Document:

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                                                                   EXHIBIT 10.21

                              CONSULTING AGREEMENT
                               (Peter Barton Hutt)

         This Consulting Agreement (this "Agreement"), dated as of September 18,
2002 (the "Effective Date"), is made by and between Mimeon, Inc., a Delaware
corporation (the "Company"), and Peter Barton Hutt, an individual (the
"Consultant").

         WHEREAS, the Company has engaged and desires to continue to engage the
Consultant to perform consulting services on behalf of the Company and the
Consultant has performed and desires to continue to perform such services on the
terms and conditions hereinafter set forth.

         NOW, THEREFORE, in consideration of the premises and the mutual
covenants set forth herein the parties hereby agree as follows:

         1.       CONSULTING SERVICES.

                  (a)      The Company hereby retains the Consultant and the
Consultant hereby agrees to perform such consulting and advisory services
relating to the Field of Interest (as defined below) as the Company may request
and as set forth in SCHEDULE A (the "Consulting Services"). For purposes of this
Agreement, "Field of Interest" shall mean the field of regulatory strategies for
drug development.

                  (b)      The Consultant agrees to make himself available to
render the Consulting Services, at such times and locations as may be mutually
agreed, from time to time as requested by the Company. Except as provided in
SCHEDULE A, the Consultant may deliver the Consulting Services over the
telephone, in person or by written correspondence. Notwithstanding the
foregoing, the Consultant shall not be required to devote more than an average
of one day per month to the performance of the Consulting Services.

                  (c)      The Consultant agrees to devote his best efforts to
performing the Consulting Services. The Consultant shall comply with all rules,
procedures and standards promulgated from time to time by the Company with
regard to the Consultant's access to and use of the Company's property,
information, equipment and facilities.

         2.       COMPENSATION.  The Company shall pay the Consultant a
consulting fee as provided in SCHEDULE A. The Company will reimburse the
Consultant for such reasonable business expenses as are incurred by the
Consultant in the performance of Consulting Services for the Company and
pre-approved in writing by the Company.

         3.       INDEPENDENT CONTRACTOR. In furnishing the Consulting Services,
the Consultant understands that he will at all times be acting as an independent
contractor of the Company and, as such, will not be an employee of the Company
and will not by reason of this Agreement or by reason of his Consulting Services
to the Company be entitled to participate in or to receive any benefit or right
under any of the Company's employee benefit or welfare plans (including, without
limitation, any social security or unemployment plans or payments). The
Consultant also will be responsible for paying all withholding and other taxes
required by law to be paid as and when the same become due and payable.
Consultant shall not enter into any agreements or incur any obligations on
behalf of the Company.

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         4.       TERM. The parties agree that the term of this Agreement shall
be retroactive to April 1, 2002 and will end on the first anniversary of the
Effective Date or upon earlier termination as provided below (the "Term");
provided, that the Term may be extended for successive one year periods by
mutual agreement of the Company and the Consultant prior to the expiration or
termination of this Agreement. This Agreement may be terminated at any time by
written agreement of both parties.

         5.       EXCEPTIONS TO THIS AGREEMENT.

                  (a)      CERTAIN OTHER CONTRACTS. The Company acknowledges
that the Consultant is now or may become a party to agreements with third
parties relating to the disclosure of information, the ownership of inventions,
restrictions against competition and/or similar matters. The Consultant
represents and agrees that the execution, delivery and performance of this
Agreement does not and will not conflict with any other agreement, policy or
rule applicable to the Consultant. The Consultant will not (i) disclose to the
Company any information that he is required to keep secret pursuant to an
existing confidentiality agreement with a third party, (ii) use the funding,
resources, facilities or inventions of any third party to perform the Consulting
Services, or (iii) perform the Consulting Services in any manner that would give
any third party rights to any intellectual property created in connection with
such services.

                  (b)      PRIOR INVENTIONS. The Consultant has informed the
Company, in writing, of any and all Inventions (as defined in Section 7) which
he claims as his own or otherwise intends to exclude from this Agreement because
it was developed by him prior to the date of this Agreement. The Consultant
acknowledges that after execution of this Agreement he shall have no right to
exclude any Inventions from this Agreement.

         6.       CONFIDENTIAL INFORMATION.

                  (a)      While providing the Consulting Services to the
Company and thereafter, the Consultant shall not, directly or indirectly, (i)
use any Confidential Information (as defined below) other than pursuant to his
provision of the Consulting Services by and for the benefit of the Company, or
(ii) disclose to anyone outside of the Company any such Confidential
Information.

