FDA Approves Mavacamten for Pediatric Patients With Obstructive HCM

The US Food and Drug Administration (FDA) has approved an expanded indication for mavacamten (Camzyos) in symptomatic obstructive hypertrophic cardiomyopathy (oHCM), covering adults and pediatric patients weighing at least 30 kg, to improve functional capacity and symptoms.¹

Bristol Myers Squibb announced the approval on September 30, 2026, based on results of the phase 3 SCOUT-HCM trial in adolescents aged 12 to <18 years. According to the company, mavacamten is now the only FDA-approved therapy for oHCM in a pediatric population.¹

The prior US label for the cardiac myosin inhibitor (CMI), granted in 2022, was limited to adults with symptomatic New York Heart Association (NYHA) class II to III oHCM. Pharmacologic management in adolescents has relied on β-blockers, calcium channel blockers, and disopyramide, with recommendations largely extrapolated from adult studies. Bristol Myers Squibb stated the new label gives mavacamten the broadest indication of any CMI.^1,3

“The FDA approval of CAMZYOS for pediatric patients with symptomatic obstructive hypertrophic cardiomyopathy represents a landmark moment for pediatric cardiology,” Joseph Rossano, MD, principal investigator of SCOUT-HCM and chief of the division of cardiology at the Children’s Hospital of Philadelphia, said in a statement. “For the first time, children with this serious condition have a therapy that is FDA-approved to reduce left ventricular outflow tract obstruction.”¹

Mavacamten efficacy in the phase 3 SCOUT-HCM trial

SCOUT-HCM (NCT06253221) is a randomized, double-blind, placebo-controlled, international trial enrolling 44 adolescents with symptomatic NYHA class II to III oHCM, randomized 1:1 to mavacamten (n = 23) or placebo (n = 21). Eligibility required left ventricular ejection fraction (LVEF) of at least 60%, a Valsalva left ventricular outflow tract (LVOT) peak gradient of at least 30 mm Hg, and a maximal gradient of at least 50 mm Hg at rest or with provocation. Background therapy with β-blockers, calcium channel blockers, disopyramide, or combinations was permitted.^1,2

Patients started once-daily mavacamten at 2.5 mg for body weight of 35 kg to less than 45 kg or 5 mg for body weight of 45 kg or more, with dose adjustment guided by echocardiographic parameters. The trial comprises a 28-week placebo-controlled period, a 28-week active-treatment period with placebo crossover, and an open-label extension of up to 144 weeks. At baseline, mean Valsalva LVOT gradients were 78 mm Hg and 81 mm Hg, and mean LVEF was 69.0% and 67.4%, in the mavacamten and placebo groups, respectively.^1,2

Mavacamten met the primary endpoint, reducing Valsalva LVOT gradient from baseline to week 28 by a mean of 49.4 mm Hg vs 1.8 mm Hg with placebo (least-squares mean difference, −48.0 mm Hg; 95% CI, −67.7 to −28.3; P < .0001). The full placebo-controlled results were published in The New England Journal of Medicine in March 2026.^1,2

Mavacamten secondary endpoints and safety in adolescents

Reductions extended to resting LVOT gradient (least-squares mean difference, −47.0 mm Hg; 95% CI, −62.7 to −31.4) and postexercise LVOT gradient (−41.7 mm Hg; 95% CI, −59.7 to −23.7) at week 28. Maximal left ventricular wall thickness declined by a least-squares mean difference of −1.8 mm (95% CI, −3.4 to −0.2), and average E/e′ ratio improved by −3.4 (95% CI, −5.1 to −1.6). Bristol Myers Squibb noted secondary endpoint CIs were not adjusted for multiplicity and should not be interpreted as formal hypothesis tests.^1,3

The company reported no new adverse reactions beyond those established in adults, and no patient developed LVEF below 50%. Serious adverse events occurred in 2 patients in each arm (9% with mavacamten vs 10% with placebo), and no adverse events led to discontinuation. During the placebo-controlled period, no atrial fibrillation, symptomatic heart failure, or deaths were reported.^1,3

The label retains the boxed warning for heart failure due to systolic dysfunction, with echocardiographic LVEF assessment required before and during treatment. Mavacamten remains available only through the Camzyos Risk Evaluation and Mitigation Strategy (REMS) program, and pediatric dosing adds a 1-mg step for dose reductions tied to CYP2C19 and CYP3A4 inhibitor interactions.¹

“This is truly a milestone moment for patients and families,” Lisa Salberg, chief executive officer and founder of the Hypertrophic Cardiomyopathy Association, said in a statement. “Having a targeted therapy for cardiac myosin is a significant breakthrough, and it’s a welcome change to bring this approval to a younger population.”¹

According to Bristol Myers Squibb, >5,000 US clinicians have prescribed mavacamten to >25,000 patients since the 2022 adult approval. The company is discussing the pediatric data with multiple global regulatory authorities, and the SCOUT-HCM active-treatment and long-term extension periods are ongoing.^1,3

References

1. Bristol Myers Squibb. U.S. Food and Drug Administration approves expanded indication for Bristol Myers Squibb's Camzyos (mavacamten) for the treatment of symptomatic obstructive hypertrophic cardiomyopathy (oHCM) in adults and pediatric patients. Published September 30, 2026. Accessed September 30, 2026. https://news.bms.com/news/corporate-financial/2026/U-S--Food-and-Drug-Administration-Approves-Expanded-Indication-for-Bristol-Myers-Squibbs-CAMZYOS-mavacamten-for-the-Treatment-of-Symptomatic-Obstructive-Hypertrophic-Cardiomyopathy-oHCM-in-Adults-and-Pediatric-Patients/default.aspx

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

3. Bristol Myers Squibb. Bristol Myers Squibb presents positive results from phase 3 SCOUT-HCM trial demonstrating efficacy and safety of Camzyos (mavacamten) in adolescents with symptomatic obstructive hypertrophic cardiomyopathy (oHCM). Published March 29, 2026. Accessed September 30, 2026. https://www.businesswire.com/news/home/20260327682053/en/