Purified Poloxamer Granted Unique Nonproprietary Name (Vepoloxamer) By U.S. Adopted Names Council

SAN DIEGO, March 11, 2014 /PRNewswire/ -- Mast Therapeutics, Inc. (NYSE MKT: MSTX) announced today that the United States Adopted Names (USAN) Council has selected "vepoloxamer" as the unique non-proprietary (generic) name for the active pharmaceutical ingredient (API) in MST-188, the Company's lead product candidate.  Mast sought a unique name for its API to clearly identify it as different from non-purified poloxamers.  In support of its application, the Company argued that drug products containing non-purified poloxamers should not be substituted for MST-188 and that confusion between the two could have serious toxicity consequences. 

"In approving our application, we believe USAN recognizes that the active ingredient in MST-188 is a new substance, with a different safety profile to that found with non-purified material," said Brian M. Culley, the Company's Chief Executive Officer.  "The unique name associated with our products will help safeguard patients from exposure to safety or other risks resulting from substitution, as well as differentiate our products in the marketplace, should any be approved." 

Unlike discrete small molecules, polymers (including the active ingredient in MST-188) are molecularly diverse; that is, polymers contain chemical 'species' with varying structural characteristics.  The Company argued that, while the major species in its purified API and the non-purified starting material are the same, the refinement of polymer populations through the Company's proprietary manufacturing process that meets the Company's proprietary specifications (including the reduction of specific populations associated with renal dysfunction), results in a new substance with a different therapeutic index. 

About the USAN Council

The USAN Council, tri-sponsored by the American Medical Association, the United States Pharmacopeial Convention and the American Pharmacists Association, serves the health professions in the United States by selecting simple, informative and unique nonproprietary names for drugs by establishing logical nomenclature classifications based on pharmacological and/or chemical relationships.  In addition, the U.S. Food and Drug Administration (FDA) cooperates with and is represented on the USAN Council. The USAN Council aims for global standardization and unification of drug nomenclature and related rules to ensure that drug information is communicated accurately and unambiguously. 

About Mast Therapeutics

Mast Therapeutics, Inc. is a publicly traded biopharmaceutical company headquartered in San Diego, California.  The Company is leveraging the MAST (Molecular Adhesion and Sealant Technology) platform, derived from over two decades of clinical, nonclinical and manufacturing experience with purified and non-purified poloxamers, to develop MST-188, its lead product candidate, for serious or life-threatening diseases with significant unmet needs.  MST-188 is a cytoprotective, hemorheologic, anti-inflammatory and anti-thrombotic agent that has potential utility in diseases or conditions characterized by microcirculatory insufficiency (endothelial dysfunction and/or impaired blood flow). 

The Company is enrolling subjects in EPIC, a pivotal phase 3 study of MST-188 in sickle cell disease.  In early 2014, the Company plans to initiate a phase 2, clinical proof of concept study in acute limb ischemia that will evaluate whether MST-188 improves the effectiveness of existing thrombolytic agents.  The Company also is evaluating development options in heart failure.  More information can be found on the Company's web site at www.masttherapeutics.com.  (Twitter: @MastThera)

Mast Therapeutics™ and the corporate logo are trademarks of Mast Therapeutics, Inc.

Forward Looking Statements

Mast Therapeutics cautions you that statements included in this press release that are not a description of historical facts are forward-looking statements that are based on the Company's current expectations and assumptions. Such forward-looking statements include, but are not limited to, statements relating to the Company's ability to prevent or delay competitors from developing and obtaining regulatory approval of drug products based on versions of the API in MST-188, the prospects for a unique non-proprietary name to help safeguard patients from risks related to drug substitution or to provide a marketing advantage for the Company, should MST-188 receive regulatory approval, and the Company's development plans for MST-188 in heart failure and acute limb ischemia, including the timing of initiation of any clinical studies.  Among the factors that could cause or contribute to material differences between the Company's actual results and the expectations indicated by the forward-looking statements are risks and uncertainties that include, but are not limited to: the uncertainty of outcomes in ongoing and future studies of MST-188 and the risk that MST-188 may not demonstrate adequate safety, efficacy or tolerability in one or more such studies, including EPIC; delays in the commencement or completion of clinical studies, including as a result of difficulties in obtaining regulatory agency agreement on clinical development plans or clinical study design, opening trial sites, enrolling study subjects, manufacturing sufficient quantities of clinical trial material, being subject to a "clinical hold," and/or suspension or termination of a clinical study, including due to patient safety concerns or lack of funding; the potential for institutional review boards or the FDA or other regulatory agencies to require additional nonclinical or clinical studies prior to initiation of any planned phase 2 clinical study of MST-188; the potential that, even if clinical studies of MST-188 in one indication are successful, clinical studies in another indication may not be successful; the risk that, even if clinical studies are successful, the FDA or other regulatory agencies may determine they are not sufficient to support a new drug application; the Company's reliance on contract research organizations (CROs), contract manufacturing organizations (CMOs), and other third parties to assist in the conduct of important aspects of development of MST-188, including clinical studies, and regulatory activities for MST-188, and that such third parties may fail to perform as expected; the Company's ability to obtain additional funding on a timely basis or on acceptable terms, or at all; the potential for the Company to delay, reduce or discontinue current and/or planned development activities, including clinical studies, partner MST-188 at inopportune times or pursue less expensive but higher-risk and/or lower return development paths if it is unable to raise sufficient additional capital as needed; the risk that, even if the Company successfully develops MST-188 in one or more indications, it may not realize commercial success with its products and may never generate revenue sufficient to achieve profitability; the risk that the Company is not able to adequately protect its intellectual property rights relating to the MAST platform and MST-188 and prevent competitors from duplicating or developing equivalent versions of its product candidates, including MST-188; and other risks and uncertainties more fully described in the Company's press releases and periodic filings with the Securities and Exchange Commission. The Company's public filings with the Securities and Exchange Commission are available at www.sec.gov.

You are cautioned not to place undue reliance on forward-looking statements, which speak only as of the date when made. Mast Therapeutics does not intend to revise or update any forward-looking statement set forth in this press release to reflect events or circumstances arising after the date hereof, except as may be required by law.

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SOURCE Mast Therapeutics, Inc.

Ioana C. Hone (ir@mastthera.com), 858-552-0866 Ext. 303