Document:

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                                                                   Exhibit 10.22

March 11, 2005

Mr. Robert J. Terifay
[ADDRESS]

Dear Bob:

On behalf of Synta Pharmaceuticals, I am pleased to offer you the position of
Senior Vice President, Commercial Development and Strategy reporting to Safi
Bachall for Synta Pharmaceuticals Corp. (hereinafter "Synta Pharmaceuticals" or
the "Company").

1. EFFECTIVE DATE: The effective date of your employment will be April 4, 2005.

2. COMPENSATION: Your initial base salary will be $270,000 annually; payable at
a semi-monthly rate of $11,250, from which all applicable taxes and other
customary employment-related deductions will be taken.

Subject to the approval of the Company's Board of Directors, you will be granted
an incentive stock option to purchase 300,000 shares of the Company's common
stock pursuant to the terms of the Synta Pharmaceuticals Corp. 2001 Stock Plan
(the "Plan") and formal stock option agreement. All stock option grants shall be
priced at the fair market value on the grant date and are subject to a vesting
schedule over four years (25% vest after the first year and the remainder in
equal portions quarterly over the next three years.)

For the first annual performance review following your hire date, all
pay-for-performance compensation (such as merit increases and annual stock
option grants) will be pro-rated to reflect your start date.

3. BENEFITS: As a full-time employee, you will be eligible to participate in
certain Company-sponsored benefit plans to the same extent as, and subject to
the same terms, conditions and limitations applicable to other employees of the
Company of similar rank and tenure. All benefits may be changed or modified from
time to time at the Company's sole discretion.

4. EMPLOYMENT PERIOD: Your employment with the Company will be at-will, meaning
that you will not be obligated to remain employed by the Company for any
specified period of time; likewise, the Company will not be obligated to
continue your employment for any specific period and may terminate your
employment at any time, with or without cause.

5. CONTINGENCIES: Our employment offer to you is contingent upon (1) your
execution of the standard form of Non-Competition, Confidentiality and
Inventions Agreement (a copy of which is attached hereto as EXHIBIT A); (2) your
ability, as required under federal law, to establish your employment eligibility
as a U.S. citizen, a lawful permanent resident of the U.S. or an individual
specifically authorized for employment by the Immigration and Naturalization
Service; and (3) completion of a satisfactory background check. If any of the
foregoing conditions are not met,

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this employment offer shall be null and void.

6. JURISDICTION AND WAIVER: In the case of any dispute, this offer of employment
shall be interpreted under the laws of the Commonwealth of Massachusetts. By
accepting this offer of employment, you agree that any action, demand, claim or
counterclaim in connection with any aspect of your employment with the Company,
or any separation of employment (whether voluntary or involuntary) from the
Company, shall be resolved in a court of competent jurisdiction in Massachusetts
by a judge alone, and you knowingly waive and forever renounce your right to a
trial before a civil jury.

7. MEDICAL SURVEILLANCE: As part of Synta's medical surveillance program, all
laboratory employees working with hazardous chemical, infectious agents, radio
labeled materials or animals are required to have an initial physical provided
by Mount Auburn Hospital. An employee may refuse an exam by signing a release.
If you want to decline from having the initial physical, please notify Human
Resources on your first day at New Employee Orientation. Your initial
surveillance examination will be scheduled to take place during the first 10
days of your employment.

8. ORIENTATION: On your first day of employment, please arrive at 9:00am for
benefits enrollment with Human Resources.

Bob, we are very enthusiastic about the prospect of your joining us as a Synta
Pharmaceuticals employee. Please indicate your acceptance of the foregoing by
signing one enclosed copy of this letter and returning it to Human Resources
within seven days of the date of this letter. After that date, this offer will
lapse. If you need additional time to respond to this offer, please let us know
immediately.

Sincerely,

SYNTA PHARMACEUTICALS CORP.

/s/ Stephen M. Gansler
--------------------------------
Stephen M. Gansler
Vice President of Human Resources

Agreed to and accepted:

Name: /s/ Robert J. Terifay          Date:    March 16, 2005
      ------------------------             -------------------------------

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                                                                       EXHIBIT A

                           Synta Pharmaceuticals Corp.
                               45 Hartwell Avenue
                               Lexington, MA 02421

March 11, 2005

Mr. Robert J. Terifay
[ADDRESS]

Dear Bob:

     This letter is to confirm our understanding with respect to (i) your
agreement not to compete with Synta Pharmaceuticals Corp. or its subsidiaries or
affiliates (collectively, the "Company") and (ii) your agreement to protect and
preserve information and property which is confidential and proprietary to the
Company (the terms and conditions agreed to in this letter shall hereinafter be
referred to as the "Agreement"). You hereby acknowledge and agree that you are
an "at-will" employee and that no provision of this Agreement shall be construed
to create an express or implied employment contract, or a promise of employment
for a specific period of time, and the Company expressly reserves the right to
end your employment at any time, with or without notice or cause.

