The ACACIA-HCM trial met both primary endpoints, potentially opening treatment to a new population of heart disease patients
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Shares of Cytokinetics surged to a new 52-week high on Tuesday after positive Phase 3 data for its heart drug aficamten showed statistically significant results in a form of hypertrophic cardiomyopathy that has no currently approved treatments. At its intraday peak, the stock reached $74.35 and subsequently moved up to $76.97.
Known as ACACIA-HCM, the trial brought together 516 people diagnosed with symptomatic non-obstructive hypertrophic cardiomyopathy, a heart condition characterized by muscle thickening that does not impede blood flow out of the heart. Over the 36-week treatment period, those on aficamten outperformed placebo recipients on two co-primary measures: a questionnaire capturing symptom burden known as the Kansas City Cardiomyopathy Questionnaire Clinical Summary Score, and a test of maximal exercise capacity, the company said.
Aficamten patients recorded a 11.4-point improvement in the symptom score versus 8.4 points for placebo, a difference that was statistically significant with a p-value of 0.021. On maximal exercise performance, aficamten patients gained 0.64 mL/kg/min versus a decline of 0.03 mL/kg/min for placebo, with a p-value of 0.003, according to Cytokinetics.
Key secondary endpoints — including the proportion of patients with improved New York Heart Association functional class, a composite exercise measure, and the cardiac stress marker NT-proBNP — also showed statistically significant improvements compared to placebo, the company said.
"Patients with non-obstructive HCM have no therapies approved to treat the underlying hypercontractility associated with the disease. We hope that will change with ACACIA-HCM," Fady I. Malik, executive vice president of research and development at Cytokinetics, said in a statement.
The company flagged a safety finding: left ventricular ejection fraction below 50% occurred in 10% of participants taking aficamten, compared to 1% on placebo. Two participants on aficamten experienced a serious adverse event of heart failure associated with that condition. Treatment interruptions due to ejection fraction dropping below 40% occurred in 3% of aficamten participants.
Aficamten is already approved in the U.S., European Union, and China under the brand name MYQORZO for the obstructive form of hypertrophic cardiomyopathy. If regulators sign off on a new indication, the addressable patient population for the drug would grow substantially, STAT News reported. Hypertrophic cardiomyopathy affects well over 300,000 diagnosed patients in the U.S., with roughly half having the non-obstructive form, the company said.
Cytokinetics said it plans to present the full ACACIA-HCM results at an upcoming medical meeting and to discuss them with the FDA and other regulators.
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