Section 6; and (ii) shall not
contain any provisions that would impair Array's ability to grant Chiroscience
the rights to which it would be entitled to under this Agreement, or that would

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   16

impair Chiroscience's free exercise of such rights, subject to Section 6.3.5.
Array shall be responsible for using reasonable efforts to ensure that the
parties to those other contracts shall fulfill their obligations to Array and
cause them to do so.

SECTION 7. CONFIDENTIALITY.

         7.1 CONFIDENTIAL INFORMATION. As a condition of this Agreement, the
Parties shall enter into the Nondisclosure Agreement attached at Exhibit G
hereto, and any confidential information exchanged hereunder, including the
Scaffolds proposed by Array for any of the Libraries to be provided hereunder,
shall be governed by such Agreement, except as otherwise expressly provided in
this Agreement and its Exhibits. The Nondisclosure Agreement supercedes all
prior agreements between the parties relating to confidentiality, and all such
prior disclosures are deemed to be bound by the terms of the Nondisclosure
Agreement. For avoidance of doubt, Array shall have the right to indicate to
third parties that a particular Library Compound is not available for
commercialization. If after the Effective Date Chiroscience wishes to disclose
to Array information that Chiroscience considers confidential or proprietary
related to (i) the activity of Compounds in biological screens or targets, (ii)
the targets against which Compounds are screened, or (iii) other development or
screening efforts with respect to Compounds, Chiroscience agrees to provide
Array with a nonconfidential summary of such information and will not disclose
such information to Array if Array notifies Chiroscience that Array does not
wish to receive such information.

         7.2 NONDISCLOSURE OF TERMS; PUBLICITY. The parties shall cooperate in
the preparation of a mutually-agreeable press release and other publicity
disclosing the existence of this Agreement in the form as set forth in Exhibit H
attached hereto. Except for the information disclosed in such press release or
publicity, neither party shall disclose the existence of this Agreement or any
terms of this Agreement without the prior, written consent of the other party
(which consent shall not be unreasonably withheld), except for such disclosure
as may be reasonably necessary to either party's bankers, investors, attorneys
or other professional advisors, or in connection with a merger or acquisition,
or as may be required by law in the offering of securities or in securities or
regulatory filings or otherwise. Either party may make public announcements
concerning this Agreement or the subject matter hereof with the prior written
consent of the other party, which consent shall not be unreasonably delayed or
withheld, and provided that the party proposing to make a public announcement
shall submit the proposed statement to the other party for review and reasonable
comment no less than [ * ] prior to such public announcement.

         7.3 PUBLICATION. Subject to Section 6, any manuscript, abstract or
presentation (including information to be presented verbally) by Chiroscience
specifically identifying the chemical structure or composition of non-exclusive
First Year Diversity Library or Second Year Diversity Library, or the Library
Compounds, [ * ] shall be subject to the reasonable prior review and reasonable
agreement of Array at least forty-five (45) days prior to any non-confidential
public submission or disclosure. The parties will treat matters of authorship of
scientific abstracts, manuscripts or other publications in a proper
collaborative spirit, giving credit where credit is due. Prior review and
agreement shall not apply to confidential

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   17

disclosures made by Chiroscience nor to patent applications (and related
Intellectual Property Protection actions) submitted by or on behalf of
Chiroscience or its Collaboration partners.

SECTION 8. REPRESENTATIONS AND WARRANTIES.

         8.1 CHIROSCIENCE. Chiroscience warrants and represents that: (i) it has
the legal power, authority and right to enter into this Agreement, and to
perform all its obligations hereunder, and (ii) this Agreement is a legal and
valid obligation binding upon it and enforceable in accordance with its terms.

         8.2 ARRAY. Array represents and warrants that: (i) it has the legal
right and power to extend the rights granted in this Agreement; (ii) this
Agreement is a legal and valid obligation binding upon it and enforceable in
accordance with its terms; and (iii) it has the legal power, authority and right
to enter into this Agreement, and to perform all its obligations hereunder.
Array covenants to Chiroscience that it will inform Chiroscience of any claim
brought or threatened by a third party against Array alleging that the
manufacture, use or sale of a Compound provided to Chiroscience hereunder
infringes a patent or other intellectual property right of a third party.

