Dated 2 June 2009

CombinatoRx, Incorporated as Vendor

and

Biomedical Sciences Investment Fund Pte Ltd as Purchaser

and

CombinatoRx (Singapore) Pte. Ltd. as Company

SHARE PURCHASE AGREEMENT

relating to the sale and purchase

of all the issued ordinary shares in the capital of

CombinatoRx (Singapore) Pte. Ltd.

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TABLE OF CONTENTS Contents    Page  1.    INTERPRETATION    2  2.    SALE AND
PURCHASE OF SALE SHARES    6  3.    COMPLETION    6  4.    TERMINATION OF
SINGAPORE TERMINATING AGREEMENTS / AMENDING      AND RESTATING THE NOTE
CONDITIONS    8  5.    RESTRICTIONS ON THE VENDOR    8  6.    WARRANTIES    11 
7.    ENTIRE AGREEMENT    13  8.    INDULGENCE, WAIVER, ETC    13  9.   
CONTINUING EFFECT OF AGREEMENT    13  10.    VARIATION    13  11.    REMEDIES
CUMULATIVE    13  12.    THIRD PARTY RIGHTS    14  13.    SUCCESSORS AND
ASSIGNS    14  14.    FURTHER ASSURANCE    14  15.    ANNOUNCEMENTS    14  16. 
  COSTS    14  17.    SEVERABILITY OF PROVISIONS    14  18.    NOTICES    15 
19.    CONFIDENTIALITY    15  20.    GOVERNING LAW AND DISPUTE RESOLUTION    16 
21.    COUNTERPARTS    17  SCHEDULE 1    18  SCHEDULE 2    19  SCHEDULE 3    20 
i         

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SCHEDULE    4    21  SCHEDULE    5    22  SCHEDULE    6    23  SCHEDULE    7   
24  SCHEDULE    8    25 

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This Agreement is made on 2 June 2009 between:

(1)      COMBINATORX, INCORPORATED (the “Vendor”), a company incorporated in the
state of Delaware, United States of America with its registered office at 245
First Street, Cambridge, Massachusetts, 02142, USA;   (2)      BIOMEDICAL
SCIENCES INVESTMENT FUND PTE LTD (the “Purchaser”), a company incorporated in
Singapore with its registered office at 250 North Bridge Road, #20-02 Raffles
City Tower Singapore 179101; and   (3)      COMBINATORX (SINGAPORE) PTE. LTD.
(the “Company”), a company incorporated in Singapore with its registered office
at 11 Biopolis Way #08-05/06 Helios Singapore 138667.  

Whereas:

(A)      The Company is a private company incorporated in Singapore under the
Companies Act, Chapter 50. The Company has at the date of this Agreement an
issued share capital of US$2,502,602.041 divided into 2,602,041 Ordinary Shares
(as defined below) and 2,500,000 Preference Shares (as defined below). Further
particulars of the Company are set out in Schedule 1.   (B)      The Parties had
entered into various agreements, details of which are set out below:     (i)   
  a subscription and shareholders agreement dated 19 August 2005 entered into
between the Parties (the “Subscription and Shareholders Agreement”);     (ii)   
  a swap-up agreement dated 30 August 2005 entered into between the Parties (the
“Swap-up Agreement”);     (iii)      a services agreement dated 19 August 2005
entered into between the Vendor and the Company (the “Services Agreement”);    
(iv)      a debenture dated 30 August 2005 entered into between the Company and
the Purchaser (the “Debenture”);     (v)      a share charge agreement dated 30
August 2005 entered into between the Shareholders (the “Share Charge
Agreement”);     (vi)      a registration rights agreement dated 30 August 2005
entered into between the Shareholders (the “Registration Rights Agreement”);    
(vii)      a preferred stock rights agreement dated 30 August 2005 entered into
between inter alia the Shareholders (the “Preferred Stock Rights Agreement”);
and     (viii)      a parent subscription agreement dated 18 August 2005 entered
into between the Company and the Vendor (the “Parent Subscription Agreement”).  
(C)      The Vendor had also issued to the Purchaser the Warrant (as defined
below) on 19 August 2005.  

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(D)      The Vendor has agreed to sell to the Purchaser, and the Purchaser has
agreed to purchase from the Vendor, the Sale Shares (as defined below) on the
terms and subject to the conditions contained in this Agreement.   (E)     
Further to the sale of the Sale Shares from the Vendor to the Purchaser pursuant
to this Agreement, the Parties have agreed to:     (i)      terminate their
respective Singapore Terminating Agreements;     (ii)      replace the Note
Conditions (as defined below) in its entirety with the New Note Conditions (as
defined below); and     (iii)      enter into:      (a)      the Intellectual
Property Assignment Agreement (as defined below); and      (b)      the
Transition Services Agreement (as defined below),  

on and subject to the terms and conditions herein contained; and

(iv)      terminate their respective US Terminating Agreements, on and subject
to the terms and conditions contained in the Termination Agreement (as defined
below).  