                  (b)      The term "Confidential Information" as used
throughout this Agreement shall mean all trade secrets, proprietary information
and other data or information (and any tangible evidence, record or
representation thereof), written or oral, whether prepared, conceived or
developed by a consultant or employee of the Company (including the Consultant)
or received by the Company from an outside source, which is in the possession of
the Company (whether or not the property of the Company). Without limiting the
generality of the foregoing, Confidential Information shall include:

                           (1)      any Invention, idea, know-how, improvement,
invention, innovation, development, concept, technical data, design, formula,
device, pattern, sequence, method, process, composition of matter, technology,
computer program or software, source code, object code, algorithm, model,
diagram, flow chart, product specification or design, plan for a new or revised
product, sample, compilation of information, or work in process, or parts
thereof,

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and any and all revisions and improvements relating to any of the foregoing (in
each case whether or not reduced to tangible form and whether or not patentable
or copyrightable); and

                           (2)      the name of any customer, supplier,
employee, prospective customer, sales agent or consultant, any sales plan,
marketing material, plan or survey, business plan or opportunity, product or
development plan or specification, business proposal, financial record, or
business record or other record or information relating to the present or
proposed business of the Company.

                  (c)      Notwithstanding the foregoing, the term Confidential
Information shall not apply to information which the Company has voluntarily
disclosed to the public without restriction or which has otherwise lawfully
entered the public domain.

                  (d)      The Consultant acknowledges that the Company from
time to time has in its possession information (including product and
development plans and specifications) which represent information which is
claimed by others to be proprietary and which the Company has agreed to keep
confidential. The Consultant agrees that all such information shall be
Confidential Information for purposes of this Agreement.

                  (e)      The Consultant agrees that all originals and all
copies of materials containing, representing, evidencing, recording, or
constituting any Confidential Information, however and whenever produced
(whether by the Consultant or others), shall be the sole property of the
Company.

                  (f)      The Consultant represents that his retention as a
consultant with the Company and his performance under this Agreement does not,
and shall not, breach any agreement that obligates him to keep in confidence any
trade secrets or confidential or proprietary information of his or of any other
party or to refrain from competing, directly or indirectly, with the business of
any other party. The Consultant shall not disclose to the Company any trade
secrets or confidential or proprietary information of any other party.

                  (g)      The Consultant acknowledges that the Company from
time to time may have agreements with other Persons (as defined in Section
12(j)) or with the United States Government, or agencies thereof, that impose
obligations or restrictions on the Company regarding inventions made during the
course of work under such agreements or regarding the confidential nature of
such work. The Consultant agrees to be bound by all such obligations and
restrictions that are known to him and to take all action necessary to discharge
the obligations of the Company under such agreements.

         7.       INVENTIONS.

                  (a)      CERTAIN INVENTIONS MADE BY OTHERS. During the Term of
this Agreement, the Consultant will use his best efforts to promptly disclose to
the President of the Company, fully, in writing and on a confidential basis, (i)
technology and product opportunities which come to the attention of the
Consultant in the Field of Interest, and (ii) any invention, improvement,
discovery, process, formula or method or other intellectual property relating to
or useful in, the Field of Interest, whether or not patentable or copyrightable,
and whether or not discovered or developed by Consultant.

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                  (b)      INVENTIONS MADE BY THE CONSULTANT. The Consultant
agrees that all Confidential Information and all other discoveries, inventions,
developments, ideas, concepts, trademarks, service marks, logos, methods,
processes, products, formulas, computer programs or software, source code,
object code, algorithms, machines, apparatuses, items of manufacture or
composition of matter, or any new uses therefor or improvements thereon, or any
designs, specifications or modifications or configurations of any kind, or works
of authorship of any kind, including, without limitation, compilations and
derivative works, whether or not patentable or copyrightable, written,
conceived, developed, reduced to practice or otherwise made by the Consultant,
either alone or with others, and in any way related to the Field of Interest or
to tasks assigned to the Consultant during the course of his relationship with
the Company, whether or not written, conceived, developed, reduced to practice
or made on the Company's premises, during the Term or thereafter if resulting or
directly derived from Confidential Information (collectively "Inventions"), and
any and all services and products which embody, emulate or employ any such
Invention or Confidential Information shall be the sole property of the Company
and all copyrights, patents, patent applications, patent rights, trademarks,
trade secrets rights and reproduction rights to, and other proprietary rights
in, each such Invention or Confidential Information, whether or not patentable
or copyrightable, shall belong exclusively to the Company. The Consultant agrees
that, to the fullest extent possible, all such Inventions shall constitute works
made for hire under the copyright laws of the United States, and, to the extent
any Invention does not constitute a work made for hire, hereby assigns to the
Company upon creation all Inventions and any and all copyrights, patents and
other proprietary rights he may have in any Invention, together with the right
to file and/or own, wholly without restrictions, applications for United States
and foreign patents, trademark registration and copyright registration and any
patent, or trademark or copyright registration issuing thereon and the
Consultant appoints any officer of the Company as his duly authorized attorney
to execute, file, prosecute and protect the same before any government agency,
court or authority. The Consultant hereby waives all claims to moral rights in
any Inventions.

         8.       CONSULTANT'S OBLIGATION TO KEEP RECORDS. Consultant shall make
and maintain adequate and current written records of all Inventions, and shall
disclose all Inventions promptly, fully, in writing and on a confidential basis
to the President of the Company immediately upon development of the same and at
any time upon request. Such records shall be available to and remain the sole
property of the Company at all times.

