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

Mirna Therapeutics Inc. (NASDAQ:MIRN): James E. Flynn’s Deerfield Management filed an amended 13D.

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Ownership Summary Table

Name Sole Voting Power Shared Voting Power Sole Dispositive Power Shared Dispositive Power Aggregate Amount Owned Power Percent of Class
Deerfield Management Company 0 850,143 0 850,143 850,143 5.22%
Deerfield Mgmt III 0 850,143 0 850,143 850,143 5.22%
Deerfield Private Design Fund III 0 850,143 0 850,143 850,143 5.22%
James E. Flynn 0 850,143 0 850,143 850,143 5.22%

Page 1 of 12 – SEC Filing

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

SCHEDULE 13G

(Rule 13d-102)

INFORMATION TO BE INCLUDED IN STATEMENTS
FILED PURSUANT

TO RULES 13d-1(b)(c), AND (d) AND AMENDMENTS
THERETO FILED

PURSUANT TO RULE 13d-2(b)

(Amendment No. ) *

Synlogic, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

87166L100

(CUSIP Number)

August 28, 2017

(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)

(Page 1 of 9
Pages)

———-

* 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 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).

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Page 2 of 12 – SEC Filing

CUSIP No.

87166L100

13G Page 2
of 9 Pages
1.

NAME OF REPORTING PERSONS

I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY)

Deerfield Management
Company, L.P.

2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

(a)

(b) ☒

3.

SEC USE ONLY

4.

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

 

 

 NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

850,143 (1)

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

850,143 (1)

9.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

850,143 (1)

10.

CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN
SHARES*

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

5.22%

12.

TYPE OF REPORTING PERSON*

PN

__________________

(1) Comprised of shares of common stock held by Deerfield Private Design Fund III, L.P., of which Deerfield Management Company,
L.P. is the investment advisor.

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Page 3 of 12 – SEC Filing

CUSIP No.

87166L100

13G Page 3
of 9 Pages
1.

NAME OF REPORTING PERSONS

I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY)

Deerfield Mgmt III, L.P.

2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

(a)

(b) ☒

3.

SEC USE ONLY

4.

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

 

 

 NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

850,143 (2)

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

850,143 (2)

9.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

850,143 (2)

10.

CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN
SHARES*

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

5.22%

12.

TYPE OF REPORTING PERSON*

PN

__________________

(2) Comprised of shares of common stock held by Deerfield Private Design Fund III, L.P., of which Deerfield Mgmt III, L.P.
is the general partner.

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Page 4 of 12 – SEC Filing

CUSIP No. 87166L100 13G Page 4
of 9 Pages
1.

NAME OF REPORTING PERSONS

I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY)

Deerfield Private Design Fund III, L.P.

2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

(a)

(b) ☒

3.

SEC USE ONLY

4.

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

 

 

 NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

850,143

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

850,143

9.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

850,143

10.

CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN
SHARES*

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

5.22%

12.

TYPE OF REPORTING PERSON*

PN

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Page 5 of 12 – SEC Filing

CUSIP No. 87166L100 13G Page 5
of 9 Pages
1.

NAME OF REPORTING PERSONS

I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY)

James E. Flynn

2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

(a)

(b) ☒

3.

SEC USE ONLY

4.

CITIZENSHIP OR PLACE OF ORGANIZATION

United States

 

 

 NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

850,143 (3)

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

850,143 (3)

9.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

850,143 (3)

10.

CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN
SHARES*

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

5.22%

12.

TYPE OF REPORTING PERSON*

IN

__________________

(3) Comprised of shares of common stock held by Deerfield Private Design Fund III, L.P.

 

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Page 6 of 12 – SEC Filing

CUSIP No. 87166L100 13G Page 6
of 9 Pages
Item 1(a). Name of Issuer:

Synlogic, Inc.

Item 1(b). Address of Issuer’s Principal Executive Offices:

200 Sidney St., Suite 320

Cambridge, MA 02139

Item 2(a). Name of Person Filing:

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

Item 2(b). Address of Principal Business Office, or if None, Residence:

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

Item 2(c). Citizenship:

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

Item 2(d). Title of Class of Securities:

Common Stock

Item 2(e). CUSIP Number:

87166L100

Item 3.

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

(a)

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

(b) Bank as defined in Section 3(a)(6) of the Exchange Act.
(c)

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

(d)

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

(e) An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E);
(f)

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

(g)

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;

(i)

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

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Page 7 of 12 – SEC Filing

CUSIP No. 87166L100 13G Page 7
of 9 Pages
(j) A non-U.S. institution in accordance with Rule 13d-1(b)(1)(ii)(J);
(k) Group, in accordance with Rule 13d-1(b)(1)(ii)(K).

If filing as a non-U.S. institution in accordance
with Rule 13d-1(b)(1)(ii)(J), please specify the type of institution: _________________

Item 4. Ownership.

