Ownership Submission
FORM 3
 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
  Hood Shana
 2. Date of Event Requiring Statement (Month/Day/Year)
01/19/2016		 3. Issuer Name and Ticker or Trading Symbol
Mast Therapeutics, Inc. [MSTX]
(Last)
(First)
(Middle)
3611 VALLEY CENTRE DRIVE, SUITE 500		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
General Counsel & VP
 5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

SAN DIEGO, CA 92130		 6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security
(Instr. 4)		 2. Amount of Securities Beneficially Owned
(Instr. 4)		 3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)		 4. Nature of Indirect Beneficial Ownership
(Instr. 5)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)		 2. Date Exercisable and Expiration Date
(Month/Day/Year)		 3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)		 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)		 6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Employee Stock Option (Right to Buy)   (1) 01/04/2026 Common Stock 409,000 $ 0.42 D  
Employee Stock Option (Right to Buy)   (2) 06/11/2025 Common Stock 215,800 $ 0.5 D  
Employee Stock Option (Right to Buy)   (3) 01/02/2025 Common Stock 176,500 $ 0.58 D  
Employee Stock Option (Right to Buy)   (4) 06/19/2024 Common Stock 93,650 $ 0.65 D  
Employee Stock Option (Right to Buy)   (5) 01/02/2024 Common Stock 25,600 $ 0.47 D  
Employee Stock Option (Right to Buy)   (6) 06/19/2023 Common Stock 95,500 $ 0.5 D  
Employee Stock Option (Right to Buy)   (7) 01/02/2023 Common Stock 22,400 $ 0.59 D  
Employee Stock Option (Right to Buy)   (8) 12/07/2021 Common Stock 37,450 $ 0.6 D  
Employee Stock Option (Right to Buy)   (9) 02/01/2021 Common Stock 27,069 $ 2.29 D  
Employee Stock Option (Right to Buy)   (10) 03/16/2020 Common Stock 11,250 $ 5.91 D  

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
Hood Shana
3611 VALLEY CENTRE DRIVE, SUITE 500
SAN DIEGO, CA 92130		       General Counsel & VP  

Signatures

/s/ Shana Hood 01/22/2016
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) This option vests and becomes exercisable in 48 substantially equal monthly installments on each monthly anniversary of January 4, 2016, subject to the reporting person's continued service with the issuer.
(2) This option vests and becomes exercisable in 48 substantially equal monthly installments on each monthly anniversary of June 11, 2015, subject to the reporting person's continued service with the issuer.
(3) This option vests and becomes exercisable in 48 substantially equal monthly installments on each monthly anniversary of January 2, 2015, subject to the reporting person's continued service with the issuer.
(4) This option vests and becomes exercisable in 48 substantially equal monthly installments on each monthly anniversary of June 19, 2014, subject to the reporting person's continued service with the issuer.
(5) This option vests and becomes exercisable in 48 substantially equal monthly installments on each monthly anniversary of January 2, 2014, subject to the reporting person's continued service with the issuer.
(6) This option vests and becomes exercisable in 48 substantially equal monthly installments on each monthly anniversary of June 19, 2013, subject to the reporting person's continued service with the issuer.
(7) This option vests and becomes exercisable in 48 substantially equal monthly installments on each monthly anniversary of January 2, 2013, subject to the reporting person's continued service with the issuer.
(8) This option vested and became exercisable in 48 substantially equal monthly installments. The first installment vested and became exercisable on January 8, 2012 and the final installment on December 8, 2015.
(9) This option vested and became exercisable as to one-fourth of the underlying shares on January 1, 2012, and thereafter in 36 substantially equal monthly installments such that it became fully vested and exercisable on January 1, 2015.
(10) This option vested and became exercisable as to one-fourth of the underlying shares on February 16, 2011, and thereafter in 36 substantially equal monthly installments such that it became fully vested and exercisable on February 16, 2014.

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