         8.3 DISCLAIMER. EXCEPT AS OTHERWISE EXPRESSLY SET FORTH IN THIS
AGREEMENT, ARRAY AND CHIROSCIENCE AND THEIR RESPECTIVE AFFILIATES MAKE NO
REPRESENTATIONS AND EXTEND NO WARRANTIES OR CONDITIONS OF ANY KIND, EITHER
EXPRESS OR IMPLIED, WITH RESPECT TO THE TA LIBRARIES, THE COMPOUNDS, OR PRODUCTS
CONTAINING THEM, OR INFORMATION DISCLOSED PURSUANT HERETO INCLUDING, BUT NOT
LIMITED TO, WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
VALIDITY OF ANY LICENSED TECHNOLOGY, PATENTED OR UNPATENTED, OR NONINFRINGEMENT
OF THE PATENT RIGHTS OF THIRD PARTIES.

SECTION 9. MISCELLANEOUS

         9.1 GOVERNING LAW. Any controversy or claim of whatsoever nature
arising out of or relating in any manner whatsoever in this Agreement or any
breach of any terms of this Agreement shall be governed by and construed in all
respects in accordance with, the laws of the state of New York.

         9.2 NO IMPLIED LICENSE. Only the licenses granted pursuant to the
express terms of this Agreement shall be of any legal force or effect. No other
license rights shall be created by implication, estoppel or otherwise. No
license on other rights granted herein shall be expanded by a change in
Chiroscience's ownership, merger, acquisition or otherwise.

         9.3 INDEPENDENT CONTRACTORS; AFFILIATES. The relationship of the
parties hereto is that of independent contractors. The parties hereto are not
deemed to be agents, partners or joint venturers of the others for any purpose
as a result of this Agreement or the transactions contemplated thereby.

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   18

         9.4 NOTICES. All notices, requests and other communications hereunder
shall be in writing and shall be personally delivered or by registered or
certified mail, return receipt requested, postage prepaid, in each case to the
respective address specified below, or such other address as may be specified in
writing to the other parties hereto and shall be deemed to have been given upon
receipt:

             Array:                Array BioPharma Inc.
                                   1885 30th Street - Bldg. AC-1
                                   Boulder, CO  80301-2505
                                   Attn:  David Snitman

             with a copy to:       Wilson Sonsini Goodrich & Rosati
                                   650 Page Mill Road
                                   Palo Alto, CA  94304-1050
                                   Attn:  Kenneth A. Clark

             Chiroscience:         Darwin Discovery Limited
                                   283 Cambridge Science Park
                                   Milton Road
                                   Cambridge CB4 0WE
                                   United Kingdom
                                   Attn:  Company Secretary
                                   FAX:  1223 420-440

                                   Chiroscience R&D Limited
                                   283 Cambridge Science Park
                                   Milton Road
                                   Cambridge CB4 0WE
                                   United Kingdom
                                   Attn:  Company Secretary
                                   FAX:  1223 420-440

                                   Chiroscience R&D, Inc.
                                   1631 220th Street SE
                                   Bothell, WA  98021
                                   Attn:  Director of Legal Affairs
                                   FAX:  425-489-8018

         9.5 SEVERABILITY. In the event that any provision of this Agreement
becomes or is declared by a court of competent jurisdiction to be illegal,
unenforceable or void, this Agreement shall continue in full force and effect to
the fullest extent permitted by law without said provision, and the parties
shall amend the Agreement to the extent feasible to lawfully include the
substance of the excluded term to as fully as possible realize the intent of the
parties and their commercial bargain.

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   19

         9.6 NO CONSEQUENTIAL DAMAGES. In no event shall any party to this
Agreement have any liability to the other for any special, consequential or
incidental damages arising under this Agreement or any dispute as to the
enforcement or construction of this Agreement under any theory of liability
(including tort, contract and breach of warranty). The remedy for material
breach of this Agreement, including the failure to deliver Compounds shall be
limited to termination of the contract, return of any amounts paid for Compounds
not delivered, and interest on such funds at the legal rate.

         9.7 SALES TAXES. Chiroscience has represented that the Compounds to be
delivered according to this Agreement are to used solely for internal research
and development by Chiroscience. Based on this representation, Array believes
that no sales taxes, use taxes, transfer taxes or similar governmental charges
will be required to be paid in connection with the transfer of the TA Libraries
hereunder. Notwithstanding the foregoing, any such taxes or charges shall be the
sole responsibility of Chiroscience, and in the event that Array is required to
pay any such amounts, Chiroscience shall promptly remit payment to Array of such
amounts.

