Exhibit 10.21


 





***Text
Omitted and Filed Separately with the Securities and Exchange Commission.

Confidential Treatment Requested Under 17 C.F.R. Sections 200.80(b)(4) and 240.24b-2


		1. CONTRACT
    ID CODE	PAGE OF PAGES
	AMENDMENT OF SOLICITATION/MODIFICATION OF CONTRACT	 	1	     3







	2.  AMENDMENT/MODIFICATION NO.	3.  EFFECTIVE DATE	4.  REQUISITION/PURCHASE REQ. NO	5.  PROJECT NO. (if applicable)
	0016	See
    Block 16C	OS124607	 










	6.  ISSUED
    BY	CODE	ASPR-BARDA	7.
                                         ADMINISTERED BY (If other than Item 6)

        
	CODE	ASPR-BARDA02
	ASPR-BARDA

                                         200 Independence Ave., S.W.

                                         Room 640-G

                                         Washington DC 20201
	ASPR-BARDA

                                         330 Independence Ave, SW, Rm G640

                                         Washington DC 20201






	8.  NAME
    AND ADDRESS OF CONTRACTOR (No., Street, County, State, and Zip Code)	S	9A.  AMENDMENT
    OF SOLICITATION NO.	 
	CHIMERIX,
INC. 1377270

        CHIMERIX, INC.      2505
        MERIDIAN P

        2505 MERIDIAN PKWY STE
        340

        DURHAM NC 277135246
	 	 	 
	9B.  DATED
    (SEE ITEM 11)	 
	 	 	 
	S	10A.
                                         MODIFICATION OF CONTRACT/ORDER NO.

        HHSO100201100013C
	 
	 	 	 
	10B.
    DATED (SEE ITEM 11) 02/16/2011	 
	CODE:     1377270	FACILITY
    CODE:	 	 	 










	11.  THIS
    ITEM ONLY APPLIES TO AMENDMENTS OF SOLICITATIONS





	£
    The above numbered, solicitation is amended as set forth in item 14. The hour and date
    specified for receipt of Offers £  is extended £
    is not extended. 

    

    Offers must acknowledge receipt of this amendment prior to the hour and date specified in the solicitation or as amended
    by one of the following methods: 
 
 (a) By completing Items 8 and 15, and returning            copies
    of the amendment; (b) By acknowledging receipt of this amendment on each copy of the offer submitted; or (c) By separate letter
    or telegram which includes a reference to the solicitation and amendment numbers, FAILURE OF YOUR ACKNOWLEDGEMENT TO BE RECEIVED
    AT THE PLACE DESIGNATED FOR THE RECEIPT OF OFFERS PRIOR TO THE HOUR AND DATE SPECIFIED MAY RESULT IN REJECTION OF YOUR OFFER.
    If by virtue of this amendment you desire to change an offer already submitted, such change may be made by telegram or letter,
    provided each telegram or letter makes reference to the solicitation and this amendment, and is received prior to the opening
    hour and date specified.








	12.
                                         ACCOUNTING AND APPROPRIATION DATA (If Required)

        See Schedule                                            Net
        Increase:                                       $306,831.00






	13.  THIS
    ITEM APPLIES ONLY TO MODIFICATIONS OF CONTRACTS/ORDERS,

IT MODIFIES THE CONTRACT/ORDER NO., AS DESCRIBED IN ITEM
    14
	£	A.
    THIS     CHANGE ORDER IS ISSUED PURSUANT TO:  (Specify Authority)  THE CHANGES SET FORTH IN ITEM
    14 ARE     MADE IN THE CONTRACT ORDER NO. IN ITEM 10A.
	 
	£	B. THE
    ABOVE NUMBERED CONTRACT/ORDER IS MODIFIED TO REFLECT THE ADMINISTRATIVE CHANGES (such as changes in paying office, appropriation
    date, etc.) SET FORTH IN ITEM 14, PURSUANT TO THE AUTHORITY OF FAR 43,103 (b).
	 	 
	£	C. THIS
    SUPPLEMENTAL AGREEMENT IS ENTERED INTO PURSUANT TO AUTHORITY OF:
	 	 
	S	D.
                                                                                                               OTHER (Specify type of modification and authority)

        Bilateral:
        Mutual Agreement of the Parties.

         






	E.  IMPORTANT: Contractor                £  is
NOT        S  is required to sign
this document and return          1        
copies to the issuing office.





	14.  DESCRIPTION
    OF AMENDMENT/MODIFICATION (Organized by UCF section headings, including solicitation/contract subject matter where feasible.





	Tax
                                         ID Number:       33-0903395

        DUNS Number:       121785997

        A.        The
        purpose of this modification is to add funding in the amount of $306,831.00 for the purpose of funding a cost growth due
        to the need to repeat several non-clinical rabbit studies under Option 1/CLIN 0002 ONLY under Contract Number HHSP100201100013C.

        

        1.          The addition of this cost growth to Option 1/CLIN 0002 under
        Contract Number HHSO100201100013C results in Contract Line Item Number (CLIN) 0002 being changed as follows:

        Total Estimated Cost: From $[...***...] By $306,831.00 TO $[...***...].

        Continued ...

         

	Except
    as provided herein, all terms and conditions of the document referenced in Item 9A or 10A, as heretofore changed, remains
    unchanged and in full force and effect.





