07:59 AM EDT, 05/27/2025 (MT Newswires) -- Rocket Pharmaceuticals ( RCKT ) said Tuesday that the US Food and Drug Administration has placed a clinical hold on the company's mid-stage trial of RP-A501, its drug for Danon disease, after a participant experienced an unexpected serious adverse event and later died from an acute infection.

The company said the incident involved clinical complications related to a capillary leak syndrome.

Rocket said that it is working with the FDA and outside experts to determine the cause and that it is committed to ensuring the safety of study patients while resuming the study as soon as possible, but it did not provide an updated timeline.

The company, which had $318.2 million in cash and equivalents as of March 31, said it would reduce cash spending by focusing on its AAV platform and evaluating other pipeline opportunities.

Shares of the company were down by more than 63% in recent Tuesday premarket activity.