     In consideration of your employment by the Company, the mutual promises and
covenants contained in this Agreement, and for other good and valuable
consideration, the receipt and sufficiency of which are hereby mutually
acknowledged, we have agreed as follows:

     1. PROHIBITED COMPETITION AND SOLICITATION.

          (a) CERTAIN ACKNOWLEDGMENTS AND AGREEMENTS.

               (i)     We have discussed, and you recognize and acknowledge the
competitive and proprietary aspects of the business of the Company.

               (ii)    You will devote your full time and efforts to the
business of the Company and, during the period of your employment with the
Company (the "Term") and for a period of twelve (12) months following
termination of your employment (whether such termination is voluntary or
involuntary), shall not participate, directly or indirectly, in any capacity, in
any business which is competitive with the Company without the prior written
consent of the Company. You acknowledge and agree that a business will be deemed
competitive with the Company if it conducts research, performs any of the
services or manufactures or sells any of the products provided or offered by the
Company or if it performs any other services and/or engages in the production,
manufacture, distribution or sale of any product that may be purchased in lieu
of purchasing services performed or products produced, manufactured, distributed
or sold by the Company within the Field of Interest (as defined below) at any
time during the period of your employment with the Company.

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               (iii)   You further acknowledge and agree that, during the course
of your employment with the Company, the Company will furnish, disclose or make
available to you confidential and proprietary information related to the
Company's business and that the Company may provide you with unique and
specialized training. You also acknowledge that such confidential information
and such training have been developed and will be developed by the Company
through the expenditure by the Company of substantial time, effort and money and
that all such confidential information and training could be used by you to
compete with the Company.

          (b) NON-SOLICITATION. During the Term and for a period of twelve (12)
months following termination of your employment, whether such termination is
voluntary or involuntary, you shall not, without the prior written consent of
the Company:

               (i)     either individually or on behalf of or through any third
party, solicit, divert or appropriate or attempt to solicit, divert or
appropriate, any customer of the Company with which you had any contact at any
time during the Term, located within the Restricted Territory with the effect or
intention of reducing or limiting the amount of business the customer does with
the Company; or

               (ii)    either individually or on behalf of or through any third
party, directly or indirectly, solicit, entice or persuade or attempt to
solicit, entice or persuade any employees of or consultants to the Company
(other than your spouse), who have been employees or consultants of the Company
at any time during the Term, or who are employees at the time of the
solicitation, to leave the services of the Company.

          (c) FIELD OF INTEREST. As used herein, the term "Field of Interest"
means the research of, and/or the development, manufacture and sale of, any
therapeutic or diagnostic product that is developed, manufactured or sold by the
Company at any time during the Term, as documented in the bi-weekly scientific
project reports or other scientific planning documents of the company (the
"Scientific Reports") prepared by the Company during the Term. You hereby
acknowledge and agree that the Field of Interest shall be assessed for purposes
of this Agreement as of the date on which your employment with the Company
terminates, which assessment shall include, without limitation, a review of the
applicable Scientific Reports.

          (d) REASONABLENESS OF RESTRICTIONS. You further acknowledge and agree
that (i) the activities which are prohibited by this Section 1 are narrow and
reasonable in relation to the skills which represent your principal salable
asset both to the Company and to your other prospective employers, and (ii)
given the global nature of the Company's business, including its need to market
its services and sell its products in a large geographic area in order to have a
sufficient customer base to make the Company's business profitable, the
geographic, length of time and substantive scope of the provisions of this
Section 1 are reasonable, legitimate and fair to you.

          (e) SURVIVAL OF ACKNOWLEDGMENTS AND AGREEMENTS. Except as expressly
set forth hereunder, your acknowledgments and agreements set forth in this
Section 1 shall survive the termination of your employment with the Company for
the periods set forth above.

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     2. PROTECTED INFORMATION.

