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Exhibit 10.3

SEVERANCE AND CHANGE OF CONTROL AGREEMENT

        This Agreement (the "Agreement") is entered into as of the 6th day of
August, 2008 by and between Synta Pharmaceuticals Corp., a Delaware corporation
(the "Company"), and Michael Bailey (the "Executive").

        WHEREAS Executive is employed by the Company, and because of such
employment, possesses detailed knowledge of the Company and its business and
operations;

        WHEREAS Executive's continued service to the Company is very important
to the future success of the Company;

        WHEREAS the Company desires to enter into this Agreement to provide
Executive with certain financial protection in the event that Executive's
employment terminates under certain circumstances, and thereby to provide
Executive with incentives to remain with the Company; and

        WHEREAS the Board of Directors of the Company (the "Board") acting
through the Compensation Committee has determined that it is in the best
interests of the Company to enter into this Agreement.

        NOW THEREFORE for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the Company and Executive agree as
follows:

1.     Definitions.

        (a)   Cause.    As used herein, "Cause" shall include (and is not
limited to): (i) material misrepresentation with respect to the Company or any
affiliate, parent or subsidiary of the Company; (ii) insubordination;
(iii) substantial malfeasance or nonfeasance of duty; (iv) unauthorized
disclosure of confidential information; (v) Executive's breach of any material
provision of any employment, consulting, advisory, non-disclosure, invention
assignment, non-competition, or similar agreement between Executive and the
Company; or (vi) conduct substantially prejudicial to the business of the
Company or any affiliate, parent or subsidiary of the Company. The Board shall
have sole discretion to determine the existence of "Cause," and its
determination will be conclusive on Executive and the Company; provided that the
Board may delegate its power to act under this paragraph (a) to a committee of
the Board in which case the determination of such committee shall be conclusive.
"Cause" is not limited to events which have occurred prior to the termination of
Executive's service, nor is it necessary that the Board's finding of "Cause"
occur prior to such termination. If the Board determines, subsequent to
Executive's termination of service, that either prior or subsequent to
Executive's termination Executive engaged in conduct which would constitute
"Cause," then Executive shall have no right to any benefit or compensation under
this Agreement.

        (b)   Change of Control.    As used herein, a "Change of Control" shall
mean the occurrence of any of the following events:

(i)Ownership.    Any "Person" (as such term is used in Sections 13(d) and 14(d)
of the Securities Exchange Act of 1934, as amended) becomes the "Beneficial
Owner" (as defined in Rule 13d-3 under said Act), directly or indirectly, of
securities of the Company representing fifty percent (50%) or more of the total
voting power represented by the Company's then outstanding voting securities
(excluding for this purpose any such voting securities held by the Company, or
any affiliate, parent or subsidiary of the Company, or by any employee benefit
plan of the Company) pursuant to a transaction or a series of related
transactions which the Board does not approve; or

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(ii)Merger/Sale of Assets.    (A) A merger or consolidation of the Company
whether or not approved by the Board, other than a merger or consolidation which
would result in the voting securities of the Company outstanding immediately
prior thereto continuing to represent (either by remaining outstanding or by
being converted into voting securities of the surviving entity or the parent of
such corporation) at least fifty percent (50%) of the total voting power
represented by the voting securities of the Company or such surviving entity or
parent of such corporation, as the case may be, outstanding immediately after
such merger or consolidation; (B) or the stockholders of the Company approve an
agreement for the sale or disposition by the Company of all or substantially all
of the Company's assets; or

(iii)Change in Board Composition.    A change in the composition of the Board,
as a result of which fewer than a majority of the directors are Incumbent
Directors. "Incumbent Directors" shall mean directors who either (A) are
directors of the Company as of the date of this Agreement, or (B) are elected,
or nominated for election, to the Board with the affirmative votes of at least a
majority of the Incumbent Directors, or by a committee of the Board made up of
at least a majority of the Incumbent Directors, at the time of such election or
nomination (but shall not include an individual whose election or nomination is
in connection with an actual or threatened proxy contest relating to the
election of directors to the Company).

        (c)   Good Reason.    As used herein, a "Good Reason" shall mean:
(i) Executive, as a condition of remaining an employee of the Company, is
required to change the principal location where Executive renders services to
the Company to a location more than fifty (50) miles from Executive's
then-current location of employment; (ii) there occurs a material adverse change
in Executive's duties, authority, reporting structure (reporting to CEO) or
responsibilities which causes Executive's position with the Company to become of
significantly less responsibility or authority than Executive's position is on
the date hereof; or (iii) there occurs a material reduction in Executive's base
salary from Executive's base salary received on the date hereof, provided that
any notice of termination by Executive for Good Reason shall be given by
Executive within fifteen (15) business days of Executive's becoming aware of the
occurrence of the facts giving rise to such Good Reason. For purposes of this
Agreement, "Good Reason" shall be interpreted in a manner, and limited to the
extent necessary, so that it will not cause adverse tax consequences for either
party with respect to Section 409A of the Internal Revenue Code of 1986, as
amended ("Code Section 409A"), and any successor statute, regulation and
guidance thereto.