(F)      The Parties further acknowledge that it is intended for the following
documents to continue to remain in existence from the Completion Date:     (i) 
    the Debenture (which shall be supplemented with the Supplemental Debenture
(as defined below) on the Completion Date);     (ii)      the Notes (as defined
below);     (iii)      the Note Certificates (as defined below);     (iv)     
the Note Conditions (which shall be replaced in its entirety with the New Note
Conditions on the Completion Date); and     (v)      the Warrant,     
(collectively, the “Existing Agreements”).  

It is agreed as follows:

1.      INTERPRETATION   1.1      Definitions: In this Agreement, unless there
is something in the subject or context inconsistent therewith, the following
expressions bear the following meanings, namely: “Articles of Association” means
the articles of association for the time being of the Company;     “Audited
Accounts” means the audited accounts of the Company for the financial period
ended on 31 December 2007;     “Board of Directors” means the board of Directors
for the time being of the Company;     “Business Day” means a day (other than a
Saturday, Sunday or public holiday) on which commercial banks are open for
business in Singapore;  

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“Company Intellectual Property” means:

(i)      all works of authorship, data, marks, names, logos or other indicia of
origin, inventions, ideas, processes, methodologies, trade secrets, know-how and
other intellectual property now or hereafter existing, which are made, created,
developed or acquired by the Company; and   (ii)      the Patent Applications;  

“Completion” means completion of the sale and purchase of the Sale Shares
pursuant to Clause 3;

“Completion Date” means 2 June 2009 (or such later Business Day as the Parties
may agree in writing);

“Directors” means the Directors for the time being of the Company and “Director”
means any of them;

“Encumbrances” means any claim, charge, mortgage, security, lien, option,
equity, power of sale, hypothecation or other third party rights, retention of
title, right of pre-emption, right of first refusal or security interest of any
kind, including but not limited to the Share Charge;

“GST” means goods and services tax chargeable under the GST Act;

“GST Act” means the Goods and Services Tax Act, Chapter 117A of Singapore;

“Intellectual Property Assignment Agreement” means the intellectual property
assignment agreement to be entered into between the Company and the Vendor, in
the form set out in Schedule 2;

“Losses” means all losses, liabilities, costs (including, without limitation,
legal costs), charges, expenses, actions, proceedings, claims and demands;

“Management Accounts” means the unaudited management accounts relating to the
Company for the period commencing 1 January 2008 to the Management Accounts
Date;

“Management Accounts Date” means 31 March 2009;

“New Articles of Association” means the new set of articles of association to be
adopted by the Company in the form set out in Appendix A;

“New Note Conditions” means the new set of terms and conditions of the Notes (as
from time to time amended, modified or supplemented) as set out in Appendix B to
replace the Note Conditions in its entirety on the Completion Date and any
reference to a specified New Note Condition shall be construed accordingly;

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“Note Certificates” means certificates issued by the Company certifying that the
Purchaser is the holder of the principal amount of each of the Notes;

“Note Conditions” means the existing terms and conditions of the Notes as set
out in Schedule 5;

“Notes” shall mean collectively, the Series 1 Notes, the Series 2 Notes, the
Series 3 Notes, the Series 4 Notes and the Series 5 Notes;

“Ordinary Shares” means the ordinary shares in the capital of the Company;

“Patent Applications” means the U.S. Patent Applications listed in Schedule 8,
any invention claimed therein, any other patent application directed to any such
invention, and all Letters Patent of the United States that may be granted
thereon and patents and any special protection certificates that issue on the
U.S. Patent Applications listed in Schedule 8, and all reissues, continuations,
continuations-in-part, divisions, revisions, reexaminations, and extensions
thereof; and all rights to claim priority on the basis of such applications, and
all applications for Letters Patent that have been or may be filed for any such
invention in any foreign country and all Letters Patent that may be granted on
any such invention in any foreign country, and all extensions, renewals, and
reissues thereof, constituting all patent rights made or developed pursuant to
the Services Agreement that have, pursuant to the provisions thereof, previously
been assigned by the Vendor to the Company;

“Parties” means the parties to this Agreement and “Party” means any one of them;

“Preference Shares” means the Series A redeemable convertible cumulative
preference shares in the capital of the Company, having the rights, privileges,
preferences and restrictions set forth in the Articles of Association;

“Property” means the leasehold property at 11 Biopolis Way Helios #08-05/06
Singapore 138667;

“Sale Shares” means 2,602,041 Ordinary Shares to be purchased by the Purchaser
from the Vendor pursuant to this Agreement, being all the Ordinary Shares in the
capital of the Company;

“Series 1 Notes” means the US$5,500,000 in aggregate principle amount of 5%
notes due 2009, issued by the Company to the Purchaser on 30 August 2005;

“Series 2 Notes” means the US$3,500,000 in aggregate principle amount of 5%
notes due 2009, issued by the Company to the Purchaser on 8 June 2006;

“Series 3 Notes” means the US$3,500,000 in aggregate principle amount of 5%
notes due 2009, issued by the Company to the Purchaser on 30 May 2007;

“Series 4 Notes” means the US$2,500,000 in aggregate principle amount of 5%
notes due 2009, issued by the Company to the Purchaser on 4 August 2008;

“Series 5 Notes” means the US$2,500,000 in aggregate principle amount of 5%
notes due 2009, issued by the Company to the Purchaser on 4 August 2008;