         9.       CONSULTANT'S OBLIGATION TO COOPERATE. The Consultant will, at
any time during or after the Term of this Agreement, upon request of the
Company, execute all documents and perform all lawful acts which the Company
considers necessary or advisable to secure its rights hereunder and to carry out
the intent of this Agreement. Without limiting the generality of the foregoing,
the Consultant will assist the Company in any reasonable manner to obtain for
its own benefit patents, copyrights or other proprietary rights in any and all
countries with respect to all Inventions assigned pursuant to Section 7, and the
Consultant will execute, when requested, all applications and assignments of all
patents, copyrights and other proprietary rights in the Inventions to the
Company or its designees, and any other lawful documents deemed necessary by the
Company to carry out the purposes of this Agreement, and the Consultant will
further assist the Company in every way to enforce any patents, copyrights and
other proprietary rights obtained, including testifying in any suit or
proceeding involving any of said patents, copyrights or other proprietary rights
or executing any documents deemed necessary by the Company, all

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without further consideration than provided for herein. It is understood that
reasonable out-of-pocket expenses of the Consultant's assistance incurred at the
request of the Company under this Section 9 will be reimbursed by the Company.

         10.      NONSOLICITATION. During the Term, the Consultant shall not (i)
solicit, encourage, or take any other action which is intended to induce any
employee of, or consultant to, the Company (or any other Person who may have
been employed by, or may have been a consultant to, the Company during the Term)
to terminate his or her employment or relationship with the Company in order to
become employed by or otherwise perform services for any other Person or (ii)
solicit, endeavor to entice away from the Company or otherwise interfere with
the relationship of the Company with any Person who is, or was within the
then-most recent 12 month period, a client or customer of the Company.

         11.      RETURN OF PROPERTY. Upon expiration or termination of the
Consultant's engagement with the Company, or at any other time upon request of
the Company, the Consultant shall return promptly any and all Confidential
Information, including customer or prospective customer lists, other customer or
prospective customer information or related materials, computer programs,
software, electronic data, specifications, drawings, blueprints, medical
devices, samples, reproductions, sketches, notes, notebooks, memoranda, reports,
records, proposals, business plans, or copies of them, other documents or
materials, tools, equipment, or other property belonging to the Company or its
customers which the Consultant may then possess or have under his control. The
Consultant further agrees that upon expiration or termination of his engagement
he shall not take with him any documents or data in any form or of any
description containing or pertaining to Confidential Information or any
Inventions.

         12.      MISCELLANEOUS.

                  (a)      ENTIRE AGREEMENT. This Agreement and the documents
referred to herein constitute the entire agreement among the parties with
respect to the subject matter hereof and supersede all other prior agreements
and understandings, both written and oral, between the parties with respect to
such subject matter.

                  (b)      ASSIGNMENT. This Agreement shall be binding upon and
inure to the benefit of the parties hereto and their respective successors and
permitted assigns, provided, however, that the obligations of the Consultant are
personal and shall not be assigned by him. Any non-consented-to assignment or
delegation by the Consultant, whether express or implied or by operation of law,
shall be void and shall constitute a breach and a default by the Consultant.

                  (c)      AMENDMENTS AND SUPPLEMENTS.  This Agreement may not
be altered, changed or amended, except by an instrument in writing signed by the
parties hereto.

                  (d)      NO WAIVER. The terms and conditions of this Agreement
may be waived only by a written instrument signed by the party waiving
compliance. The failure of any party hereto to enforce at any time any of the
provisions of this Agreement shall in no way be construed to be a waiver of any
such provision, nor in any way to affect the validity of this Agreement or any
part hereof or the right of such party thereafter to enforce each and every such

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provision. No waiver of any breach of or non-compliance with this Agreement
shall be held to be a waiver of any other or subsequent breach or
non-compliance.

                  (e)      GOVERNING LAW.  This Agreement shall be governed by,
and construed and enforced in accordance with, the substantive laws of the
Commonwealth of Massachusetts, without regard to its principles of conflicts of
laws.

                  (f)      NOTICE. All notices and other communications
hereunder (other than Consulting Services, which shall be delivered in the
manner specified in Section 1 and SCHEDULE A) shall be in writing and shall be
deemed given if delivered by hand, sent by facsimile transmission with
confirmation of receipt, sent via a reputable overnight courier service with
confirmation of receipt requested, or mailed by registered or certified mail
(postage prepaid and return receipt requested) to the parties at the following
addresses (or at such other address for a party as shall be specified by like
notice), and shall be deemed given on the date on which delivered by hand or
otherwise on the date of receipt as confirmed:

         To the Company:

                  Mimeon, Inc.
                  45 Moulton Street
                  Cambridge, MA  02138
                  Attention:  President
                  Fax:  617.876.8012

         To the Consultant:

                  Peter Barton Hutt
                  c/o Covington & Burling
                  1201 Pennsylvania, NW
                  Washington, DC 20004
                  Fax: 202-778-5522

                  (g)      REMEDIES. The Consultant recognizes that money
damages alone would not adequately compensate the Company in the event of breach
by the Consultant of this Agreement, and the Consultant therefore agrees that,
in addition to all other remedies available to the Company at law, in equity or
otherwise, the Company shall be entitled to injunctive relief for the
enforcement hereof. All rights and remedies hereunder are cumulative and are in
addition to and not exclusive of any other rights and remedies available at law,
in equity, by agreement or otherwise.