          (a) CONFIDENTIALITY OBLIGATIONS. You shall at all times, both during
the Term and thereafter, maintain in confidence and shall not, without the prior
written consent of the Company, use, except in the course of performance of your
duties for the Company, disclose or give to others any Confidential Information
of the Company. As used herein, the term "Confidential Information" shall mean
any information which is disclosed to or developed by you during the course of
performing services for, or receiving training from, the Company, and is not
generally available to the public, including but not limited to confidential
information concerning business plans, customers, future customers, suppliers,
licensors, licensees, partners, investors, affiliates or others, training
methods and materials, financial information, sales prospects, client lists,
Company Inventions (as defined in Section 3), or any other scientific,
technical, trade or business secret or confidential or proprietary information
of the Company or of any third party provided to you during the Term. In the
event anyone not employed or otherwise engaged by the Company seeks information
from you in regard to any such Confidential Information or any other secret or
confidential work of the Company, or concerning any fact or circumstance
relating thereto, you will promptly notify the chief executive officer of the
Company.

          (b) LIMITED EXCEPTIONS. The restrictions in Section 2(a) hereof shall
not apply to information that, as can be established by competent written
records: (i) was publicly known at the time of the Company's communication
thereof to you; (ii) becomes publicly known through no fault of yours subsequent
to the time of the Company's communication thereof to you; (iii) was in your
possession free of any obligation of confidence at the time of the Company's
communication thereof to you; or (iv) is developed by you independently of and
without reference to or use of any of the Company's Confidential Information. In
the event that you are required by law, regulation or court order to disclose
any of the Company's Confidential Information, you shall (i) first notify the
Company of such disclosure requirement and (ii) furnish only that portion of the
Confidential Information that is legally required and will exercise all
reasonable efforts to obtain reliable assurances that confidential treatment
will be accorded the Confidential Information.

     3. OWNERSHIP OF INTELLECTUAL PROPERTY IDEAS.

          (a) PROPERTY OF THE COMPANY. As used in this Agreement, the term
"Inventions" shall mean all ideas, discoveries, creations, manuscripts and
properties, innovations, improvements, know-how, inventions, designs,
developments, apparatus, techniques, methods, biological processes, cell lines,
laboratory notebooks and formulae, whether patentable, copyrightable or not,
including all rights to obtain, register, perfect and enforce any of the
foregoing. You hereby agree that any Inventions which you may conceive, reduce
to practice or develop during the Term in connection with the business
activities of the Company or otherwise within the Field of Interest, alone or in
conjunction with any other party, whether during or out of regular business
hours, and whether at the request or upon the suggestion of the Company, or
otherwise (collectively, the "Company Inventions"), shall be the sole and
exclusive property of the Company. You hereby assign to the Company all of your
right, title and interest in and to all

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such Company Inventions and hereby agree that you shall not publish any of the
Company Inventions without the prior written consent of the Company.

          (b) COOPERATION. During the Term, you agree that, without further
compensation, you will disclose promptly to the Company in writing, all Company
Inventions you conceive, reduce to practice or develop during the Term (or, if
based on or related to any Confidential Information of the Company obtained by
you during the Term, within one (1) year after the termination of your
employment). You further agree that you will fully cooperate with the Company,
its attorneys and agents in the preparation and filing of all papers and other
documents as may be reasonably required to perfect the Company's rights in and
to any of such Company Inventions, including, but not limited to, joining in any
proceeding to obtain patents, copyrights, trademarks or other legal rights of
the United States and of any and all other countries on such Company Inventions;
PROVIDED, THAT, the Company will bear the expense of such proceedings (including
all of your reasonable expenses). You further agree that any patent or other
legal right covering any Company Invention so issued to you, personally, shall
be assigned by you to the Company without charge by you. You further acknowledge
that all original works of authorship made by you, whether alone or jointly with
others within the scope of your employment and which are protectable by
copyright are "works made for hire" within the meaning of the United States
Copyright Act, 17 U.S.C. Section 101, as amended, the copyright of which shall
be owned solely, completely and exclusively by the Company. If any Company
Invention is considered to be work not included in the categories of work
covered by the United States Copyright Act, 17 U.S.C. Section 101, as amended,
such work shall be owned solely by, or hereby assigned or transferred completely
and exclusively to, the Company. If the Company is unable because of your mental
or physical incapacity or for any other reason, after reasonable effort, to
secure your signature on any document or documents needed to obtain or enforce
any patent, copyright, trademarks or any other rights covering Inventions or
original works of authorship assigned by you to the Company as required above,
you hereby irrevocably designate and appoint the Company and its duly authorized
officers and agents as your agent and attorney-in-fact, to act for and in your
behalf and stead to execute and file any application or assignment and to do all
other lawfully permitted acts to further the prosecution and issuance to the
Company of patents, copyright registrations, trademark registrations or similar
protections covering the Inventions with the same legal force and effect as if
executed by you.