         9.8 COMPLETE AGREEMENT. This Agreement with its Exhibits, together with
the Nondisclosure Agreement, constitutes the entire agreement, both written and
oral, between the parties with respect to the subject matter hereof, and all
prior agreements respecting the subject matter hereof, either written or oral,
expressed or implied, shall be abrogated, canceled, and are null and void and of
no effect. There are no covenants, promises, agreements, warranties,
representations, conditions or understandings, either oral or written, between
the parties other than as set forth herein and therein. No amendment or change
hereof or addition hereto shall be effective or binding on either of the parties
hereto unless reduced to writing and executed by the respective duly authorized
representatives of Array and Chiroscience.

         9.9 DEFAULT. In the event that either party shall fail to comply with a
material term of this Agreement (for purposes of this Section 9.9, the
"Defaulting Party"), the other party shall provide the Defaulting Party with
written notice through the CMT, specifying the nature of the non-compliance. The
Defaulting Party shall have thirty (30) days from receipt of notice to cure the
non-compliance, except as otherwise provided for in the Agreement. If the
Defaulting Party disputes the allegations of the notice, then the parties shall
attempt in good faith to resolve the matter informally through the CMT. The
failure of Array to substantially deliver the entire First Year Diversity
Library within one (1) year of the Effective Date shall be deemed a material
breach of this Agreement.

         9.10 INDEMNIFICATION AND INSURANCE.

                  9.10.1 INDEMNIFICATION. Each party (for purposes of this
Section 9.10, the "Indemnitor") shall indemnify, defend, and hold harmless
(collectively "Indemnification Obligations") the other party and its affiliates
and their directors, officers, employees, and agents and their respective
successors, heirs and assigns (for purposes of this Section 9.10, the
"Indemnitees"), against any liability, damage, loss, or expense (including
reasonable attorneys fees and expenses of litigation) incurred by or imposed
upon the

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   20

Indemnitees or any one of them in connection with any claims, suits, actions,
demands, or judgments arising out of any theory of product liability (including,
but not limited to, actions in the form of tort, warranty, or strict liability)
concerning any product (or any process or service) that is made, used, or sold
by or under authority of the Indemnitor pursuant to any right or license granted
under this Agreement or to any breach of the parties respective warranties;
provided, however, that such Indemnification Obligations shall not apply to any
liability, damage, loss, or expense to the extent directly attributable to the
negligent activities, reckless misconduct, or intentional misconduct of the
Indemnitees.

               9.10.2 PROCEDURES. Any Indemnitee that intends to claim
Indemnification Obligations under Section 9.10.1 shall promptly notify the
appropriate Indemnitor of any claim in respect of which the Indemnitee intends
to claim such indemnification, and the Indemnitor shall assume the defense
thereof with competent and qualified counsel; provided, however, that an
Indemnitee shall have the right to retain its own counsel, with the fees and
expenses to be paid by the Indemnitor, if representation of such Indemnitee by
the counsel retained by the Indemnitor would be inappropriate due to actual
material conflict of interests between such Indemnitee and any other party
represented by such counsel in such proceedings. The failure to deliver notice
to the Indemnitor within a reasonable time after the commencement of any such
action shall not relieve the Indemnitor of any liability to the Indemnitee under
this Section, except to the extent that one or more legal defenses or rights may
have been forfeited or impaired by such delay. Each party and its affiliates and
their employees and agents shall cooperate fully with the other party and its
legal representatives in the investigation of any action, claim or liability
covered by this indemnification.

               9.10.3 INSURANCE. Each party shall maintain reasonably adequate
insurance or self-insurance coverage for its own potential liabilities to the
Indemnitees as set forth in this Section 9.10.

         9.11 ARBITRATION. Any dispute or controversy pertaining to this
Agreement or the enforcement or construction of this Agreement shall initially
be referred to the CMT. The parties agree to attempt to resolve any such dispute
in good faith through the CMT. In the event the dispute is not resolved within
thirty (30) days by the CMT, the dispute shall be referred to senior management
of the parties, who shall attempt in good faith to resolve it. Any dispute which
cannot be resolved within thirty (30) days after referral to the respective
Chief Executive Officers of the parties shall be finally settled by binding
arbitration, conducted in accordance with the Commercial Arbitration Rules of
the American Arbitration Association by one arbitrator appointed by agreement of
the parties. The arbitration shall be held in New York City, New York. New York
law shall be applied to all matters in dispute between the parties with respect
to this Agreement. Each party shall bear its own costs and attorneys' and
witness' fees. The costs of the administration of the arbitration, including
arbitrator's fees and administrative fees and expenses, shall be shared equally
by the parties.

