MyoKardia Shares Surge 32% On Positive Mid-stage Trial Results For Heart Muscle Disease

MyoKardia Inc. shares surged 31.8% in premarket trade Monday on positive mid-stage clinical trial results for its mavacamten therapy. Patients on the therapy met the trial's primary endpoint and key secondary endpoints in the phase 2 trial, the company said. MyoKardia expects to start its next clinical trial by the end of this year, depending on discussions with the Food and Drug Administration. The latest data came from the clinical trial's first patient cohort, in which 11 patients were enrolled and 10 patients completed the study. The one patient in question had a history of atrial fibrillation and experienced an episode of atrial fibrillation during the trial. All other safety problems were mild to moderate, according to MyoKardia, and "a majority of the [adverse events] were deemed to be unrelated to the study drug." The Independent Data Monitoring Committee reviewed the trial's safety data and recommended the study be continued, the company said. Mavacamten is intended for symptomatic, obstructive hypertrophic cardiomyopathy, which occurs when heart muscle cells enlarge and block blood flow, and is a common cause of sudden cardiac arrest, according to the American Heart Association. MyoKardia shares have surged 20.4% over the last three months, compared with a 3.2% rise in the S&P 500 .