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     4.   PROVISIONS NECESSARY AND REASONABLE/BREACH/ATTORNEYS' FEES. You agree
that (i) the provisions of Sections 1, 2 and 3 of this Agreement are necessary
and reasonable to protect the Company's Confidential Information, Company
Inventions, and goodwill and (ii) in the event of any breach of any of the
covenants set forth herein, the Company would suffer substantial irreparable
harm and would not have an adequate remedy at law for such breach. In
recognition of the foregoing, you agree that in the event of a breach or
threatened breach of any of these covenants, in addition to such other remedies
as the Company may have at law, without posting any bond or security, the
Company shall be entitled to seek and obtain equitable relief, in the form of
specific performance, and/or temporary, preliminary or permanent injunctive
relief, or any other equitable remedy which then may be available. The seeking
of such injunction or order shall not affect the Company's right to seek and
obtain damages or other equitable relief on account of any such actual or
threatened breach. In the event the Company takes any court action with respect
to your breach or threatened breach of this Agreement, and prevails in such
action, you shall be obligated to reimburse the Company for its reasonable
attorneys' fees and costs incurred in such action.

     5.   DISCLOSURE TO FUTURE EMPLOYERS. You agree that you will provide, and
that the Company may similarly provide in its discretion, a copy of the
covenants contained in Sections 1, 2 and 3 of this Agreement to any business or
enterprise which you may directly, or indirectly, own, manage, operate, finance,
join, control or in which you participate in the ownership, management,
operation, financing, or control, or with which you may be connected as an
officer, director, employee, partner, principal, agent, representative,
consultant or otherwise.

     6.   REPRESENTATIONS REGARDING PRIOR WORK AND LEGAL OBLIGATIONS.

          (a) You represent that you have no agreement or other legal obligation
with any prior employer or any other person or entity that restricts your
ability to engage in employment discussions with, employment with, or to perform
any function for, the Company.

          (b) You represent that you have been advised by the Company that at no
time should you divulge to or use for the benefit of the Company, any trade
secret or confidential or proprietary information of any previous employer. You
acknowledge that you have not divulged or used any such information for the
benefit of the Company.

          (c) You acknowledge that the Company is basing important business
decisions on these representations, and affirm that all of the statements
included herein are true.

     7.   RECORDS. Upon termination of your employment relationship with the
Company, you shall deliver to the Company any property of the Company which may
be in your possession including products, materials, memoranda, notes, records,
reports, or other documents or photocopies of the same.

     8.   NO CONFLICTING AGREEMENTS. You hereby represent and warrant that you
have no commitments or obligations inconsistent with this Agreement and you
hereby agree to indemnify

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and hold the Company harmless against loss, damage, liability or expense arising
from any claim based upon circumstances alleged to be inconsistent with such
representation and warranty.

     9.   GENERAL.

          (a) NOTICES. All notices, requests, consents and other communications
hereunder shall be in writing, shall be addressed to the receiving party's
address set forth below or to such other address as a party may designate by
notice hereunder, and shall be either (i) delivered by hand, (ii) made by telex,
telecopy or facsimile transmission with confirmed receipt thereof (and with a
copy of such telex, telecopy or facsimile, together with a copy of the
confirmation sent to the recipient by regular U.S. mail on the next business
day), (iii) sent by overnight courier, or (iv) sent by registered mail, return
receipt requested, postage prepaid.

If to the Company:   Synta Pharmaceuticals Corp.
                     45 Hartwell Avenue
                     Lexington, MA  02421
                     Attn: Chief Executive Officer

If to you:           To the address set forth on the signature page of
                     this Agreement.

     All notices, requests, consents and other communications hereunder shall be
deemed to have been given either (i) if by hand, at the time of the delivery
thereof to the receiving party at the address of such party set forth above,
(ii) if made by telex, telecopy or facsimile transmission, at the time that
receipt thereof has been acknowledged by electronic confirmation or otherwise,
(iii) if sent by overnight courier, on the next business day following the day
such notice is delivered to the courier service, or (iv) if sent by registered
mail, on the fifth business day following the day such mailing is made.

          (b) ENTIRE AGREEMENT. This Agreement embodies the entire agreement and
understanding between the parties hereto with respect to the subject matter
hereof and supersedes all prior oral or written agreements and understandings
relating to the subject matter hereof. No statement, representation, warranty,
covenant or agreement of any kind not expressly set forth in this Agreement
shall affect, or be used to interpret, change or restrict, the express terms and
provisions of this Agreement.

          (c) MODIFICATIONS AND AMENDMENTS. The terms and provisions of this
Agreement may be modified or amended only by written agreement executed by the
parties hereto.

