FDA accepts mavacamten (Camzyos) application for adolescent obstructive hypertrophic cardiomyopathy

The US Food and Drug Administration (FDA) has accepted a supplemental New Drug Application (sNDA) for mavacamten (Camzyos; Bristol Myers Squibb) as a potential treatment for adolescents aged 12 years to younger than 18 years with symptomatic obstructive hypertrophic cardiomyopathy (oHCM), according to an announcement from the company.¹

If approved, mavacamten would become the first cardiac myosin inhibitor indicated for adolescents with the condition. The application has received Priority Review, and the FDA assigned a Prescription Drug User Fee Act date of September 30, 2026.

Obstructive hypertrophic cardiomyopathy is a primary cardiac disorder characterized by abnormal thickening of the heart muscle that can obstruct blood flow from the left ventricle. In adolescents, the condition is associated with exercise intolerance and can affect daily functioning and quality of life. Although currently available therapies may improve symptoms, treatment options remain limited and may be associated with adverse effects or the need for invasive procedures.

“The acceptance of this NDA allows us the potential to extend our leadership in oHCM to a younger patient population with a high unmet medical need,” said Cristian Massacesi, MD, executive vice president, chief medical officer and head of development at Bristol Myers Squibb. “We are encouraged by the possibility of bringing this potentially paradigm-shifting treatment to adolescents at a time when a condition like oHCM can significantly impact both physical and emotional aspects of their lives.”

Phase 3 trial met primary endpoint

The sNDA submission is supported by findings from the phase 3 SCOUT-HCM trial, a randomized, double-blind, placebo-controlled international study evaluating mavacamten in adolescents with symptomatic oHCM. The trial enrolled 44 patients aged 12 years to younger than 18 years with New York Heart Association (NYHA) class II or III disease. Twenty-three patients were assigned to mavacamten and 21 to placebo. The mean age was approximately 14.6 years, and baseline left ventricular outflow tract (LVOT) gradients were similar between treatment groups.

According to Bristol Myers Squibb, the study met its primary endpoint, demonstrating a clinically meaningful and statistically significant reduction in Valsalva-provoked LVOT gradient at week 28. Patients treated with mavacamten experienced a least-squares mean reduction of 48.5 mm Hg from baseline, compared with a reduction of 0.5 mm Hg among patients receiving placebo, representing a between-group difference of 48.0 mm Hg (95% CI, –67.7 to –28.3; P < .001).

LVOT obstruction is a hallmark of oHCM and contributes to symptoms including exercise intolerance, dyspnea, chest discomfort, and fatigue. Reducing the pressure gradient is considered an important therapeutic goal because it can improve cardiac function and symptom burden.

Secondary endpoints included resting and postexercise LVOT gradients, peak oxygen consumption, symptoms, health status, safety outcomes, and pharmacokinetic measures. Results from the 28-week placebo-controlled phase of SCOUT-HCM were presented at the American College of Cardiology Annual Scientific Session & Expo 2026 and simultaneously published in The New England Journal of Medicine.²

The safety profile observed in adolescents was generally consistent with previous studies in adults. The overall incidence of adverse events was similar between treatment groups. Serious adverse events occurred in 2 patients receiving mavacamten and 2 receiving placebo. In the mavacamten group, 1 patient experienced 2 episodes of syncope and another received an inappropriate shock from an implantable cardioverter-defibrillator. In the placebo group, serious adverse events included chest pain in 1 patient and depression with suicidal ideation in another.

Importantly, no patient experienced a reduction in left ventricular ejection fraction below 50%, a key safety concern associated with cardiac contractility. No deaths occurred during the study.

Potential expansion of treatment options

Mavacamten is currently approved in the United States for adults with symptomatic New York Heart Association class II or III oHCM to improve functional capacity and symptoms. The therapy is a selective, reversible cardiac myosin inhibitor designed to reduce excessive cardiac muscle contraction, which contributes to obstruction in oHCM. By targeting the underlying hypercontractility of the disease, the medication can reduce LVOT obstruction and improve cardiac efficiency.

If approved for adolescents, mavacamten could expand treatment options for pediatric cardiologists caring for patients with symptomatic oHCM. The potential indication would introduce a disease-targeted pharmacologic therapy for a patient population that currently faces limited treatment choices and may otherwise require long-term medical management or invasive interventions.

References

1. Bristol Myers Squibb. FDA accepts supplemental New Drug Application for Camzyos (mavacamten) for the treatment of symptomatic obstructive hypertrophic cardiomyopathy in adolescents. News release. June 1, 2026.
2. Rossano JW, Canter C, Wolf CM, et al. Mavacamten in Adolescents with Obstructive Hypertrophic Cardiomyopathy. N Engl J Med. Published online March 29, 2026. doi:10.1056/NEJMoa2601103