                  (h)      SURVIVAL; VALIDITY. (i) Notwithstanding the
termination of the Consultant's relationship with the Company (whether pursuant
to Section 4 or otherwise), the Consultant's covenants and obligations set forth
in Sections 6, 7, 9, 10, 11 and 12 shall remain in effect and be fully
enforceable in accordance with the provisions thereof. (ii) In the event that
any provision of this Agreement shall be determined to be unenforceable by
reason of its extension for too great a period of time or over too large a
geographic area or over too great a range of activities, it shall be interpreted
to extend only over the maximum period of time, geographic area or range of
activities as to which it may be enforceable. (iii) If, after application of
Section 12(h)(ii), any

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provision of this Agreement shall be determined to be invalid, illegal or
otherwise unenforceable by a court of competent jurisdiction, the validity,
legality and enforceability of the other provisions of this Agreement shall not
be affected thereby. (iv) Except as otherwise provided in this Section 12(h),
any invalid, illegal or unenforceable provision of this Agreement shall be
severable, and after any such severance, all other provisions hereof shall
remain in full force and effect.

                  (i)      CONSTRUCTION. A reference to a Section or a Schedule
shall mean a Section in or Schedule to this Agreement unless otherwise expressly
stated. The titles and headings herein are for reference purposes only and shall
not in any manner limit the construction of this Agreement which shall be
considered as a whole. The words "include," "includes" and "including" when used
herein shall be deemed in each case to be followed by the words "without
limitation." Whenever the context may require, any pronouns used herein shall
include the corresponding masculine, feminine or neuter forms, and the singular
form of names and pronouns shall include the plural and vice-versa.

                  (j)      CERTAIN DEFINITIONS.  "Person" shall mean an
individual, a corporation, an association, a partnership, an estate, a trust and
any other entity or organization.

                  (k)      COUNTERPARTS.  This Agreement may be executed in one
or more counterparts, all of which together shall constitute one and the same
Agreement.

                                      *****

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         IN WITNESS WHEREOF, the parties have caused this Consulting Agreement
to be executed as an agreement under seal as of the date first written above.

                                    MIMEON, INC.

                                    By: /s/ Susan K. Whoriskey, Ph.D.
                                       -----------------------------------------
                                    Susan K. Whoriskey, Ph.D
                                    Vice President Licensing and Business
                                    Development

                                    CONSULTANT

                                    /s/ Peter Barton Hutt
                                    --------------------------------------------
                                    Peter Barton Hutt

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                                   SCHEDULE A

         1.       Description of Consulting Services.

                  The Consultant shall provide such consulting services as the
Company reasonably requests in connection with the operation of the Company's
business.

         2.       Compensation.

                  The Company shall grant to Consultant a Non-Statutory Stock
Option to purchase 5,000 shares of Mimeon, Inc. common stock at a purchase price
of $0.278 per share pursuant to and in accordance with the Non-Statutory Stock
Option agreement attached hereto as Exhibit A.

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                              [Letterhead of MOMENTA]

September 29, 2003

Peter Barton Hutt, Esq.
402 Prince Street
Alexandria, Virginia  22314

Dear Peter:

Reference is made to the Consulting Agreement dated September 18, 2002 between
Momenta Pharmaceuticals, Inc. and you (the "Agreement"). Capitalized terms used
herein and not otherwise defined shall have the meanings given such terms in the
Agreement.

Pursuant to Section 4 of the Agreement, Company and Consultant hereby agree to
extend the Term of the Agreement for one additional year, from September 18,
2003 through September 17, 2004 (the "Renewal Period"). Except as otherwise
agreed to in this Letter Agreement, the same terms and conditions as are set
forth in the Agreement shall apply to the rendering of Consulting Services
during the Renewal Period.

As compensation for the Consulting Services during the Renewal Period,
Consultant will be granted an additional non-statutory stock option to purchase
5,000 shares of the Common Stock of the Company, at an exercise price equal to
the fair market value of a share of Common Stock on the date of grant by the
Company, with such option to vest in 12 equal monthly installments over the
one-year Renewal Period.

With respect to Section 4 of the Agreement, Company and Consultant agree that
Company will have the right to terminate the Agreement on written notice to
Consultant in the case of: (a) a breach by Consultant of a material provision of
the Agreement, where such breach cannot be cured or is not cured within fifteen
(15) days after Consultant's receiving written notice of such breach from
Company; (b) a physical or mental inability of Consultant to perform the
Consulting Services, which physical or mental inability exists for a period of
at least one hundred eighty (180) consecutive days; (c) a material and
intentional misappropriation or destruction of Company's funds, properties or
assets; or (d) a conviction of a crime involving moral turpitude or constituting
a felony or an entering of a plea of nolo contendere to the same.

If the foregoing is in conformity with your understanding, please sign both
copies of this Letter Agreement and return one fully-executed copy to me.

