Exhibit 10.60
  CONFIDENTIAL
 
  th
 1.
    
    Position and Title. You will continue your role as Executive Vice President and
Chief Medical Officer, reporting directly to me as the President and Chief Executive Officer.
You will also continue as an executive officer of Idenix within the meaning of Rule 16a-1
under the Securities Exchange Act and an executive officer within the meaning of Rule 3b-7
under the Exchange Act.
 2.
    
    Base Salary. Your semi-monthly base salary will be $13,750 (equivalent to an
annualized rate of $330,000), subject to applicable withholding and payable in accordance with
normal payroll practices of Idenix. The Base Salary shall continue to be reviewed annually
for additional increases, if any, which is the sole discretion of the Idenix Compensation
Committee of the Board of Directors (the Board). After any such increase, the term Base
Salary as utilized herein shall thereafter refer to the increased amount. Base Salary shall
not be reduced at any time without your express prior written consent.
 3.
    
    Equity. You are eligible for an annual target stock option award for the purchase of
60,000 shares of common stock of Idenix that will be granted pursuant to the terms of the
Idenix Pharmaceuticals, Inc. 2005 Stock Incentive Plan and its standard option award agreement
(the Plan). The number of shares for which such award is ultimately granted will be in the
absolute discretion of the Compensation Committee of the Board of Directors.
 4.
    
    Benefits. You will continue be eligible to participate in all benefit plans and
programs Idenix provides generally to its senior level executives, subject to, and on a basis
consistent with, the participation requirements and other terms and conditions of such plans
and programs. Such programs currently include medical, dental, disability, life insurance and
a 401(k) plan. Of course, the Company reserves the right to modify or eliminate such programs
from time to time.
 5.
    
    Location. You will continue to be based at Idenix offices in Cambridge,
Massachusetts.




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6.
    
    Incentive Based Compensation. You are eligible for an annual target cash bonus
(Target Bonus) equal to 50% of your Base Salary. Your target bonus as a percentage of Base
Salary may, at the discretion of the Board, be periodically reviewed for increase. After any
such increase, the term Target Bonus as used herein shall thereafter refer to the increased
amount. The Target Bonus shall not be reduced at any time without your express prior written
consent.
 7.
    
    Termination. You and Idenix each agree that your employment with Idenix is that of
an employee at will. Both you and Idenix have the right to terminate your employment
relationship at any time for any or no reason, subject to the provisions of this letter.




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8.
    
    Termination Within One Year After a Change in Control. If your employment is
terminated by Idenix (or any successor to Idenix) without Cause or you terminate your
employment for Good Reason, in each case within one (1) year following a Change in Control
(all such terms as defined in Appendix A hereto) you shall be entitled to receive the benefits
in Section 7(A)(i), (ii) and (iii) above plus a lump-sum payment equivalent to the sum of (A)
one times your Base Salary, and (B) the greater of (i) one times your Target Bonus for the
year in which the termination of employment occurs, or (ii) one times the actual bonus payable
to you for the year preceding the year in which termination of employment occurs. Your
eligibility to receive the payments, benefits and entitlements provided in this Section 8
shall be subject to the terms of Section 7(B).
 9.
    
    Excise Tax Provision. Anything herein to the contrary notwithstanding, to the extent
that any payment, entitlement or benefit provided under this offer or any other agreement,
plan, policy, program or arrangement of the Company (the Payments) would be subject to the
imposition of the excise tax imposed under Section 4999 of the Internal Revenue Code of 1986,
as amended (the Code), or any similar Federal or state law (an Excise Tax), the Payments
shall be reduced (but not below zero) to the maximum amount as will result in no portion of
the Payments being subject to such Excise Tax (the Safe Harbor Cap), but only if the net
after-tax amount that would be received by you, taking into account all applicable Federal,
state and local income taxes and the imposition of the Excise Tax, is greater than the net
after-tax amount, similarly determined, that would be received by you if Payments are not
reduced to the Safe Harbor Cap. If there is a reduction, it shall be implemented as follows:
(i) any cash payments, (ii) any taxable benefits, (iii) any nontaxable benefits, and (iv) any
vesting of equity awards, in each case in reverse order beginning with payments or benefits
that are to be paid the farthest in time from the date of change in control, to the extent
necessary to avoid imposition of the excise tax under Code Section 4999.
 10.
    
