Mavacamten shows benefit in adolescents with obstructive hypertrophic cardiomyopathy

Bristol Myers Squibb announced positive topline results from the phase 3 SCOUT-HCM trial evaluating mavacamten (Camzyos) in adolescents with symptomatic obstructive hypertrophic cardiomyopathy (oHCM). The randomized, double-blind, placebo-controlled study met its primary endpoint, demonstrating a statistically significant reduction in Valsalva left ventricular outflow tract (LVOT) gradient at week 28 compared with placebo, indicating improved LVOT obstruction in this younger patient population.^1,2

SCOUT-HCM is the first phase 3 randomized, placebo-controlled trial to evaluate a cardiac myosin inhibitor in adolescents with oHCM. The trial enrolled 44 patients aged 12 years to younger than 18 years with symptomatic disease and LVOT obstruction. Participants were randomized 1:1 to receive mavacamten or placebo for 28 weeks, followed by a 28-week active-treatment period in which patients originally assigned to placebo crossed over to mavacamten, and a long-term open-label extension period of up to 144 weeks. The primary endpoint was the change from baseline to week 28 in Valsalva LVOT gradient, with secondary endpoints assessing additional LVOT measures, exercise capacity, symptoms, health status, safety, and pharmacokinetics.²

According to the company, statistical significance was also achieved across multiple secondary endpoints that captured clinically meaningful aspects of oHCM. Safety findings in adolescents were reported to be consistent with the established safety profile of mavacamten in adults, with no new safety signals identified in the pediatric population. The study remains ongoing, with patients continuing into active treatment and long-term extension phases.¹

“Adolescent oHCM is a serious, rare disease associated with substantial morbidity and mortality. The SCOUT-HCM topline results highlight the potential for Camzyos to be the first cardiac myosin inhibitor for adolescent patients with oHCM,” said Cristian Massacesi, MD, executive vice president, chief medical officer, and head of development at Bristol Myers Squibb. “Camzyos has redefined the treatment paradigm for symptomatic oHCM in adults, with over 20,000 patients started in the U.S. alone, and we look forward to the potential opportunity to transform clinical care in the adolescent patient population.”¹

Hypertrophic cardiomyopathy in children and adolescents is a rare condition but is associated with a higher lifetime burden of complications than disease diagnosed in adulthood. Adolescents with obstructive disease often experience reduced exercise tolerance, dyspnea, and syncope, and are at increased risk for arrhythmias and sudden cardiac death. Current guideline-recommended pharmacologic therapies for pediatric oHCM are limited to beta-blockers, non-dihydropyridine calcium channel blockers, and disopyramide, which primarily address symptoms and may be poorly tolerated. Patients with persistent obstruction may require septal reduction therapy, which can be technically challenging in younger patients and is not without risk.

Mavacamten is a selective, reversible inhibitor of cardiac myosin designed to reduce excessive actin-myosin cross-bridge formation in the sarcomere, thereby decreasing hypercontractility and dynamic LVOT obstruction. In adult patients with symptomatic oHCM, the agent has demonstrated improvements in LVOT gradients, exercise capacity, symptoms, and cardiac structure across multiple phase 3 trials. SCOUT-HCM was designed to evaluate whether these benefits could extend to adolescent patients, whose disease burden and pathophysiology may resemble that of adults with oHCM.²

Joseph Rossano, MD, principal investigator of SCOUT-HCM and chief of the Division of Cardiology at Children’s Hospital of Philadelphia, emphasized the significance of the findings for pediatric cardiology. “The SCOUT-HCM study is important for patients and the field of pediatric cardiology, being one of the very few pediatric cardiology randomized and placebo-controlled clinical trials that has generated positive phase 3 results,” he said. “Treatment options for adolescents with oHCM are currently limited to medical symptom management or invasive surgery. As a clinician who has cared for patients in this field for decades, I am very excited about the potential opportunity that a therapy like this could hold for the patient population if approved by the FDA.”¹

The company stated that detailed SCOUT-HCM results will be presented at an upcoming medical congress and discussed with regulatory authorities. Mavacamten is currently approved in the United States for adults with symptomatic New York Heart Association class II-III oHCM and is approved in more than 50 countries worldwide for adult indications. If supported by regulatory review, the SCOUT-HCM findings may represent an important step toward expanding disease-modifying therapy options for adolescents with obstructive hypertrophic cardiomyopathy.¹

References

1. Bristol Myers Squibb. Bristol Myers Squibb Announces Positive Topline Results from Phase 3 SCOUT-HCM Trial Evaluating Camzyos (mavacamten) in Adolescents with Symptomatic Obstructive Hypertrophic Cardiomyopathy (oHCM). Bristol Myers Squibb. January 12, 2026. Accessed January 14, 2026. https://news.bms.com/news/corporate-financial/2026/Bristol-Myers-Squibb-Announces-Positive-Topline-Results-from-Phase-3-SCOUT-HCM-Trial-Evaluating-Camzyos-mavacamten-in-Adolescents-with-Symptomatic-Obstructive-Hypertrophic-Cardiomyopathy-oHCM/default.aspx
2. Rossano J, Canter C, Wolf C, et al. Mavacamten in symptomatic adolescent patients with obstructive hypertrophic cardiomyopathy: design of the phase 3 SCOUT-HCM trial. Am Heart J. 2026;292:107283. doi:10.1016/j.ahj.2025.107283