	15A.  NAME
    AND TITLE OF SIGNER 	16A.  NAME
    AND TITLE OF CONTRACTING OFFICER 
	Michael
    Rogers, Chief Development Officer	ETHAN
    J. MUELLER
	15B.  CONTRACTOR/OFFEROR	15C.  DATE SIGNED	16B.  UNITED
    STATES OF AMERICA	16C.  DATE
    SIGNED
	   /s/
Michael Rogers

        (Signature
        of person authorized to sign)
	12/9/13	/s/Ethan
                                         J. Mueller

        (Signature
        of Contracting Officer)
	12/10/13

         






	NSN 7540-01-152-8070	 	STANDARD FORM 30 (REV. 10-83)
	Previous Edition Unusable	 	Prescribed by GSA FAR (48 CFR)
    53.24


 ***Confidential
Treatment Requested


 




    	 



    	 



    

 





	CONTINUATION
    SHEET	REFERENCE
        NO. OF DOCUMENT BEING CONTINUED

        HHSO100201100013C/0016
	PAGE   OF	 
	2	3













	NAME
                                         OF OFFEROR OR CONTRACTOR

        CHIMERIX, INC. 1377270






	ITEM NO.

        (A)
	SUPPLIER/SERVICES

        (B)
	QUANTITY

        (C)
	UNIT

        (D)
	UNIT PRICE

        (E)
	AMOUNT

        (F)

	 	 

                                                                                                                         





No change
to the Total Fixed Fee Amount of $[...***...].


 


Total
Estimated Cost Plus Fixed Fee: From $5,000,000.00 By $306,831.00 To $5,306,831.00.


 


2.    This
modification and the addition of this cost growth of $306,831.01 to Option 1/CLIN 0002 also results in an increase in the total
amount of the contract from $35,955,542.00 by $306,831.00 to $36,262,373.00 as well as the following:


 


Total
Estimated Cost of the Contract: From $[...***...] By $306,831.00 To $[...***...].


 


No change
to the Total Fixed Fee Amount of $[...***...].


 


Total
Estimated Cost Plus Fixed Fee of the Contract: From $35,955,542.00 By $306,831.00 To $36,262,373.00.


 


3.    This
modification hereby results in an increase in the total amount of the contract from $35,955,542.00 by $306,831.00 to $36,262,373.00.


 


4.    Block
15G of the SF 26, the amount of $35,955,542.00 shall be changed to $36,262,373.00. Also in Block 14 of the SF 26, the following
CAN Number is added as follows:


 


Appropriation
Year: 2014; Object Class: 25106; CAN 1992003 $306,831.00


 


5.    The
period of performance for Option 1/CLIN 0042 of Contract Number HHS0100201100013C remains unchanged at 1 June 2013 through 1 May
2014. The Statement of Work also remains unchanged. This bilateral modification does not authorize the performance of any other
unexercised Option segments under the contract.


 


6.    Total
expenses for all domestic and foreign tr.:1Tel (transportation, lodging, subsistence, and incidental expenses) incurred
in direct performance of this contract shall not exceed $[...***...] during the base segment/CLIN 0001 and $[...***...]
during Option Period 1/CLIN 0002 without the prior written approval of the Contracting Officer.


 


B.    This
is a bilateral modification. The scope, period of performance and all other terms and conditions contract number HHSO1002011000130
remain unchanged.


 


Delivery:
05/31/2014


Delivery
Location Code: HHS HHS


200
Independence Avenue, SW

Washington
DC 20201 US


 

FOB:
Destination

Continued
....
	 	 	 	 











	NSN 7540-01-152-8067	OPTIONAL FORM 336 
                                  (4-86)

                           Sponsored by GSA

                           FAR (48 CFR) 53.110





***Confidential
Treatment Requested


 






    	 



    	 



    

  


	CONTINUATION
    SHEET	REFERENCE
                                         NO. OF DOCUMENT BEING CONTINUED

        HHSO100201100013C/0016
	PAGE   OF	   
	3	      3





	NAME
        OF OFFEROR OR CONTRACTOR

        CHIMERIX, INC. 1377270






	ITEM NO.

        (A)
	SUPPLIER/SERVICES

        (B)
	QUANTITY

        (C)
	UNIT

        (D)
	UNIT PRICE

        (E)
	AMOUNT

        (F)

	 	 

                                                                                         Period
                                         of Performance: 02/16/2011 to 05/31/2014


 


Change
Item 2 to read as follows(amount shown is the obligated amount):


 


Non-Clinical
development PK and efficacy studies and stability studies.


 


Reports
and Other Data Deliverables.


 


Amount:
$5,000,000.00


Accounting
Info:


2013.1992002.25106
Appr. Yr.: 2013 CAN: 1992002 Object Class: 25106 Funded: $0.00


 


Amount:
$306,831.00

 Accounting Info:


..2014.1992003.25106
Appr. Yr.: 2014 CAN: 1992003 Object Class: 25106


Funded:
$306,831.00

         
	 	 	 	 

                                                                                 

                                                                                 

                                                                                 

                                                                                306,831.00 

	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 
	 	 	 	 	 	 





	NSN 7540-01-152-8067	OPTIONAL FORM 336-(4-86)
	 	Sponsored by GSA
	 	FAR (48 CFR) 53.110