Data from the late-stage MAPLE-HCM study position Cytokinetics’ cardiac myosin inhibitor aficamten as a potential first-line therapy for patients with obstructive hypertrophic cardiomyopathy.
Cytokinetics’ aficamten significantly improved exercise capacity in a Phase III study of patients with obstructive hypertrophic cardiomyopathy, sending the biotech’s shares soaring 40% on Tuesday morning.
The data from the MAPLE-HCM study, presented at the 2025 European Society of Cardiology Congress on Saturday, showed that after 24 weeks of treatment, patients on aficamten saw a 1.1-mL/kg/min increase in pVO2, a measure of oxygen supply that indicates exercise capacity. Counterparts on the standard-of-care beta-blocker metoprolol, meanwhile, saw a 1.2-mL/kg/min decrease in pVO2 over the same time span.
Writing to investors on Monday, analysts at Truist Securities said that these findings position aficamten as a “potentially best-in-class” cardiac myosin inhibitor for obstructive hypertrophic cardiomyopathy (HCM), adding that the data support a first-line indication for the drug.
“Beta blockers have been the standard of care in [the first-line setting] for HCM for the past several decades despite limited evidence and. . .feedback indicating lack of consistent and broad efficacy,” Truist wrote. MAPLE-HCM’s data are “robust,” the analysts added, noting that outperforming metoprolol could help aficamten stand out in the HCM space.
Designed to be taken orally, aficamten is a selective blocker of cardiac myosin, a protein involved in the contraction of the heart muscles. This mechanism of action allows the drug to suppress the hypercontraction of the heart, a symptom typical of HCM. Cytokinetics in December 2024 filed for the approval of aficamten in obstructive HCM, which the FDA gave an initial action date of Sept. 26, 2025.
In May this year, however, the regulator pushed back its decision deadline by three months in order to review a follow-on submission regarding risk management. A verdict is now expected by Dec. 26. Data from MAPLE-HCM were not part of Cytokinetics’ original submission, and the company plans to file these findings in the future, according to Truist.
With Saturday’s readout, Cytokinetics gains ground on Bristol Myers Squibb, which owns Camzyos, a similar cardiac myosin inhibitor approved for obstructive HCM. In April this year, the pharma reported that the drug failed the Phase III ODYSSEY-HCM study, unable to best placebo at improving exercise capacity at 48 weeks in patients with non-obstructive disease. Camzyos also did not result in significantly better symptoms and physical function versus placebo.
