EXPLORER-HCM Trial finds substantial health status improvements with mavacamten in patients with symptomatic obstructive hypertrophic cardiomyopathy (oHCM)

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Saint Luke's Mid America Heart Institute shared trial findings at American College of Cardiology’s 2021 Scientific Session

The benefits observed were amongst the largest we have ever seen from a medication to improve the symptoms, function and quality of life of patients with heart failure.

The EXPLORER-HCM (Evaluate Mavacamten (MYK-461) in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy) Randomized Clinical Trial has shown significant improvement in the symptoms, function, and quality of life in patients with obstructive hypertrophic cardiomyopathy (oHCM) with taking mavecamten. This comes following no major advances for treating oHCM in more than 30 years, where the primary goals of treatment are to improve patients’ health status, their symptoms, function and quality of life.

EXPLORER-HCM was completed in May 2020. A detailed analysis, based upon the Kansas City Cardiomyopathy Questionnaire developed by Dr. John Spertus at Saint Luke’s Mid America Heart Institute, were presented publicly by him for the first time at the American College of Cardiology’s 2021 Scientific Session Late-Breaking Clinical Trials on May 16, 2021 and published in The Lancet.

Hypertrophic cardiomyopathy is a complex type of heart disease that causes a thickening of the heart muscle. The common but largely underrecognized genetic condition is a chronic disease that can worsen over time, leading to poor function, quality of life, and long-term complications. People with oHCM have an increased risk of developing atrial fibrillation, heart failure and sudden cardiac arrest.

The EXPLORER-HCM clinical trial, the largest placebo-controlled trial in oHCM to date, was designed to test the impact of mavecamten, a first-in-class cardiac myosin inhibitor, on patients’ physical functioning and health status. The phase 3, double-blind, randomized trial was conducted at 68 cardiovascular centers in 13 countries. Participants were randomly assigned to take mavacamten or a placebo once daily over 30 weeks with an 8-week washout period.

Patients with symptomatic oHCM who took mavacamten showed substantial improvements in physical function, symptom relief, and quality of life, as measured by the Kansas City Cardiomyopathy Questionnaire. More than one-third of patients on mavecamten showed a very large improvement in the KCCQ score compared to those on the placebo. Benefits were observed early after treatment and notably regressed once treatment was stopped.

“It is a remarkable advance to the limited resources available to treat these patients,” said Dr. Spertus. “The benefits observed were amongst the largest we have ever seen from a medication to improve the symptoms, function and quality of life of patients with heart failure. Finding that these benefits dissipated after stopping medication further supports the direct benefits of treatment and underscores the potential for this new treatment to help patients with oHCM.”

The study was funded by MyoKardia Inc., a wholly owned subsidiary of Bristol Myers Squibb.

Mavacamten, which is manufactured by Bristol Myers Squibb, is an investigational oral therapy that is not yet approved for use by the FDA.

The full article in the Lancet can be read here:

Saint Luke’s Mid America Heart Institute, a member of Saint Luke’s Health System and a teaching affiliate of the University of Missouri-Kansas City, is one of the preeminent cardiovascular programs in the country. Its legacy of innovation began more than 35 years ago when it opened as the nation’s first heart hospital. Since then, the Heart Institute has earned a world-wide reputation for excellence in the treatment of heart disease, including interventional cardiology, cardiovascular surgery, imaging, heart failure, transplant, heart disease prevention, women’s heart disease, electrophysiology, outcomes research, and health economics. With more than 60 full-time board certified cardiovascular specialists on staff, the Heart Institute offers one of the largest heart failure/heart transplant programs in the country, has the largest experience with transcatheter aortic valve replacement in the Midwest, and is a global teaching site for the newest approaches to opening challenging blocked arteries using minimally invasive techniques.

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Laurel Gifford
Saint Luke's Health System
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