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                                                                   Exhibit 10.42

                          REGISTRATION RIGHTS AGREEMENT

This Registration Rights Agreement (the "AGREEMENT") is made and entered into as
of this __ day of August, 2005 by and among CombinatoRx, Incorporated, a
Delaware corporation (the "COMPANY") and BioMedical Sciences Investment Fund Pte
Ltd (the "INVESTOR").

                                   AGREEMENT:

     WHEREAS, the parties desire to enter into this Agreement in connection with
the issuance and sale of shares of the Series A Preference Stock, $0.001 par
value per share (the "PREFERRED STOCK") and certain secured Notes (the "NOTES")
of CombinatoRx (Singapore) Pte Ltd (the "SUBSIDIARY") to the Investor pursuant
to a Subscription and Shareholders Agreement by and among the Subsidiary, the
Investor and the Company dated as of even date herewith (the "SSA");

     WHEREAS, the SSA provides for the possible conversion of the Preferred
Stock and the Notes into Common Stock of the Company.

     WHEREAS, the Investor desires to be granted the rights created herein.

     NOW, THEREFORE, in consideration of the premises and for other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

     1.  DEFINITIONS.

         1.1   CERTAIN DEFINED TERMS. As used in this Agreement, the following
terms shall have the following respective meanings:

     "BUSINESS DAY" means a day other than a Saturday, Sunday or other day on
which commercial banks are authorized or required to close under the laws of the
United States or the State of New York.

     "COMMON STOCK" means the Company's common stock, $0.001 par value per
share.

     "ELIGIBLE FILING DATE" shall have the meaning set forth in Section 2.1.

     "EXCHANGE ACT" shall mean the United States Securities Exchange Act of
1934, as amended, or any successor federal statute, and the rules and
regulations of the SEC issued under such act, as they each may, from time to
time, be in effect.

     "FORM S-3" means such form under the Securities Act as in effect on the
date hereof or any registration statement under the Securities Act subsequently
adopted by the SEC which permits inclusion or incorporation of substantial
information by reference to other documents filed by the Company with the SEC.

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     "PERSON" or "PERSON" means any individual, corporation, partnership,
limited liability company, joint venture, association, joint-stock company,
trust, unincorporated organization or government or other agency or political
subdivision thereof.

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

     "REGISTRABLE SECURITIES" means any Common Stock acquired by the Investor
pursuant to the terms of the SSA.

     "REGISTRATION STATEMENT" shall have the meaning set forth in Section
2.1(a).

     "REGISTRATION PERIOD" shall have the meaning set forth in Section 2.1(a).

     "SEC" shall mean the United States Securities and Exchange Commission or
any other federal agency at the time administering the Securities Act.

     "Securities Act" means the United States Securities Act of 1933, as
amended, or any successor federal statute, and the rules and regulations of the
SEC issued under such act, as they each may, from time to time, be in effect.

     "SUSPENSION" shall have the meaning set forth in Section 3.3.

     "SUSPENSION NOTICE" shall have the meaning set forth in Section 3.3.

         1.2   CONSTRUCTION. Unless the context otherwise requires

             (1) a term has the meaning assigned to it;

             (2) "or" is not exclusive;

             (3) words in the singular include the plural, and words in the
plural include the singular; and

             (4) "herein," "hereof" and other words of similar import refer to
this Agreement as a whole and not to any particular Article, Section or other
subdivision.

     2.  REGISTRATION RIGHTS.

         2.1   The Company shall, as promptly as possible upon receipt by the
Investor of Registrable Securities and after twelve (12) months after the
effective date of the first registration statement filed by the Company for an
underwritten public offering of securities of the Company (the "ELIGIBLE FILING
DATE"):

               (A) prepare and file with the SEC (which filing shall in no event
         occur more than ten (10) days after the Eligible Filing Date) a
         registration statement on Form S-3 (the "REGISTRATION STATEMENT"), to
         enable the resale of the Registrable Securities by the Investor from
         time to time and use all commercially reasonable