Very truly yours,

/s/ Susan K. Whoriskey
Susan K. Whoriskey
Vice President, Licensing and Business Development

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Peter Barton Hutt, Esq.
September 29, 2003
Page 2

Agreed and accepted:

/s/ Peter Barton Hutt
-----------------------------
Peter Barton Hutt

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                                                                   EXHIBIT 10.22

                       RESTRICTED STOCK PURCHASE AGREEMENT
                               (Peter Barton Hutt)

     This Restricted Stock Purchase Agreement dated as of June 13, 2001 (this
"Agreement") is made by and between Mimeon, Inc., a Delaware corporation (the
"Company"), and Peter Barton Hutt, (the "Purchaser").

     l.   DEFINITIONS. As used in this Agreement, the following terms shall have
the following meanings:

          QUALIFIED OFFERING: A firm commitment underwritten public offering of
the Company's Common Stock pursuant to an effective registration statement under
the Securities Act of 1933, as amended (the "Act"), in which the price per share
is at least $5.00 (subject to equitable adjustment in the event of stock splits
and the like) and the aggregate gross proceeds to the Company from such offering
are not less than $10,000,000.

          QUALIFIED SALE: The sale of all or substantially all of assets or
issued and outstanding capital stock of the Company, or merger or consolidation
involving the Company in which stockholders of the Company immediately before
such merger or consolidation do not own immediately after such merger or
consolidation capital stock or other equity interests of surviving corporation
or entity representing more than fifty percent in voting power of capital stock
or other equity interests of such surviving corporation or entity outstanding
immediately after such merger or consolidation.

          SERVICE: Service as an employee, officer or director of, or a
consultant or advisor to, the Company or its successors.

          SHARES: The shares of Common Stock issued to Purchaser hereunder and
any other securities of the Company which may be issued in exchange for or in
respect of such shares of Common Stock, whether by way of stock split, stock
dividend, combination of shares, reclassification, recapitalization,
reorganization or any other means.

          UNVESTED SHARES:  Any Shares that are not Vested Shares.

          VESTED: Released from the Company's Repurchase Option (as defined in
Section 5(a)).

          VESTED SHARES: Any Shares that have vested in accordance with Section
5(b).

     2.   PURCHASE AND SALE OF SHARES. The Company hereby sells to Purchaser,
and Purchaser hereby purchases from the Company, 23,438 shares of the Company's
common stock, $0.0001 par value per share ("Common Stock"), for a purchase price
per share of $0.0001, and an aggregate purchase price of $2.35. The Company
acknowledges receipt from Purchaser of $2.35 in cash, in full payment of such
purchase price. Purchaser and the Company hereby agree that the fair market
value of the Shares on the date hereof is $0.0001 per share.

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     3.   REPRESENTATIONS OF PURCHASER. Purchaser understands that the Shares
are not registered under the Act, and represents to the Company, and agrees that
the Company is entitled to rely on such representations, as follows:

          (a)  Purchaser understands that the Shares have not been registered
under the Act, or registered or qualified under the securities or "Blue Sky"
laws of any jurisdiction, and are being sold pursuant to exemptions contained in
the Act and exemptions contained in other applicable securities or "Blue Sky"
laws. Purchaser understands further that the Company's reliance on these
exemptions is based in part on the representations made by Purchaser in the
Agreement. In this connection, Purchaser represents and warrants that the offer
and sale of the Shares were made solely in Virginia.

          (b)  Purchaser understands the term "accredited investor" as used in
Regulation D promulgated under the Act and represents and warrants to the
Company that he is an "accredited investor" for purposes of acquiring the
Shares. The nature and amount of Purchaser's investment in the Shares is
consistent with Purchaser's investment objectives, abilities, and resources.
Purchaser understands that the Shares are an illiquid investment, which will not
become freely transferable by reason of any "change of circumstances" whatever.
Purchaser has adequate means of providing for Purchaser's current needs and
possible contingencies and has no need for liquidity in Purchaser's investment.

          (c)  Purchaser is acquiring the Shares for Purchaser's own account for
investment, and not for, with a view to, or in connection with the resale or
distribution thereof. Purchaser has no present intention to sell, hypothecate,
distribute or otherwise transfer the Shares or any portion thereof or any
interest therein.

          (d)  Purchaser understands that the Shares will constitute "restricted
securities" within the meaning of Rule 144 promulgated under the Act and that,
as such, the Shares must be held indefinitely unless they are subsequently
registered under the Act or unless an exemption from the registration
requirements thereof is available. Purchaser has been advised that Rule 144,
which permits the resale, subject to various terms and conditions, of small
amounts of such "restricted securities" after they have been held for one year,
does not now apply to the Company, because the Company is not now required to
file, and does not file, current reports under the Securities Exchange Act of
1934, and because information concerning the Company substantially equivalent to
that which would be available if the Company were required to file such reports
is not now publicly available. The Company may become a reporting entity at some
future date, but no assurance can be given that it will do so.

          (e)  In connection with Purchaser's acquisition of the Shares,
Purchaser accepts the condition that the Company may maintain "stop transfer"
orders with respect to the Shares and that each certificate or other document
evidencing the Shares will bear conspicuous legends in substantially the form
set forth in Section 7 of this Agreement.

