Rocket Pharmaceuticals Updates Phase 2 Trial of RP-A501 for Danon Disease

CRANBURY, NJ, USA, May 27, 2025 – Rocket Pharmaceuticals, Inc., a leading biotechnology firm focused on genetic therapies for rare diseases, has issued an update regarding its investigational gene therapy, RP-A501, targeted at Danon disease. The company is currently examining an unexpected serious adverse event (SAE) that emerged during its Phase 2 pivotal trial. This event involved a patient who developed capillary leak syndrome as a result of the trial procedure. Despite efforts to manage the situation, this patient unfortunately succumbed to acute systemic infection.

In response to this adverse event, Rocket Pharmaceuticals has initiated a thorough investigation into the cause and is actively coordinating with the U.S. Food and Drug Administration (FDA) and other stakeholders. The primary concern has centered around a new immune suppression agent introduced into the patient's pre-treatment regimen, designed to mitigate complement activation observed in some patients. This agent was exclusive to the AAV9-Danon program.

Upon initial notification of the adverse event, Rocket Pharmaceuticals voluntarily halted further dosing in the trial. Subsequently, on May 23, 2025, the FDA imposed a clinical hold to facilitate further assessment. The company is diligently working towards ensuring the safety of all participants while striving to resume the trial promptly. Presently, Rocket is unable to forecast the completion timeline for the Phase 2 trial due to the ongoing clinical hold.

Gaurav Shah, M.D., CEO of Rocket Pharmaceuticals, expressed profound sorrow over the patient’s passing. He emphasized the company's dedication to developing gene therapies that tackle the root causes of severe diseases such as Danon disease, and extended gratitude to the patients and families involved in this crucial research. Rocket Pharmaceuticals has also conveyed heartfelt condolences to the family of the patient, as well as the caregivers and clinical team.

Furthermore, Rocket Pharmaceuticals continues its collaboration with the Danon Foundation, an organization devoted to advancing research and providing support for those affected by Danon disease. This partnership remains integral to the progress in research and improving treatments for patients.

Financially, Rocket Pharmaceuticals is strategically prioritizing investment in its AAV platform and exploring ways to enhance the value of its broader pipeline. As of March 31, 2025, the company reported cash, cash equivalents, and investments amounting to $318.2 million. These resources are expected to support operations until 2027, excluding potential proceeds from the sale of Priority Review Vouchers contingent upon approval of hematology therapies.

The RP-A501 Phase 2 trial is a global, single-arm, multi-center study designed to assess the efficacy and safety of the treatment in 12 patients suffering from Danon disease. Details about the study are available under the NCT identifier NCT06092034. RP-A501 is a pioneering gene therapy targeted at cardiovascular conditions, specifically Danon disease, which is caused by mutations in the LAMP2 gene. The therapy involves a single dose administered intravenously, aiming to restore cardiac function by delivering the functional LAMP2B gene directly to heart cells.

Rocket Pharmaceuticals is committed to advancing its investigational genetic therapies to address complex and rare diseases. Its cardiovascular portfolio includes programs for conditions such as Danon Disease, PKP2-arrhythmogenic cardiomyopathy, and BAG3-associated dilated cardiomyopathy. Meanwhile, the company's hematology portfolio features treatments for genetic disorders like Fanconi Anemia, Leukocyte Adhesion Deficiency-I, and Pyruvate Kinase Deficiency.

Rocket Pharmaceuticals endeavors to develop transformative therapeutic options that bring hope to patients suffering from rare diseases, fostering longer and healthier lives.