13G Filing: James E. Flynn and Mirna Therapeutics Inc. (MIRN)

Synlogic, Inc.

200 Sidney St., Suite 320

Cambridge, MA 02139

James E. Flynn, Deerfield Management Company, L.P., Deerfield Mgmt III, L.P. and Deerfield Private Design Fund III, L.P.

James E. Flynn, Deerfield Mgmt III, L.P., Deerfield Management Company, L.P., Deerfield Private Design Fund III, L.P. 780
Third Avenue, 37th Floor, New York, NY 10017

Deerfield Mgmt III, L.P., Deerfield Private Design Fund III, L.P. and Deerfield Management Company, L.P. – Delaware limited
partnerships;

James E. Flynn – United States citizen

Common Stock

87166L100

If This Statement is Filed Pursuant to
Rule 13d-1(b), or 13d-2(b) or (c), Check Whether the Person Filing is a:

Broker or dealer registered under Section 15 of the
Exchange Act.

Insurance company as defined in Section 3(a)(19) of
the Exchange Act.

Investment company registered under Section 8 of the
Investment Company Act.

An employee benefit plan or endowment fund in accordance
with Rule 13d-1(b)(1)(ii)(F);

A parent holding company or control person in accordance
with Rule 13d-1(b)(1)(ii)(G);

(h)

A savings association as defined in Section 3(b) of
the Federal Deposit Insurance Act;

A church plan that is excluded from the definition
of an investment company under Section 3(c)(14) of the Investment Company Act;