          (f)  Purchaser has consulted Purchaser's attorney or accountant with
respect to Purchaser's purchase of the Shares. Purchaser has fully investigated
the Company and its

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business and financial condition and has knowledge of the Company's current
activities. Purchaser acknowledges that the Company has granted Purchaser and
Purchaser's attorney or accountant access to all information about the Company
which they have requested and has offered each of them access to all further
information which they deemed relevant to an investment decision with respect to
the Shares. Purchaser and Purchaser's attorney or accountant have had the
opportunity to ask questions of, and receive answers from, representatives of
the Company concerning such information and the Company's financial condition
and prospects.

     4.   RESTRICTIONS ON TRANSFER. The following restrictions on transfer of
the Shares shall apply:

          (a)  SECURITIES LAWS. Except for purchases of Unvested Shares by the
Company as contemplated by Section 5, no Shares, nor any interest therein, may
be sold, assigned, pledged or otherwise transferred at any time or under any,
circumstances unless (i) the Shares proposed to be transferred have been
registered under the Act and qualified under applicable state securities laws,
or (ii) the Company has received, or agreed to waive, an opinion of counsel
acceptable to the Company to the effect that such transfer may be effected
without registration under the Act or qualification under the securities laws of
relevant states and the proposed transferee has made such representations and
agreements as the Company shall require to assure compliance with the Act and
such laws.

          (b)  TERMINATION OF REPURCHASE OPTION. Except for purchases of
Unvested Shares by the Company as contemplated by Section 5, no Shares, nor any
interest therein, may be sold, assigned, pledged or otherwise transferred until
the Repurchase Option shall have terminated with respect to such Shares.

          (c)  RIGHT OF FIRST OFFER. In the event that at any time Purchaser
desires to sell, assign or otherwise transfer any of the Vested Shares then held
by Purchaser, he shall first offer the Vested Shares desired to be transferred
to the Company by giving written notice of the proposed transfer. The notice
shall state the number of Vested Shares proposed to be transferred, the name of
the person or persons to whom it is proposed to transfer the Vested Shares, the
price at which the Vested Shares are intended to be transferred and all other
terms of the transaction, which must be bona fide. Such notice shall constitute
an offer by Purchaser to the Company for the Company to purchase such Vested
Shares on such terms and at a price per Vested Share equal to the price stated
in the notice. The Company may accept the offer as to all, but not less than
all, of the Vested Shares offered by notifying Purchaser in writing within 30
days after receipt of such notice of its acceptance of the offer. If the offer
is accepted, Purchaser shall sell the offered Vested Shares to the Company on
the terms and at the price per Vested Share as aforesaid, free of all
encumbrances, and shall deliver the certificates representing such Vested
Shares, duly endorsed in blank by Purchaser or with duly executed stock powers
attached thereto, all in form suitable for the transfer of such Vested Shares to
the Company, within 30 days of the date of acceptance of the offer to sell,
against payment therefor at the same price per Vested Share and according to the
same terms as were offered by the proposed transferee. If within the applicable
time period Purchaser does not receive notice of the Company's intention

                                        3
<Page>

to purchase the offered Vested Shares, the offer shall be deemed to have been
rejected. In such event, Purchaser may transfer title to the offered Vested
Shares within 90 days from the date of his written notice to the Company of his
intention to sell, but such transfer shall be made only to the proposed
transferee or transferees and at the proposed price and on such other terms as
stated in such notice. Vested Shares that are so transferred to such transferee
or transferees shall remain subject to this Section 3 and as a condition to any
transfer Purchaser shall obtain a written agreement from the transferee by which
the transferee agrees to be bound by this Section 3.

          (d)  PERMITTED TRANSFERS. Any portion or all of the Vested Shares may,
without compliance with the provisions of Section 4(c), be transferred by
Purchaser to a member of his immediate family or to a family partnership or
family trust, or on Purchaser's death may be transferred to Purchaser's estate
or to those entitled to a distribution of the Vested Shares under the laws of
descent and distribution, provided that Shares that are so transferred shall
remain subject to this Section 4 and as a condition to any transfer Purchaser
shall obtain a written agreement from the transferee by which the transferee
agrees to be bound by this Section 4.

          (e) REMEDIES. No sale, assignment, pledge or other transfer of Shares
shall be effective or given effect on the books of the Company unless all of the
applicable provisions of this Section 4 have been duly complied with. If any
transfer of Shares is made or attempted in violation of the foregoing
restrictions, or if Shares are not offered to the Company as required hereby,
the Company shall have the right to purchase such Shares from the purported
owner thereof or his transferee at any time before or after the transfer, as
herein provided. In addition to any other legal or equitable remedies which it
may have, the Company may enforce its rights by actions for specific performance
(to the extent permitted by law) and may refuse to recognize any transferee as
one of its stockholders for any purpose, including, without limitation, for
purposes of dividend and voting rights, until all applicable provisions hereof
have been complied

          (f)  LOCK-UP. Purchaser agrees that for a period of up to 180 days
from the effective date of any registration of securities of the Company (upon
request of the Company or the underwriters managing any underwritten offering of
the Company's securities), he will not sell, make any short sale or loan of,
grant any option for the purchase of, or otherwise dispose of any Shares held by
him without the prior written consent of the Company or such underwriters, as
the case may be.

