UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

 

SCHEDULE 13G

(Rule 13d-102)

 

Information Statement Pursuant to Rules 13d-1 and 13d-2

Under the Securities Exchange Act of 1934

(Amendment No.      )*

 

Sienna Biopharmaceuticals, Inc.

 

(Name of Issuer)

 

Common stock, par value $0.0001 per share

 

(Title of Class of Securities)

 

82622H108

 

(CUSIP Number)

 

July 27, 2017

 

Date of Event Which Requires Filing of the Statement

 

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

 

¨Rule 13d-1(b)
xRule 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 disclosures provided in a prior cover page.

 

The information required on 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).

 

 

 

  

CUSIP No. 82622H108 13G Page 2 of 13 Pages

   

 

1.

 

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

 

Partner Fund Management, L.P.

 

2.

 

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)      ¨

(b)     x

 

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

 

1,580,532 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

 

9.

 

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

 

10.

 

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

¨

 

11.

 

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

 

7.7%1

 

 

 

12.

 

TYPE OF REPORTING PERSON

IA; PN

 

 

1The percentages reported in this Schedule 13G are based upon 20,538,258 shares of common stock outstanding (composed of (i) 19,888,258 shares outstanding following completion of the issuer's initial public offering according to the prospectus supplement filed by the issuer with the Securities and Exchange Commission ("SEC") on July 27, 2017, plus (ii) 650,000 additional shares outstanding as a result of the underwriters' exercise of their option according to the Form 8-K filed by the issuer with the SEC on August 1, 2017). All of the other numbers and percentages reported in this Schedule 13G are as of 9:00 a.m. (ET) on the date of filing.

 

 

 

 

CUSIP No. 82622H108 13G Page 3 of 13 Pages

 

 

1.

 

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

 

Partner Fund Management GP, LLC

 

2.

 

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)      ¨

(b)     x

 

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

 

1,580,532 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

 

9.

 

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

 

10.

 

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

¨

 

11.

 

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

 

7.7%

 

 

 

12.

 

TYPE OF REPORTING PERSON

OO

 

 

 

 

CUSIP No. 82622H108 13G Page 4 of 13 Pages

  

 

1.

 

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

 

Partner Investment Management, L.P.

 

2.

 

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)      ¨

(b)     x

 

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

 

300,940 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

 

9.

 

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

 

10.

 

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

¨

 

11.

 

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

 

1.5%

 

 

 

12.

 

TYPE OF REPORTING PERSON

IA; PN

 

 

 

  

CUSIP No. 82622H108 13G Page 5 of 13 Pages

  

 

1.

 

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

 

Partner Investment Management GP, LLC

 

2.

 

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)      ¨

(b)     x

 

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

 

300,940 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

 

9.

 

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

 

10.

 

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

¨

 

11.

 

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

 

1.5%

 

 

 

12.

 

TYPE OF REPORTING PERSON

OO

 

 

 

 

CUSIP No. 82622H108 13G Page 6 of 13 Pages

 

 

1.

 

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

 

Brian D. Grossman

 

2.

 

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)      ¨

(b)     x

 

3.

 

SEC USE ONLY

 

 

4.

 

CITIZENSHIP OR PLACE OF ORGANIZATION

U.S. Citizen

 

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

 

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

 

1,881,472 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

 

9.

 

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

 

10.

 

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

¨

 

11.

 

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

 

9.2%

 

 

 

12.

 

TYPE OF REPORTING PERSON

IN

 

 

 

 

CUSIP No. 82622H108 13G Page 7 of 13 Pages

  

 

1.

 

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

 

Christopher M. James

 

2.

 

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)      ¨

(b)     x

 

3.

 

SEC USE ONLY

 

 

4.

 

CITIZENSHIP OR PLACE OF ORGANIZATION

U.S. Citizen

 

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

 

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

 

1,881,472 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

 

9.

 

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

 

10.

 

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

¨

 

11.

 

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

 

9.2%

 

 

 

12.

 

TYPE OF REPORTING PERSON

IN

 

 

 

  

CUSIP No. 82622H108 13G Page 8 of 13 Pages

  

Item 1(a)Name of Issuer

Sienna Biopharmaceuticals, Inc.