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         efforts to cause such Registration Statement to be declared effective
         as promptly as possible after filing, but in any event, within ninety
         (90) days following the such filing or, in the event of a review of the
         Registration Statement by the SEC, within one hundred twenty (120) days
         following such filing (such date as is applicable the "Required
         Registration Date"), and to remain continuously effective until the
         earlier of (1) the second anniversary of the effective date of the
         Registration Statement (subject to Section 3.6 hereof), (2) the date on
         which all Registrable Securities have been sold thereunder or (3) the
         date on which the Registrable Securities can be sold by nonaffiliates
         of the Company pursuant to Rule 144(k) promulgated under the Securities
         Act (the "REGISTRATION PERIOD"). In the event the Registration
         Statement cannot be kept effective for such period, the Company shall
         use commercially reasonable efforts to prepare and file with the SEC
         and have declared effective as promptly as possible another
         registration statement on the same terms as the initial Registration
         Statement and such registration statement shall be considered the
         Registration Statement for the purposes hereof. In the event that the
         Company does not meet the requirements for the use of Form S-3, the
         Company shall use such other form as is available for such a
         registration, and shall convert such other form to Form S-3, or file a
         replacement registration statement on Form S-3, as promptly as
         practicable after the first date on which it meets such requirements;

               (B) prepare and file with the SEC such amendments (including
         post-effective amendments) and supplements to the Registration
         Statement and the prospectus included in the Registration Statement
         (the "PROSPECTUS", as amended or supplemented by any prospectus
         supplement and by all other amendments thereto and all material
         incorporated by reference in such Prospectus) used in connection
         therewith as may be necessary to keep the Registration Statement
         effective and to comply with the provisions of the Securities Act with
         respect to the disposition of all securities covered by such
         Registration Statement at all times until the end of the Registration
         Period;

               (C) furnish to the Investor with respect to the Registrable
         Securities registered under the Registration Statement such reasonable
         number of copies of such Registration Statement and any Prospectus in
         conformity with the requirements of the Securities Act, each amendment
         and supplement thereto and any documents incorporated by reference
         therein and such other documents as the Investor may reasonably
         request, in order to facilitate the public sale or other disposition of
         all or any of the Registrable Securities (and the Company hereby
         consents to the Investor's use of the Prospectus in such sale or other
         disposition);

               (D) use its commercially reasonable efforts to register or
         qualify the Registrable Securities under such other securities or blue
         sky laws is such jurisdictions as are specified in writing by the
         Investor; use its commercially reasonable efforts to keep each such
         registration or qualification (or exemption therefrom) effective during
         the Registration Period and take any other action that may be
         reasonably necessary to enable the Investor to consummate the
         disposition in such jurisdiction of the Registrable Securities;
         provided, however, that the

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         Company shall not be required to qualify to do business or consent to
         service of process in any jurisdiction in which it is not now so
         qualified or has not so consented;

               (E) take all such action as is required of it to cause the
         Registrable Securities to be listed on the national securities exchange
         or automated quotation system on which the Common Stock is then traded;

               (F) promptly notify the Investor in writing (i) when the
         Registration Statement, a Prospectus or any supplement or amendment to
         either of them has been filed and, with respect to the Registration
         Statement or any post-effective amendment thereto, when the same has
         been declared effective and (ii) of the issuance by any state
         securities or other regulatory authority of any order suspending the
         qualification or exemption from qualification of any of the Registrable
         Securities under state securities or "blue sky" laws or the initiation
         of any proceedings for that purpose;

               (G) promptly notify the Investor in writing of the existence of
         any fact or the happening of any event, during the Registration Period
         (but not as to the substance of any such fact or event), that makes any
         statement of a material fact made in the Registration Statement, the
         Prospectus, any amendment or supplement thereto, or any document
         incorporated by reference therein untrue, or that requires the making
         of any additions to or changes in the Registration Statement or the
         Prospectus in order to make the statements therein not misleading
         (PROVIDED, HOWEVER, that no notice by the Company shall be required
         pursuant to this subsection (g) in the event that the Company either
         contemporaneously files a prospectus supplement to update the
         Prospectus or a Form 8-K or other appropriate Exchange Act report that
         is incorporated by reference into the Registration Statement, which, in
         either case, contains the requisite information with respect to such
         material event that results in such Registration Statement no longer
         containing any such untrue or misleading statements), provided,
         however, that the Company shall be under no obligation to file such
         prospectus supplement, Form 8-K or other appropriate Exchange Act
         report that is incorporated by reference into the Registration
         Statement to update the Prospectus if in the good faith judgment of the
         Company's Board of Directors it would be seriously detrimental to the
         Company and its stockholders for such supplement, Form 8-K or other
         report to be filed. After any notice provided to Investor pursuant to
         this subsection (g) during the Registration Period, the Company may
         require the Investor to discontinue disposition of any Registrable
         Securities until advised in writing by the Company that the use of the
         Prospectus may be resumed, and if applicable, the Investor is provided
         with a supplemented or amended Prospectus as contemplated by this
         subsection (g);

               (H) furnish to the Investor upon written request, from the date
         of this Agreement until the end of the Registration Period, one copy of
         its periodic reports filed with the SEC pursuant to the Exchange Act
         and the rules and regulations promulgated thereunder