        (d)   Base Salary.    As used herein, "Base Salary" shall mean
Executive's annual base salary, excluding reimbursements, bonuses, benefits, and
amounts attributable to stock options and other non-cash compensation.

2.    Severance for Termination by the Company Other than For Cause or by
Executive for Good Reason.    In the event that (i) Executive's employment is
terminated by action of the Company other than for Cause, or (ii) Executive
terminates Executive's employment for Good Reason, then Executive shall receive
the following (subject to Executive's execution of a release of claims as
described in Section 7):

        (a)   Severance Payments.    Continuation of payments in an amount equal
to Executive's then-current Base Salary for a six (6) month period less all
customary and required taxes and employment-related deductions, in accordance
with the Company's normal payroll practices (provided such payments will be made
at least monthly.)

        (b)   Equity Acceleration.    Acceleration of vesting of any and all
outstanding stock option awards that would have vested during the period
commencing on Executive's date of termination through and including the date
that is six (6) months following Executive's date of termination.

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        (c)   COBRA Payments.    Upon completion of the appropriate COBRA(1)
forms, and subject to all the requirements of COBRA, the Company shall continue
Executive's participation in the Company's health and dental insurance plans at
the Company's cost (except for Executive's co-pay, if any, which shall be
deducted from Executive's severance compensation) for the six (6) months
following Executive's date of termination, to the same extent that such
insurance is provided to similarly situated Company executives, provided that
this benefit will cease and the Company will be under no obligation to provide
it if Executive has become eligible for coverage under another employer's group
coverage, and Executive hereby agrees to notify the Company promptly and in
writing should that occur.

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        (1)   "COBRA" is the Consolidated Omnibus Budget Reconciliation Act of
1985, as amended.

        (d)   No Duplication.    In the event that Executive is eligible for the
severance payments and benefits under Section 3 below, Executive shall not be
eligible for and shall not receive any of the severance payments and benefits as
provided in this Section 2.

3.    Change of Control Severance.    In the event that a Change of Control
occurs and within a period of one (1) year following the Change of Control,
either: (i) Executive's employment is terminated other than for Cause, or
(ii) Executive terminates Executive's employment for Good Reason, then Executive
shall receive the following (subject to Executive's execution of a release of
claims, as described in Section 7):

        (a)   Lump Sum Severance Payment.    Within thirty (30) days following
Executive's termination, payment of an amount equal to twelve (12) months of
Executive's then-current Base Salary less all customary and required taxes and
employment-related deductions.

        (b)   Separation Bonus.    Within thirty (30) days following Executive's
termination, payment of a separation bonus in an amount equal to the target
annual bonus to which Executive may have been entitled for the year in which
Executive is terminated, prorated for the portion of the year in which Executive
was employed.

        (c)   Equity Acceleration.    Full acceleration as of the date of
termination of vesting of any and all equity awards outstanding immediately
prior to termination.

        (d)   COBRA Payments.    Upon completion of the appropriate COBRA forms,
and subject to all the requirements of COBRA, the Company shall continue
Executive's participation in the Company's health and dental insurance plans at
the Company's cost (except for Executive's co-pay, if any, which shall be
deducted from Executive's severance compensation) for the twelve (12) months
following Executive's date of termination, to the same extent that such
insurance is provided to similarly situated Company executives, provided that
this benefit will cease and the Company will be under no obligation to provide
it if Executive has become eligible for coverage under another employer's group
coverage, and Executive hereby agrees to notify the Company promptly and in
writing should that occur.

        (e)   No Duplication.    In the event that Executive is eligible for the
severance payments and benefits under Section 2 above, Executive shall not be
eligible for and shall not receive any of the severance payments and benefits as
provided in this Section 3.

4.    No Severance.    In the event that Executive's employment is terminated
for any reason other than those outlined in Sections 2 or 3, then Executive
shall have no right to any of the severance payments and benefits provided under
this Agreement.

5.    Distribution Limitation.    If any payment or benefit Executive would
receive under this Agreement, when combined with any other payment or benefit
Executive receives pursuant to a Change of Control (for purposes of this
section, a "Payment") would: (i) constitute a "parachute payment" within the
meaning of Section 280G of the Internal Revenue Code of 1986, as amended (the
"Code"); and (ii) but for this sentence, be subject to the excise tax imposed by
Section 4999 of the Code (the "Excise Tax"), then such Payment shall be either:
(x) the full amount of such Payment; or (y) such lesser amount (with

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cash payments being reduced before stock option compensation) as would result in
no portion of the Payment being subject to the Excise Tax, whichever of the
foregoing amounts, taking into account the applicable federal, state and local
employments taxes, income taxes, and the Excise Tax, results in Executive's
receipt, on an after-tax basis, of the greater amount of the Payment
notwithstanding that all or some portion of the Payment may be subject to the
Excise Tax.