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“Share Charge” means the first fixed charge given by the Vendor over the Sale
Shares in favour of the Purchaser pursuant to the Share Charge Agreement;

“Shareholders” means the Purchaser and the Vendor;

“Singapore Dollars” and the sign “S$” mean the lawful currency of the Republic
of Singapore;

“Singapore Terminating Agreements” means the Subscription and Shareholders
Agreement, the Parent Subscription Agreement and the Share Charge Agreement;

“Stamp Duty Documents” means:

(i)      a letter in the form prescribed by the Stamp Duty Branch of the Inland
Revenue Authority of Singapore and signed by a director or the secretary of the
Company incorporating a working sheet computing the net asset value per Sale
Share; and/or   (ii)      such other documents as may be prescribed from time to
time by the Stamp Duty Branch of the Inland Revenue Authority of Singapore for
the purpose of assessing the stamp duty payable on a transfer of shares;  

“Supplemental Debenture” means the supplemental debenture to be entered into
between the Company and the Purchaser, in the form set out in Schedule 7, on the
Completion Date;

“Taxation” includes all forms of taxation and statutory, governmental, state,
provincial, local governmental or municipal impositions, duties, contributions
and levies, including GST and any other form of value-added tax, in each case
whether of Singapore or elsewhere in the world whenever imposed and whether
chargeable directly or primarily against or attributable directly or primarily
to the relevant company or any other person and all penalties, charges, costs
and interest relating thereto;

“Termination Agreement” means the termination agreement to be entered into
between the Company, the Vendor and the Purchaser, in the form set out in
Schedule 3, on the Completion Date to terminate the US Terminating Agreements;

“Transition Services Agreement” means the transition services agreement to be
entered into between the Company and the Vendor, in the form set out in Schedule
4;

“United State Dollars” and the sign “US$” mean the lawful currency of the United
States of America;

“US Terminating Agreements” means the Registration Rights Agreement, the Swap-Up
Agreement and the Services Agreement;

“Warrant” means the Common Stock Purchase Warrant dated 19 August 2005 issued by
the Vendor to the Purchaser on 19 August 2005, such warrant which may be
exercised by the holder thereof to subscribe for 25,000 common stock of the
Vendor, in the form as set out in Schedule 6; and

“Warranties” means the representations, warranties and undertakings on the part
of the Vendor contained in this Agreement.

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1.2      Miscellaneous:     1.2.1      Except where the context otherwise
requires, words denoting the singular shall include the plural and vice versa;
words denoting any gender shall include all genders; words denoting persons
shall include firms and corporations and vice versa.     1.2.2      References
to this Agreement include any Recitals and Schedules to it and references to
Clauses, Schedules and Appendices are to the clauses of, and schedules and
appendices to, this Agreement. References to paragraphs are to paragraphs of the
Schedules.     1.2.3      Headings are for convenience only and shall not affect
the interpretation of this Agreement.   2.      SALE AND PURCHASE OF SALE SHARES
  2.1      Sale and Purchase of Sale Shares: Subject to the terms and conditions
of this Agreement, the Vendor shall sell, as legal and beneficial owner, and the
Purchaser relying on the Warranties and other undertakings contained in this
Agreement shall purchase, the Sale Shares, free from all Encumbrances and
together with all rights and advantages now and hereafter attaching thereto as
at Completion.   2.2      Waiver of Moratorium: The Parties hereby consent to
the proposed sale by the Vendor of the Sale Shares to the Purchaser pursuant to
the terms herein, notwithstanding that the sale of the Sale Shares shall take
place prior to the fourth anniversary of the Initial Closing Date (as defined in
the Subscription and Shareholders Agreement).   2.3      Waiver of Share
Buyback: The Company hereby waives any and all rights of its share buy-back over
the Sale Shares conferred by the Subscription and Shareholders Agreement and the
Articles of Association, for the purposes of the sale by the Vendor to the
Purchaser of the Sale Shares as contemplated by this Agreement.   2.4     
Consideration: The consideration for the purchase of the Sale Shares to be sold
by the Vendor shall be the sum of US$1.00 payable by the Purchaser to the Vendor
on Completion in accordance with Clause 3.3.   3.      COMPLETION   3.1     
Date and Place: Subject as hereinafter provided, Completion shall take place at
the registered office of the Company (or at such other place as the Parties may
agree in writing) on the Completion Date.   3.2      Obligations of the Vendor:
On Completion, the Vendor or the Company shall deliver or make available to the
Purchaser:     3.2.1      a duly executed transfer of the Sale Shares in favour
of the Purchaser, accompanied by:      (i)      the share certificate(s) in
respect of the Sale Shares; and      (ii)      the Stamp Duty Documents;  

