Ownership Submission
FORM 3
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF 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 *
  5AM Ventures II LP
2. Date of Event Requiring Statement (Month/Day/Year)
02/11/2014
3. Issuer Name and Ticker or Trading Symbol
Flexion Therapeutics Inc [FLXN]
(Last)
(First)
(Middle)
2200 SAND HILL ROAD, SUITE 110
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

MENLO PARK, CA 94025
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 Beneficially Owned
1.Title of Security
(Instr. 4)
2. Amount of Securities Beneficially Owned
(Instr. 4)
3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)
4. Nature of Indirect Beneficial Ownership
(Instr. 5)
Common Stock 12,299 (1)
I
By entities affiliated with 5AM Ventures II, L.P. (2) (3)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)
2. Date Exercisable and Expiration Date
(Month/Day/Year)
3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)
4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)
6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Series A Preferred Stock   (4)   (4) Common Stock 1,291,505 (1) $ 0 (4) I By entities affiliated with 5AM Ventures II, L.P. (3) (4)
Series B Preferred Stock   (5)   (5) Common Stock 208,272 (1) $ 0 (5) I By entities affiliated with 5AM Ventures II, L.P. (3) (5)

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
5AM Ventures II LP
2200 SAND HILL ROAD, SUITE 110
MENLO PARK, CA 94025
    X    
5AM CO-INVESTORS II LP
2200 SAND HILL ROAD, SUITE 110
MENLO PARK, CA 94025
    X    

Signatures

/s/ 5AM Ventures II L.P. by 5AM Partners II LLC, Its General Partner by Andrew J. Schwab 02/11/2014
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(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) Share numbers assume or give effect to the 1-for-8.13 reverse stock split of the Issuer's Common Stock effected on January 27, 2014, which will be effective for the Preferred Stock upon its conversion to Common Stock immediately prior to the closing of the Issuer's initial public offering.
(2) Shares held as follows: 11,833 by 5AM Ventures II, L.P. and 466 by 5AM Co-Investors II, L.P.
(3) 5AM Partners II, LLC is the general partner of 5AM Ventures II, L.P. and 5AM Co-Investors II, L.P. 5AM Partners II, LLC may be deemed to have shared voting and investment power over the shares held by 5AM Ventures II, L.P. and 5AM Co-Investors II, L.P. 5AM Partners II, LLC disclaims beneficial ownership of such shares, except to the extent of its pecuniary interest therein.
(4) The shares of Series A Preferred Stock have no expiration date and are convertible at any time at the election of the holder without payment of further consideration. Each share of Series A Preferred Stock will automatically convert on a 1-for-8.13 basis into shares of Common Stock upon the closing of the Issuer's initial public offering. Upon conversion the shares are held as follows: 1,242,480 by 5AM Ventures II, L.P. and 49,025 by 5AM Co-Investors II, L.P.
(5) The shares of Series B Preferred Stock have no expiration date and are convertible at any time at the election of the holder without payment of further consideration. Each share of Series B Preferred Stock will automatically convert on a 1-for-8.13 basis into shares of Common Stock upon the closing of the Issuer's initial public offering. Upon conversion the shares are held as follows: 200,366 by 5AM Ventures II, L.P. and 7,906 shares by 5AM Co-Investors II, L.P.

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