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               (I) cooperate with the Investor to facilitate the timely
         preparation and delivery of certificates (which shall not bear any
         restrictive legends unless required under applicable law) representing
         securities sold under any Registration Statement, and enable such
         securities to be in such denominations and registered in such names as
         the Investor may request and keep available and make available to the
         Company's transfer agent prior to the effectiveness of such
         registration statement a supply of such certificates

               (J) provide a transfer agent and registrar for all Registrable
         Securities registered hereunder and provide a CUSIP number for the
         Registrable Securities included in any Registration Statement not later
         than the effective date of such Registration Statement

               (K) cooperate with the Investor and its counsel in connection
         with any filings required to be made with the National Association of
         Securities Dealers, Inc.;

               (L) promptly file all documents required to be filed with the SEC
         pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act;

               (M) following the effectiveness of such Registration Statement,
         notify the Investor promptly of any request by the SEC for the amending
         or supplementing of such Registration Statement or Prospectus or for
         additional information

               (N) prepare and file with the SEC promptly any amendments or
         supplements to such Registration Statement or Prospectus which, in the
         reasonable opinion of counsel for the Company, is required in
         connection with the distribution of the Registrable Securities

               (O) advise the Investor, promptly after the Company shall receive
         notice or obtain knowledge thereof, of the issuance of any stop order
         by the SEC suspending the effectiveness of such Registration Statement
         or the initiation or threatening of any proceeding for such purpose and
         promptly use its commercially reasonable efforts to prevent the
         issuance of any stop order or to obtain its withdrawal at the earliest
         possible moment if such stop order should be issued; and

               (P) bear all expenses in connection with the procedures described
         in paragraphs (a) through (o) of this Section 2.1 and the registration
         of the Registrable Securities pursuant to the Registration Statement
         other than fees and expenses, if any, of legal counsel or other
         advisers to the Investor or underwriting discounts, brokerage fees and
         commissions incurred by the Investor, if any.

         2.2   It shall be a condition precedent to the obligations of the
Company to take any action pursuant to this Section 2 with respect to
Registrable Securities held by the Investor that:

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               (A) the Investor shall timely furnish to the Company a completed
         Registration Statement questionnaire on or before the Eligible Filing
         Date and such other written information regarding itself, the
         Registrable Securities and the intended method of disposition of the
         Registrable Securities as shall reasonably be required to effect the
         registration of the Registrable Securities and as shall be reasonably
         be requested by the Company in advance or from time to time; and

               (B) the Investor is unable otherwise to sell in a single
         transaction the Registrable Securities eligible to be sold pursuant to
         the limitations set forth in the SSA without registration of such
         Registrable Securities. For purposes of this Section 2.2, the sale of
         Registrable Securities without registration shall mean that the
         Registrable Securities may be sold by the Investor pursuant to
         Regulation S or Rule 144 under the Securities Act or any other
         applicable provisions of the Securities Act pursuant to which the
         subsequent sale by the purchaser of such securities would not be
         subject to registration. In the event of a disagreement as to the
         salability of the Registrable Securities without registration as
         described in this Section 2.2(b), or as to the salability of the
         Registrable Securities by nonaffiliates of the Company pursuant to Rule
         144(k) promulgated under the Securities Act as described in Section
         2.1(a), the Company shall be entitled to rely on the opinion of Ropes &
         Gray LLP or any other recognized United States securities law counsel,
         provided, however, that if, in the opinion of Skadden, Arps, Slate,
         Meagher & Flom or other recognized United States securities law counsel
         to the Investor such Registrable Securities are not so salable without
         registration, the Parties shall resolve such dispute on the basis of a
         legal opinion of a mutually acceptable recognized United States
         securities law counsel.

         2.3 LIMITATION ON SUBSEQUENT REGISTRATION RIGHTS. The Company
acknowledges and agrees that the Company will not grant or allow any other
Persons any registration rights with respect to any securities of the Company
which (i) impair the rights of the Investor to exercise its rights under this
Agreement, or (ii) conflict with or violate the provisions of this Agreement.