6.    Timing of Payments.    Notwithstanding any other provision with respect to
the timing of payments under Sections 2 or 3, if, at the time of Executive's
termination, Executive is deemed to be a "specified employee" of the Company
(within the meaning of Code Section 409A(a)(2)(B)(i) and any successor statute,
regulation and guidance thereto ("Code Section 409A")), then limited only to the
extent necessary to comply with the requirements of Code Section 409A, any
payments to which Executive may become entitled under Sections 2 or 3 which are
subject to Code Section 409A (and not otherwise exempt from its application)
will be withheld until the first (1st) business day of the seventh (7th) month
following the termination of Executive's employment, at which time Executive
shall be paid an aggregate amount equal to the accumulated, but unpaid, payments
otherwise due to Executive under the terms of Sections 2 or 3.

7.    Release of Claims.    The Company shall not be obligated to pay Executive
any of the compensation set forth in Sections 2 and 3 unless and until Executive
has executed a timely full and general release of all claims against the Company
and any affiliate, parent or subsidiary, and its and their officers, directors,
employees, and agents, in a form satisfactory to the Company.

8.    No Impact on Employment Status.    This Agreement is not intended to
confer, and shall not be interpreted as conferring, any additional employment
rights on Executive, and has no impact on either party's right to terminate
Executive's employment under contract or applicable law.

9.    Enforceability; Reduction.    If any provision of this Agreement shall be
deemed invalid or unenforceable as written, this Agreement shall be construed,
to the greatest extent possible, or modified, to the extent allowable by law, in
a manner which shall render it valid and enforceable and any limitation on the
scope or duration of any provision necessary to make it valid and enforceable
shall be deemed to be a part thereof. No invalidity or unenforceability of any
provision contained herein shall affect any other portion of this Agreement.

10.   Notices.

        (a)   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, (iii) sent by overnight courier, or
(iv) sent by registered or certified mail, return receipt requested, postage
prepaid.

If to the Company:

President and Chief Executive Officer
Synta Pharmaceuticals Corp.
45 Hartwell Avenue
Lexington, MA 02421

With a copy to:

General Counsel
Synta Pharmaceuticals Corp.
45 Hartwell Avenue
Lexington, MA 02421

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If to Executive:

Michael Bailey
[ADDRESS]

        (b)   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 or certified mail, on the fifth (5th) business day following
the day such mailing is made.

11.    Entire Agreement / No Duplication of Compensation or Benefits.    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
including, but not limited to, any offer letter or employment agreement
previously entered into between the Executive and the Company. 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. The terms of
Sections 2 and 3 above shall replace any agreement, policy or practice which
otherwise would obligate the Company to provide any severance compensation
and/or benefits to Executive, provided that this provision shall not be
construed to otherwise limit Executive's rights to payments or benefits provided
under any pension plan (as defined in Section 3(2) of the Employee Retirement
Income Security Act of 1974, as amended), deferred compensation, stock, stock
option or similar plan sponsored by the Company.

12.    Modifications and Amendments.    The terms and provisions of this
Agreement may be modified or amended only by written agreement executed by all
parties hereto. Any such amendment shall comply with the requirements of Code
Section 409A, if applicable.

13.    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.

14.    Assignment.    The rights and obligations under this Agreement may be
assigned by the Company.

15.    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.

16.    Arbitration.    Any controversy, dispute or claim arising out of or in
connection with this Agreement will be settled by final and binding arbitration
to be conducted in Boston, Massachusetts pursuant to the national rules for the
resolution of employment disputes of the American Arbitration Association then
in effect. The decision or award in any such arbitration will be final and
binding upon the parties, and judgment upon such decision or award may be
entered in any court of competent jurisdiction, or application may be made to
any such court for judicial acceptance of such decision or award and an order of
enforcement. In the event that any procedural matter is not covered by the
aforesaid rules, the procedural law of Massachusetts will govern. Any
disagreement as to whether a particular dispute is arbitrable under this
Agreement shall itself be subject to arbitration in accordance

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with the procedures set forth herein. Notwithstanding the foregoing, any right
or obligation arising out of or concerning any separate contract or agreement
between the parties (including but not limited to any employee, non-competition,
non-solicitation, non-disclosure and invention agreement) shall be decided in
accordance with the dispute resolution mechanism provided for by such contract
or agreement.

17.    Governing Law / Jurisdiction / Service of Process.    This Agreement and
the rights and obligations of the parties hereunder shall be construed in
accordance with and governed by the law of the Commonwealth of Massachusetts,
without giving effect to the conflict of law principles thereof. Any legal
action or proceeding with respect to this Agreement that is not subject to
arbitration pursuant to Section 16 will be brought in the courts of the
Commonwealth of Massachusetts in Middlesex County or of the United States of
America for the District of Massachusetts, sitting in Boston. 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 exclusive
jurisdiction of the aforesaid courts. Each of the parties hereto irrevocably
consents to the service of process of any of the aforementioned courts in any
such action or proceeding by the mailing of copies thereof by certified mail,
postage prepaid, to the party at its address set forth in Section 10.

18.    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.

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

    SYNTA PHARMACEUTICALS CORP.
 
 
By:
 
/s/ Safi R. Bahcall

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Safi R. Bahcall, Ph.D.
President and Chief Executive Officer
 
 
EXECUTIVE:
 
 
/s/ Michael Bailey

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Michael Bailey
Senior Vice President, Commercial Operations and
Chief Business Officer

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Exhibit 10.3