Stock Update (NYSEMKT:MSTX): Here’s Why Mast Therapeutics Inc Shares Crashed 84%

Tuesday turned out to be a nightmare for shareholders of Mast Therapeutics Inc (NYSEMKT:MSTX), as the biotech company disclosed that its Phase 3 clinical study of its investigational new drug vepoloxamer (also known as MST-188) for the treatment of individuals with sickle cell disease experiencing vaso-occlusive crisis (VOC) did not meet its primary efficacy endpoint of demonstrating a statistically significant reduction in the mean duration of VOC (82 hours in the vepoloxamer group compared to 78 hours in the placebo group in the intent-to-treat population (p=0.09)).

There were no statistically significant differences between treatment groups in the intent-to-treat population across the two secondary efficacy endpoints, rate of re-hospitalization for VOC and the occurrence of acute chest syndrome. Consistent with previously conducted studies, vepoloxamer was generally well tolerated with no statistically significant differences in treatment-related serious adverse events in the vepoloxamer group compared to the placebo group. No deaths occurred on the study.

Mast Therapeutics shares reacted to the disappointing news, crashing nearly 84% to $0.093 in after-hours trading.

“We are exceedingly disappointed with these top-line results. While clearly not the outcome we wanted, we believe the insights and data from the largest placebo-controlled clinical trial ever completed in sickle cell disease will substantially advance the understanding of vaso-occlusive crisis and the still maturing clinical science necessary to support the development of new therapeutics for this debilitating disease,” statedBrian M. Culley, the Company’s Chief Executive Officer. “We wish to reiterate our sincere appreciation for all of the patients, caregivers, and others who aided us in conducting this informative study.”

“These analyses are limited to just top-line data, so in the coming weeks the Company intends to review the full data set from EPIC. In addition, we plan to perform an interim analysis of the ongoing heart failure trial of vepoloxamer. However, based on the data we’ve seen to date, we expect we will terminate all clinical development of vepoloxamer. Consequently, while we evaluate our options, we intend to significantly and immediately reduce our operating expenses and continue our efforts with AIR001, our lead asset in heart failure with preserved ejection fraction, which currently is the subject of a 100-patient phase 2 study expected to complete enrollment by the end of 2017,” continued Mr. Culley. (Original Source)

On the ratings front, MSTX stock has been the subject of a number of recent research reports. In a report issued on September 12, Maxim analyst Jason McCarthy reiterated a Buy rating on MSTX, with a price target of $5.00, which represents a potential upside of 747.5% from where the stock closed today. Separately, on August 2, Roth Capital’s Michael Higgins reiterated a Buy rating on the stock and has a price target of $2.

According to, which ranks over 7,500 financial analysts and bloggers to gauge the performance of their past recommendations, Jason McCarthy and Michael Higgins have a total average return of 1.6% and 1.4% respectively. McCarthy has a success rate of 43% and is ranked #1472 out of 4166 analysts, while Higgins has a success rate of 51% and is ranked #1781.

Mast Therapeutics is a biopharmaceutical company, which engages in developing novel therapies for serious or life-threatening diseases with significant unmet needs. It provides products MST-188 has cytoprotective and hemorheologic properties and inhibits inflammatory processes and thrombosis. 


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