In the leadup to the FDA decision for Cytokinetics’s obstructive hypertrophic cardiomyopathy drug, the outstanding question wasn’t so much whether the agency would approve the medication, but rather how the product’s label would match up against a Bristol Myers Squibb medicine that was first to market in the indication.
The verdict is in and the label for the drug, aficamten, comes with less restrictive safety and monitoring requirements, features that could help make the product competitive. The late Friday FDA approval makes the once-daily pill the first commercialized product for Cytokinetics. The South San Francisco-based biotech will market the new drug under the brand name Myqorzo.
Hypertrophic cardiomyopathy (HCM) develops as heart muscle becomes abnormally thick, making it more difficult for the organ to pump blood. In obstructive HCM (oHCM), the thicker cardiac 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 U.S. diagnosed with HCM, but notes that the market could be larger as an estimated 400,000 to 800,000 remain undiagnosed. About half of HCM patients have oHCM.
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Older heart drugs, such as blood pressure-lowering beta blockers and calcium channel blockers, can be used to treat oHCM, but they were not specifically developed for this disease and they do not address its underlying cause. The heart muscle thickening develops from excessive heart muscle contractions driven by mutated versions of myosin, a cardiac protein. Cytokinetics’s Myqorzo is a small molecule inhibitor of myosin. Results from a placebo-controlled Phase 3 clinical trial showed the once-daily pill helped the heart’s ability to work during exercise among other measures of heart function.
The 2022 FDA approval of BMS’s Camzyos made it the first drug developed specifically for adults with oHCM, validating the approach of using a small molecule to inhibit cardiac myosin. For the first nine months of this year, BMS reported $714 million in Camzyos sales, a more than 88% increase compared to the same period in 2024, putting it on track to achieve blockbuster status. But this drug also comes with the risk of heart failure. Camzyzos can lead to reduction in the volume of blood the heart’s left ventricle pumps with each contraction. A black box warning on the product’s label flags this left ventricular ejection fraction (LVEF) risk. 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 on the drug and during treatment to monitor LVEF.
The FDA’s approval of Myqorzo for adults with oHCM also highlights a heart failure risk due to reduced LVEF, a risk outlined in a black box warning. But analysts view the Cytokinetics product’s label as less restrictive. In a note sent to investors, Leerink Partners analyst Roanna Ruiz said Myqorzo’s REMS requires fewer echocardiograms and has more flexibility in conducting them at the start of dosing and during dose titration. The Cytokinetics drug does not require pharmacy level drug-drug interaction screening, which reduces the burden to pharmacists. Ruiz added that Myqorzo does not have the embryo-fetal toxicity warning that Camzyos does, which should enable the Cytokinetics drug to capture more women of childbearing age who have oHCM. Cytokinetics highlighted those differences in its approval announcement.
“Our first FDA approval stands as a testament to the strength of our science and the bold, trailblazing research that has defined Cytokinetics’s leadership in muscle biology,” President and CEO Robert Blum said. “I’m pleased that the approved label and REMS reflect the distinct characteristics of Myqorzo including a straightforward, flexible dosing regimen, no requirement for drug-drug interaction monitoring and a predictable safety profile.”
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Cytokinetics is well capitalized to commercialize its new drug. In an investor presentation, the company said its cash and investments totaled about $1.25 billion as of the end of September. The company said the price for Myqorzo will be disclosed in January, when it expects the new product will launch. But additional clinical trials are ongoing that could expand Myqorvo’s label. A Phase 3 study in oHCM is testing it against standard of care beta blockers; preliminary results announced in May showed statistically significant improvement from baseline to week 24. Yet another Phase 3 study is evaluating the drug in non-obstructive HCM. Success in this study could further differentiate Myqorzo from Camzyos, which earlier this year failed a Phase 3 test in this indication. Cytokinetics is also testing the drug in pediatric patients with HCM.
The growth opportunities for Myqorzo extend overseas. Last week, regulators in China approved the drug for oHCM. That regulatory decision triggers a milestone payment from Sanofi, which holds the rights to the Cytokinetics drug in China. Bayer has rights to the molecule in Japan. Cytokinetics retains rights European rights to Myqorzo. A key European Medicines Agency committee 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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