 

Item 1(b)Address of Issuer’s Principal Executive Offices
30699 Russell Ranch Road, Suite 140, Westlake Village, California 91362

 

Item 2(a)Name of Person Filing

This Schedule 13G is being jointly filed by Partner Fund Management, L.P. (“PFM”), Partner Fund Management GP, LLC (“PFM-GP”), Partner Investment Management, L.P. (“PIM”), Partner Investment Management GP, LLC (“PIM-GP”), Brian D. Grossman (“Grossman”) and Christopher M. James (“James” and, collectively with PFM, PFM-GP, PIM, PIM-GP and Grossman, the “Reporting Persons”) with respect to shares of common stock of the above-named issuer owned by PFM Healthcare Emerging Growth Master Fund, L.P., a Cayman Islands limited partnership (“HEGM”), PFM Healthcare Opportunities Master Fund, L.P., a Cayman Islands limited partnership (“HCOPP”), PFM Healthcare Principals Fund, L.P., a Delaware limited partnership (“HCP”), PFM Healthcare Master Fund, L.P., a Cayman Islands limited partnership (“HCM”), PFM Healthcare Long Master Fund, L.P., a Cayman Islands limited partnership (“HCLM”), and Partner Investments, L.P., a Delaware limited partnership (“PI” and, collectively with HEGM, HCOPP, HCP, HCM and HCLM, the “Funds”).

 

PFM is the investment advisor for HEGM, HCM, HCLM and HCOPP. PIM is the investment advisor for HCP and PI. PFM-GP and PIM-GP are, respectively, the general partners of PFM and PIM. Grossman is the portfolio manager for the health care strategy for the Funds. James is the portfolio manager for the diversified strategy for the Funds. Grossman and James are co-managing members of PFM-GP and PIM-GP.

 

The filing of this statement shall not be construed as an admission that any of the Reporting Persons is the beneficial owner of any securities covered by the statement other than the securities actually owned by such person (if any).

 

Item 2(b)Address of Principal Business Office
The address of the principal business office of each of the Reporting Persons is c/o Partner Fund Management, L.P., 4 Embarcadero Center, Suite 3500, San Francisco, CA 94111.

 

Item 2(c)Citizenship
Each of PFM and PIM is organized as a limited partnership under the laws of the State of Delaware. Each of PFM-GP and PIM-GP is organized as a limited liability company under the laws of the State of Delaware. Each of Grossman and James is a U.S. citizen.

 

 

 

 

CUSIP No. 82622H108 13G Page 9 of 13 Pages

 

Item 2(d)Title of Class of Securities

Common stock, $0.0001 par value

 

Item 2(e)CUSIP Number
82622H108

 

Item 3If this statement is filed pursuant to Rules 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;
       
  (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: ____________.

 

 

 

 

CUSIP No. 82622H108 13G Page 10 of 13 Pages

  

Item 4Ownership

 

A.Partner Fund Management, L.P. and Partner Fund Management GP, LLC

 

(a)

PFM and PFM-GP may be deemed to beneficially own 1,580,532 shares of Common Stock.

 

(b)The number of shares PFM and PFM-GP may be deemed to beneficially own constitutes approximately 7.7% of the Common Stock outstanding.

 

(c)Number of shares as to which such person has:

 

(i)sole power to vote or to direct the vote: 0

 

(ii)shared power to vote or to direct the vote: 1,580,532

 

(iii)sole power to dispose or to direct the disposition of: 0

 

(iv)shared power to dispose or to direct the disposition of: 1,580,532

 

B.Partner Investment Management, L.P. and Partner Investment Management GP, LLC

 

(a)PIM and PIM-GP may be deemed to beneficially own 300,940 shares of Common Stock.

 

(b)The number of shares PIM and PIM-GP may be deemed to beneficially own constitutes approximately 1.5% of the Common Stock outstanding.

 

(c)Number of shares as to which such person has:

 

(i)sole power to vote or to direct the vote: 0

 

(ii)shared power to vote or to direct the vote: 300,940

 

(iii)sole power to dispose or to direct the disposition of: 0

 

(iv)shared power to dispose or to direct the disposition of: 300,940

 

 

 

 

CUSIP No. 82622H108 13G Page 11 of 13 Pages

 

C.Brian D. Grossman

 

(a)Grossman may be deemed to beneficially own 1,881,472 shares of Common Stock.

 

(b)The number of shares Grossman may be deemed to beneficially own constitutes approximately 9.2% of the Common Stock outstanding.

 

(c)Number of shares as to which such person has:

 

(i)sole power to vote or to direct the vote: 0

 

(ii)shared power to vote or to direct the vote: 1,881,472

 

(iii)sole power to dispose or to direct the disposition of: 0

 

(iv)shared power to dispose or to direct the disposition of: 1,881,472

 

D.Christopher M. James

 

(a)James may be deemed to beneficially own 1,881,472 shares of Common Stock.

