Positive results from SEQUOIA-HCM, the pivotal phase III clinical trial of aficamten in patients with obstructive hypertrophic cardiomyopathy

The results of SEQUOIA-HCM show that treatment with aficamten significantly improved exercise capacity compared to placebo, increasing peak oxygen uptake (pVO2) measured by cardiopulmonary exercise testing (CPET) by a least square mean difference (95% CI) of 1.74 (1.04 - 2.44) mL/kg/min (p=0.000002). The treatment effect with aficamten was consistent across all prespecified subgroups reflective of patient baseline characteristics and treatment strategies, including patients receiving or not receiving background beta-blocker therapy.

Statistically significant (p<0.0001) and clinically meaningful improvements were also observed in all 10 prespecified secondary endpoints, including kansas city cardiomyopathy questionnaire clinical summary score (kccq-css) at weeks 12 and 24, the proportion of patients with greater than 1 class improvement in new york heart association (nyha) functional class at weeks 12 and 24, change in provoked left ventricular outflow tract gradient (lvot-g) and proportion less than 30 mmhg at weeks 12 and 24, as well as exercise workload and guideline-eligibility for septal reduction therapy.

Aficamten was well-tolerated in SEQUOIA-HCM with an adverse event profile comparable to placebo. Treatment emergent serious adverse events occurred in 8 (5.6%) and 13 (9.3%) patients on aficamten and placebo, respectively. Core echocardiographic left ventricular ejection fraction (LVEF) was observed to be less than 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. The full results from SEQUOIA-HCM will be presented at an upcoming medical conference.

“The results from SEQUOIA-HCM meet our high expectations for both efficacy and safety, demonstrating that aficamten added to standard of care therapy had a positive impact on exercise capacity as well as rapid and sustained effects on symptoms and functional class in patients with obstructive HCM while maintaining the safety and tolerability that we have previously observed,” said Fady I. Malik, M.D., Ph.D., Cytokinetics’ Executive Vice President of Research & Development. “We believe these results are consistent with those observed in REDWOOD-HCM, the Phase II clinical trial of aficamten, and FOREST-HCM, the ongoing open label extension clinical trial, and may reflect a profile enabling of aficamten to become the cardiac myosin inhibitor of choice among physicians and patients. We thank the patients, investigators and site personnel who participated in SEQUOIA-HCM and continue to support our ongoing clinical research and look forward to sharing the full results from this trial at a medical meeting in 2024.”

“Cardiac myosin inhibition represents an exciting new therapy option for patients with symptomatic obstructive HCM and I am pleased to see these impressive results from SEQUOIA-HCM,” said Martin Maron, M.D., Director, Hypertrophic Cardiomyopathy Center, Lahey Hospital and Medical Center, Burlington, MA; Tufts University School of Medicine, and National Principal Investigator of SEQUOIA-HCM. “A therapy like aficamten that improves exercise capacity in a clinically meaningful manner, absent low LVEF events that interrupt treatment, should be a welcome addition for HCM patients as well as the clinicians who treat them.”

About Aficamten and the Broad Phase III Clinical Trials Program: Aficamten is an investigational selective, small molecule cardiac myosin inhibitor discovered following an extensive chemical optimization program that was conducted with careful attention to therapeutic index and pharmacokinetic properties and as may translate into next-in-class potential in clinical development. Aficamten was designed to reduce the number of active actin-myosin cross bridges during each cardiac cycle and consequently suppress the myocardial hypercontractility that is associated with hypertrophic cardiomyopathy (HCM). In preclinical models, aficamten reduced myocardial contractility by binding directly to cardiac myosin at a distinct and selective allosteric binding site, thereby preventing myosin from entering a force producing state.

The development program for aficamten is assessing its potential as a treatment that improves exercise capacity and relieves symptoms in patients with HCM as well as its potential long-term effects on cardiac structure and function. Aficamten was evaluated in SEQUOIA-HCM (Safety, Efficacy, and Quantitative Understanding of Obstruction Impact of Aficamten in HCM), a pivotal Phase III clinical trial in patients with symptomatic obstructive hypertrophic cardiomyopathy (HCM). Aficamten is currently the subject of two ongoing Phase III clinical trials: MAPLE-HCM (Metoprolol vs Aficamten in Patients with LVOT Obstruction on Exercise Capacity in HCM), evaluating aficamten as monotherapy compared to metoprolol as monotherapy in patients with obstructive HCM, and ACACIA-HCM (Assessment Comparing Aficamten to Placebo on Cardiac Endpoints In Adults with Non-Obstructive HCM), evaluating aficamten in patients with symptomatic non-obstructive HCM. Aficamten received Breakthrough Therapy Designation for the treatment of symptomatic obstructive HCM from the FDA as well as the National Medical Products Administration (NMPA) in China.