         2.4 In addition to any other remedies available to the Investor under
this Agreement or at law or equity, if no Registration Statement has been
declared effective by the Required Registration Date or such Registration
Statement is not available with respect to all Registrable Securities at any
time on or after the Required Registration Date and during the Registration
Period (except during a Suspension permitted by Section 3.2 or 3.3) the Company
shall cause to be wire transferred to an account specified by the Investor on
the last Business Day of each month an amount, in immediately available United
States funds, equal to:

                                     1/20% x ND x MV

                           Where:

                               ND =  the number of business days in such month
                                     that the Registration Statement has not
                                     been declared effective by the Required
                                     Registration Date or such Registration
                                     Statement is

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                                     not available (each such day a
                                     "Shortfall Day") with respect to
                                     Registrable Securities that may not
                                     otherwise be sold by the Investor
                                     immediately pursuant to Rule 144 without
                                     compliance with the registration
                                     requirements of the Securities Act after
                                     giving effect to any limitations on the
                                     Investor's ability to sell Registrable
                                     Securities imposed by the SSA ("Non-Rule
                                     144 Stock"); and

                               MV =  the average closing price of a single
                                     share of Common Stock on the Shortfall Days
                                     in such month multiplied by the average
                                     number of shares of Non-Rule 144 Stock
                                     issued and outstanding on each of the days
                                     included in "ND" above.

     3.  TRANSFER OF REGISTRABLE SECURITIES AFTER REGISTRATION; SUSPENSION.

         3.1   The Investor agrees that it will not offer to sell or make any
sale, assignment, pledge, hypothecation or other transfer with respect to the
Registrable Securities that would constitute a sale within the meaning of the
Securities Act except pursuant to an effective registration statement under the
Securities Act or pursuant to an available exemption therefrom.

         3.2   In addition to any suspension rights under Section 3.3 below, if
(i) an event has occurred and is continuing as a result of which any such
Registration Statement or Prospectus would, in the Company's reasonable
judgment, contain an untrue statement of a material fact or omit to state a
material fact required to be stated therein or necessary to make the statements
therein not misleading or (ii) if the Company notifies the Investor that any
filing of any Registration Statement pursuant to this Agreement, any filing of
any amendment thereto, any furnishing of any supplement to a Prospectus included
in a Registration Statement pursuant to Section 2.1(g) hereof, any other filing
with the SEC, the effectiveness of any Registration Statement or other filing
with the SEC, or any similar action would, in the good faith judgment of outside
counsel to the Company, require the disclosure of material non-public
information which the Company has a bona fide business purpose for preserving as
confidential and which the Company would not otherwise be required to disclose,
then the Company may, on not more than two (2) non-consecutive occasions for not
more than thirty (30) days on each such occasion, (x) refrain from filing any
Registration Statement pursuant to this Agreement, filing any amendment thereto,
furnishing any supplement to a Prospectus included in a Registration Statement
pursuant to Section 2.1(g) hereof, making any other filing with the SEC
otherwise required by this Agreement, causing the effectiveness of any
Registration Statement or other filing with the SEC, or taking any similar
action and (y) suspend use of the Prospectus, on written notice to the Investor
(which notice will not disclose the content of any material non-public
information and will indicate the date of the beginning and end of the intended
period of suspension, if known), in which case the Investor shall discontinue
disposition of Registrable Securities covered by the Registration Statement or
Prospectus until copies of a supplemented or amended Prospectus are distributed
to the Investor or until the Investor are advised in writing by the Company that
sales of Registrable Securities under the applicable Prospectus may be resumed
and have received copies of any additional or supplemental filings that are
incorporated or deemed incorporated by reference in any such Prospectus. The
suspension and notice thereof

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described in clause (y) of this Section 3.2 shall be held in strictest
confidence and shall not be disclosed by the Investor.

         3.3   Subject to Section 3.4 below, in the event of: (1) any request by
the SEC or any other federal or state governmental authority during the period
of effectiveness of the Registration Statement for amendments or supplements to
a Registration Statement or related prospectus or for additional information,
(2) the issuance by the SEC or any other federal or state governmental authority
of any stop order suspending the effectiveness of a Registration Statement or
the initiation of any proceedings for that purpose, (3) the receipt by the
Company of any notification suspending the qualification or exemption from
qualification of any of the Registrable Securities for sale in any jurisdiction
or the initiation of any proceeding for such purpose, or (4) any event or
circumstance which necessitates the making of any changes in the Registration
Statement or Prospectus, or any document incorporated or deemed to be
incorporated therein by reference, so that, in the case of the Registration
Statement, it will not contain any untrue statement of a material fact or any
omission to state a material fact required to be stated therein or necessary to
make the statements therein not misleading, and that in the case of the
Prospectus, it will not contain any untrue statement of a material fact or any
omission to state a material fact required to be stated therein or necessary to
make the statements therein, in the light of the circumstances under which they
were made, not misleading, then the Company shall deliver a certificate in
writing to the Investor (the "SUSPENSION NOTICE") to the effect of the foregoing
(which notice will not disclose the content of any material non-public
information and will indicate the date of the beginning and end of the intended
period of suspension, if known), and, upon receipt of such Suspension Notice,
the Investor will discontinue disposition of Registrable Securities covered by
to the Registration Statement or Prospectus (a "SUSPENSION") until the
Investor's receipt of copies of a supplemented or amended Prospectus prepared
and filed by the Company, or until the Investor are advised in writing by the
Company that the current Prospectus may be used, and have received copies of any
additional or supplemental filings that are incorporated or deemed incorporated
by reference in any such prospectus. In the event of any Suspension, the Company
will use its commercially reasonable efforts to cause the use of the Prospectus
so suspended to be resumed as soon as possible after delivery of a Suspension
Notice to the Investor.