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

(a) Amount beneficially owned**:

Deerfield Management Company, L.P. – 850,143 shares

Deerfield Mgmt III, L.P. – 850,143 shares

Deerfield Private Design Fund
III, L.P. – 850,143 shares

James E. Flynn – 850,143 shares

(b) Percent of class**:

Deerfield Management Company, L.P. – 5.22%

Deerfield Mgmt III, L.P. – 5.22%

Deerfield Private Design Fund III, L.P. – 5.22%

James E. Flynn – 5.22%

(c) Number of shares as to which such person has**:
(i) Sole power to vote or to direct the vote: All Reporting Persons 0
(ii) Shared power to vote or to direct the vote:

Deerfield
Management Company, L.P. – 850,143

Deerfield Mgmt III, L.P. – 850,143

Deerfield Private Design Fund III, L.P. – 850,143

James E. Flynn – 850,143

(iii)

Sole power to dispose or to direct the disposition of:

All Reporting Persons – 0
(iv)

Shared power to dispose or to direct the disposition
of:

Deerfield Management Company, L.P. – 850,143

Deerfield Mgmt III, L.P. – 850,143

Deerfield Private Design Fund III, L.P. –
850,143

James E. Flynn – 850,143

**See footnotes on cover pages which are incorporated by reference
herein.

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Page 8 of 12 – SEC Filing

CUSIP No. 87166L100 13G Page 8
of 9 Pages
Item 5. Ownership of Five Percent or Less of a Class.

If this statement is being filed to report
the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the
class of securities check the following ☐.

Item 6. Ownership of More Than Five Percent on Behalf of Another Person.

If any other person
is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of,
such securities, a statement to that effect should be included in response to this item and, if such interest relates to more
than five percent of the class, such person should be identified. A listing of the shareholders of an investment company registered
under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not
required.

N/A
Item 7.

Identification and Classification of the Subsidiary
Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.

If a parent holding company or Control person has filed this
schedule, pursuant to Rule 13d-1(b)(1)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the
Item 3 classification of the relevant subsidiary. If a parent holding company or control person has filed this schedule pursuant
to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary.

N/A
Item 8. Identification and Classification of Members of the Group.

If a group has filed this schedule pursuant
to ss.240.13d-1(b)(1)(ii)(J), so indicate under Item 3(j) and attach an exhibit stating the identity and Item 3 classification
of each member of the group. If a group has filed this schedule pursuant to ss.240.13d-1(c) or ss.240.13d-1(d), attach an exhibit
stating the identity of each member of the group.

See Exhibit B
Item 9. Notice of Dissolution of Group.

Notice of dissolution of a group may be furnished as an exhibit
stating the date of the dissolution and that all further filings with respect to transactions in the security reported on will
be filed, if required, by members of the group, in their individual capacity. See Item 5.

N/A
Item 10. Certifications.

“By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired
and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities
and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect,
other than activities solely in connection with a nomination under §240.14a-11.”

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Page 9 of 12 – SEC Filing

CUSIP No. 87166L100 13G Page 9
of 9 Pages

SIGNATURE

After reasonable inquiry and to the best
of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

DEERFIELD MANAGEMENT COMPANY, L.P.

By: Flynn Management LLC, General Partner

By: /s/ Jonathan Isler

       Jonathan Isler, Attorney-In-Fact

DEERFIELD MGMT III, L.P.

By: J.E. Flynn Capital III, LLC, General Partner

By: /s/ Jonathan Isler

       Jonathan Isler, Attorney-In-Fact

DEERFIELD PRIVATE DESIGN FUND III, L.P.

By: Deerfield Mgmt III, L.P., General Partner

By: J.E. Flynn Capital III, LLC, General Partner

By: /s/ Jonathan Isler

       Jonathan Isler, Attorney-In-Fact

JAMES E. FLYNN

/s/ Jonathan Isler

Jonathan Isler, Attorney-In-Fact

Date: September 5, 2017

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Page 10 of 12 – SEC Filing

Exhibit List

Exhibit A . Joint Filing Agreement.

Exhibit B. Item 8 Statement.

Exhibit C.(1) Power of Attorney.

(1) Power of Attorney previously filed as Exhibit 24 to a Form
3 with regard to Proteon Therapeutics, Inc. filed with the Securities and Exchange Commission on August 4, 2017 by Deerfield Special
Situations Fund, L.P., Deerfield Partners, L.P., Deerfield International Master Fund, L.P., Deerfield Private Design Fund III,
L.P., Deerfield Private Design Fund IV, L.P., Deerfield Mgmt, L.P., Deerfield Mgmt III, L.P., Deerfield Mgmt IV, L.P., Deerfield
Management Company, L.P., and James E. Flynn.

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Page 11 of 12 – SEC Filing

Exhibit A

Agreement

The undersigned agree that this
Schedule 13G, and all amendments thereto, relating to the Common Stock of Synlogic, Inc. shall be filed on behalf of the
undersigned.

DEERFIELD MANAGEMENT COMPANY, L.P.

By: Flynn Management LLC, General Partner

By: /s/ Jonathan Isler

       Jonathan Isler, Attorney-In-Fact

DEERFIELD MGMT III, L.P.

By: J.E. Flynn Capital III, LLC, General Partner

By: /s/ Jonathan Isler

       Jonathan Isler, Attorney-In-Fact

DEERFIELD PRIVATE DESIGN FUND III, L.P.

By: Deerfield Mgmt III, L.P., General Partner

By: J.E. Flynn Capital III, LLC, General Partner

By: /s/ Jonathan Isler

       Jonathan Isler, Attorney-In-Fact

JAMES E. FLYNN


/s/ Jonathan Isler 

Jonathan Isler, Attorney-In-Fact

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Page 12 of 12 – SEC Filing

Exhibit B

Due
to the relationships between them, the reporting persons hereunder may be deemed to constitute a “group” with one another for
purposes of Section 13(d)(3) of the Securities Exchange Act of 1934.

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