          (d) WAIVERS AND CONSENTS. The terms and provisions of this Agreement
may be waived, or consent for the departure therefrom granted, only by written
document executed by the party entitled to the benefits of such terms or
provisions. No such waiver or consent shall be deemed to be or shall constitute
a waiver or consent with respect to any other terms or provisions of this
Agreement, whether or not similar. Each such waiver or consent shall be
effective only in the specific instance and for the purpose for which it was
given, and shall not constitute a continuing waiver or consent.

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          (e) ASSIGNMENT. The Company may assign its rights and obligations
hereunder to any person or entity that succeeds to all or substantially all of
the Company's business or that aspect of the Company's business in which you are
principally involved. Your rights and obligations under this Agreement may not
be assigned by you without the prior written consent of the Company.

          (f) BENEFIT. All statements, representations, warranties, covenants
and agreements in this Agreement shall be binding on the parties hereto and
shall inure to the benefit of the respective successors and permitted assigns of
each party hereto. Nothing in this Agreement shall be construed to create any
rights or obligations except among the parties hereto, and no person or entity
shall be regarded as a third-party beneficiary of this Agreement.

          (g) GOVERNING LAW. This Agreement and the rights and obligations of
the parties hereunder shall be construed in accordance with and governed by the
laws of the Commonwealth of Massachusetts, without giving effect to the conflict
of laws principles thereof.

          (h) JURISDICTION. Any legal action or proceeding with respect to this
Agreement may be brought in the courts of the Commonwealth of Massachusetts or
of the United States of America. By execution and delivery of this Agreement,
each of the parties hereto accepts for itself and in respect of its property,
generally and unconditionally, the jurisdiction of the aforesaid courts.

          (i) SEVERABILITY. The parties intend this Agreement to be enforced as
written. However, (i) if any portion or provision of this Agreement shall to any
extent be declared illegal or unenforceable by a duly authorized court having
jurisdiction, then the remainder of this Agreement, or the application of such
portion or provision in circumstances other than those as to which it is so
declared illegal or unenforceable, shall not be affected thereby, and each
portion and provision of this Agreement shall be valid and enforceable to the
fullest extent permitted by law and (ii) if any provision, or part thereof, is
held to be unenforceable because of the duration of such provision or the
geographic area covered thereby, the Company and you agree that the court making
such determination shall have the power to reduce the duration and/or geographic
area of such provision, and/or to delete specific words and phrases
("blue-penciling"), and in its reduced or blue-penciled form such provision
shall then be enforceable and shall be enforced.

          (j) HEADINGS AND CAPTIONS. The headings and captions of the various
subdivisions of this Agreement are for convenience of reference only and shall
in no way modify, or affect the meaning or construction of any of the terms or
provisions hereof.

          (k) NO WAIVER OF RIGHTS, POWERS AND REMEDIES. No failure or delay by a
party hereto in exercising any right, power or remedy under this Agreement, and
no course of dealing between the parties hereto, shall operate as a waiver of
any such right, power or remedy of the party. No single or partial exercise of
any right, power or remedy under this Agreement by a party hereto, nor any
abandonment or discontinuance of steps to enforce any such right, power or
remedy, shall preclude such party from any other or further exercise thereof or
the exercise of any other right, power or remedy hereunder. The election of any
remedy by a party hereto shall

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not constitute a waiver of the right of such party to pursue other available
remedies. No notice to or demand on a party not expressly required under this
Agreement shall entitle the party receiving such notice or demand to any other
or further notice or demand in similar or other circumstances or constitute a
waiver of the rights of the party giving such notice or demand to any other or
further action in any circumstances without such notice or demand.

          (l) COUNTERPARTS. This Agreement may be executed in one or more
counterparts, and by different parties hereto on separate counterparts, each of
which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

     If the foregoing accurately sets forth our agreement, please so indicate by
signing and returning to us the enclosed copy of this letter.

                                            Very truly yours,

                                            SYNTA PHARMACEUTICALS CORP.

                                       By:      /s/ Stephen M. Gansler
                                            ---------------------------------
                                            Stephen M. Gansler
                                            Vice President of Human Resources

Agreed to and accepted:

         /s/ Robert J. Terifay
-----------------------------------
Name:

Robert J. Terifay
-----------------------------------

[ADDRESS]
         --------------------------
Address:

Date:    March 16, 2005
     ------------------------------

                                      A-10<Page>

                                                                   Exhibit 10.23

                            INDEMNIFICATION AGREEMENT

     THIS AGREEMENT is made and entered into this ___ day of _______________,
20__ by and between SYNTA PHARMACEUTICALS CORP., a Delaware corporation (the
"CORPORATION"), and _______________ ("AGENT").

