Obstructive Hypertrophic Cardiomyopathy Study from MyoKardia Meets Primary, Secondary Endpoints

MyoKardia announced positive topline data from the company’s Phase 3 pivotal EXPLORER-HCM clinical trial of mavacamten for the treatment of patients with symptomatic, obstructive hypertrophic cardiomyopathy (HCM).  Mavacamten demonstrated a robust treatment effect: the primary and all secondary endpoints of the EXPLORER trial were met with statistical significance (p≤0.0006 for all endpoints). Mavacamten was well tolerated, and meaningful improvements in symptoms, functional status and quality of life, as well as reduction or elimination in obstruction of the left ventricle, were observed among patients on treatment versus placebo.

“The extraordinary data from the EXPLORER pivotal trial confirm mavacamten’s ability to relieve dynamic outflow obstruction, control symptoms and improve quality of life in patients with hypertrophic cardiomyopathy," said Iacopo Olivotto, M.D., Careggi University Hospital and lead clinical investigator for the EXPLORER-HCM clinical trial. "HCM is the most common inherited cardiovascular disease, and patients face an uncertain journey that all too frequently includes debilitating symptoms, as well as serious complications, such as heart failure, stroke and cardiac arrest.  Mavacamten is the first drug developed to target the specific molecular defect of the disease.  EXPLORER represents a major achievement toward a precision-medicine approach in cardiomyopathies and should provide great hope to a community painfully aware of the lack of disease-specific treatment options.”

The 30-week treatment with mavacamten resulted in a highly statistically significant outcome relative to placebo (p=0.0005) for the primary endpoint in the EXPLORER-HCM trial, a composite functional analysis designed to capture the treatment effect of mavacamten relative to placebo on both symptoms and cardiac function.

All secondary endpoints also demonstrated statistically significant and clinically meaningful improvements for mavacamten as compared to placebo.  Secondary endpoints in the EXPLORER-HCM trial evaluated improvements in post-exercise left ventricular outflow tract (LVOT) peak gradient (p<0.0001), New York Heart Association (NYHA) functional classification (p<0.0001), peak VO2 (p=0.0006), the Kansas City Cardiomyopathy Clinical Summary Score (KCCQ-CSS) (p<0.0001), and the HCM Symptom Questionnaire Shortness of Breath Domain Score (p<0.0001).