    Section 409A. All payment for which provision is made in this offer letter shall be
subject to the terms set forth in Appendix B.
 11.
    
    Disclosure of Inventions: You acknowledge and reaffirm your obligations pursuant to
Sections 11 and 12 of your January 4, 2007 offer letter. You further acknowledge and represent
that you have complied with all your obligations pursuant thereto.
 12.
    
    Noncompetition and Non-Solicitation: In consideration of the benefits in this offer
letter:




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13.
    
    Nondisparagement. You understand and agree that during your employment you shall not
make any false, disparaging or derogatory statements to any person or entity, including,
without limitation, any media outlet, industry group, financial institution or current or
former employee, consultant, client or customer of the Company, regarding the Company or any
of its directors, officers, employees, agents or representatives or about the Companys
business affairs or financial condition; provided, however, that nothing herein shall be
construed as preventing you from making truthful disclosures to any governmental entity or in
any litigation or arbitration or as otherwise required by applicable law.




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14.
    
    Governing Law. This offer and your employment shall be governed by and construed in
accordance with the laws of the Commonwealth of Massachusetts (without reference to the
conflict of laws provisions thereof.)
   
   th
 /s/ Douglas L. Mayers
Douglas L. Mayers, M.D.




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Appendix A
 Change in Control
      Good Reason
 Termination for Cause nolo contendere




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Appendix B
 Payments Subject to Section 409A
      provided however




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Appendix C
 Form of Severance and General Release Agreement
  
   et seq
  1.
    
    Termination Date. Your effective date of termination from the Company is [Insert
Termination Date] (the Termination Date). As of the Termination Date, all salary payments
from the Company will cease and any benefits you had as of the Termination Date under
Company-provided benefit plans, programs, or practices will terminate, except as required by
federal or state law.




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2.
    
    Description of Severance Compensation. If you timely sign and return this Agreement
and do not revoke your acceptance, the Company will provide the severance benefits in
accordance with Section(s)
 _____ 

of your Employment Letter with the Company dated
,
 _____ 

(the Severance Benefits). You will not be eligible for, nor shall you
have a right to receive, any payments or benefits from the Company following the Termination
Date other than as described in this paragraph 2.
 3.
    
    Release. In consideration of the Severance Benefits, which you acknowledge you would
not otherwise be entitled to receive, you hereby fully, forever, irrevocably and
unconditionally release, remise and discharge the Company, its affiliates, subsidiaries,
parent companies, predecessors, and successors, and all of their respective past and present
officers, directors, stockholders, partners, members, employees, agents, representatives, plan
administrators, attorneys, insurers and fiduciaries (each in their individual and corporate
capacities) (collectively, the Released Parties) from any and all claims, charges,
complaints, demands, actions, causes of action, suits, rights, debts, sums of money, costs,
accounts, reckonings, covenants, contracts, agreements, promises, doings, omissions, damages,
executions, obligations, liabilities, and expenses (including attorneys fees and costs), of
every kind and nature that you ever had or now have against any or all of the Released
Parties, including, but not limited to, any and all claims arising out of or relating to your
employment with and/or separation from the Company, including, but not limited to, all claims
under Title VII of the Civil Rights Act of 1964, 42 U.S.C. § 2000e et seq., the Americans With
Disabilities Act of 1990, 42 U.S.C. § 12101 et seq., the Age Discrimination in Employment Act,
29 U.S.C. § 621 et seq., the Genetic Information Nondiscrimination Act of 2008, 42 U.S.C. §
2000ff et seq., the Family and Medical Leave Act, 29 U.S.C. § 2601 et seq., the Worker
Adjustment and Retraining Notification Act (WARN), 29 U.S.C. § 2101 et seq., 18 U.S.C.
1514(A), the Rehabilitation Act of 1973, 29 U.S.C. § 701 et seq., Executive Order 11246,
Executive Order 11141, the Fair Credit Reporting Act, 15 U.S.C. § 1681 et seq., and the
Employee Retirement Income Security Act of 1974 (ERISA), 29 U.S.C. § 1001 et seq., all as
amended; all claims arising out of the Massachusetts Fair Employment Practices Act., Mass.
Gen. Laws ch. 151B, § 1 et seq., the Massachusetts Civil Rights Act, Mass. Gen. Laws ch. 12,
§§ 11H and 11I, the Massachusetts Equal Rights Act, Mass. Gen. Laws. ch. 93, § 102 and Mass.
Gen. Laws ch. 214, § 1C, the Massachusetts Labor and Industries Act, Mass. Gen. Laws ch. 149,
§ 1 et seq., Mass. Gen. Laws ch. 214, § 1B (Massachusetts right of privacy law), the
Massachusetts Maternity Leave Act, Mass. Gen. Laws ch. 149, § 105D, and the Massachusetts
Small Necessities Leave Act, Mass. Gen. Laws ch. 149, § 52D, all as amended; all common law
claims including, but not limited to, actions in defamation, intentional infliction of
emotional distress, misrepresentation, fraud, wrongful discharge, and breach of contract; all
claims to any non-vested ownership interest in the Company, contractual or otherwise, and any
claim or damage arising out of your employment with and/or separation from the Company
(including a claim for retaliation) under any common law theory or any federal, state or local
statute or ordinance not expressly referenced above; provided, however, that nothing in this
Agreement prevents you from filing a charge with, cooperating with, or participating in any
proceeding before the Equal Employment Opportunity Commission or a state fair employment
practices agency (except that you acknowledge that you may not recover any monetary benefits
in connection with any such claim, charge or proceeding).




