<SEC-DOCUMENT>0001209191-15-079124-index.html : 20151110
<SEC-HEADER>0001209191-15-079124.hdr.sgml : 20151110
<ACCEPTANCE-DATETIME>20151109164840
ACCESSION NUMBER:		0001209191-15-079124
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20151105
FILED AS OF DATE:		20151109
DATE AS OF CHANGE:		20151109

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Mast Therapeutics, Inc.
		CENTRAL INDEX KEY:			0001160308
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				841318182
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		3611 VALLEY CENTRE DRIVE
		STREET 2:		SUITE 500
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92130
		BUSINESS PHONE:		8585520866

	MAIL ADDRESS:	
		STREET 1:		3611 VALLEY CENTRE DRIVE
		STREET 2:		SUITE 500
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92130

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ADVENTRX PHARMACEUTICALS INC
		DATE OF NAME CHANGE:	20030613

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BIOKEYS PHARMACEUTICALS INC
		DATE OF NAME CHANGE:	20010928

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Greenleaf Peter
		CENTRAL INDEX KEY:			0001363683

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-32157
		FILM NUMBER:		151216342

	MAIL ADDRESS:	
		STREET 1:		ONE MEDIMMUNE WAY
		CITY:			GAITHERSBURG
		STATE:			MD
		ZIP:			20878
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc3.xml
<DESCRIPTION>FORM 3 SUBMISSION
<TEXT>
Document 1 - file: doc3.html

Document 1 - RAW XML: doc3.xml

</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24.3_613616
<SEQUENCE>2
<FILENAME>poa.txt
<DESCRIPTION>POA DOCUMENT
<TEXT>
Document 2 - file: poa.txt

</DOCUMENT>
</SEC-DOCUMENT>