                                    RECITALS

     WHEREAS, Agent performs a valuable service to the Corporation in his
capacity as [a director/an officer] of the Corporation;

     WHEREAS, the Corporation has adopted provisions in its Certificate of
Incoorporation (the "Charter") and bylaws (the "BYLAWS") providing for the
indemnification of the directors, officers, employees and other agents of the
Corporation, including persons serving at the request of the Corporation in such
capacities with other corporations or enterprises, as authorized by the Delaware
General Corporation Law, as amended (the "CODE");

     WHEREAS, the Charter, the Bylaws and the Code, by their non-exclusive
nature, permit contracts between the Corporation and its agents, officers,
employees and other agents with respect to indemnification of such persons; and

     WHEREAS, in order to induce Agent to serve as [a director/an officer] of
the Corporation, the Corporation has determined and agreed to enter into this
Agreement with Agent.

     NOW, THEREFORE, in consideration of Agent's service as [a director/an
officer] of the Corporation after the date hereof, the parties hereto agree as
follows:

                                    AGREEMENT

     1.   SERVICES TO THE CORPORATION. Agent will serve, at the will of the
Corporation or under separate contract, if any such contract exists, as [a
director/an officer] of the Corporation or as a director, officer or other
fiduciary of an affiliate of the Corporation (including any employee benefit
plan of the Corporation) faithfully and to the best of his ability so long as he
[is duly elected and qualified in accordance with the provisions of the Bylaws
or other applicable charter documents/is a duly appointed officer] of the
Corporation or such affiliate; PROVIDED, HOWEVER, that Agent may at any time and
for any reason resign from such position (subject to any contractual obligation
that Agent may have assumed apart from this Agreement) and that the Corporation
or any affiliate shall have no obligation under this Agreement to continue Agent
in any such position.

     2.   INDEMNITY OF AGENT. The Corporation hereby agrees to hold harmless and
indemnify Agent to the fullest extent authorized or permitted by the provisions
of the Charter, the Bylaws and the Code, as the same may be amended from time to
time (but, only to the extent that such amendment permits the Corporation to
provide broader indemnification rights than the Charter, the Bylaws or the Code
permitted prior to adoption of such amendment).

<Page>

     3.   ADDITIONAL INDEMNITY. In addition to and not in limitation of the
indemnification otherwise provided for herein, and subject only to the
exclusions set forth in Section 4 hereof, the Corporation hereby further agrees
to hold harmless and indemnify Agent:

          (a)  against any and all expenses (including attorneys' fees), witness
fees, damages, judgments, fines and amounts paid in settlement and any other
amounts that Agent becomes legally obligated to pay because of any claim or
claims made against or by him in connection with any threatened, pending or
completed action, suit or proceeding, whether civil, criminal, arbitrational,
administrative or investigative (including an action by or in the right of the
Corporation) to which Agent is, was or at any time becomes a party or a witness,
or is threatened to be made a party or a witness, by reason of the fact that
Agent is, was or at any time becomes a director, officer, employee or other
agent of Corporation, or is or was serving or at any time serves at the request
of the Corporation as a director, officer, employee or other agent of another
corporation, partnership, joint venture, trust, employee benefit plan or other
enterprise; and

          (b)  otherwise to the fullest extent as may be provided to Agent by
the Corporation under the non-exclusivity provisions of the Code, the Charter
and the Bylaws.

     4.   LIMITATIONS ON ADDITIONAL INDEMNITY. No indemnity pursuant to Section
3 hereof shall be paid by the Corporation:

          (a)  on account of any claim against Agent for an accounting of
profits made from the purchase or sale by Agent of securities of the Corporation
pursuant to the provisions of Section 16(b) of the Securities Exchange Act of
1934 and amendments thereto or similar provisions of any federal, state or local
statutory law;

          (b)  on account of Agent's conduct that is established by a final
judgment as knowingly fraudulent or deliberately dishonest or that constituted
willful misconduct;

          (c)  on account of Agent's conduct that is established by a final
judgment as constituting a breach of Agent's duty of loyalty to the Corporation
or resulting in any personal profit or advantage to which Agent was not legally
entitled;

          (d)  for which payment is actually made to Agent under a valid and
collectible insurance policy or under a valid and enforceable indemnity clause,
bylaw or agreement, except in respect of any excess beyond payment under such
insurance, clause, bylaw or agreement;

          (e)  if indemnification is not lawful (and, in this respect, both the
Corporation and Agent have been advised that the Securities and Exchange
Commission believes that indemnification for liabilities arising under the
federal securities laws is against public policy and is, therefore,
unenforceable and that claims for indemnification should be submitted to
appropriate courts for adjudication); or

          (f)  in connection with any proceeding (or part thereof) initiated by
Agent, or any proceeding by Agent against the Corporation or its directors,
officers, employees or other agents, unless (i) such indemnification is
expressly required to be made by law, (ii) the proceeding was authorized by the
Board of Directors of the Corporation, (iii) such

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indemnification is provided by the Corporation, in its sole discretion, pursuant
to the powers vested in the Corporation under the Code, or (iv) the proceeding
is initiated pursuant to Section 9 hereof.