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3.2.2      the written resignations of each of the directors of the Company and
the alternate directors of the Company except Choo Heng Tong and Ralf Marius
Altmeyer from his office as a director and an alternate director (as the case
may be) to take effect on the Completion Date, with acknowledgements signed by
each of them in a form satisfactory to the Purchaser to the effect that they
have no claim against the Company for loss of office or otherwise;   3.2.3     
(for the Purchaser itself and as agent for the Company) the certificates of
incorporation, corporate seals (if any), cheque books, statutory and other books
of the Company (duly written up-to-date);   3.2.4      all the financial and
accounting books and records of the Company and (for the Purchaser itself and as
agent for the Company) all documentation relating to the Property;   3.2.5     
bank statements of all bank accounts of the Company as at the Completion Date;  
3.2.6      copies of resolutions, duly certified as true copies by a Director,
of the Board of Directors and the Shareholders, under which the Board of
Directors and the Shareholders respectively have (in terms approved by the
Purchaser prior to the Completion Date):     (i)      approved the entry into by
the Company of this Agreement, the Termination Agreement, the Transition
Services Agreement, the Intellectual Property Assignment Agreement, the
Supplemental Debenture and the issue of the New Note Conditions to replace the
Note Conditions in its entirety;     (ii)      approved the registration of the
share transfer referred to in Clause 3.2.1, subject only to it being stamped;  
  (iii)      accepted the resignations referred to in Clause 3.2.2 and approving
the appointment of Yeo Su Ling as Director of the Company;     (iv)      (if so
required by the Purchaser) revoked all existing authorities to bankers in
respect of the operation of the bank accounts of the Company and giving
authority in favour of such persons as the Purchaser may nominate to operate
such accounts;     (v)      approved the adoption of the New Articles of
Association, in substitution for and to the exclusion of the Articles of
Association on the Completion Date; and     (vi)      approved the change of
name of the Company to ExCRX Singapore Pte. Ltd. on the Completion Date.  
3.2.7      copies of resolutions, duly certified as true copies by the Secretary
of the Vendor, of the board of directors of the Vendor, under which the board of
directors of the Vendor have approved (in terms approved by the Purchaser prior
to the Completion Date) the entry into by the Vendor of this Agreement, the
Transition Services Agreement, the Intellectual Property Assignment Agreement
and the Termination Agreement;   3.2.8      the New Note Conditions;  

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  3.2.9      the Supplemental Debenture dated the Completion Date, duly executed
by the Company;     3.2.10      the Termination Agreement dated the Completion
Date, duly executed by the Vendor and the Company;     3.2.11      the
Intellectual Property Assignment Agreement dated the Completion Date, duly
executed by the Vendor and the Company;     3.2.12      the Transition Services
Agreement dated the Completion Date, duly executed by the Vendor and the
Company; and     3.2.13      evidence, satisfactory to the Purchaser, of the due
fulfilment of the discharge of the Share Charge.   3.3      Obligations of the
Purchaser: On Completion and against compliance with the foregoing provisions of
this Clause, the Purchaser shall pay the sum of US$1.00 to the Vendor in cash,
receipt of which shall be acknowledged by the Vendor.   4.      TERMINATION OF
SINGAPORE TERMINATING AGREEMENTS / AMENDING AND RESTATING THE NOTE CONDITIONS  
4.1      In consideration of the mutual covenants and agreements herein
contained, the Parties to the Singapore Terminating Agreements hereby release
and discharge each other Party(ies) to such Singapore Terminating Agreements
from the further performance of, and any duties, obligations or liabilities
owing to it under such Singapore Terminating Agreements, with effect from the
Completion Date. The Parties agree that any provisions contained in the
Singapore Terminating Agreements that are stated to survive the termination
thereof shall be of no further force or effect as of the Completion Date.   4.2 
    Notwithstanding the provisions of Clause 4.1 above and subject to Clause
4.3, each of the Parties agrees that each of the Existing Agreements shall
continue to remain in existence and the performance of, and any duties,
obligations or liabilities owing to any Party under such Existing Agreements
shall not be released and discharged by any Party from the Completion Date.  
4.3      The obligations of the parties under the New Note Conditions are
conditional upon Completion taking place pursuant to Clause 3 of this Agreement
and for the avoidance of doubt, until Completion has occurred, the Note
Conditions will continue in full force and effect in accordance with its terms.
  4.4      The Parties agree that on Completion the Note Conditions shall be
replaced in its entirety by the New Note Conditions.   5.      RESTRICTIONS ON
THE VENDOR   5.1      In consideration of the Purchaser agreeing to acquire the
Sale Shares on the terms set out herein, the Vendor irrevocably and
unconditionally acknowledges and covenants that:  

