Bristol Myers Squibb has announced positive data from the phase-III SCOUT-HCM trial of Camzyos (mavacamten), the first study of a Cardiac Myosin Inhibitor (CMI) in adolescents (aged 12 years to <18 years) with symptomatic obstructive hypertrophic cardiomyopathy (oHCM). The SCOUT-HCM trial met its primary endpoint, demonstrating a clinically meaningful and statistically significant reduction from baseline in Valsalva Left Ventricular Outflow Tract (LVOT) gradient at week 28 with Camzyos versus placebo, with a significant Least-Squares (LS) mean difference (95 percent CI) at week 28 of −48.0 (−67.7, −28.3) mm Hg; P < 0.0001.

Additionally, Camzyos showed meaningful improvement over placebo in multiple secondary endpoints at 28 weeks, and similar safety findings were observed in the Camzyos and placebo groups. The data are being presented as a late-breaking clinical trial presentation at the American College of Cardiology’s (ACC) Annual Scientific Session and Expo 2026, with simultaneous publication in The New England Journal of Medicine.

“Paediatric HCM is a rare cardiac disorder that is associated with severe, sometimes life-threatening, symptoms. With no approved therapies for paediatric patients with oHCM and current recommendations for pharmacological therapy primarily extrapolated from evidence obtained from adult studies, the positive results of this trial represent a significant advance in the field of paediatric cardiology and the potential for a meaningful new therapy for adolescent patients if approved by the FDA,” said Joseph Rossano, MD, Principal Investigator of SCOUT-HCM and Chief of the Division of Cardiology, Children’s Hospital of Philadelphia.

SCOUT-HCM evaluated Camzyos compared to placebo in 44 patients aged 12 to <18 years old with symptomatic oHCM and New York Heart Association (NYHA) class II-III symptoms over a 28-week period. In addition to meeting the primary endpoint of reduction of Valsalva LVOT gradient, Camzyos showed meaningful improvements over placebo in LV obstruction, diastolic function, maximal left ventricular wall thickness, NYHA class and mitral valve dysfunction at 28 weeks.

“The SCOUT-HCM results underscore the potential for Camzyos to become the first CMI for adolescents, reinforcing our leadership in the CMI space and our role in reshaping the scientific understanding of oHCM and how the disease is diagnosed, evaluated and potentially treated. With these meaningful safety and efficacy data, we are excited about the potential to provide a paradigm-changing treatment for adolescents and their families,” said Cristian Massacesi, MD, Executive Vice President, Chief Medical Officer and Head of Development, Bristol Myers Squibb.

Improvements were seen in resting and post-exercise LVOT gradients with Camzyos versus placebo, with an LS mean difference of −47.0 mm Hg (−62.7, −31.4); nominal p < 0.0001, and −41.7 mm Hg (−59.7, −23.7); nominal p < 0.0001, respectively. The primary endpoint was supported by the proportion of patients who achieved reduction in maximal LVOT gradient (resting or Valsalva) to <30 mm Hg, from baseline to 28 weeks.

Additionally, positive structural changes were observed with Camzyos versus placebo, as shown by improvement in maximal LV wall thickness LS mean difference (95 percent CI) of −1.8 (−3.4, −0.2) mm; nominal p = 0.0269 and average E/e’ ratio (ratio between early mitral inflow velocity and mitral annular early diastolic velocity) of LS mean difference (95 percent CI) of −3.4 (−5.1, −1.6); nominal p = 0.0002.

Similar safety findings were observed in the Camzyos and placebo groups, including Treatment-Emergent Adverse Events (TEAEs) (18 versus 17 participants experiencing at least one respectively), treatment-related TEAEs (two versus three, respectively), Treatment-Emergent Serious Adverse Events (TESAEs) (two for both groups), and treatment-related TESAEs (one versus zero, respectively). During the 28-week study period, there were no TEAE?related treatment discontinuations or deaths, no cases of atrial fibrillation or symptomatic heart failure, and no patient experienced a Left Ventricular Ejection Fraction (LVEF) of <50 percent. Overall, these findings demonstrate that the safety profile of Camzyos treatment in symptomatic adolescents with oHCM was similar to that reported in adults, with no new safety signals identified.

The 28-week active treatment period of SCOUT-HCM is ongoing, and Bristol Myers Squibb will work with key investigators to present the 56-week data at an upcoming medical congress.