Bristol Myers Squibb reports 56-week SCOUT-HCM results showing sustained LVOT gradient reductions with Camzyos in adolescents with symptomatic oHCM.
Written By: Neha Vishwakarma, PharmD
Reviewed By: Pharmacally Editorial Team
Bristol Myers Squibb (BMS) has presented 56-week results from the Phase 3 SCOUT-HCM trial evaluating Camzyos (mavacamten) in patients aged 12 to under 18 years with symptomatic obstructive hypertrophic cardiomyopathy (oHCM). Presented at the Hypertrophic Cardiomyopathy Medical Society (HCMS) Scientific Sessions in Chicago on November 6, 2026, the findings showed continued reductions in left ventricular outflow tract (LVOT) gradients and no new safety signals. The results build on the 28-week findings that supported the US pediatric approval of Camzyos in September 2026.
Addressing oHCM in children and adolescents
oHCM is characterized by thickening of the heart muscle that obstructs blood flow from the left ventricle. Mavacamten is a selective, reversible, allosteric inhibitor of cardiac myosin that reduces excessive myocardial contractility, thereby lowering LVOT obstruction.
Initially approved in the US in 2022 for adults with symptomatic oHCM, Camzyos became the first cardiac myosin inhibitor approved for pediatric patients weighing at least 30 kg with symptomatic oHCM in September 2026. The drug is approved in more than 60 countries and regions, although its European indication currently covers adults with symptomatic NYHA class II-III oHCM.
SCOUT-HCM trial design
SCOUT-HCM (NCT06253221) is an international, randomized, double-blind, placebo-controlled Phase 3 trial involving 44 patients aged 12 to under 18 years. The study comprises three periods: an initial 28-week placebo-controlled phase, a subsequent 28-week active-treatment phase in which placebo recipients switch to mavacamten, and an open-label extension lasting up to 144 weeks.
Participants were randomized 1:1 to receive once-daily mavacamten or placebo, with dose adjustments guided by echocardiographic assessments. At baseline, mean left ventricular ejection fraction (LVEF) was 69.0% in the mavacamten group and 67.4% in the placebo group. Mean Valsalva LVOT gradients were 78 mmHg and 81 mmHg, respectively. Beta-blockers were the most commonly used background therapy.
The primary endpoint was the change from baseline in Valsalva LVOT gradient at Week 28. Secondary endpoints included resting and post-exercise LVOT gradients, peak oxygen consumption, improvement in NYHA functional class and the shortness-of-breath domain of the HCM Symptom Questionnaire. These secondary endpoints were descriptive.
Key results at 56 weeks
Of the 44 randomized participants, 43 completed the initial double-blind period, including 23 assigned to mavacamten and 20 to placebo. All 43 subsequently received mavacamten through Week 56.
Patients receiving mavacamten continuously experienced a mean reduction of 48.1 mmHg in Valsalva LVOT gradient from baseline at Week 56. Participants who switched from placebo to mavacamten also achieved a similar reduction, indicating a consistent haemodynamic response following treatment initiation.
Descriptive improvements were observed across key secondary endpoints, including post-exercise LVOT gradients, peak oxygen consumption (pVO₂), improvement in NYHA functional class and the shortness-of-breath domain of the HCM Symptom Questionnaire. These findings provide additional clinical context to the haemodynamic response, although the secondary endpoints were descriptive and should not be interpreted as confirmatory evidence of clinical benefit.
No participant experienced an LVEF reduction below 50% during the 56-week evaluation period.
Treatment-related treatment-emergent adverse events (TEAEs) and serious TEAEs were reported as five and two events, respectively, in the continuous-mavacamten group over 56 weeks. The placebo-to-mavacamten crossover group reported one treatment-related TEAE and no serious TEAEs during its 28-week mavacamten exposure (Weeks 28–56). No new safety signals emerged.
Expert perspective and additional evidence
Cordula Wolf, MD, Associate Professor at the Technical University of Munich (TUM) University Hospital German Heart Centre, said the findings represent the first evaluation of a cardiac myosin inhibitor in this pediatric population over this duration in a double-blind study. She highlighted their relevance to discussions between healthcare providers, patients and families regarding treatment decisions.
BMS is also presenting adult Camzyos data at the American Heart Association Scientific Sessions 2026. These include four-year safety findings from the REMS programme, cardiac MRI observations from the EXPLORER cohort of the MAVA-LTE study, changes in a proteomic cardiovascular risk score and real-world MARVEL-HCM findings across sarcomere variant subgroups.
Clinical interpretation and limitations
The 56-week findings extend evidence that mavacamten can maintain reductions in LVOT obstruction during continued treatment. The similar response after placebo recipients switched to mavacamten further supports its haemodynamic activity in adolescents with symptomatic oHCM.
The absence of LVEF values below 50% is reassuring within the study population. However, it does not eliminate the established risk of systolic dysfunction and heart failure associated with mavacamten. The drug carries a boxed warning, requires regular echocardiographic monitoring and is available in the US through the CAMZYOS Risk Evaluation and Mitigation Strategy (REMS) programme.
Its prescribing information also includes important drug-interaction restrictions. Concomitant use with strong CYP2C19 inhibitors or moderate-to-strong CYP2C19 or CYP3A4 inducers is contraindicated. Use with disopyramide and certain other negative inotropic combinations should be avoided because of the risk of ventricular dysfunction and heart failure. The drug may also cause fetal harm, requiring appropriate reproductive safety counseling.
The findings must be interpreted in light of the trial’s limitations. Only 44 patients were enrolled, limiting the ability to characterize uncommon adverse events. Furthermore, the placebo-controlled comparison ended at Week 28. The subsequent 28-week period therefore provides evidence of continued treatment response rather than comparative efficacy. Longer-term clinical outcomes, including arrhythmias, septal reduction procedures and effects on growth and development, remain important areas for continued evaluation.
The ongoing open-label extension, lasting up to 144 weeks, will provide further information on the long-term efficacy and safety of mavacamten in adolescents. Additional pediatric evidence and regulatory assessments will help determine whether its use can be extended to younger populations and other regions.
Reference
56-week Phase 3 SCOUT-HCM results presented at the HCMS Scientific Sessions, Bristol Myers Squibb, November 6, 2026,
A Study to Evaluate Mavacamten in Adolescents with Symptomatic Obstructive Hypertrophic Cardiomyopathy, ClinicalTrials.gov ID NCT06253221
About the Writer
Neha Vishwakarma (LinkedIn) is a Pharm.D professional with experience in clinical pharmacy, pharmacovigilance, and clinical research. She has hands-on experience in ADR assessment, ICSR processing, medication safety, and clinical data evaluation. Her research background in surgical site infections and antibiotic use supports her focus on evidence-based healthcare writing.