     5.   CONTINUATION OF INDEMNITY. All agreements and obligations of the
Corporation contained herein shall continue during the period Agent is a
director, officer, employee or other agent of the Corporation (or is or was
serving at the request of the Corporation as a director, officer, employee or
other agent of another corporation, partnership, joint venture, trust, employee
benefit plan or other enterprise) and shall continue thereafter so long as Agent
shall be subject to any possible claim or threatened, pending or completed
action, suit or proceeding, whether civil, criminal, arbitrational,
administrative or investigative, by reason of the fact that Agent was serving in
the capacity referred to herein.

     6.   PARTIAL INDEMNIFICATION. Agent shall be entitled under this Agreement
to indemnification by the Corporation for a portion of the expenses (including
attorneys' fees), witness fees, damages, judgments, fines and amounts paid in
settlement and any other amounts that Agent becomes legally obligated to pay in
connection with any action, suit or proceeding referred to in Section 3 hereof
even if not entitled hereunder to indemnification for the total amount thereof,
and the Corporation shall indemnify Agent for the portion thereof to which Agent
is entitled.

     7.   NOTIFICATION AND DEFENSE OF CLAIM. Not later than thirty (30) days
after Agent becomes aware, by written or other overt communication, of any
pending or threatened litigation, claim or assessment, Agent will, if a claim in
respect thereof is to be made against the Corporation under this Agreement,
notify the Corporation of such pending or threatened litigation, claim or
assessment; but the omission so to notify the Corporation will not relieve it
from any liability which it may have to Agent otherwise than under this
Agreement. With respect to any such pending or threatened litigation, claim or
assessment as to which Agent notifies the Corporation of the commencement
thereof:

          (a)  the Corporation will be entitled to participate therein at its
own expense;

          (b)  except as otherwise provided below, the Corporation may, at its
option and jointly with any other indemnifying party similarly notified and
electing to assume such defense, assume the defense thereof, with counsel
reasonably satisfactory to Agent. After notice from the Corporation to Agent of
its election to assume the defense thereof, the Corporation will not be liable
to Agent under this Agreement for any legal or other expenses subsequently
incurred by Agent in connection with the defense thereof except for reasonable
costs of investigation or otherwise as provided below. Agent shall have the
right to employ separate counsel in such action, suit or proceeding but the fees
and expenses of such counsel incurred after notice from the Corporation of its
assumption of the defense thereof shall be at the expense of Agent unless (i)
the employment of counsel by Agent has been authorized by the Corporation, (ii)
Agent shall have reasonably concluded, and so notified the Corporation, that
there is an actual conflict of interest between the Corporation and Agent in the
conduct of the defense of such action or (iii) the Corporation shall not in fact
have employed counsel to assume the defense of such action, in each of which
cases the fees and expenses of Agent's separate counsel shall be at the expense
of the Corporation. The Corporation shall not be entitled to assume the defense
of

                                        3
<Page>

any action, suit or proceeding brought by or on behalf of the Corporation or as
to which Agent shall have made the conclusion provided for in clause (ii) above;
and

          (c)  the Corporation shall not be liable to indemnify Agent under this
Agreement for any amounts paid in settlement of any action or claim effected
without its written consent, which shall not be unreasonably withheld. The
Corporation shall be permitted to settle any action or claim except that it
shall not settle any action or claim in any manner which would impose any
penalty or limitation on Agent without Agent's written consent, which may be
given or withheld in Agent's sole discretion.

     8.   EXPENSES. The Corporation shall advance, prior to the final
disposition of any proceeding, promptly following request therefor, all expenses
incurred by Agent in connection with such proceeding upon receipt of an
undertaking by or on behalf of Agent to repay said amounts if it shall be
determined ultimately that Agent is not entitled to be indemnified under the
provisions of this Agreement, the Charter, the Bylaws, the Code or otherwise.