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5.1.1      on the Completion Date, it no longer has any interest in the Company
and that the Company may negotiate or carry on or be engaged in any business
which is of the same or similar type to the business as carried on by the
Company or the Vendor at any time prior to the Completion Date;   5.1.2      on
or at any time after the Completion Date, the Purchaser, as sole shareholder of
the Company on the Completion Date, may deal with the Company in any way as it
deems fit and may sell the shares in the capital of the Company or implement any
joint venture or merger and acquisition opportunities for the Company (the “M&A
Transaction”) to or with any third party company (whether incorporated in
Singapore or otherwise and whether engaging or been engaged in any business
which is of the same or similar type to the business as carried on by the
Company or the Vendor at any time prior to the Completion Date or otherwise)
(the “Third     Party Company”);   5.1.3      on or at any time after the
Completion Date, the Company may deal with the Company Intellectual Property
(including but not limited to a transfer, assignment or licence to any Third
Party Company or the creation of a charge, grant of an Encumbrance or any other
form of commercial exploitation of the subject matter in question) and any
intellectual property rights therein, on such terms and conditions as the
Company or the Purchaser may deem fit, subject to the terms of the Intellectual
Property Assignment Agreement;   5.1.4      during the Non-Competition Period,
the Vendor shall not, without the prior written consent of the Purchaser,
whether directly or indirectly and whether alone or in conjunction with, or on
behalf of, any other person and whether as principal, shareholder, director,
employee, service provider, agent, consultant, partner or otherwise:     (i)   
  compete with the Company by carrying on the business of discovering,
developing or commercializing novel combination therapies for the treatment of
Non-Competition Infectious Disease anywhere in the Restricted Territory other
than (A) in connection with Biodefence Applications or Permitted Topical
Applications or (B) in the event of a Change of Control of the Vendor, if the
party acquiring the Vendor has an active program in the area of a
Non-Competition Infectious Disease (a “Competing Business”);     (ii)     
canvass, solicit or approach, or cause to be canvassed, solicited or approached,
for orders any person who at any time during the 12 months preceding the
Completion Date is or was negotiating or in discussions with the Company for the
supply of any goods, rights or services or is or was a client or customer of the
Company, where the orders relate to the conduct of a Competing Business; and    
(iii)      solicit or entice, or endeavour to solicit or entice away from the
Company or employ an person employed in a managerial, research, pre-clinical,
clinical, technical, sales or development capacity at the Completion Date or at
any time during the period of six months immediately preceding the Completion
Date; and  

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For the purposes of this Clause 5.1.4:

“Biodefence Applications” means the discovery, development or commercialization
of any product(s) developed or to be developed for biodefence application(s)
pursuant to contracts between the U.S Government and agencies thereof and the
Vendor engaging the Vendor to perform research directed at biological
understanding of, or the diagnosis, prevention or treatment of diseases or
conditions caused by, bio-agents, disease organisms, or organism-produced toxins
used as weapons or for other military or terrorist purposes, including, without
limitation, the services to be performed by the Vendor under the Vendor’s
current NIAID or USAMRIID contracts or any extension of such NIAID or USAMRIID
contracts;

“Change of Control” means a merger, reorganization or consolidation in which the
shareholders of Vendor immediately prior to such transaction would hold less
than fifty percent (50%) of the securities or other ownership or voting
interests representing the equity of the surviving entity immediately after such
merger, reorganization or consolidation, or a bona fide sale of all or
substantially all of Vendor’s assets or business to a third party.

“Non-Competition Infectious Disease” means any of the following:

(i)      Diseases caused by Human and Animal Viruses belonging to the
Orthomyxoviridae family including Influenza A viruses;   (ii)      Diseases
caused by members of the Paramyxoviridae family including the Respiratory
Syncytial Virus; or   (iii)      Diseases caused by Hepatitis C Virus, ie the
hepacivirus genus of the Flaviviridae family;  

“Permitted Topical Applications” means the discovery, development or
commercialization of any product(s) developed or to be developed for the
treatment of acne and impetigo through Topical application of one or more
therapeutic products provided, however, that all of the Vendor’s interests in
any patents, copyright and other intellectual property rights in any systemic
application of any such therapeutic product shall be assigned or exclusively
licensed to the Company at no costs to the Company;

“Non-Competition Period” means:

(i)      the period commencing on the Completion Date and ending four months
after the Completion Date (the “Fourth Month”);   (ii)      the period
commencing on the Fourth Month and ending four months after the Fourth Month
(the “Eight Month”); and   (iii)      the period commencing on the Eight Month
and ending four months after the Eight Month; and  

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  “Restricted Territory” means Singapore, Australia, Malaysia, Hong Kong,
Indonesia, the People’s Republic of China, the United States of America, the
European Union, Switzerland, New Zealand, Philippines, Taiwan, India, Pakistan,
Sri Lanka and Africa.     5.1.5      it has received independent legal advice
relating to all the matters provided for in this Agreement, including the
provisions of Clause 5.1.4. The Vendor agrees that it considers that the
restrictions contained in Clause 5.1.4 are no greater than is reasonable and
necessary for the protection of the interest of the Purchaser but if any such
restriction shall be held to be void but would be valid if deleted in part or
reduced in application, such restriction shall apply with such deletion or
modification as may be necessary to make it valid and enforceable.   6.     
WARRANTIES   6.1      The Vendor hereby represents and warrants to and
undertakes with the Purchaser as follows:     6.1.1      it is a company duly
incorporated and validly existing under its laws of incorporation;     6.1.2   
  it is, and will on Completion have legal title to and beneficial ownership of
all of the Sale Shares and be legally and beneficially entitled to transfer the
Sale Shares to the Purchaser or its nominee, on the terms and subject to the
conditions of this Agreement;     6.1.3      the Sale Shares are and will, on
Completion, be free from all and any Encumbrances whatsoever;     6.1.4      it
has full power, authority and legal right to enter into this Agreement and to
observe and perform its obligations hereunder and has taken all necessary
corporate (if required) and other actions to authorise its execution, delivery
and performance of this Agreement and all such other documents and instruments
as are specified or referred to in this Agreement;     6.1.5      this Agreement
constitutes legal, valid and binding obligations enforceable against it in
accordance with the terms of this Agreement and the performance by it of its
obligations under this Agreement shall not:      (i)      result in a breach of
its Certificate of Incorporation and/or equivalent constitutional documents and
do not infringe, or constitute a default under, any directive, instrument,
contract, document or agreement to which it is a party or by which it is bound
(whether in Singapore or elsewhere); and      (ii)      result in a breach of
any law, rule, regulation, ordinance, order, judgment or decree of or
undertaking to any court, government body, statutory authority or regulatory,
administrative or supervisory body;     6.1.6      the Management Accounts have
been prepared in accordance with the accounting policies used in preparing the
Audited Accounts applied on a consistent basis;  

