MyoKardia’s Phase II trial for oHCM drug meets endpoints


MyoKardia has reported positive top-line results from the first cohort of its Phase II PIONEER-HCM clinical trial of mavacamten in patients with symptomatic, obstructive hypertrophic cardiomyopathy (oHCM).

Mavacamten is an oral, allosteric modulator of cardiac myosin and received orphan drug designation from the US Food and Drug Administration (FDA) for symptomatic oHCM in April last year.

The open-label Phase II trial met the primary endpoint with a statistically significant improvement of change in post-exercise peak left ventricular outflow tract (LVOT) gradient from baseline to week 12. It also met the key secondary endpoints.

PIONEER-HCM is designed to evaluate the efficacy, safety, pharmacokinetics, pharmacodynamics and tolerability of mavacamten. The first patient cohort enrolled a total of 11 patients, ten of which completed the trial.

All ten subjects are reported to have experienced a decrease in post-exercise peak LVOT gradient from a baseline mean of 125mmHg, following treatment for 12 weeks.

"We believe these results further demonstrate the potential of mavacamten in oHCM and we intend to move decisively and with urgency to develop this potential therapy for patients."

The trial included two dosing cohorts, one for a 10mg or 15mg daily dose of mavacamten with discontinued beta blocker therapy, and another for a lower daily dose with the continuation of beta blocker therapy.

In addition to the primary endpoint, the trial included other endpoints such as the change from baseline to week 12 in peak VO2, VE/VCO2, NYHA Class, NT-proBNP, as well as safety endpoints of treatment-related adverse events (AE), changes from baseline in laboratory test results, vital signs, and electrocardiograms.

MyoKardia chief medical officer Marc Semigran said: “We believe these results further demonstrate the potential of mavacamten in oHCM and we intend to move decisively and with urgency to develop this potential therapy for patients.

“We look forward to discussing with FDA the potential for EXPLORER-HCM to serve as a pivotal study.”

Expected to commence by the end of this year, the EXPLORER-HCM trial will be the next stage in the development of mavacamten for symptomatic oHCM.

The firm has already concluded enrolment for the second cohort of PIONEER-HCM and expects to report top-line findings from this cohort in the first quarter of next year.