FDA approves Camzyos for adolescents with symptomatic obstructive hypertrophic cardiomyopathy

The US Food and Drug Administration (FDA) has approved mavacamten (Camzyos; Bristol Myers Squibb) for adolescents aged 12 years to younger than 18 years with symptomatic obstructive hypertrophic cardiomyopathy (oHCM).¹

The approval expands the use of mavacamten, a selective cardiac myosin inhibitor previously approved for adults with symptomatic New York Heart Association (NYHA) class II or III oHCM, to a younger patient population. Mavacamten is the first cardiac myosin inhibitor approved for adolescents with symptomatic oHCM.¹

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 can be associated with exercise intolerance, dyspnea, chest discomfort, and fatigue and can affect daily functioning and quality of life. Treatment options for younger patients have been limited and may include medications to manage symptoms as well as invasive procedures in patients with persistent obstruction.^1-3

The FDA decision was supported by findings from the phase 3 SCOUT-HCM trial, which demonstrated a significant reduction in left ventricular outflow tract (LVOT) obstruction among adolescents treated with mavacamten.^2,3

“This approval represents an important change in the treatment landscape because it gives pediatric cardiologists for the first time a therapy that directly targets the underlying hypercontractility responsible for obstruction in hypertrophic cardiomyopathy,” said Joseph Rossano, MD, chief of the Division of Cardiology at Children’s Hospital of Philadelphia, in an interview with Contemporary Pediatrics. “Historically, treatment in this age group has relied largely on medications such as beta-blockers or calcium-channel blockers, with much of that practice extrapolated from adult experience. Although those medications can help control symptoms, they do not specifically address the molecular mechanism of the disease.”

Rossano added that adolescents who remained symptomatic despite medical therapy could ultimately require an invasive septal-reduction procedure.

“Mavacamten adds a disease-targeted, evidence-based option for these symptomatic patients,” Rossano said. “It will not be appropriate for every adolescent with HCM—it was studied in patients with symptomatic obstructive disease—but for eligible patients it gives clinicians and families a meaningful new choice.”

Phase 3 trial met primary endpoint

SCOUT-HCM was 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 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 LVOT gradients were similar between treatment groups.^2,3

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).^2,3

LVOT obstruction is a hallmark of oHCM and contributes to symptoms including exercise intolerance, dyspnea, chest discomfort, and fatigue. Reducing the pressure gradient is an important treatment goal because obstruction contributes to symptoms and impaired functional capacity.

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.^2,3

The safety profile observed in adolescents was generally consistent with previous studies of mavacamten 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.

No patient experienced a reduction in left ventricular ejection fraction below 50%, an important safety consideration with a therapy that reduces cardiac contractility. No deaths occurred during the study.

Approval expands treatment options for adolescents

Mavacamten is a selective, reversible cardiac myosin inhibitor designed to reduce excessive cardiac muscle contraction, a key component of the pathophysiology of oHCM. By targeting cardiac hypercontractility, mavacamten can reduce LVOT obstruction and improve cardiac function.¹

The adolescent approval introduces a disease-targeted pharmacologic option for pediatric cardiologists treating patients with symptomatic oHCM. Until now, treatment options for adolescents have largely relied on therapies aimed at controlling symptoms and, for some patients with persistent severe obstruction, invasive interventions.¹

The approval also extends the clinical experience with mavacamten into a population that may require decades of management for oHCM. Longer-term follow-up of adolescents treated with the cardiac myosin inhibitor will help further define the durability of its effects, long-term safety, and its role within the treatment pathway as patients transition from pediatric to adult cardiovascular care.

References

1. FDA. FDA approves first drug to improve functional capacity and symptoms in children with rare inherited heart condition. FDA. September 30, 2026. Accessed September 30, 2026. https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-first-drug-improve-functional-capacity-and-symptoms-children-rare-inherited-heart

2. 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. Accessed September 30, 2026. https://news.bms.com/news/corporate-financial/2026/U-S--Food-and-Drug-Administration-Accepts-for-Priority-Review-Bristol-Myers-Squibbs-Supplemental-New-Drug-Application-for-Camzyos-mavacamten-to-Treat-Adolescents-with-Symptomatic-Obstructive-Hypertrophic-Cardiomyopathy-oHCM/default.aspx

3. 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