Mavacamten: Real-World Experience from 22 Months of the Risk Evaluation and Mitigation Strategy (REMS) Program.

Background: Mavacamten is the only cardiac myosin inhibitor approved by the US FDA for treatment of symptomatic New York Heart Association class II-III obstructive hypertrophic cardiomyopathy (HCM) patients. Under the risk evaluation and mitigation strategy (REMS) program for mavacamten, patients are required to be monitored for development of systolic heart failure, and reduction of left ventricular ejection fraction (LVEF) to <50%. We report results from the mavacamten REMS database (28-Apr-2022 to 27-Feb-2024). Methods: Data on healthcare providers and pharmacy certification, patient monitoring (from Patient Status Forms, based partly on echocardiograms), and screening for drug interactions prior to each dispense were collected. Results: Of 6,299 patients who received ≥1 dose of mavacamten, 60.0% were women; 64.6% were >60 years of age. Of 5,573 patients with submitted Patient Status Forms, 256 (4.6%) developed LVEF <50% and 71 (1.3%) experienced heart failure requiring hospitalization (HFH). On the 29,111 status forms in these patients, each representing an assessment of an echocardiogram, LVEF <50% was reported on 276 (0.9%) and HFH was reported on 86 (0.3%). Of 1,929 patients with ≥1 year of treatment, 78 (4.0%) had an LVEF reduction to <50% and 4 (0.2%) experienced LVEF <50% + HFH but later resumed treatment. Of 3,228 patients initiated on 5 mg/day mavacamten and were treated for at least 6 months, 2,391 (74.1%) remained at 5 or 10 mg/day. At 3- and 6-months following mavacamten treatment initiation, 57.2% and 70.3%, respectively, demonstrated post-Valsalva LV outflow tract gradient <30 mmHg. Conclusions: We describe the feasibility and experience of the first 22 months of the REMS program for prescribing mavacamten in >6,000 symptomatic obstructive HCM patients. The need for temporary interruption for LVEF <50% was low, including for patients on therapy ≥1 year, with even fewer LVEF reductions associated with HFH.