         3.4   Provided that a suspension is not then in effect, the Investor
may sell Registrable Securities under the Registration Statement, provided that
the selling Investor arranges for delivery of a current Prospectus to the
transferee of such Registrable Securities to the extent such delivery is
required by applicable law.

         3.5   In the event of a sale of Registrable Securities by the Investor,
the Investor must also deliver to the Company's transfer agent, with a copy to
the Company, a certificate of subsequent sale reasonably satisfactory to the
Company, so that ownership of the Registrable Securities may be properly
transferred. The Company will cooperate to facilitate the timely preparation and
delivery of certificates (unless otherwise required by applicable law)
representing Registrable Securities sold.

         3.6   For the purpose of determining the Registration Period pursuant
to Section 2.1, the occurrence of any Suspension pursuant to Section 3.3 or the
non-effectiveness of the Registration Statement during any period during which
such effectiveness is required pursuant to

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the terms of Section 2.1(a) shall cause the second anniversary of the effective
date of the Registration Statement to be deemed extended by a number of days
equivalent to the duration of any Suspension or the number of days of such
non-effectiveness.

     4.  INDEMNIFICATION.

         For the purpose of this Section 4, the term "REGISTRATION STATEMENT"
shall include any preliminary or final Prospectus, exhibit, supplement or
amendment included in or relating to the Registration Statement referred to in
Section 2, together with any document incorporated by reference into any of the
same.

         4.1   INDEMNIFICATION BY THE COMPANY. The Company agrees to indemnify
and hold harmless each of the Investor, and each of its employees, advisors,
agents, representatives, partners, officers and directors, and each person, if
any, who controls the Investor within the meaning of the Securities Act or the
Exchange Act (all such persons together, the "Investor Indemnitees"), to the
fullest extent permitted by law, against any and all losses, claims, damages,
liabilities or expenses, joint or several, to which the Investor or such
controlling person may become subject, under the Securities Act, the Exchange
Act or any other federal or state statutory law or regulation, or at common law
or otherwise (including in settlement of any litigation, if such settlement is
effected with the written consent of the Company, which consent shall not be
unreasonably withheld) (including, without limitation, attorneys' fees and
disbursements), insofar as such losses, claims, damages, liabilities or expenses
(or actions in respect thereof as contemplated below) arise out of, are based
upon, relate to or result from any untrue statement or alleged untrue statement
of any material fact contained in the Registration Statement, the Prospectus, or
any amendment or supplement thereto, or arise out of, are based upon, relate to
or result from the omission or alleged omission to state in any of them a
material fact required to be stated therein or necessary to make the statements
in any of them, in light of the circumstances under which they were made, not
misleading, and will reimburse the Investor Indemnitees for any reasonable legal
and other expenses as such reasonable expenses are incurred by the Investor
Indemnitees in connection with investigating, defending (or preparing to
defend), settling, compromising or paying any such loss, claim, damage,
liability, expense or action; PROVIDED, HOWEVER, that the Company will not be
liable in any such case to the extent that any such loss, claim, damage,
liability, expense or action arises out of, is based upon, relates to or results
from (1) an untrue statement or alleged untrue statement or omission or alleged
omission made in the Registration Statement, the Prospectus or any amendment to
or supplement of the Registration Statement or Prospectus made in reliance upon
and in conformity with information furnished to the Company by or on behalf of
the Investor expressly for use in the Registration Statement or the Prospectus,
(2) the failure of the Investor to comply with the covenants and agreements
contained in this Agreement respecting sale of the Registrable Securities, or
(3) any untrue statement or omission of a material fact required to make such
statement not misleading in any Prospectus that is corrected in any subsequent
Prospectus that was delivered to the Investor before the pertinent sale or sales
by the Investor.

