Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
BVF PARTNERS L P/IL
  2. Issuer Name and Ticker or Trading Symbol
INFINITY PHARMACEUTICALS, INC. [INFI]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)
1 SANSOME ST, 30TH FL
3. Date of Earliest Transaction (Month/Day/Year)
04/09/2018
(Street)

SAN FRANCISCO, CA 94104
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock, $0.001 par value (1) 04/09/2018   P   228,691 A $ 1.9 4,738,476 D (2)  
Common Stock, $0.001 par value (1) 04/09/2018   P   208,872 A $ 1.9 3,177,359 D (3)  
Common Stock, $0.001 par value (1) 04/09/2018   P   62,437 A $ 1.9 853,020 D (4)  
Common Stock, $0.001 par value (1) 04/10/2018   P   546,865 A $ 2 5,285,341 D (2)  
Common Stock, $0.001 par value (1) 04/10/2018   P   365,682 A $ 2 3,543,041 D (3)  
Common Stock, $0.001 par value (1) 04/10/2018   P   97,453 A $ 2 950,473 D (4)  

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
BVF PARTNERS L P/IL
1 SANSOME ST
30TH FL
SAN FRANCISCO, CA 94104
    X    
BIOTECHNOLOGY VALUE FUND L P
1 SANSOME ST
30TH FL
SAN FRANCISCO, CA 94104
    X    
BIOTECHNOLOGY VALUE FUND II LP
1 SANSOME ST
30TH FL
SAN FRANCISCO, CA 94104
      See Explanation of Responses
Biotechnology Value Trading Fund OS LP
P.O. BOX 309 UGLAND HOUSE
GRAND CAYMAN, E9 KY1-1104
      See Explanation of Responses
BVF Partners OS Ltd.
P.O. BOX 309 UGLAND HOUSE
GRAND CAYMAN, E9 KY1-1104
      See Explanation of Responses
BVF INC/IL
1 SANSOME ST
30TH FL
SAN FRANCISCO, CA 94104
    X    
LAMPERT MARK N
1 SANSOME ST
30TH FL
SAN FRANCISCO, CA 94104
    X    

Signatures

 BVF Partners L.P., By: BVF Inc., its general partner, By: /s/ Mark N. Lampert, President   04/11/2018
**Signature of Reporting Person Date

 Biotechnology Value Fund, L.P., By: BVF Partners L.P., its general partner, By: BVF Inc., its general partner, By: /s/ Mark N. Lampert, President   04/11/2018
**Signature of Reporting Person Date

 Biotechnology Value Fund II, L.P., By: BVF Partners L.P., its general partner, By: BVF Inc., its general partner, By: /s/ Mark N. Lampert, President   04/11/2018
**Signature of Reporting Person Date

 BVF Partners OS Ltd., By: BVF Partners L.P., its sole member, By: BVF Inc., its general partner, By: /s/ Mark N. Lampert, President   04/11/2018
**Signature of Reporting Person Date

 Biotechnology Value Trading Fund OS LP, By: BVF Partners L.P., its investment manager, BVF Inc., its general partner, By: /s/ Mark N. Lampert, President   04/11/2018
**Signature of Reporting Person Date

 BVF Inc., By: /s/ Mark N. Lampert, President   04/11/2018
**Signature of Reporting Person Date

 /s/ Mark N. Lampert   04/11/2018
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) This Form 4 is filed jointly by Biotechnology Value Fund, L.P. ("BVF"), Biotechnology Value Fund II, L.P. ("BVF2"), Biotechnology Value Trading Fund OS LP ("Trading Fund OS"), BVF Partners OS Ltd. ("Partners OS"), BVF Partners L.P. ("Partners"), BVF Inc. and Mark N. Lampert (collectively, the "Reporting Persons"). Each of the Reporting Persons is a member of a Section 13(d) group that collectively owns more than 10% of the Issuer's outstanding shares of Common Stock. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein except to the extent of his or its pecuniary interest therein.
(2) Securities owned directly by BVF. As the general partner of BVF, Partners may be deemed to beneficially own the securities owned directly by BVF. As the investment adviser and general partner of Partners, BVF Inc. may be deemed to beneficially own the securities owned directly by BVF. As a director and officer of BVF Inc., Mr. Lampert may be deemed to beneficially own the securities owned directly by BVF.
(3) Securities owned directly by BVF2. As the general partner of BVF2, Partners may be deemed to beneficially own the securities owned directly by BVF2. As the investment adviser and general partner of Partners, BVF Inc. may be deemed to beneficially own the securities owned directly by BVF2. As a director and officer of BVF Inc., Mr. Lampert may be deemed to beneficially own the securities owned directly by BVF2.
(4) Securities owned directly by Trading Fund OS. As the general partner of Trading Fund OS, Partners OS may be deemed to beneficially own the securities owned directly by Trading Fund OS. As the investment manager of Trading Fund OS and the sole member of Partners OS, Partners may be deemed to beneficially own the securities owned directly by Trading Fund OS. As the investment adviser and general partner of Partners, BVF Inc. may be deemed to beneficially own the securities owned directly by Trading Fund OS. As a director and officer of BVF Inc., Mr. Lampert may be deemed to beneficially own the securities owned directly by Trading Fund OS.

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