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  6.1.7      the Management Accounts are fair and not misleading and do not
materially misstate the assets and liabilities of the Company as at the
Management Accounts Date nor the profits and losses of the Company for the
period ended on such date. For the purposes of this Clause 6.1.7, “materially
misstate” means any figures of the assets, liabilities, profits and/or losses of
the Company set out in the Management Accounts which is incorrect or inaccurate
by 20 per cent. or more;   6.2      The Purchaser hereby represents and warrants
to and undertakes with the Vendor as follows:     6.2.1      it is a company
duly incorporated and validly existing under its laws of incorporation;    
6.2.2      it has full power, authority and legal right to enter into this
Agreement and to observe and perform its obligations hereunder and has taken all
necessary corporate (if required) and other actions to authorise its execution,
delivery and performance of this Agreement and all such other documents and
instruments as are specified or referred to in this Agreement; and     6.2.3   
  this Agreement constitutes legal, valid and binding obligations enforceable
against it in accordance with the terms of this Agreement and the performance by
it of its obligations under this Agreement shall not:      (i)      result in a
breach of its memorandum and articles of association or equivalent
constitutional documents and do not infringe, or constitute a default under, any
directive, instrument, contract, document or agreement to which it is a party or
by which it is bound (whether in Singapore or elsewhere); and      (ii)     
result in a breach of any law, rule, regulation, ordinance, order, judgment or
decree of or undertaking to any court, government body, statutory authority or
regulatory, administrative or supervisory body.   6.3      Effect of Completion:
The Warranties given by the Vendor and the Purchaser shall not in any respect be
extinguished or affected by Completion and shall survive for one year
thereafter.   6.4      Reliance: The Vendor acknowledges that the Purchaser has
entered into this Agreement in reliance upon, among other things, the Warranties
and on the undertakings contained in Clause 5. Save as expressly otherwise
provided, the Warranties shall be separate and independent and shall not be
limited by reference to anything in this Agreement.   6.5      Indemnities:    
6.5.1      The Vendor covenants with the Purchaser to indemnify and save
harmless the Purchaser from and against any and all Losses which the Purchaser
may at any time and from time to time sustain, incur or suffer by reason of any
breach of any representation, warranty or undertaking given by the Vendor under
this Agreement.     6.5.2      The Purchaser covenants with the Vendor to
indemnify and save harmless the Vendor from and against any and all Losses which
the Vendor may at any time and from time to time sustain, incur or suffer by
reason of any breach of any  

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representation, warranty or undertaking given by the Purchaser under this
Agreement.

7.      ENTIRE AGREEMENT     This Agreement embodies all the terms and
conditions agreed upon between the Parties as to the subject matter of this
Agreement and supersedes and cancels in all respects all previous agreements and
undertakings, if any, between the Parties with respect to the subject matter
hereof, whether such be written or oral.   8.      INDULGENCE, WAIVER, ETC.    
No failure on the part of the Purchaser to exercise and no delay on the part of
the Purchaser in exercising any right hereunder will operate as a release or
waiver thereof, nor will any single or partial exercise of any right under this
Agreement preclude any other or further exercise of it.   9.      CONTINUING
EFFECT OF AGREEMENT     All provisions of this Agreement shall not, so far as
they have not been performed at Completion, be in any respect extinguished or
affected by Completion or by any other event or matter whatsoever and shall
continue in full force and effect.   10.      VARIATION     No variation of this
Agreement shall be effective unless in writing and signed by or on behalf of
each of the Parties to this Agreement.   11.      REMEDIES CUMULATIVE     No
remedy conferred by any of the provisions of this Agreement is intended to be
exclusive of any other remedy which is otherwise available at law, in equity, by
statute or otherwise, and each and every other remedy shall be cumulative and
shall be in addition to every other remedy given hereunder or now or hereafter
existing at law, in equity, by statute or otherwise. The election of any one or
more of such remedies by either Party shall not constitute a waiver by such
Party of the right to pursue any other available remedies.  

