FDA approval puts new cytokinetic heart drug in competition with fast-growing BMS Med

Before the FDA’s decision on Cytokinetics’ obstructive hypertrophic cardiomyopathy drug, the outstanding question was not so much whether the agency would approve the drug, but rather how the product’s label would match that of a Bristol Myers Squibb drug that was the first to be marketed for this indication.

The verdict is in and the drug’s label, aficamten, has less restrictive safety and monitoring requirements, features that could help make the product competitive. The FDA’s approval late Friday makes the once-daily pill the first marketed product for cytokinetics. The South San Francisco-based biotech will market the new drug under the brand name Myqorzo.

Hypertrophic cardiomyopathy (HCM) develops when the heart muscle becomes abnormally thick, making it harder for the organ to pump blood. In obstructive HCM (oHCM), the thicker heart muscle makes the inside of the left ventricle smaller and stiffer, limiting the heart’s pumping ability. Symptoms include dizziness, fatigue and shortness of breath. The disorder can progress to heart failure. Cytokinetics says more than 300,000 patients in the United States have been diagnosed with HCM, but notes that the market could be larger, since between 400,000 and 800,000 are estimated to remain undiagnosed. About half of HCM patients have oHCM.

Older cardiac medications, such as beta-blockers and calcium channel blockers, may be used to treat oHCM, but they were not specifically developed for this disease and do not address its underlying cause. Heart muscle thickening develops from excessive contractions of the heart muscle caused by mutated versions of the heart protein myosin. Myqorzo from Cytokinetics is a small molecule myosin inhibitor. Results from a placebo-controlled phase 3 clinical trial showed that the once-daily pill improved the heart’s ability to function during exercise, among other measures of heart function.

The 2022 FDA approval of BMS’ Camzyos made it the first drug developed specifically for adults with oHCM, validating the approach of using a small molecule to inhibit cardiac myosin. Through the first nine months of this year, BMS reported $714 million in Camzyos sales, an increase of more than 88% from the same period in 2024, putting it on track to achieve blockbuster status. But this medication also carries a risk of heart failure. Camzyzos may cause a reduction in the volume of blood pumped by the left ventricle of the heart with each contraction. A black boxed warning on the product label indicates this risk of left ventricular ejection fraction (LVEF). The FDA’s approval of Camzyos also comes with a Risk Evaluation and Mitigation Strategy (REMS), a risk mitigation program that requires echocardiograms before starting treatment and during treatment to monitor LVEF.

The FDA’s approval of Myqorzo for adults with oHCM also highlights a risk of heart failure due to reduced LVEF, a risk described in a black boxed warning. But analysts consider the Cytokinetics product label to be less restrictive. In a note sent to investors, Leerink Partners analyst Roanna Ruiz said Myqorzo’s REMS requires fewer echocardiograms and provides more flexibility to perform them at the start of dosing and during dose titration. The Cytokinetic drug does not require drug interaction screening at the pharmacy level, reducing the burden on pharmacists. Ruiz added that Myqorzo does not carry an embryo-fetal toxicity warning like Camzyos, which should allow the Cytokinetic drug to capture more women of childbearing age with oHCM. Cytokinetics highlighted these differences in its approval announcement.

“Our first FDA approval is a testament to the strength of our science and the bold, pioneering research that has defined Cytokinetics’ leadership in muscle biology,” said President and CEO Robert Blum. “I am pleased that the approved label and REMS reflect Myqorzo’s distinct features, including a simple and flexible dosing regimen, no drug interaction monitoring requirements, and a predictable safety profile.

Cytokinetics has good capital to market its new drug. In an investor presentation, the company said its cash and investments totaled about $1.25 billion at the end of September. The company said the price of Myqorzo will be disclosed in January, when it plans to launch the new product. But other clinical trials are underway and could expand the Myqorvo label. A phase 3 study of oHCM is testing it against standard beta blockers; preliminary results announced in May showed statistically significant improvement from baseline to week 24. Another phase 3 study is evaluating the drug in non-obstructive HCM. The success of this study could further differentiate Myqorzo from Camzyos, which failed a phase 3 test in this indication earlier this year. Cytokinetics is also testing the drug in pediatric patients with HCM.

Growth opportunities for Myqorzo extend overseas. Last week, Chinese regulators approved the drug for oHCM. This regulatory decision triggers a milestone payment from Sanofi, which holds the rights to the drug Cytokinetics in China. Bayer holds the rights to the molecule in Japan. Cytokinetics retains European rights to Myqorzo. A key committee of the European Medicines Agency recently issued a positive opinion for the drug; a regulatory decision in Europe is expected in the first quarter of 2026.

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