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4.
    
    Post-Separation Obligations. You acknowledge and reaffirm your obligation to keep
confidential and not to disclose any and all non-public information concerning the Company
that you acquired during the course of your employment with the Company, including, but not
limited to, any non-public information concerning the Companys business affairs, business
prospects, and financial condition. Your further acknowledge and reaffirm your obligations
under Sections
 _____ 

and
 _____ 

of the Employment Letter, which remain in full force and effect.
 5.
    
    Non-Disparagement. You understand and agree that, in consideration of the Severance
Benefits, you shall not make any false, disparaging or derogatory statements to any person or
entity, including, without limitation, any media outlet, industry group, financial institution
or current or former employee, consultant, client or customer of the Company, regarding the
Company or any of its directors, officers, employees, agents or representatives or about the
Companys business affairs or financial condition; provided, however, that nothing herein
shall be construed as preventing you from making truthful disclosures to any governmental
entity or in any litigation or arbitration or as otherwise required by applicable law.
 6.
    
    Cooperation. To the extent permitted by law, you agree to cooperate with the Company
in the defense or prosecution of any claims or actions which already have been brought, are
currently pending, or which may be brought in the future against or on behalf of the Company,
whether before a state or federal court, any state or federal government agency, or a mediator
or arbitrator. In addition, the Company shall reimburse you for reasonable out-of-pocket
expenses incurred at the request of the Company with respect to your compliance with this
paragraph. Your full cooperation in connection with such claims or actions shall include, but
not be limited to, being available to meet with counsel to prepare its claims or defenses, to
prepare for trial or discovery or an administrative hearing or a mediation or arbitration and
to act as a witness when requested by the Company at reasonable times mutually agreed to by
you and the Company. You agree that you will notify the Company promptly in the event that
you are served with a subpoena or in the event that you are asked to provide a third party
with information concerning any actual or potential complaint or claim against the Company.
 7.
    
    Return of Company Property. You represent and confirm that you have returned to the
Company all Company-owned property in your possession or control and that you have left intact
all electronic Company documents, including, without limitation, those that you developed or
helped to develop during your employment. You further confirm that you have cancelled all
accounts for your benefit, if any, in the Companys name,
including, without limitation, credit cards, telephone charge cards, cellular phone and/or
pager accounts, and computer accounts.




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8.
    
