Sec Form 4 Filing - Frazier Life Sciences VIII, L.P. @ Aptinyx Inc. - 2018-06-25

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 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

OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5

1. Name and Address of Reporting Person Frazier Life Sciences VIII, L.P. 2. Issuer Name and Ticker or Trading Symbol Aptinyx Inc. [ APTX] 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) 601 UNION STREET, SUITE 3200 3. Date of Earliest Transaction (MM/DD/YY) 06/25/2018 (Street) SEATTLE, WA98101 4. If Amendment, Date Original Filed (MM/DD/YY) 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 06/25/2018 C 1,047,450 ( 1 ) A 1,047,450 D ( 2 ) Common Stock 06/25/2018 C 1,197,076 ( 1 ) A 2,244,526 D ( 2 ) Common Stock 06/25/2018 C 795,553 ( 1 ) A 3,040,079 D ( 2 ) Common Stock 06/25/2018 P 150,000 ( 3 ) A $ 16 3,190,079 D ( 2 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 Series A-1 Convertible Preferred Stock ( 1 ) 06/25/2018( 1 ) C 28,895,188 ( 1 ) ( 1 ) Common Stock 1,047,450 ( 1 ) 0 I See Footnote ( 2 ) Series A-2 Convertible Preferred Stock ( 1 ) 06/25/2018( 1 ) C 33,022,786 ( 1 ) ( 1 ) Common Stock 1,197,076 ( 1 ) 0 I See Footnote ( 2 ) Series B Convertible Preferred Stock ( 1 ) 06/25/2018( 1 ) C 21,946,301 ( 1 ) ( 1 ) Common Stock 795,553 ( 1 ) 0 I See Footnote ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Frazier Life Sciences VIII, L.P. 601 UNION STREET, SUITE 3200 SEATTLE, WA98101 X FHM LIFE SCIENCES VIII, L.P. 601 UNION STREET, SUITE 3200 SEATTLE, WA98101 X FHM LIFE SCIENCES VIII, L.L.C. 601 UNION STREET, SUITE 3200 SEATTLE, WA98101 X Heron Patrick J 601 UNION STREET, SUITE 3200 SEATTLE, WA98101 X Signatures FRAZIER LIFE SCIENCES VIII, L.P. By: FHM Life Sciences VIII, L.P. Its: general partner By FHM Life Sciences VIII, L.L.C. Its: general partner, By: /s/ Steve Bailey 06/26/2018 Signature of Reporting Person Date FHM LIFE SCIENCES VIII, L.P. By: FHM Life Sciences VIII, L.L.C. Its: general partner By: /s/ Steve Bailey 06/26/2018 Signature of Reporting Person Date FHM LIFE SCIENCES VIII, L.L.C. By: /s/ Steve Bailey 06/26/2018 Signature of Reporting Person Date /s/ Patrick J. Heron 06/26/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each share of Series A-1 Convertible Preferred Stock, Series A-2 Convertible Preferred Stock and Series B Convertible Preferred Stock automatically converted into shares of Common Stock on a 27.58621-for-one basis immediately prior to the closing of the Issuer's initial public offering without payment or consideration. The shares of Series A-1 Convertible Preferred Stock, Series A-2 Convertible Preferred Stock and Series B Convertible Preferred Stock had no expiration date. ( 2 )The shares are held directly by Frazier Life Sciences VIII, L.P. ("FLS-VIII") and this report is filed jointly by Frazier Life Sciences VIII, L.P. ("FLS-VIII L.P."), FHM Life Sciences VIII, L.P. (FHM-VIII L.P."), FHM Life Sciences VIII, L.L.C. ("FHM-VIII LLC") and Patrick J. Heron. Shares are held directly by FLS-VIII. FHM-VIII L.P. serves as the sole general partner of FLS-VIII and owns no shares directly. FHM-VIII LLC serves as the sole general partner of FHM-VIII L.P. and owns no shares directly. Mr. Heron and James Topper are members of FHM-VIII LLC and share voting and dispositive power over the shares held by FLS-VIII; however, they disclaim beneficial ownership of the shares held by FLS-VIII except to the extent of their pecuniary interests therein. ( 3 )On June 25, 2018, FLS-VIII purchased 150,000 shares of common stock of the Issuer at a price of $16.00 per share pursuant to an underwritten public offering.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* 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).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.