SCOUT-HCM
Mavacamten in Symptomatic Adolescents With Obstructive Hypertrophic Cardiomyopathy
Presented by Joseph Rossano — Children's Hospital of Philadelphia
Subspecialty: Heart Failure
Published in NEJM
Key Result
Mavacamten reduced LVOT gradient by 48.0 mmHg more than placebo (p<0.0001) in adolescent oHCM — first positive Phase 3 trial extending mavacamten to patients ages 12-17. Consistent efficacy across all secondary endpoints with favorable safety.
What did this trial find?
The Phase 3 SCOUT-HCM trial demonstrated that mavacamten significantly reduced LVOT gradient by 48.0 mmHg more than placebo in adolescents aged 12-17 with symptomatic obstructive HCM, marking the first positive Phase 3 trial of a cardiac myosin inhibitor in a pediatric population. All secondary endpoints favored mavacamten with a reassuring safety profile. Coverage is largely straightforward and positive, driven primarily by the lead investigator and the sponsor's CMO, with no notable independent critical commentary or controversy in available sources.
Why does this trial matter?
Mostly straightforward coverage. This is the first Phase 3 trial of a cardiac myosin inhibitor in adolescents and the results were unambiguously positive. All available quotes come from the lead investigator (Rossano) or the sponsor CMO (Massacesi). No independent editorials, outside expert commentary, or critical/cautionary voices were found in the source material. There is no meaningful controversy or interpretive debate — the coverage is uniformly positive and focused on the unmet need and the strength of the primary endpoint result.
Study Design
Phase 3, randomized, double-blind, placebo-controlled trial (N=43, ages 12-17)
Clinical Implications
Extends mavacamten's proven benefit in adult oHCM to adolescents, potentially expanding the indication for Camzyos to younger patients with symptomatic obstructive HCM.
Abstract
The Phase 3 SCOUT-HCM trial evaluated mavacamten (Camzyos), a cardiac myosin inhibitor, in 43 adolescents ages 12-17 with symptomatic obstructive HCM over 28 weeks. Patients had NYHA class II-III symptoms, peak LVOT gradients >50 mmHg, and LVEF >60%. The primary endpoint was met: Valsalva LVOT gradient reduction averaged 48.5 mmHg with mavacamten vs 0.5 mmHg with placebo (least-squares mean difference -48.0 mmHg, p<0.0001). Secondary endpoints improved including resting LVOT (-39.0 vs 8.1 mmHg), maximal LV wall thickness, NYHA class, diastolic function, mitral valve dysfunction, peak VO2, and symptom measures. Safety was similar between groups with no LVEF reduction to <50% and no deaths.