Cytokinetics, Inc. is advancing aficamten, a next-in-class cardiac myosin inhibitor, toward potential regulatory approval for the treatment of obstructive hypertrophic cardiomyopathy (HCM). The European Medicines Agency (EMA) has validated the Marketing Authorization Application (MAA) for aficamten, while the U.S. Food and Drug Administration (FDA) has accepted the New Drug Application (NDA) for the drug. These regulatory milestones follow the positive results from the SEQUOIA-HCM Phase 3 clinical trial, positioning aficamten as a potential new treatment option for patients with symptomatic obstructive HCM.
EMA Validates MAA for Aficamten
On December 23, 2024, Cytokinetics announced that the EMA validated the MAA for aficamten. This validation means that the Committee for Medicinal Products for Human Use (CHMP) will now review the application. The MAA is supported by data from the SEQUOIA-HCM trial, which demonstrated significant improvements in exercise capacity and other key clinical metrics in patients with symptomatic obstructive HCM.
Robert I. Blum, President and Chief Executive Officer of Cytokinetics, stated, "With regulatory filings for aficamten already under review in both the U.S. and China, the validation of the MAA marks an important milestone in bringing this potential medicine to even more patients with HCM worldwide."
FDA Accepts NDA for Aficamten
The FDA has accepted Cytokinetics' NDA for aficamten, assigning it a standard review with a Prescription Drug User Fee Act (PDUFA) target action date of September 26, 2025. The FDA is not currently planning to hold an advisory committee meeting to discuss the application.
The NDA is also supported by the results from the SEQUOIA-HCM trial. The study met its primary endpoint, demonstrating a statistically significant improvement in exercise capacity, measured by peak oxygen uptake (pVO2), in patients treated with aficamten compared to placebo. Specifically, aficamten increased pVO2 by 1.8 ml/kg/min compared to baseline, versus 0.0 ml/kg/min with placebo (least square mean (LSM) difference [95% CI] of 1.74 mL/kg/min [1.04 - 2.44]; p=0.000002).
Clinical Trial Data and Endpoints
The SEQUOIA-HCM trial (Safety, Efficacy, and Quantitative Understanding of Obstruction Impact of Aficamten in HCM) was a pivotal Phase 3 clinical trial evaluating aficamten in patients with symptomatic obstructive HCM. The trial's primary endpoint was the change in peak oxygen uptake (pVO2) measured by cardiopulmonary exercise testing (CPET). Key secondary endpoints included the Valsalva left ventricular outflow tract (LVOT) gradient, New York Heart Association (NYHA) Functional Class, Kansas City Cardiomyopathy Clinical Summary Score (KCCQ-CSS), and the proportion of patients with LVOT gradient <30 mmHg.
Statistically significant improvements were observed in all 10 prespecified secondary endpoints. Treatment emergent serious adverse events occurred in 5.6% of patients on aficamten and 9.3% of patients on placebo. Core echocardiographic left ventricular ejection fraction (LVEF) was observed to be <50% in 5 patients (3.5%) on aficamten compared to 1 patient (0.7%) on placebo. There were no instances of worsening heart failure or treatment interruptions due to low LVEF.
Hypertrophic Cardiomyopathy: A Significant Unmet Need
Hypertrophic cardiomyopathy (HCM) is a disease in which the heart muscle becomes abnormally thick (hypertrophied), affecting the heart's ability to pump blood effectively. It is the most common monogenic inherited cardiovascular disorder, with an estimated 280,000 diagnosed patients in the U.S. and potentially hundreds of thousands more undiagnosed. Patients with HCM are at increased risk of atrial fibrillation, stroke, sudden cardiac death, and other cardiovascular complications.
Aficamten: A Potential Next-Generation Therapy
Aficamten is an investigational selective, small molecule cardiac myosin inhibitor designed to reduce myocardial hypercontractility associated with HCM. It works by reducing the number of active actin-myosin cross bridges during each cardiac cycle. In addition to the SEQUOIA-HCM trial, aficamten is being evaluated in several other clinical trials, including:
- MAPLE-HCM: Aficamten as monotherapy compared to metoprolol in obstructive HCM
- ACACIA-HCM: Aficamten in non-obstructive HCM
- CEDAR-HCM: Aficamten in a pediatric population with obstructive HCM
- FOREST-HCM: An open-label extension study of aficamten in patients with HCM
With regulatory submissions underway in the U.S., Europe, and China, aficamten represents a promising advancement in the treatment of obstructive hypertrophic cardiomyopathy.
