SYNLOGIC, INC. — Director's Dealing 2017

Aug 30, 2017

SEC Form 3 — Initial Statement of Beneficial Ownership

Issuer: SYNLOGIC, INC. (SYBX)
CIK: 0001527599
Period of Report: 2017-08-28

Reporting Person: ORBIMED ADVISORS LLC (Director)
Reporting Person: ISALY SAMUEL D (Director)
Reporting Person: OrbiMed Capital GP VI LLC (Director)

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	1314996	Indirect

Footnotes

F1: These shares are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisers Act of 1940, as amended, is the sole managing member of GP VI. Samuel D. Isaly ("Isaly"), a natural person, is the managing member of, and holder of a controlling interest in, Advisors. By virtue of such relationships, GP VI, Advisors and Isaly may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to have beneficial ownership over such securities. The Reporting Persons have designated a representative, currently Chau Khuong, a Private Equity Partner of Advisors, to serve on the Issuer's board of directors.

F2: This report on Form 3 is jointly filed by OPI VI, GP VI, Advisors and Isaly. Each of GP VI, Advisors, Isaly and the Reporting Person disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity or person is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.