         4.2   INDEMNIFICATION BY THE INVESTOR. The Investor will indemnify and
hold harmless the Company, each of its directors, each of its officers who
signed the Registration Statement and each person, if any, who controls the
Company within the meaning of the

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Securities Act, against any losses, claims, damages, liabilities or expenses to
which the Company, its directors, its officers who signed the Registration
Statement and any controlling persons may become subject, under the Securities
Act, the Exchange Act, or any other federal or state statutory law or
regulation, or at common law or otherwise (including in settlement of any
litigation, if such settlement is effected with the written consent of the
Investor, which consent shall not be unreasonably withheld) insofar as such
losses, claims, damages, liabilities or expenses (or actions in respect thereof
as contemplated below) arise out of, are based upon, relate to or result from
any untrue statement or alleged untrue statement of any material fact contained
in the Registration Statement, the Prospectus, or any amendment or supplement to
the Registration Statement or Prospectus, or arise out of, are based upon,
relate to or result from the omission or alleged omission to state therein a
material fact required to be stated therein or necessary to make the statements
therein not misleading, in each case to the extent, but only to the extent, that
such untrue statement or alleged untrue statement or omission or alleged
omission was made in the Registration Statement, the Prospectus, or any
amendment or supplement thereto, solely in reliance upon and in conformity with
written information furnished to the Company by or on behalf of the Investor
expressly for use therein, and the Investor will reimburse the Company, each of
its directors, each of its officers who signed the Registration Statement, and
any controlling persons for any reasonable legal and other expense incurred by
the Company, its directors, its officers who signed the Registration Statement,
and any controlling persons, in connection with investigating, defending (or
preparing to defend), settling, compromising or paying any such loss, claim,
damage, liability, expense or action; PROVIDED, HOWEVER, that the Investor shall
not be liable for any such untrue statement or alleged untrue statement or
omission or alleged omission with respect to which the Investor has delivered to
the Company in writing a correction before the occurrence of the event from
which such loss was incurred. Notwithstanding the provisions of this Section
4.2, the Investor shall not be liable for any indemnification obligation under
this Agreement in excess of the aggregate amount of net proceeds received by the
Investor from the sale of the Registrable Securities pursuant to the
Registration Statement.

         4.3   INDEMNIFICATION PROCEDURE. Promptly after receipt by an
indemnified party under this Section 4 of notice of the threat or commencement
of any action, such indemnified party will, if a claim in respect thereof is to
be made against an indemnifying party under this Section 4, promptly notify the
indemnifying party in writing of the claim; but the omission so to notify the
indemnifying party will not relieve it from any liability which it may have to
any indemnified party for contribution or otherwise under the indemnity
agreement contained in this Section 4 or otherwise, to the extent it is not
prejudiced as a result of such failure. The reasonable fees and expenses of
counsel for the indemnified party shall be at the expense of the indemnifying
party.

     5.  RULE 144 INFORMATION.

         5.1   Until the expiration of the Registration Period, the Company
shall (i) make and keep public information available, as those terms are defined
in Rule 144 under the Securities Act, at all times after the effective date that
the Company becomes subject to the reporting requirements of the Securities Act
or the Exchange Act; (ii) file in a timely manner all reports required to be
filed by it under the Securities Act and the Exchange Act and the rules and
regulations promulgated thereunder; (iii) furnish to Investor, so long as
Investor owns any

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Registrable Securities, upon request by Investor, (a) a written statement by the
Company that it has complied with the reporting requirements of Rule 144 and of
the Securities Act and the Exchange Act, (b) a copy of the most recent annual or
quarterly report of the Company and (c) such other publicly available reports
and documents of the Company and other publicly available information in the
possession of or reasonably obtainable by the Company as a Holder may reasonably
request in availing itself of any rule or regulation of the SEC allowing a
Holder to sell any such securities without registration; and (iv) take such
further action to the extent required to enable the Investor to sell the
Registrable Securities pursuant to Rule 144 under the Securities Act (as such
rule may be amended from time to time).

     6.  REPRESENTATIONS AND WARRANTIES

         6.1   CERTAIN REPRESENTATIONS AND WARRANTIES OF THE INVESTOR.  The
Investor represents and warrants to the Company as of the date hereof as
follows:

               (A)  BINDING AGREEMENT. The Investor has the capacity to execute
         and deliver this Agreement and to consummate the transactions
         contemplated hereby. The Investor has duly and validly executed and
         delivered this Agreement and this Agreement constitutes a legal, valid
         and binding obligation of the Investor, enforceable against the
         Investor in accordance with its terms, except as such enforceability
         may be limited by applicable bankruptcy, insolvency, reorganization or
         other similar laws affecting creditors' rights generally and by general
         equitable principles (regardless of whether enforceability is
         considered in a proceeding in equity or at law).

