Mast Therapeutics Signs Definitive Agreement To Acquire Aires Pharmaceuticals, Inc.

SAN DIEGO, Feb. 10, 2014 /PRNewswire/ -- Mast Therapeutics, Inc. (NYSE MKT: MSTX) today announced that it has entered into a definitive agreement to acquire Aires Pharmaceuticals, Inc. (Aires), a privately-held, clinical stage pharmaceutical company developing therapies to treat pulmonary vascular disorders such as pulmonary arterial hypertension and pulmonary hypertension due to heart failure. Aires' lead product, AIR001, is an intermittently nebulized formulation of nitrite and has orphan drug status with the U.S. Food and Drug Administration and the European Medicines Agency for the treatment of pulmonary arterial hypertension. 

"The acquisition of Aires will enhance our pipeline with a phase 2 asset with more than 120 human subject exposures and which is a strategic complement to our lead program, MST-188. With total consideration of approximately 6% of Mast equity, it represents excellent value for our stockholders," stated Brian M. Culley, Chief Executive Officer of Mast Therapeutics, Inc.

"Nitrite has demonstrable beneficial properties, including vasodilation and the reduction of inflammation and undesirable cell growth. These are important therapeutic objectives and an ideal complement to MST-188 and its ability to improve blood flow and seal cellular membranes. In addition, we intend to investigate the hypothesis that AIR001 positively affects mitochondrial activity and myocyte energetics. With this acquisition, and the initiation of our phase 2 trial of MST-188 for the treatment of acute limb ischemia later this quarter, we are taking additional steps towards building a sustainable company with a valuable pipeline addressing significant unmet needs in both specialized and major markets," Mr. Culley continued.

"Another highlight of this acquisition is its favorable economics. Aires had completed several venture financings, including a $20 million Series B round. We are paying significantly less than that to acquire the program and we currently estimate that our development costs for AIR001 for the first 12 months will be approximately $2 million.  Our estimated costs for AIR001 will change as we refine our development strategy over the next few months, but Aires is expected to contribute approximately $3 million of net cash at the closing of the merger, so, as currently contemplated, our first year of development of AIR001 will not require additional capital investment by Mast," Mr. Culley concluded.

Under the terms of the all-stock transaction, Aires would become a wholly-owned subsidiary of Mast Therapeutics, Inc. in exchange for shares of Mast common stock representing approximately 6% of Mast's outstanding common stock, 80% of which would be subject to a six-month holdback for certain indemnification claims of Mast. There are no milestone obligations payable to Aires.  The acquisition is expected to close in February 2014, subject to customary closing conditions.

About AIR001
AIR001 (sodium nitrite) inhalation solution, also known as Aironite®, is an intermittently nebulized formulation of nitrite. Under hypoxic conditions, AIR001 is converted to nitric oxide.  Nitrite mediated nitric oxide formation has several beneficial effects, including dilation of blood vessels and reduction of inflammation and undesirable cell growth. 

AIR001 has been granted orphan drug status by the U.S. Food and Drug Administration and the European Medicines Agency for the treatment of pulmonary arterial hypertension.

Conference Call Information
Interested parties may access the conference call by dialing (877) 870-4263 from the U.S. and (412) 317-0790 from outside the U.S. and should request the Mast Therapeutics Corporate Update Call. The webcast will be available live via the Internet by accessing the Investors section of Mast's website at www.masttherapeutics.com/investors/. Replays of the webcast will be available on the Company's website for 30 days and a phone replay will be available through March 5, 2014 by dialing (877) 344-7529 from the U.S. and (412) 317-0088 from outside the U.S. and entering conference reference number 10040517. 

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 the first quarter of 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 is also evaluating development options for MST-188 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.  Aironite® is a trademark of Aires Pharmaceuticals, 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 completion of the acquisition of Aires Pharmaceuticals, the amount of the Company's common stock issuable as merger consideration, the amount of Aires' net cash at closing of the merger, the Company's development plans for AIR001, as well as the cost and timing of activities related to those plans, and the Company's development plans for MST-188 in acute limb ischemia and heart failure, 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 potential that the acquisition may be delayed and/or terminated; the potential that the number of shares of the Company's common stock issuable to Aires' stockholders as merger consideration will be greater or less than the Company's estimated amount as a result of differences between the Company's estimate of and Aires' actual net cash at closing and/or the volatility in the closing sales prices of the Company's common stock; the uncertainty of outcomes in ongoing and future studies of any investigational drug, including MST-188 and AIR001, and the risk that they 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 or AIR001; the potential that, even if clinical studies of a product candidate 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 its product candidates, 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 its product candidates 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 a product candidate 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, following the acquisition, AIR001, and prevent competitors from duplicating or developing equivalent versions of its product candidates; 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

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