The FDA has expanded approval of mavacamten (Camzyos) to treat children with symptomatic obstructive hypertrophic cardiomyopathy (HCM), making it the first cardiac myosin inhibitor cleared for pediatric patients weighing at least 30 kg. The drug was originally approved for adults in 2022.
The expansion rests on the phase III SCOUT-HCM trial, which enrolled 44 adolescents. At 28 weeks, mavacamten reduced the Valsalva left ventricular outflow tract gradient by 48.0 mm Hg more than placebo, a statistically significant improvement. The trial also reported gains in diastolic function, cardiac hypertrophy, and markers of cardiac stress and injury.
Because mavacamten can cause heart failure from systolic dysfunction, it is available only through a restricted REMS program. No new safety signals appeared in adolescents, with no drops in ejection fraction below 50% and no cases of atrial fibrillation, symptomatic heart failure, or death. Another cardiac myosin inhibitor, aficamten (Myqorzo), remains approved only for adults.