    Business Expenses and Final Compensation. You acknowledge that you have been
reimbursed by the Company for all business expenses incurred in conjunction with the
performance of your employment and that no other reimbursements are owed to you. You further
acknowledge that you have received payment in full for all services rendered in conjunction
with your employment by the Company, including, without limitation, payment for all wages,
bonuses, equity, commissions and accrued, unused vacation time, and that no other compensation
is owed to you.
 9.
    
    Amendment and Waiver. This Agreement shall be binding upon the parties and may not
be modified in any manner, except by an instrument in writing of concurrent or subsequent date
signed by duly authorized representatives of the parties hereto. This Agreement is binding
upon and shall inure to the benefit of the parties and their respective agents, assigns,
heirs, executors, successors and administrators. No delay or omission by the Company in
exercising any right under this Agreement shall operate as a waiver of that or any other
right. A waiver or consent given by the Company on any one occasion shall be effective only
in that instance and shall not be construed as a bar to or waiver of any right on any other
occasion.
 10.
    
    Validity. Should any provision of this Agreement be declared or be determined by any
court of competent jurisdiction to be illegal or invalid, the validity of the remaining parts,
terms or provisions shall not be affected thereby and said illegal or invalid part, term or
provision shall be deemed not to be a part of this Agreement.
 11.
    
    Tax Provision. In connection with the Severance Benefits to be provided to you
pursuant to this Agreement, the Company shall withhold and remit to the tax authorities the
amounts required under applicable law, and you shall be responsible for all applicable taxes
with respect to such Severance Benefits under applicable law. You acknowledge that you are
not relying upon advice or representation of the Company with respect to the tax treatment of
any of the Severance Benefits.
 12.
    
    Compliance with Section 409A. The severance payments and benefits shall be subject
to and compliant with any requirements provided under Section 409A of the Internal Revenue
Code of 1986, as amended (Section 409A). The Company shall have no liability to you or any
other person if the payments and benefits provided that are intended to be exempt from or
compliant with Section 409A are not so exempt or compliant.
 13.
    
    Nature of Agreement. You understand and agree that this Agreement is a severance
agreement and does not constitute an admission of liability or wrongdoing on the part of the
Company.




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14.
    
    Acknowledgments. You acknowledge that you have been given at least twenty-one (21)
days to consider this Agreement, and that the Company advised you to consult with an attorney
of your own choosing prior to signing this Agreement. You understand that you
may revoke this Agreement for a period of seven (7) days after you sign it by notifying me
in writing, and the Agreement shall not be effective or enforceable until the expiration of
this seven (7) day revocation period. You understand and agree that by entering into this
Agreement, you are waiving any and all rights or claims you might have under the Age
Discrimination in Employment Act, as amended by the Older Workers Benefits Protection Act,
and that you have received consideration beyond that to which you were previously entitled.
 15.
    
    Voluntary Assent. You affirm that no other promises or agreements of any kind have
been made to or with you by any person or entity whatsoever to cause you to sign this
Agreement, and that you fully understand the meaning and intent of this Agreement. You state
and represent that you have had an opportunity to fully discuss and review the terms of this
Agreement with an attorney. You further state and represent that you have carefully read this
Agreement, understand the contents herein, freely and voluntarily assent to all of the terms
and conditions hereof, and sign your name of your own free act.
 16.
    
    Applicable Law. This Agreement shall be interpreted and construed by the laws of the
Commonwealth of Massachusetts, without regard to conflict of laws provisions. You hereby
irrevocably submit to and acknowledge and recognize the jurisdiction of the courts of the
Commonwealth of Massachusetts, or if appropriate, a federal court located in the Commonwealth
of Massachusetts (which courts, for purposes of this Agreement, are the only courts of
competent jurisdiction), over any suit, action or other proceeding arising out of, under or in
connection with this Agreement or the subject matter hereof.
 17.
    
    Entire Agreement  This Agreement contains and constitutes the entire understanding
and agreement between the parties hereto with respect to your severance benefits and the
settlement of claims against the Company and cancels all previous oral and written
negotiations, agreements, and commitments in connection therewith. Nothing in this paragraph,
however, shall modify, cancel or supersede your obligations set forth in paragraph 4 above.
 
 Very truly yours,By:[Name][Title]
  [Insert Employee Name]
    
    
    
    Date