          (g)  TERMINATION OF RESTRICTIONS. Sections 4(c) and 4(d) shall
terminate upon the earlier to occur of: (i) immediately prior to the
consummation of a Qualified Sale; or (ii) the closing of a Qualified Offering.

     5.   REPURCHASE OF UNVESTED SHARES.

          (a)  REPURCHASE OPTION.

               (i)  In the event of the termination of Purchaser's Service by
Purchaser or the Company for any reason, with or without cause, the Company
shall upon the date of such termination (the "Termination Date") have an
irrevocable, exclusive option (the "Repurchase

                                        4
<Page>

Option") for a period of 90 days from such date to repurchase all or any portion
of the Unvested Shares at the per share repurchase price of $0.0001 per share,
appropriately adjusted in the event of a stock dividend, stock split,
recapitalization, combination of shares or similar event occurring subsequent to
the date of this Agreement.

               (ii) Unless the Company notifies Purchaser within 90 days from
the date of termination of Purchaser's Service that it does not intend to
exercise its Repurchase Option with respect to some or all of the Unvested
Shares, the Repurchase Option shall be deemed automatically exercised by the
Company as of the 90th day following such termination, provided that the Company
may notify Purchaser that it is exercising its Repurchase Option as of a date
prior to such 90th day. Unless Purchaser is otherwise notified by the Company
pursuant to the preceding sentence that the Company does not intend to exercise
its Repurchase Option as to some or all of the Unvested Shares to which it
applies at the time of termination, execution of this Agreement by Purchaser
constitutes written notice to Purchaser of the Company's intention to exercise
its Repurchase Option with respect to all Unvested Shares to which such
Repurchase Option applies. The Company, at its choice, may satisfy its payment
obligation to Purchaser with respect to exercise of the Repurchase Option by
either (A) delivering a check to Purchaser in the amount of the purchase price
for the Unvested Shares being repurchased, or (B) in the event Purchaser is
indebted to the Company, canceling an amount of such indebtedness equal to the
purchase price for the Unvested Shares being repurchased, or (C) by a
combination of (A) and (B) so that the combined payment and cancellation of
indebtedness equals such purchase price, provided that the Company shall use
good faith efforts to satisfy its payment obligation to Purchaser within 15 days
after Company's notice of exercise of the Repurchase Option (or deemed
exercise), and that if such check is not delivered or such cancellation is not
effective within such 15 days from such date, the amount of the Company's
unsatisfied payment obligation shall bear interest at a rate of nine percent
(9%) per annum until the Company has satisfied its payment obligation under this
paragraph (ii). In the event of any deemed automatic exercise of the Repurchase
Option pursuant to this Section 5(a)(ii) and Purchaser is then indebted to the
Company, the amount of such indebtedness equal to the purchase price of the
Unvested Shares being repurchased shall be deemed automatically canceled as of
the date of Company's notice of exercise of the Repurchase Option (or deemed
exercise). As a result of any repurchase of Unvested Shares pursuant to this
Section 5(a), the Company shall become the legal and beneficial owner of the
Unvested Shares being repurchased and shall have all rights and interest therein
or related thereto, and the Company shall have the right to transfer to its own
name the number of Unvested Shares being repurchased by the Company, without
further action by Purchaser.

          (b)  VESTING.

               (i)  The Shares will become vested as follows:

                    (A)  one sixteenth (1/16) of the Shares shall vest on
September 13, 2001; and

                                        5
<Page>

                    (B)  an additional one sixteenth (1/16) of the Shares shall
vest on the last day of each consecutive three-month period thereafter until
100% of the Shares have become vested; PROVIDED, however, that the vesting of
Shares on any such vesting date shall be conditioned upon Purchaser's continuing
Service with the Company from the date hereof through such vesting date.
Fractional shares shall be rounded down to the nearest whole share.

               (ii) Notwithstanding Section 4(b)(i), all Shares shall be deemed
to have vested immediately prior to the consummation of a Qualified Sale.

     6.   CUSTODY OF CERTIFICATES. In order to facilitate the exercise of the
Repurchase Option, the Company or its counsel shall hold all certificates
representing Unvested Shares, together with an adequate number of undated and
otherwise blank stock powers executed by purchaser. The Company shall have the
right to cause transfers of Unvested Shares to be effected pursuant to Section
5. After any Shares become Vested Shares, the Company shall, upon request of
Purchaser, deliver to Purchaser a certificate or certificates representing such
Vested Shares. After the Company sends Purchaser a notice that it does not
intend to exercise its Repurchase Option as to certain Unvested Shares, the
Company shall, upon request of Purchaser, deliver to Purchaser a certificate or
certificates representing such Unvested Shares.

     7.   LEGENDS. Each certificate representing Shares shall prominently bear
legends in substantially the following forms:

     These securities have not been registered under the Securities Act of 1933.
     They may not be sold, offered for sale, pledged or hypothecated in the
     absence of a registration statement in effect with respect to the
     securities under such Act or an opinion of counsel satisfactory to the
     Corporation that such registration is not required.

