UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934*

(Amendment No. 2)

APTINYX INC.

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

03836N103

(CUSIP Number)

December 31, 2023

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

☐	Rule 13d-1(b)

☒	Rule 13d-1(c)

☐	Rule 13d-1(d)

*	The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

13G

CUSIP No. 03836N103

13G

CUSIP No. 03836N103

13G

CUSIP No. 03836N103

13G

CUSIP No. 03836N103

13G

CUSIP No. 03836N103

13G

CUSIP No. 03836N103

13G

CUSIP No. 03836N103

13G

CUSIP No. 03836N103

Item 1(a).

Name of Issuer:

Aptinyx Inc. (the “Issuer”)

Item 1(b).

Address of Issuer’s Principal Executive Offices:

c/o Verdolino & Lowey, P.C., 124 Washington Street, Suite 101, Foxborough, MA 02035

Item 2(a).

Name of Person Filing:

Item 2(b).

Address of Principal Business Office or, if none, Residence:

Item 2(c).

Citizenship:

(i) Invus Public Equities, L.P. (“Invus Public Equities”)

750 Lexington Avenue, 30th Floor, New York, NY 10022

Citizenship: Bermuda limited partnership

(ii) Invus Public Equities Advisors, LLC (“Invus PE Advisors”)

750 Lexington Avenue, 30th Floor, New York, NY 10022

Citizenship: Delaware limited liability company

(iii) Artal International S.C.A. (“Artal International”)

NAMES OF REPORTING PERSONS

Invus Public Equities, L.P.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a) ☐ (b) ☐

SEC USE ONLY

CITIZENSHIP OR PLACE OF ORGANIZATION

Bermuda

Aptinyx Inc. SC 13G/A