(Reuters) -Tenaya Therapeutics said on Friday the U.S. Food and Drug Administration has placed a clinical hold on its trial of an experimental gene therapy for a type of rare inherited heart disease.
Shares of the company slipped more than 20% in extended trading.
The early-to-mid stage trial was testing Tenaya’s therapy, TN-201, in patients with hypertrophic cardiomyopathy linked to mutations in the MYBPC3 gene. The condition causes the heart muscle to thicken abnormally, reducing its ability to pump blood effectively.
The FDA requested changes to the trial protocol to standardize patient monitoring and the management of immunosuppression drugs, which help prevent the body from rejecting the gene therapy.
Tenaya said the FDA’s decision was based primarily on data previously reviewed by the trial’s independent safety board during summer 2025. That board concluded TN-201 had an acceptable safety profile and allowed the trial to expand enrollment at two different dose levels.
The gene therapy has been generally well tolerated so far, with no significant new safety issues since the summer review, the company said, adding that it was working with the FDA to address the concerns and plans to restart patient dosing once the protocol changes are in place at trial sites.
Tenaya does not expect the hold to delay its planned data releases or overall development timeline for the therapy.
(Reporting by Kamal Choudhury in Bengaluru; Editing by Shilpi Majumdar)
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