CRANBURY, N.J. — Rocket Pharmaceuticals announced Friday that a patient enrolled in its Phase 2 clinical trial for RP-A501, an experimental gene therapy for Danon disease, has died following a serious adverse event (SAE), prompting the U.S. Food and Drug Administration (FDA) to place the trial on clinical hold.
The company disclosed that the patient suffered complications related to capillary leak syndrome, an immune-related condition. The incident occurred after the patient received a novel immune suppression agent recently added to the pre-treatment protocol. This agent, which had been introduced to reduce complement activation previously observed in some patients, was unique to Rocket’s AAV9-based Danon gene therapy program.
Rocket voluntarily paused dosing after the adverse event was first reported. The FDA subsequently placed a clinical hold on the trial on May 23 to allow for further investigation. The patient later died from an acute systemic infection.
“We are heartbroken by this loss and are fully committed to our mission to develop gene therapies that address the underlying cause of devastating diseases like Danon,” said Dr. Gaurav Shah, Chief Executive Officer of Rocket Pharmaceuticals. “We are immensely grateful for the patients and families who participate in this important research.”
The company is conducting a comprehensive root cause analysis and is in ongoing discussions with the FDA, clinical investigators, independent data safety monitors, and other scientific experts to determine the path forward. While the clinical hold remains in effect, Rocket said it is unable to provide a timeline for the trial’s completion.
Rocket also expressed its condolences to the patient’s family and care team, reaffirming its commitment to collaboration with the Danon Foundation, a nonprofit focused on research, advocacy, and patient support for individuals affected by the rare genetic condition.
As of March 31, 2025, Rocket reported cash, cash equivalents, and investments totaling $318.2 million. The company stated it is prioritizing continued investment in its AAV gene therapy platform while evaluating cost reductions across the broader pipeline. With current resources, Rocket expects to fund operations into 2027, not accounting for potential revenue from Priority Review Voucher sales related to its hematology portfolio.