     The securities represented by this certificate have been acquired for
     investment and have not been registered or qualified under the securities
     or "Blue Sky" laws of any jurisdiction. They may not be offered or sold
     without an opinion of counsel to the Corporation to the effect that the
     proposed transaction will be exempt from registration, qualification, and
     filings in all applicable jurisdictions.

     The Corporation is authorized to issue more than one class or series of
     stock. The powers, designations, preferences and relative participating,
     optional or other special rights, and the qualifications, limitations or
     restrictions of such preferences and/or rights of each class of stock or
     series of any class set forth in the Certificate of Incorporation of the
     Corporation. The Corporation will furnish a copy of the Certificate of
     Incorporation of the Corporation to the holder of this certificate without
     charge upon request.

     The securities represented by this certificate are subject to restrictions
     on transfer and repurchase rights pursuant to the terms of a Restricted
     Stock Purchase Agreement, as amended from time to time, between the owner
     of this certificate and the Corporation. The Corporation will furnish a
     copy of this agreement to the holder hereof without charge upon written
     request.

                                        6
<Page>

     8.   MISCELLANEOUS.

          (a)  ENTIRE AGREEMENT. This Agreement constitutes the entire agreement
between the parties with respect to the subject matter hereof, and supersedes
all prior agreements, negotiations, representations and proposals, written or
oral, relating to such subject matter.

          (b)  AMENDMENTS. Neither this Agreement nor any provision hereof may
be changed or modified except by an agreement in writing executed by Purchaser
and on behalf of the Company.

          (c)  BINDING EFFECT OF THE AGREEMENT. This Agreement shall inure to
the benefit of, and be binding upon, the Company, Purchaser and their respective
estates, heirs, executors, transferees, successors, assigns and legal
representatives.

          (d)  PROVISIONS SEVERABLE. In the event that any provision of this
Agreement shall be determined to be invalid, illegal or otherwise unenforceable
by any court of competent jurisdiction, the validity, legality and
enforceability of the other provisions of this Agreement shall not be affected
thereby. Any invalid, illegal or unenforceable provision of this Agreement shall
be severed, and after any such severance, all other provisions hereof shall
remain in full force and effect.

          (e)  NOTICES. All notices under this Agreement shall be effective (i)
upon personal or facsimile delivery, (ii) two business days after deposit in the
United States mail as registered or certified mail postage fully prepaid, or
(iii) one business day after pickup by any overnight commercial courier service,
in each case sent or addressed to the Company at its principal office and to
Purchaser at his record address as carried in the stock records of the Company
or at such other address as he may from time to time designate in writing to the
Company.

          (f)  CONSTRUCTION. A reference to a Section shall mean a Section of
this Agreement unless otherwise expressly stated. The titles and headings herein
are for reference purposes only and shall not in any manner limit the
construction of this Agreement which shall be considered as a whole. The words
"include," "includes" and "including" when used herein shall be deemed in each
case to be followed by the words "without limitation." Whenever the context may
require, any pronouns used herein shall include the corresponding masculine,
feminine or neuter forms, and the singular form of names and pronouns shall
include the plural and vice-versa.

          (g)  NO EMPLOYMENT AGREEMENT. This Agreement shall not be construed as
an agreement by the Company to employ Purchaser, nor is the Company obligated to
employ Purchaser by reason of this Agreement or the issuance of the Shares to
Purchaser.

                                        7
<Page>

          (h)  SECTION 83(b) ELECTION. Purchaser will furnish to the Company a
copy of any election made by Purchaser under Section 83(b) of the Internal
Revenue Code of 1986, as amended, with respect to his acquisition of the Shares.

          (i)  APPLICABLE LAW. This Agreement shall be construed and enforced in
accordance with the laws of The Commonwealth of Massachusetts, without regard to
its principles of conflicts of laws. Purchaser consents to jurisdiction and
venue in any state or federal court in The Commonwealth of Massachusetts for the
purposes of any action relating to or arising out of this Agreement or any
breach or alleged breach hereof and to service of process in any such action by
certified or registered mail, return receipt requested.

          (j)  DISPOSITION OF SHARES; PURCHASE BY NOMINEE OR DESIGNEE. Any
Shares that the Company elects to purchase hereunder may be disposed of by it in
such manner as it deems appropriate with or without restrictions on the transfer
thereof, and the Company may require their transfer to a nominee or designee as
part of any purchase of the Shares from Purchaser.

          (k)  WITHHOLDING TAXES. Purchaser acknowledges and agrees that the
Company has the right to deduct from payments of any kind otherwise due to
Purchaser any federal, state or local taxes of any kind required by law to be
withheld with respect to the purchase of the Shares by Purchaser.

                                        8
<Page>

     IN WITNESS WHEREOF, the parties hereto have executed this Restricted Stock
purchase Agreement as of the date first above written.

                              MIMEON, INC.

                              By:  /s/ Ganesh Venkataraman
                                 -----------------------------
                              Name:
                              Title:

                              /s/  Peter Barton Hutt
                              --------------------------------
                              Peter Barton Hutt

                                        9

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