SYNLOGIC, INC. — Director's Dealing 2018

Jan 30, 2018

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: SYNLOGIC, INC. (SYBX)
CIK: 0001527599
Period of Report: 2018-01-26

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

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2018-01-26	Common Stock	A	715000	$9.75	Acquired	2029996	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. By virtue of such relationships, GP VI and Advisors 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. Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

F2: Each of GP VI and Advisors 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 pecuniary interest therein, if any. The Reporting Persons have designated a representative, Chau Khuong, an employee of Advisors, to serve on the Issuer's board of directors. 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.