Cytokinetics Inc. (CYTK) has secured US approval for its first commercial medicine, setting up direct competition with a key heart drug sold by Bristol Myers Squibb Co. (BMY).

The newly cleared therapy, branded Myqorzo, is approved to treat obstructive hypertrophic cardiomyopathy. The inherited disease causes abnormal thickening of the heart muscle, which can restrict blood flow and trigger chest pain and shortness of breath.

As part of the decision, the Food and Drug Administration required a boxed warning for the risk of heart failure. Access to the drug will be limited through a restricted distribution program.

The approval places Cytokinetics in competition with Bristol’s Camzyos, which entered the US market in 2022. Both medicines belong to the cardiac myosin inhibitor class, which works by reducing excessive heart muscle contraction linked to the disease.

Camzyos has become an important product for Bristol as the company faces looming patent expirations on older drugs, including the blood thinner Eliquis. Loss of exclusivity is expected to pressure sales across parts of Bristol’s portfolio in coming years.

By the end of the decade, Camzyos is projected to generate about 10% of Bristol’s total revenue, according to estimates from Morningstar analyst Karen Andersen. Analysts expect demand for both drugs to rise initially as physicians gain experience and the treated population grows.

Over the next three years, Camzyos revenue is forecast to double to roughly $2 billion. Wall Street projections suggest Cytokinetics’ therapy could reach about $1 billion in annual sales by 2028.

Raymond James analyst Sean McCutcheon said Cytokinetics’ entry poses a risk to Camzyos’ growth outlook. The degree of impact may depend on how strict patient monitoring requirements prove to be for the newer drug.

Cytokinetics’ shares slipped about 1% in after-hours trading following the announcement. The approval concludes a development path that began with a 2012 collaboration with MyoKardia Inc., which Bristol later acquired for roughly $13 billion.