Mavacamten Shows Improvements for Pediatric Obstructive Hypertrophic Cardiomyopathy

Mavacamten (Camzyos) demonstrated statistically significant reductions in baseline in Valsalva left ventricular outflow tract (LVOT) gradient at week 28 compared with the placebo for patients aged 12 years to less than 18 with symptomatic obstructive hypertrophic cardiomyopathy (oHCM). Investigators of the study (NCT06253221) added that the drug also met multiple secondary end points, including outcomes for clinically meaningful aspects of the disease.¹

“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,” Joseph Rossano, MD, principal investigator and chief of the division of cardiology at Children’s Hospital of Philadelphia, Pennsylvania, said in a news release.¹ “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."

The safety results were consistent with the established profile of the drug in adults, and no new safety signals were reported in this patient population. The study will continue with the long-term extension period.¹

About the SCOUT-HCM Trial

The SCOUT-HCM Trial is a phase 3, randomized, placebo-controlled, double-blind study for adolescent patients who were symptomatic with oHCM. Investigators aimed to determine the efficacy, safety, and pharmacokinetics of mavacamten. Patients included also had a presence of LVOT obstruction.^2,3

Investigators identified a target sample of 40 patients from sites across Australia, Canada, France, Germany, Italy, Spain, the Republic of Ireland, the United Kingdom, and the United States. Patients could continue their existing HCM therapy, including beta-blockers, nondihydropyridine calcium channel blockers, disopyramide, or a combination of the medications. Investigators screened patients, which included physical examination, vital signs, electrocardiogram monitoring, and more. After approximately 5 weeks of screening, treatment was randomized for patients 1:1 who either received oral mavacamten or the placebo once daily for 28 weeks. At week 28, patients who received the placebo crossed over to receive mavacamten for 28 weeks.²

The primary end point included the change from baseline in LVOT gradient at week 28. Secondary end points included change from baseline in resting LVOT gradient, change in post-exercise peak LVOT gradient, change in maximal wall thickness, change in ratio between early mitral inflow velocity and mitral annular early diastolic velocity, proportion of patients achieving an increase in peak oxygen uptake test, proportion of patients with at least 1 class improvement in New York Heart Association class, number of patients with treatment-emergent adverse events (AEs), and number of participants with treatment-emergent serious AEs.³

What Is Obstructive Hypertrophic Cardiomyopathy?

oHCM occurs when the heart muscles become thick and make it harder for the heart to pump blood. According to the Mayo Clinic, many people do not even realize they have it because it has few symptoms, if any at all. However, a small number of patients can experience serious symptoms such as shortness of breath and chest pain.⁴

It can also cause the heart’s electrical system to change, resulting in irregular heartbeats or sudden death. It is typically caused by changes in genes, affecting the 2 bottom chambers of the heart. Complications of oHCM can include atrial fibrillation, blocked blood flow, mitral valve disease, dilated cardiomyopathy, heart failure, fainting, and sudden cardiac death.⁴

“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,” Cristian Massacesi, MD, executive vice president, chief medical officer, and head of development at Bristol Myers Squibb, said in the news release.¹ “Camzyos has redefined the treatment paradigm for symptomatic oHCM in adults, with over 20,000 patients started in the US alone, and we look forward to the potential opportunity to transform clinical care in the adolescent patient population.”

REFERENCES

1. Bristol Myers Squibb announces positive topline results from phase 3 SCOUT-HCM trial evaluating Camzyos (mavacamten) in adolescents with symptomatic obstructive hypertrophic cardiomyopathy (oHCM). News release. Bristol Myers Squibb. January 12, 2026. Accessed January 13, 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

3. A study to evaluate mavacamten in adolescents with symptomatic obstructive hypertrophic cardiomyopathy. ClinicalTrials.gov identification: NCT06253221. December 19, 2025. Accessed January 13, 2026. https://www.clinicaltrials.gov/study/NCT06253221

4. Mayo Clinic. Hypertrophic cardiomyopathy. February 23, 2024. Accessed January 13, 2026. https://www.mayoclinic.org/diseases-conditions/hypertrophic-cardiomyopathy/symptoms-causes/syc-20350198