               (B)  NO CONFLICT. Neither the execution and delivery of this
         Agreement by the Investor, nor the performance by the Investor of its
         obligations hereunder will, (i) require any consent, approval,
         authorization or permit of, registration, declaration or filing (except
         for such filings as may be required under the federal securities laws
         and the rules and regulations thereunder, any "blue sky" or other state
         securities laws or as would not reasonably be expected to prevent or
         materially delay or otherwise impair the Investor's ability to perform
         its obligations hereunder) with, or notification to, any governmental
         entity, (ii) result in a violation of, or default under, or conflict
         with any provision of its certificate of incorporation, bylaws,
         partnership agreement, limited liability company agreement or similar
         organizational documents, (iii) result in a violation or breach of, or
         constitute (with or without due notice or lapse of time or both) a
         default (or give rise to any right of termination, cancellation, or
         acceleration) under any contract, trust, agreement, instrument,
         commitment, arrangement or understanding applicable to the Investor or
         its Registrable Securities, or result in the creation of a security
         interest, lien, charge, encumbrance, equity or claim with respect to
         any of the Investor's Registrable Securities, except, in the case of
         clause (iii), as would not prevent or materially delay or otherwise
         materially impair the Investor's ability to perform its obligations
         hereunder, (iv) require any consent, authorization or approval of any
         person other than a governmental entity, except, in the case of clause
         (iv), as would not reasonably be expected to prevent, materially delay
         or otherwise materially impair the Investor's ability to perform its
         obligations

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         hereunder or (v) violate or conflict with any order, writ, injunction,
         decree, rule, regulation or law applicable to the Investor or its
         Registrable Securities.

         6.2   CERTAIN REPRESENTATIONS AND WARRANTIES OF THE COMPANY.  The
Company represents and warrants to the Investor as of the date hereof as
follows:

               (A)  BINDING AGREEMENT. The Company is a corporation duly
         incorporated, validly existing and in good standing under the laws of
         the State of Delaware and has full corporate power and authority to
         execute and deliver this Agreement and to consummate the transactions
         contemplated hereby. The execution and delivery of this Agreement by
         the Company and the consummation of the transactions contemplated
         hereby have been duly and validly authorized by the Board of Directors
         of the Company, and no other corporate proceedings on the part of the
         Company are necessary to authorize the execution, delivery and
         performance of this Agreement by the Company and the consummation of
         the transactions contemplated hereby. The Company has duly and validly
         executed this Agreement and this Agreement constitutes a legal, valid
         and binding obligation of the Company, enforceable against the Company
         in accordance with its terms, except as such enforceability may be
         limited by applicable bankruptcy, insolvency, reorganization or other
         similar laws affecting creditors' rights generally and by general
         equitable principles (regardless of whether enforceability is
         considered in a proceeding in equity or at law).

               (B)  NO CONFLICT. Neither the execution and delivery by the
         Company of this Agreement, nor the performance by the Company of its
         obligations hereunder will, (i) require any consent, approval,
         authorization or permit of, registration, declaration or filing (except
         for such filings as may be required under the federal securities laws
         and the rules and regulations thereunder, any "blue sky" or other state
         securities laws or as would not reasonably be expected to prevent or
         materially delay or otherwise impair the Company's ability to perform
         its obligations hereunder) with, or notification to, any governmental
         entity, (ii) result in a violation of, or default under, or conflict
         with any provision of its Certificate of Incorporation or Bylaws, (iii)
         result in a violation or breach of, or constitute (with or without due
         notice or lapse of time or both) a default (or give rise to any right
         of termination, cancellation, or acceleration) under any contract,
         trust, agreement, instrument, commitment, arrangement or understanding
         applicable to the Company, except, in the case of clause (iii), as
         would not prevent or materially delay or otherwise materially impair
         the Company's ability to perform its obligations hereunder, (iv)
         require any consent, authorization or approval of any person other than
         a governmental entity, except, in the case of clause (iv), as would not
         reasonably be expected to prevent, materially delay or otherwise
         materially impair the Company's ability to perform its obligations
         hereunder or (v) violate or conflict with any order, writ, injunction,
         decree, rule, regulation or law applicable to the Company.

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     7.  MISCELLANEOUS.

         7.1   SUCCESSORS. This Agreement shall inure to the benefit of and be
binding upon the parties hereto and their respective heirs, successors, assigns,
administrators, executors and other legal representatives. To the extent any
assignee of any of the Investor's rights under the SSA is also an owner of
Registrable Securities, such assignee shall have the same rights and
responsibilities hereunder with respect to such Registrable Securities as the
Investor has hereunder with respect to the Registrable Securities and any
reference to "the Investor" in this Agreement shall also be deemed to include
any such assignee.