 

(b)The number of shares James may be deemed to beneficially own constitutes approximately 9.2% of the Common Stock outstanding.

 

(c)Number of shares as to which such person has:

 

(i)sole power to vote or to direct the vote: 0

 

(ii)shared power to vote or to direct the vote: 1,881,472

 

(iii)sole power to dispose or to direct the disposition of: 0

 

(iv)shared power to dispose or to direct the disposition of: 1,881,472

 

Item 5Ownership 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 5 percent of the class of securities, check the following ¨.

 

Item 6Ownership of More than Five Percent on Behalf of Another Person
Not Applicable

 

Item 7Identification and Classification of the Subsidiary which Acquired the Security Being Reported on by the Parent Holding Company
See Item 2 above

 

Item 8Identification and Classification of Members of the Group
Not Applicable

 

 

 

 

CUSIP No. 82622H108 13G Page 12 of 13 Pages

  

Item 9Notice of Dissolution of Group
Not Applicable

 

Item 10Certification
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.

 

 

 

 

CUSIP No. 82622H108 13G Page 13 of 13 Pages

  

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

 

Dated this 7th day of August, 2017.

 

PARTNER FUND MANAGEMENT, L.P.   PARTNER FUND MANAGEMENT GP, LLC
       
By: Partner Fund Management GP, LLC   By: /s/ Darin Sadow
  its general partner     Darin Sadow, Authorized Signatory
         
By: /s/ Darin Sadow      
  Darin Sadow, Authorized Signatory      
     
PARTNER INVESTMENT MANAGEMENT, L.P.   PARTNER INVESTMENT MANAGEMENT GP, LLC
     
By: Partner Investment Management GP, LLC,   By: /s/ Darin Sadow
  its general partner     Darin Sadow, Authorized Signatory
       
By: /s/ Darin Sadow    
  Darin Sadow, Authorized Signatory    
     
BRIAN D. GROSSMAN   CHRISTOPHER M. JAMES
     
By: /s/ Darin Sadow   By: /s/ Darin Sadow
  Darin Sadow, attorney-in-fact*     Darin Sadow, attorney-in-fact**

  

 

*Darin Sadow is signing on behalf of Brian Grossman as attorney-in-fact pursuant to a power of attorney dated August 4, 2011, and incorporated by reference herein. The power of attorney was filed as an attachment to a filing by certain of the Reporting Persons on Schedule 13G for K-V Pharmaceutical Company on August 5, 2011.

 

**Darin Sadow is signing on behalf of Christopher M. James as attorney-in-fact pursuant to a power of attorney dated August 4, 2011, and incorporated by reference herein. The power of attorney was filed as an attachment to a filing by certain of the Reporting Persons on Schedule 13G for K-V Pharmaceutical Company on August 5, 2011.

  

 

 

 

EXHIBIT 99.1

 

JOINT FILING AGREEMENT

 

The undersigned hereby agree that the Statement on Schedule 13G filed herewith (and any amendments thereto), relating to the common stock of Sienna Biopharmaceuticals, Inc., a Delaware corporation, is being filed jointly with the Securities and Exchange Commission pursuant to Rule 13d-1(c) under the Securities Exchange Act of 1934, as amended, on behalf of each of the undersigned.

 

This Agreement may be executed in counterparts and each of such counterparts taken together shall constitute one and the same instrument.

 

Dated this 7th day of August, 2017.

 

PARTNER FUND MANAGEMENT, L.P.   PARTNER FUND MANAGEMENT GP, LLC
     
By: Partner Fund Management GP, LLC   By: /s/ Darin Sadow
  its general partner     Darin Sadow, Authorized Signatory
       
By: /s/ Darin Sadow    
  Darin Sadow, Authorized Signatory    
     
PARTNER INVESTMENT MANAGEMENT, L.P.   PARTNER INVESTMENT MANAGEMENT GP, LLC
     
By: Partner Investment Management GP, LLC,   By: /s/ Darin Sadow
  its general partnerBy:     Darin Sadow, Authorized Signatory
       
By: /s/ Darin Sadow    
  Darin Sadow, Authorized Signatory    
     
BRIAN D. GROSSMAN   CHRISTOPHER M. JAMES
     
By: /s/ Darin Sadow   By: /s/ Darin Sadow
  Darin Sadow, attorney-in-fact     Darin Sadow, attorney-in-fact