Pilot Study Designed to Enable Progression to Larger Phase 2 Trial to Finalize Dosing and Endpoints Prior to Single Pivotal StudyTrial Will Assess 12-week Safety and Tolerability in Outpatient Setting; Topline Data Expected in Second Half of 2017 SOUTH SAN FRANCISCO, Calif., Nov. 02, 2016 (GLOBE NEWSWIRE) -- MyoKardia, Inc. (Nasdaq:MYOK), a clinical stage biopharmaceutical company pioneering a precision medicine approach for the treatment of heritable cardiovascular diseases, today announced dosing of the first patient in its Phase 2 PIONEER-HCM study of MYK-461. PIONEER-HCM is assessing safety, tolerability and efficacy of MYK-461 in patients with symptomatic, obstructive hypertrophic cardiomyopathy (oHCM). The U.S. Food and Drug Administration (FDA) has granted the company Orphan Drug Designation for MYK-461 for the treatment of symptomatic oHCM. Relationships among important disease biomarkers such as contractility, left ventricular outflow tract (LVOT) gradient and anticipated registrable endpoints of functional capacity and clinical symptoms are to be studied in the 12-week trial. Topline data from PIONEER-HCM is expected in the second half of 2017. "The initiation of PIONEER-HCM is an important milestone for MyoKardia and for patients with oHCM," said Tassos Gianakakos, chief executive officer. "PIONEER-HCM was designed to provide important outpatient safety support and operational insights that we believe will allow for more efficient subsequent clinical studies. PIONEER will generate data relating to a wide range of clinically meaningful measurements, including those we believe appropriate to support a new drug application for MYK-461 in oHCM. Furthermore, we expect PIONEER to help enable future studies evaluating MYK-461 in both non-obstructive and pediatric HCM patients. This is an important and exciting step toward potentially providing the first targeted therapy designed to correct the underlying biomechanical cause of this debilitating disease." PIONEER-HCM is planned to assess the effect of multiple doses of MYK-461 in symptomatic oHCM patients. The primary endpoint of PIONEER-HCM is the level of reduction in post-exercise LVOT gradient over 12 weeks of drug exposure. PIONEER-HCM will also explore the relationship between reduction in contractility and LVOT gradient, endpoints measuring functional capacity (i.e., exercise) and clinical symptoms in addition to gathering safety and tolerability data on MYK-461 in an outpatient setting.