         7.2   GOVERNING LAW.  This Agreement shall be governed by and construed
under the laws of the State of New York without regard to the principles of
conflicts of law.

         7.3   COUNTERPARTS.  This Agreement may be executed in any number of
counterparts, each of which shall be an original but all of which together shall
constitute one instrument.

         7.4   TITLES AND SUBTITLES.  The titles and subtitles used in this
Agreement are used for convenience only and are not to be considered in
construing or interpreting this Agreement.

         7.5   NOTICES. All notices, requests, consents, and other
communications under this Agreement shall be in writing and shall be deemed
delivered three business days after being sent via a reputable international
courier service guaranteeing three business day delivery, in each case to the
intended recipient as set forth below:

               (A) If to the Company, at 650 Albany Street, Boston, MA 02118,
         Attention: Chief Financial Officer, or at such other address as may
         have been furnished in writing by the Company to the other parties
         hereto, with a copy to Ropes & Gray LLP, One International Place,
         Boston, MA 02110, Attention: Geoffrey Davis, Esq.; or

               (B) If to the Investor, at 20 Biopolis Way, #09-01 Centros,
         Singapore 138668, Attention: Chief Executive Officer, Chu Swee Yeok, or
         at such other address as may have been furnished in writing by the
         Investor, with copies to each of Skadden, Arps, Slate, Meagher & Flom
         LLP, 30/F Tower Two, Lippo Centre, 89 Queensway, Central, Hong Kong,
         Attention: Alec P. Tracy and Allen & Gledhill, One Marina Boulevard
         #28-00, Singapore 018989, Attention: Tan Su May.

     Any party may give any notice, request, consent or other communication
under this Agreement using any other means (including, without limitation,
personal delivery, messenger service, telecopy, first class mail or electronic
mail), but no such notice, request, consent or other communication shall be
deemed to have been duly given unless and until it is actually received by the
party for whom it is intended. Any party may change the address to which
notices, requests, consents or other communications hereunder are to be
delivered by giving the other parties notice in the manner set forth in this
Section 7.5.

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         7.6   ATTORNEY'S FEES. In the event that any suit or action is
instituted to enforce any provision in this Agreement, the prevailing party in
such dispute shall be entitled to recover from the losing party all reasonable
fees, costs and expenses of enforcing any right of such prevailing party under
or with respect to this Agreement, including without limitation, such reasonable
fees and expenses of attorneys and accountants, which shall include, without
limitation, all fees, costs and expenses of appeals.

         7.7   AMENDMENTS OR WAIVER. Any provision of this Agreement may be
amended or the observance thereof may be waived (either generally or
specifically and either retroactively or prospectively), only by an instrument
in writing executed by the Company and the Investor.

         7.8  SEVERABILITY. In the event that one or more of the provisions of
this Agreement are held to be unenforceable under applicable law, such provision
shall be excluded from this Agreement and the balance of the Agreement shall be
interpreted as if such provision were so excluded and shall be enforceable in
accordance with its terms.

         7.9   ENTIRE AGREEMENT. This Agreement constitutes the full and entire
understanding and agreement between the parties regarding the subject matters
hereof.

         7.10  SPECIFIC PERFORMANCE. The parties hereto hereby declare that it
is impossible to measure in money the damages which will accrue to a party
hereto or to their heirs, personal representatives, or assigns by reason of a
failure to perform any of the obligations under this Agreement and agree that
the terms of this Agreement shall be specifically enforceable. If any party
hereto or his heirs, personal representatives, or assigns institutes any action
or proceeding to specifically enforce the provisions hereof, any person against
whom such action or proceeding is brought hereby waives the claim or defense
therein that such party or such personal representative has an adequate remedy
at law, and such person shall not offer in any such action or proceeding the
claim or defense that such remedy at law exists. The remedies provided for
herein are cumulative and are not exclusive of any remedies that may be
available to any party hereunder at law or in equity or otherwise.

         7.11  WAIVER. No waivers of any breach of this Agreement extended by
any party hereto to any other party shall be construed as a waiver of any rights
or remedies of any other party hereto or with respect to any subsequent breach.
No failure or delay on the part of any party hereto in exercising any right,
power or remedy hereunder shall operate as a waiver thereof, nor shall any
single or partial exercise of any such right, power or remedy preclude any other
or further exercise thereof or the exercise of any other right, power or remedy.

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IN WITNESS WHEREOF, the parties hereto have executed this Registration Rights
Agreement as of the date first above written.

THE COMPANY:                                  THE INVESTOR:

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