Frank Vinluan , 2025-05-02 18:32:00
Cytokinetics aims to compete with a Bristol Myers Squibb heart drug projected to become a blockbuster seller, and the company’s value proposition is that its drug candidate has a potential safety edge. The biotech needs to wait a little longer to see what the FDA thinks.
The agency has pushed back the September target date for a regulatory decision in order to review a proposed safety plan for the drug, aficamten, Cytokinetics announced after Thursday’s market close. The new decision deadline is Dec. 26.
Aficamten is under review as a treatment for obstructive hypertrophic cardiomyopathy, a disorder in which cardiac muscle becomes abnormally thick, making it harder for the heart to pump blood. Cytokinetics’s drug is a small molecule designed to inhibit the mutated versions of a heart muscle protein that leads to this thickening.
BMS drug Camzyos was the first in this class of myosin inhibitor medicines. Its 2022 FDA approval introduced an alternative to older heart drugs that offered limited efficacy. BMS reported $602 million in sales for Camzyos in 2024, up from $231 million in the prior year.
The Camzyos label carries a black box warning for complication risks such as heart failure. This drug is available only under a Risk Evaluation and Mitigation Strategy (REMS). For drugs that come with serious safety risks, a REMS informs prescribers and patients about the risks and set up a framework for monitoring for or managing them.
Phase 3 results for the Cytokinetics drug showed an adverse event profile similar to a placebo and no reported cases of heart failure. The application seeking FDA approval contained “a distinct risk mitigation approach specific to aficamten,” according to Cyotkinetics’s annual report. But that approach was not a formal REMS.
“We believe the commercial prospects of aficamten are highly dependent on whether FDA approves aficamten with a label and/or post-marketing conditions that are less challenging to prescribers and patients than the REMS applicable to Camzyos,” the company stated in the report.
In its Thursday announcement, Cytokinetics said that during aficamten’s review, the FDA asked the company to submit a REMS “based on the inherent characteristics of aficamten.” The company complied with the request. However, the agency considers this additional information a major amendment to the drug’s application. Major amendments trigger a three-month extension of a drug’s review.
Cytokinetics said the FDA did not ask for additional clinical data or studies. In a prepared statement, Cytokinetics President and CEO Robert Blum said the company “remains confident in the distinct benefit-risk and pharmaceutic profile of aficamten and continue to expect a differentiated label and risk mitigation profile upon its potential approval by FDA.”
In a note sent to investors, Leerink Partners analyst Roanna Ruiz said the FDA’s request for a REMS after aficamten’s initial submission could indicate that the agency is reassessing its approach to managing risks for the broader class of myosin inhibitors. On an optimistic note, she added that the delay could give Cytokinetics more time to negotiate with the FDA a REMS differentiated from that of the BMS drug. But she added that this development raises several questions, such as what spurred the FDA to ask for a safety plan after it had accepted the initial filing without one.
“Despite this uncertainty, we remain constructive that this may be a procedural delay that doesn’t fundamentally change the approval prospects for afi[camten], albeit there is somewhat more uncertainty as to what afi’s final REMS could look like,” Ruiz said.
Photo by Flickr user xvire1969 via a Creative Commons license
