FDA Approves Mavacamten for Obstructive HCM

The long-anticipated, delayed FDA approval of mavacamten finally happened. But the path forward for Bristol Myers Squibb drug for obstructive hypertrophic cardiomyopathy (HCM) is far from clear.

The company is selling the drug under the name Camzyos. The original PDUFA date — the date by which the FDA is supposed to make a decision — for mavacamten was Jan. 28. In November 2021, the agency moved the decision date to April 28.

The approval of mavacamten is noteworthy because it is a first-in-class drug that is designed to treat the underlying dysfunction of cardiac muscle cells that leads to hypertrophy (thickening) of the heart muscle. The prevalence of HCM is about 1 in 500, according to one frequently cited study that usedelectrocardiograms to screen people. Other studies have found it to be more common.

Before the announcement of the approval last night, Wall Street analysts had projected mavacamten would easily be a blockbuster with annual sales of $2 billion. But Bristol Myers Squibb CEO Giovanni Caforio and other company officials held an earnings call this morning that included news of dipping sales of Revlimid (lenalidomide) because of biosimilars coming on the market, so the company’s stock price was on track to close at a price lower than yesterday’s price.

Reuters and several other news outlets reported that Bristol Myers Squibb is pricing mavacamten at $89,500 a year, which is six times higher than the $12,000-$15,000 price range suggestedby Institute for Clinical and Economic Review when it conducted its cost-effectiveness review of mavacamten last year.

The mavacamten works by reducing the contraction of heart muscles. In some patients that goes effect goes too far and results in heart failure. The FDA’s approval of the drug includes a requirement that it only be available through a Risk Evaluation and Mitigation Strategy (REMS) program. Approvals tied to REMS programs are common for drugs that have serious side effects.

The REMS program for mavacamtem means prescribers and patients must enroll in the program. Pharmacies must also be certified and can only dispense the drug to patients who have are enrolled in the program.

According to the press release issued by Bristol Myers Squibb about the mavacamten approval, seven (6%) patients in the mavacamten group in the pivotal phase 3 trail experienced drops in left ventricular ejection fraction to below 50%, a marker for heart failure. The press release said all seven recovered when they stopped taking mavacamten.