Cytokinetics Reports New Aficamten Analyses From ACACIA-HCM and MAPLE-HCM

Cytokinetics released additional Phase 3 analyses of aficamten on Aug. 29, adding new evidence from two hypertrophic cardiomyopathy trials as the company works to expand the clinical and commercial reach of its first approved medicine. The updated data came from ACACIA-HCM in symptomatic non-obstructive hypertrophic cardiomyopathy and from MAPLE-HCM in symptomatic obstructive hypertrophic cardiomyopathy.

The new ACACIA-HCM analysis focused on cardiac structure and diastolic function, while the MAPLE-HCM analysis examined whether aficamten’s previously reported advantage over metoprolol changed depending on what therapy patients were taking before entering the study. Cytokinetics said both analyses were presented Aug. 29 at the European Society of Cardiology Congress 2026 in Munich and were published simultaneously in peer-reviewed journals.

ACACIA-HCM adds exploratory evidence on cardiac structure and filling

ACACIA-HCM is a Phase 3, randomized, double-blind, placebo-controlled trial evaluating aficamten in patients with symptomatic non-obstructive hypertrophic cardiomyopathy. Cytokinetics said the study randomized and treated 517 participants outside Japan on a 1:1 basis with aficamten or placebo. The dual primary endpoints were change in Kansas City Cardiomyopathy Questionnaire Clinical Summary Score and change in maximal exercise performance, or peak VO2, from baseline to Week 36.

The company had already reported on Aug. 28 that ACACIA-HCM met both primary endpoints, showing statistically significant improvements in patient-reported health status and exercise performance compared with placebo. Cytokinetics also said it plans to submit a supplemental New Drug Application to the U.S. Food and Drug Administration in the fourth quarter of 2026 seeking to expand aficamten into symptomatic non-obstructive HCM. The earlier ACACIA release framed the trial as the first Phase 3 study in non-obstructive HCM to show statistically significant improvement across both patient-reported and physician-assessed endpoints.

The Aug. 29 analysis explored what may sit behind those symptom and exercise benefits. Cytokinetics said aficamten improved several measures of diastolic function both at the time of the primary analysis at 36 weeks and at end of treatment, which could extend to 72 weeks with a median exposure of 49 weeks. Peak E velocity improved versus placebo at both time points, with p-values of 0.001 and 0.034, while septal e-prime velocity improved at both points with p-values below 0.001.

Septal E over e-prime showed only a trend toward improvement at Week 36, with a p-value of 0.07, but reached statistical significance at end of treatment with p below 0.001. Left atrial volume index followed a similar pattern, showing a trend at Week 36 and then a statistically significant improvement at end of treatment with a p-value of 0.022. Cytokinetics argued that these results support improved diastolic function as a potential mechanism behind the gains in functional capacity and symptom relief seen in patients with non-obstructive HCM.

The company also reported changes in cardiac structure. Left ventricular wall thickness decreased by 0.2 centimeters at end of treatment, while left ventricular end-systolic and end-diastolic volumes increased. Aficamten also produced a statistically significant reduction in left ventricular ejection fraction, though Cytokinetics said average ejection fraction remained within the normal range at end of treatment. Because these are exploratory analyses rather than additional primary endpoints, they do not independently establish a new efficacy claim. Even so, they broaden the clinical narrative around aficamten as Cytokinetics prepares a regulatory filing for a patient population in which there are still no approved disease-targeting therapies.

MAPLE-HCM analysis examines the role of prior beta-blocker use

The second disclosure came from MAPLE-HCM, a Phase 3, randomized, double-blind active-comparator trial comparing aficamten monotherapy with metoprolol monotherapy in symptomatic obstructive HCM. Cytokinetics has previously said MAPLE-HCM enrolled 175 patients and was designed to test change in peak oxygen uptake from baseline to Week 24 as its primary endpoint.

Primary results from MAPLE-HCM were released in 2025 and showed superiority of aficamten to metoprolol on peak oxygen uptake, with a least-squares mean treatment difference of 2.3 mL/kg/min and a p-value below 0.001. Cytokinetics also reported that key secondary endpoints favored aficamten, adding to the case that the drug could outperform long-established standard beta-blocker therapy in obstructive HCM.

The new MAPLE-HCM analysis is post-hoc rather than part of the original primary testing plan. It asks whether the advantage for aficamten differed depending on patients’ pre-trial treatment. At screening, 123 patients were taking a beta blocker and 52 were not. Of the 52 not taking a beta blocker, 22 had received no standard-of-care therapy for at least 12 months before screening. All patients underwent a two-week washout before randomization.

Across both groups, aficamten still outperformed metoprolol. Cytokinetics said aficamten improved peak oxygen uptake by 3.1 mL/kg/min versus metoprolol among patients who had not previously been taking beta blockers and by 1.9 mL/kg/min among patients who had previously been taking beta blockers. Both results had p-values below 0.001. The interaction p-value was 0.133, meaning the analysis did not demonstrate a statistically significant difference in treatment effect between the two prior-treatment groups.

The company also reported that aficamten improved several key secondary endpoints over metoprolol regardless of pre-trial treatment, including KCCQ Clinical Summary Score, New York Heart Association functional class, Valsalva left ventricular outflow tract gradient and NT-proBNP. Cytokinetics said there were no differences in the safety profile of aficamten, including serious adverse-event rates, between the prior-treatment groups. The implication is narrow but useful. This was not a new randomized trial of different pre-treatment strategies. Instead, it was an attempt to test whether the previously reported aficamten-versus-metoprolol outcome remained broadly consistent once the patient population was divided by therapy history.

Why the new analyses matter commercially and regulatorily

Aficamten is no longer just a pipeline drug. The FDA approved it in 2025 under the MYQORZO brand for adults with symptomatic obstructive hypertrophic cardiomyopathy. That means new trial analyses can influence not only the scientific profile of the medicine but also the size of the addressable market, the company’s regulatory agenda and the eventual revenue potential of an already launched product.

The non-obstructive HCM opportunity is especially important because it could materially broaden aficamten’s use beyond its first approved indication. Cytokinetics said in its Aug. 6 second-quarter update that it expected to submit the supplemental NDA for aficamten in non-obstructive HCM in the fourth quarter of 2026. The company also reported approximately $25 million in MYQORZO net product revenue for the second quarter, more than 700 unique prescribers and roughly 1,500 patients dispensed the medicine as of June 30. That makes the ACACIA dataset financially relevant as well as clinically interesting.

The new analyses do not themselves change aficamten’s approved label. The ACACIA findings on wall thickness and diastolic function are exploratory, while the MAPLE subgroup work is post-hoc. Investors and clinicians therefore should not read the Aug. 29 disclosures as standalone registration-grade endpoints. Their value is that they deepen the evidence base around how the drug may work in non-obstructive HCM and whether its previously observed benefit in obstructive HCM appears robust across different treatment histories.

For Cytokinetics, the next major milestone remains the regulatory submission in non-obstructive HCM. If the company files in the fourth quarter as planned, FDA reviewers will be assessing a fuller package that includes the already positive ACACIA primary endpoints plus this added set of mechanistic and structural observations. The MAPLE analysis, meanwhile, may help physician positioning if aficamten continues to be compared with conventional beta-blocker treatment in practice. Taken together, the two analyses expand the supporting evidence base for aficamten but stop short of changing clinical practice or regulatory status on their own.