         9.12 RENEWAL OPTION. Chiroscience may request a one-time renewal of
this Agreement for an additional one (1) year period, by written notice at least
ninety (90) days

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   21

prior to the second anniversary of the Effective Date. Such renewal would
provide for the delivery of a third year Diversity Library of up to [ * ]
Compounds on a non-exclusive basis. The parties agree to negotiate the terms of
any such renewal in good faith, but agree that such renewal terms would not
include royalty provisions or milestones, or provide for more than a [ * ]
increase in the cost per Compound and would reflect terms substantially similar
to Sections 1, 2.1, 2.2, 2.5, 2.7, 3, 4, 6, 7, 8 and 9 (other than this Section
9.12), and Exhibits A, C, G of this Agreement. It being understood that Sections
3.2 and 3.3 will be modified to reflect the agreed upon cost per Compound and
number of Compounds to be included in the third year Diversity Library.

         9.13 TERM AND TERMINATION. The term of this Agreement shall be two (2)
years from the Effective Date, unless terminated earlier for material breach or
as provided in 2.3 above, or extended pursuant to Section 9.12 or other
agreement of the parties. Either party may terminate this Agreement on thirty
(30) days' notice for material breach that is not cured within such thirty (30)
day period, except as provided otherwise in the Agreement. Termination of this
Agreement shall not relieve the parties of any obligation accruing prior to such
termination. In addition, Sections 1, 5.4, 5.5, 5.9, 6.1, 7, 8, and 9 (other
than Section 9.12) and Exhibit G, shall survive the expiration or any
termination hereof. Furthermore, Sections 2.5, 5.6, 5.10, 6.2, 6.3, 6.4 and 6.5
shall survive the expiration of this Agreement or a termination under (i)
Section 2.3 or (ii) under this Section 9.13 by reason of material breach by
Array, but shall not survive termination under this Section 9.13 by reason of
material breach by Chiroscience. For purposes of the foregoing, if a Section
that so survives is expressly stated to continue for a period of time specified
in such surviving Section, the same shall survive only for the remainder of the
period specified in such Section.

         9.14 CHANGE OF CONTROL. This Agreement shall not be assignable by
either party without the written consent of the other party hereto; except that
either party may assign this Agreement without the other party's consent to an
entity that succeeds to substantially all of the business or assets of the
assigning party, by way of merger, transfer of assets, or otherwise.

         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed by their authorized representatives and delivered in duplicate
originals.

DARWIN DISCOVERY LIMITED                   ARRAY BIOPHARMA INC.

By:                                        /s/ David Snitman
          ----------------------------

Name:                                      Dr. David Snitman
          ----------------------------

Its:                                       Chief Operating Officer
          ----------------------------

Dated:                                     Dated:
          ----------------------------            -----------------------------

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   22

                                    EXHIBIT A

              Characterization of the First Year Diversity Library

                                      [ * ]

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   23

                                    EXHIBIT B

              Characterization of the Second Year Diversity Library

                                      [ * ]

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   24

                                    EXHIBIT B

              Characterization of the Second Year Diversity Library

                                      [ * ]

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   25

                                    EXHIBIT C

                            QUALITY CONTROL CRITERIA

                                      [ * ]

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   26

                                    EXHIBIT D

                            INDEMNIFICATION AGREEMENT

                                      [ * ]

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   27

                                    EXHIBIT E

                 CHIROSCIENCE STANDARD CONFIDENTIALITY AGREEMENT
                                   (U.S. Form)

                                      [ * ]

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   28

                                    EXHIBIT F

                              ACKNOWLEDGMENT LETTER

                                      [ * ]

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   29

                                    EXHIBIT G

                         MUTUAL NONDISCLOSURE AGREEMENT

                                      [ * ]

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

<PAGE>   30

                                    EXHIBIT H

                                  PRESS RELEASE

                                      [ * ]

[ * ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission pursuant to Rule 406 of the Securities Act of 1933, as amended.

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