– Study will evaluate whether MST-188 improves the effectiveness of rt-PA
– Represents second clinical-stage program for MST-188
– Potential application in other settings in which rt-PA is used

SAN DIEGO, CA, USA I March 26, 2014 I Mast Therapeutics, Inc. (NYSE MKT: MSTX) announced today that it has initiated a phase 2, clinical proof-of-concept study of MST-188 in combination with recombinant tissue plasminogen activator (rt-PA) in patients with acute lower limb ischemia.  Acute limb ischemia (ALI), an acute complication of peripheral arterial disease, describes a sudden decrease in perfusion of a limb, typically in the legs, that often threatens viability of the limb.  Patients presenting with ALI have a poor short-term outlook, with 30-day amputation rates as high as 30% and a mortality rate around 15%.  MST-188 for the treatment of ALI has been granted orphan drug designation by the U.S. Food and Drug Administration. 

Martin Emanuele, PhD, Senior Vice President, Development, said: “Numerous experimental models, as well as clinical studies, demonstrate that MST-188 facilitates thrombolysis, repairs damaged cell membranes, and improves microvascular blood flow.  When combined with rt-PA, we believe these activities will translate into faster thrombolysis in patients with ALI and in other acute thrombotic events such as stroke, while at the same time reducing vessel re-occlusion, reperfusion injury, and tissue necrosis.” 

Brian M. Culley, Chief Executive Officer, said: “Initiating the ALI study represents further execution of our long-term strategy to maximize the value of MST-188 through its development in multiple areas of significant unmet medical need.  I congratulate our clinical operations team for initiating this study consistent with our guidance, while at the same time opening 40 clinical sites in the U.S., as well as clinical sites in multiple countries outside the U.S., in our pivotal phase 3 EPIC study in sickle cell disease.”

About the Phase 2 Study
The study will enroll approximately 60 patients from approximately 15 sites within and outside the U.S. with Rutherford Category IIa and IIb acute lower limb ischemia receiving catheter-directed rt-PA and compare a high and low dose of MST-188 against rt-PA alone. The primary objectives are to evaluate the safety and efficacy of MST-188 in combination with rt-PA and whether MST-188 results in more rapid thrombolysis and tissue perfusion. Secondary objectives are to assess the clinically-meaningful benefit of MST-188 in combination with rt-PA by measures such as duration of thrombolytic therapy, amputation-free survival, target limb re-interventions, and the need for endovascular or open surgical re-interventions. These objectives will be measured through up to 90 days of follow-up. The study is expected to take approximately 18 months to enroll.

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, and has initiated a phase 2, clinical proof of concept study to evaluate whether MST-188 improves the effectiveness of rt-PA in patients with acute limb ischemia.  The Company also is developing MST-188 in heart failure and plans to announce its clinical development plans in this indication in the second half of 2014.  More information can be found on the Company’s web site at www.masttherapeutics.com.  (Twitter: @MastThera)

SOURCE: Mast Therapeutics