AMCP Nexus 2021: What the Future May Hold for Mavacamten

If mavacamten is approved and is affordable, it is likely to slot in as a second-line therapy for hypertrophic cardiomyopathy (HCM), a Mayo Clinic HCM expert said on Monday at a continuing education session on HCM at the AMCP Nexus 2021 meeting in Denver

Steve R. Ommen, M.D., FACC, FAHA, a professor of medicine at the Mayo Clinic College of Medicine in Rochester, Minnesota, and director of Mayo’s HCM clinic, said in a brief interview after the continuing education session that mavacamten “would probably be a therapy that patients could try if the first-line therapy doesn’t work.”

Ommen elaborated: “If your patient is failing beta blockers or calcium channel blockers, your discussion is probably, 'We’ve got options. We can give you disopyramide, here is the success rate, here is its downsides. We’ve got mavacamten, here is its success rate, here is its down sides. Or you could have surgery slash ablation, here’s its success rate, here is its down sides.'"

Ommen was chair of the writing committee for the HCM diagnosis and treatment guidelines issued In 2020 by the American Heart Association and the American College of Cardiology that emphasized shared decision making with patients when making HCM treatment choices.

The FDA is scheduled to decide on Bristol Myers Squibb’s application for approval of mavacamten in January 2022. The drug has received an extraordinary amount of attention partly because it would be the first agent designed to address the underlying pathology of HCM, not just the symptoms. Mavacamten inhibits myosin, a contractile protein that plays a role in the thickening of the heart muscle that characterizes HCM.

Bristol Myers Squibb sponsored the educational session at which Ommen spoke. Edward Gill, M.D., FASE, FAHA, FACC, FACP, FNLA, of the University of Colorado Hospital, and Patty Taddei-Allen, Pharm.D., MBA, BCACP, BCGP, vice president of clinical programs and services at WellDyne, also spoke.

Ommen noted that in the pivotal phase 3 trial of mavacamten, called Explorer-HCM, less than half (37%) of the patients treated with the medication in the 30-week trial reached the primary end point, a composite of a lab measure that is an indication of cardiac function with an improvement in functional status. In the placebo group, 17% of patients reached the primary end point. Ommen also mentioned that about 10% of patients in the mavacamten experienced a sharp decline in ejection fraction, which he said raises a question whether patients taking mavacamten might need to be monitored with regular echocardiograms.

One of the major concerns with HCM is the association with a heightened risk for sudden cardiac death. Some HCM patients get implantable cardioverter defibrillators as a preventive measure against a sudden cardiac event. Ommen commented that there is “no signal” from the Explorer-HCM trial that mavacamten reduces the risk of sudden cardiac death among HCM patients.