Patient Death in Rocket Pharmaceuticals Gene Therapy Trial Prompts FDA Clinical Hold

A patient participating in Rocket Pharmaceuticals' pivotal Phase II trial for its gene therapy RP-A501 targeting Danon disease has died after developing complications, notably capillary leak syndrome and an acute systemic infection1 2 3 4 5.

Rocket Pharmaceuticals had already voluntarily paused dosing in the trial before the U.S. Food and Drug Administration (FDA) issued a formal clinical hold on May 23, 20251 2 3 4.

Danon disease is a rare genetic heart disorder associated with severe cardiac complications, often requiring advanced therapies such as gene therapy4.

The serious and unexpected adverse event has heightened concerns over the unpredictability of toxicities in gene therapies, impacting investor confidence and causing Rocket’s stock price to fall over 60% after the news was announced1 2.

Rocket Pharmaceuticals is working closely with the FDA, trial monitors, and independent investigators to determine the root cause of the adverse event, reviewing all aspects of the case as part of an ongoing investigation2 4.