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12.      THIRD PARTY RIGHTS     A person who is not a party to this Agreement
has no rights under the Contracts (Rights of Third Parties) Act, Chapter 53B of
Singapore, to enforce or enjoy any term of this Agreement.   13.      SUCCESSORS
AND ASSIGNS     This Agreement shall be binding on and shall enure for the
benefit of each of the Parties’ successors and assigns. Any reference in this
Agreement to either of the Parties shall be construed accordingly.   14.     
FURTHER ASSURANCE     At any time after the date of this Agreement the Vendor
shall, and shall use its best endeavours to procure that any necessary third
party shall, execute such documents and do such acts and things as the Purchaser
may require for the purpose of giving to the Purchaser the full benefit of all
the provisions of this Agreement.   15.      ANNOUNCEMENTS   15.1      None of
the Parties shall make or authorise the making of any announcement (including
but not limited to the filing or the reporting to any governmental agency)
concerning the subject matter of this Agreement at any time without the prior
written approval of the other Parties.   15.2      None of the Parties shall use
the name of the other Parties, either expressly or by implication, for any
purpose whether in relation to any news, advertisement, promotional materials or
other form of publicity without obtaining the prior written consent of the other
Parties. Notwithstanding the generality of this Clause 15.2 but subject always
to Clause 19, the Parties may notify third parties of the fact that this
Agreement is in effect.   16.      COSTS     Each of the Vendor and the
Purchaser shall bear its own costs, including attorney’s fees of Ropes & Gray
LLP for the Vendor and Allen & Gledhill LLP for the Purchaser, in connection
with the preparation and negotiation of this Agreement, the Transition Services
Agreement, and the Intellectual Property Assignment Agreement and the
consummation of the transactions contemplated thereby and the Company shall bear
the reasonable fees and expenses of DrewCorp Services Pte Ltd in connection with
the Completion (not exceeding S$1,000 in the aggregate).   17.      SEVERABILITY
OF PROVISIONS     If any provision of this Agreement is held to be illegal,
invalid or unenforceable in whole or in part in any jurisdiction, this Agreement
shall, as to such jurisdiction, continue to be valid as to its other provisions
and the remainder of the affected provision; and the legality, validity and
enforceability of such provision in any other jurisdiction shall be unaffected.
 

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18.      NOTICES   18.1      All notices, demands or other communications
required or permitted to be given or made hereunder shall be in writing and may
be delivered personally or sent by prepaid registered post (by air-mail if to or
from an address outside Singapore) with recorded delivery, or by facsimile
transmission addressed to the intended recipient thereof at its address or at
its facsimile number set out in this Agreement (or to such other address or
facsimile number as a party to this Agreement may from time to time duly notify
the other in writing). Any such notice, demand or communication shall be deemed
to have been duly served (if delivered personally or given or made by facsimile)
immediately or (if given or made by letter) 48 hours after posting or (if made
or given to or from an address outside Singapore) 10 days after posting and in
proving the same it shall be sufficient to show that personal delivery was made
or that the envelope containing the same was duly addressed, stamped and posted
or that the facsimile transmission was properly addressed and despatched. The
addresses and facsimile numbers of the Parties for the purpose of this Agreement
are:  

Vendor    :    245 First Street, Fourth Floor          Cambridge, Massachusetts
02142          USA                  Attention    :    Mr. Jason Cole, General
Counsel          Facsimile No.    :    (617) 301-7460    Purchaser    :    250
North Bridge Road  #20-02 Raffles City Tower         Singapore 179101         
Attention    : Ms Chu Swee Yeok          Facsimile No.    : (65) 6832 6838   
Company    :    11 Biopolis Way #08-05/06 Helios          Singapore 138667     
        Attention    : Mirza Cifric          Facsimile No.    : (65) 6775 9857 

19.      CONFIDENTIALITY   19.1      Subject to Clause 19.3, the Vendor shall
treat as confidential and not disclose or use any information which relates to:
 

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  19.1.1      the provisions of this Agreement or the subject matter of this
Agreement or any document referred to in this Agreement (including the Singapore
Terminating Agreements);     19.1.2      the negotiations relating to this
Agreement (and such other agreements); or     19.1.3      the Purchaser’s
business, financial or other affairs, including future plans and targets).  
19.2      Subject to Clause 19.3, the Purchaser shall treat as confidential and
not disclose or use any information which relates to:     19.2.1      the
provisions of this Agreement or the subject matter of this Agreement;    
19.2.2      the negotiations relating to this Agreement (and such other
agreements); or     19.2.3      the Vendor’s business, financial or other
affairs (including future plans and targets).   19.3      Neither Clause 19.1
nor 19.2 shall prohibit disclosure or use of any information if and to the
extent:     19.3.1      the disclosure or use is required by law, any regulatory
body or the rules and regulations of any recognised stock exchange;     19.3.2 
    the disclosure or use is required to vest the full benefit of this Agreement
in the Vendor or the Purchaser, as the case may be;     19.3.3      the
disclosure or use is required for the purpose of any judicial proceedings
arising out of this Agreement or any other agreement entered into under or
pursuant to this Agreement or the disclosure is reasonably required to be made
to a Taxation authority in connection with the Taxation affairs of the
disclosing Party;     19.3.4      the disclosure is made to professional
advisers of the Purchaser or the Vendor on terms that such professional advisers
undertake to comply with the provisions of Clause 19.1 or 19.2 in respect of
such information as if they were a party to this Agreement;     19.3.5      the
information becomes publicly available (other than by a breach of this
Agreement);     19.3.6      the other Parties have given prior written approval
to the disclosure or use; or     19.3.7      the information is independently
developed after Completion, provided that prior to disclosure or use of any
information pursuant to Clause 19.3.1, 19.3.2, 19.3.3 (except in the case of
disclosure to a Taxation authority) or 19.3.4, the Party concerned shall
promptly notify the other Party of such requirement with a view to providing the
other Party with the opportunity to contest such disclosure or use or otherwise
to agree to the timing and content of such disclosure or use.   20.     
GOVERNING LAW AND DISPUTE RESOLUTION   20.1      This Agreement shall be
governed by, and construed in accordance with, the laws of Singapore.  