     9.   ENFORCEMENT. Any right to indemnification or advances granted by this
Agreement to Agent shall be enforceable by or on behalf of Agent in any court of
competent jurisdiction if (i) the claim for indemnification or advances is
denied, in whole or in part, or (ii) no disposition of such claim is made within
ninety (90) days of request therefor. Agent, in such enforcement action, if
successful in whole or in part, shall be entitled to be paid also the expense of
prosecuting his claim. It shall be a defense to any action for which a claim for
indemnification is made under Section 3 hereof (other than an action brought to
enforce a claim for expenses pursuant to Section 8 hereof, PROVIDED that the
required undertaking has been tendered to the Corporation) that Agent is not
entitled to indemnification because of the limitations set forth in Section 4
hereof. Neither the failure of the Corporation (including its Board of Directors
or its stockholders) to have made a determination prior to the commencement of
such enforcement action that indemnification of Agent is proper in the
circumstances, nor an actual determination by the Corporation (including its
Board of Directors or its stockholders) that such indemnification is improper
shall be a defense to the action or create a presumption that Agent is not
entitled to indemnification under this Agreement or otherwise.

     10.  SUBROGATION. In the event of payment under this Agreement, the
Corporation shall be subrogated to the extent of such payment to all of the
rights of recovery of Agent, who shall execute all documents required and shall
do all acts that may be necessary to secure such rights and to enable the
Corporation effectively to bring suit to enforce such rights.

     11.  NON-EXCLUSIVITY OF RIGHTS. The rights conferred on Agent by this
Agreement shall not be exclusive of any other right which Agent may have or
hereafter acquire under any statute, provision of the Corporation's Certificate
of Incorporation or Bylaws, agreement, vote of stockholders or directors, or
otherwise, both as to action in his official capacity and as to action in
another capacity while holding office.

     12.  SURVIVAL OF RIGHTS.

          (a)  The rights conferred on Agent by this Agreement shall continue
after Agent has ceased to be a director, officer, employee or other agent of the
Corporation or to serve

                                        4
<Page>

at the request of the Corporation as a director, officer, employee or other
agent of another corporation, partnership, joint venture, trust, employee
benefit plan or other enterprise, and shall inure to the benefit of Agent's
heirs, executors and administrators.

          (b)  The Corporation shall require any successor (whether direct or
indirect, by purchase, merger, consolidation or otherwise) to all or
substantially all of the business or assets of the Corporation, expressly to
assume and agree to perform this Agreement in the same manner and to the same
extent that the Corporation would be required to perform if no such succession
had taken place.

     13.  SEPARABILITY. Each of the provisions of this Agreement is a separate
and distinct agreement and independent of the others, so that if any provision
hereof shall be held to be invalid or unenforceable for any reason, such
invalidity or unenforceability shall not affect the validity or enforceability
of the other provisions hereof. Furthermore, if this Agreement shall be
invalidated in its entirety on any ground, then the Corporation shall
nevertheless indemnify Agent to the fullest extent provided by the Charter, the
Bylaws, the Code or any other applicable law.

     14.  GOVERNING LAW. This Agreement shall be interpreted and enforced in
accordance with the laws of the State of Delaware.

     15.  AMENDMENT AND TERMINATION. No amendment, modification, termination or
cancellation of this Agreement shall be effective unless in writing signed by
both parties hereto.

     16.  IDENTICAL COUNTERPARTS. This Agreement may be executed in one or more
counterparts, each of which shall for all purposes be deemed to be an original
but all of which together shall constitute but one and the same Agreement. Only
one such counterpart need be produced to evidence the existence of this
Agreement.

     17.  HEADINGS. The headings of the sections of this Agreement are inserted
for convenience only and shall not be deemed to constitute part of this
Agreement or to affect the construction hereof.

     18.  NOTICES. All notices, requests, demands and other communications
hereunder shall be in writing and shall be deemed to have been duly given (i)
upon delivery if delivered by hand to the party to whom such communication was
directed or (ii) upon the third business day after the date on which such
communication was mailed if mailed by certified or registered mail with postage
prepaid:

          (a)  If to Agent, at the address indicated on the signature page
hereof.

          (b)  If to the Corporation, to:

               Synta Pharmaceuticals Corp.
               45 Hartwell Avenue
               Lexington, MA 02421
               Attention: Chief Executive Officer

                                        5
<Page>

     or to such other address as may have been furnished to Agent by the
Corporation.

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement on and
as of the day and year first above written.

                                          SYNTA PHARMACEUTICALS CORP.

                                          By:
                                             --------------------------
                                          Name:
                                          Title:

                                          AGENT

                                          -----------------------------
                                          [Name]

                                          Address:

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

                                        6

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