Aug 03, 2026 —
Rocket Pharmaceuticals announced a positive early clinical safety update from the initial three patients treated under the modified protocol for its global pivotal Phase 2 trial of RP-A501, an investigational AAV9 gene therapy for Danon disease.
The patients received RP-A501 at a recalibrated dose of 3.8 × 10¹³ GC/kg together with a refined immunomodulatory regimen consisting of rituximab, sirolimus, and corticosteroids. Treatment was conducted sequentially, with at least four weeks between infusions.
To date, Rocket reported that RP-A501 has been well tolerated in the initial three patients treated under the modified protocol. No thrombotic microangiopathy, or TMA, capillary leak syndrome, or other significant safety concerns have been observed.
Rocket is actively engaging with the U.S. Food and Drug Administration to align on the pathway for dosing additional patients and completing the pivotal Phase 2 trial. The company expects to provide a regulatory pathway update in the second half of 2026.
The pivotal Phase 2 study was designed as a 12-patient, single-arm trial evaluating RP-A501 in Danon disease. Rocket remains on track to provide a comprehensive Danon disease program update in the second half of 2026.
RP-A501 consists of a recombinant adeno-associated virus serotype 9, or AAV9, capsid carrying a functional human LAMP2B transgene. The therapy is administered as a single intravenous infusion and is designed to deliver the functional LAMP2B gene to cardiac cells.
Danon disease is a rare X-linked inherited lysosomal-associated disorder caused by mutations in the LAMP2 gene. LAMP2 is involved in autophagy and is primarily expressed in heart, skeletal muscle, and brain tissue. Loss of LAMP2 function leads to accumulation of autophagosomes and glycogen, particularly in cardiac muscle.
The disease has a severe clinical course and can lead to progressive cardiomyopathy and heart failure. In male patients, Danon disease is frequently associated with death during adolescence or early adulthood. Cardiac transplantation is currently the only definitive treatment option, but it is associated with substantial complications and is not curative.
Rocket said the recalibrated Phase 2 dose was selected to preserve the therapeutic potential observed in Phase 1 while optimizing the benefit-risk profile. The adjustment accounts for the higher proportion of full capsids in the current drug product and was developed in consultation with experts and the FDA.
RP-A501 has received RMAT, Fast Track, Rare Pediatric Disease, and Orphan Drug designations from the FDA, as well as ATMP and PRIME designations in the European Union. The early safety update represents an important step as Rocket works with regulators to define the path toward completing the pivotal study.