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20.2      In case any dispute or difference shall arise amongst any of the
Parties as to the construction of this Agreement or as to any matter or thing of
whatsoever nature arising out of this Agreement, including any question
regarding its existence, validity or termination, such dispute or difference
shall be referred to and finally resolved by binding arbitration under the Rules
(the "LCIA Rules") of the London Court of International Arbitration (the "LCIA
Court"), for the time being in force, which LCIA Rules are deemed to be
incorporated by reference to this Clause. The parties also agree that the
arbitration shall be conducted in according to the 1999 International Bar
Association Rules on the Taking of Evidence in International Commercial
Arbitration. The arbitration panel shall consist of three members. Except where
otherwise agreed by the parties or determined by the LCIA Court, for the
purposes of Article 8.1 of the LCIA Rules the Parties agree that in the case of
any dispute (i) between the Purchaser and the Vendor, (ii) between the Company
and the Purchaser or (iii) between the Company and the Vendor, each of the two
parties to such a dispute shall represent separate sides for the formation of
the arbitral tribunal as claimant and respondent respectively (or vice versa).
Accordingly, each of such parties shall nominate one member of the panel. The
two members shall agree on the third member within thirty (30) days. If the two
members of the panel are unable to agree on the third, the LCIA Court shall
appoint the third member. The language to be used in the arbitral proceeding
shall be English and all arbitral proceedings shall be conducted in London,
England, which shall be the seat of arbitration. Each party shall bear its own
costs associated with the arbitration of any dispute, and all fees and other
costs of the arbitration proceeding shall be shared equally between the parties.
The award shall be final and binding on the parties and may be entered and
enforced in any court having jurisdiction.   21.      COUNTERPARTS     This
Agreement may be entered into in any number of counterparts, all of which taken
together shall constitute one and the same instrument. Any Party may enter into
this Agreement by signing any such counterpart. Signatures may be exchanged by
facsimile, with original signatures to follow. Each Party agrees that it will be
bound by its own facsimile signature and that it accepts the facsimile signature
of the other Parties.  

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Schedule 1

Particulars of the Company

(1)      Registration Number : 200511269N   (2)      Registered Office : 11
Biopolis Way #08-05/06 Helios, Singapore 138667   (3)      Date of Incorporation
: 16 August 2005   (4)      Issued and Paid-up Share Capital : US$2,502,602.041
  (5)      Shareholders and Number of Shares Held     (a)      Vendor -
2,602,041 Ordinary Shares, fully paid     (b)      Purchaser - 2,500,000
Preference Shares, fully paid   (6)      Directors     (a)      Alexis A Borisy
(appointed Robert Malcolm Alexander Forrester as an alternate director)     (b) 
    Ralf Marius Altmeyer     (c)      Choo Heng Tong   (7)      Secretary :
Esther Au Siew Peng   (8)      Auditors : Ernst & Young LLP  

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Schedule 2

Intellectual Property Assignment Agreement

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Schedule 3

Termination Agreement

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Schedule 4

Transition Services Agreement

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Schedule 5

Note Conditions

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Schedule 6

Warrant

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Schedule 7

Supplemental Debenture

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Schedule 8

U.S Patent Applications

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Appendix A

New Articles of Association

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Appendix B

New Note Conditions

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In witness whereof this Agreement has been entered into on the date stated at
the beginning.

The Vendor          SIGNED by Robert Forrester    )       /s/ Robert Forrester 
for and on behalf of    )      CombinatoRx, Incorporated    )      in the
presence of:    )        /s/ Jason F. Cole            Witness’s signature       
  Name: Jason F. Cole          Address: 245 First Street, Cambridge, MA 02142   
    The Purchaser          SIGNED by Chu Swee Yeok    )    /s/ Chu Swee Yeok 
for and on behalf of    )      Biomedical Sciences Investment Fund Pte Ltd)     
in the presence of:    )        /s/Laura Chang          Witness’s signature     
    Name: Laura Chang          Address: 250 North Bridge Road                   
             #20-02 Raffles City Tower                                 Singapore
179101         

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The Company          SIGNED by Yeo Su Ling    )    /s/ Yeo Su Ling  for and on
behalf of    )      CombinatoRx (Singapore) Pte. Ltd.    )      in the presence
of:    )        /s/ Laura Chang          Witness’s signature          Name:
Laura Chang          Address: 250 North Bridge Road                             
   #20-02 Raffles City Tower                                 Singapore 179101   
     

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