Initial three patients were treated safely; RP-A501 was well-tolerated with no TMA or capillary leak syndrome observed

Rocket is actively engaging with the FDA to align on the path to pivotal trial completion; regulatory pathway update expected in the second half of 2026

Comprehensive Danon disease program update on track for the second half of 2026

Rocket Pharmaceuticals, Inc. (Rocket or the Company) (NASDAQ:RCKT), a fully integrated, commercial-stage biotechnology company advancing genetic medicines for rare and devastating diseases, focused on inherited cardiovascular disorders, today announced a positive clinical safety update regarding the initial three patients treated under the modified protocol for its global, pivotal Phase 2 trial of RP-A501 in Danon disease. Early safety has been promising with the Company now engaging with the U.S. Food and Drug Administration (FDA) to align on the pathway for treating additional patients and completing the pivotal Phase 2 trial under the modified protocol.

The patients received RP-A501 at the recalibrated dose of 3.8 × 10¹³ GC/kg together with a refined immunomodulatory regimen comprised of rituximab, sirolimus, and corticosteroids. Treatment proceeded sequentially, with a minimum of four weeks between infusions. To date, no thrombotic microangiopathy (TMA), capillary leak syndrome, or other significant safety concerns have been observed in these patients. The pivotal Phase 2 trial was designed as a 12-patient, single-arm study. The Company is actively engaging with the FDA to align on the path to dosing additional patients and completing the trial and expects to provide an update on the regulatory pathway in the second half of 2026.

The Company remains on track to provide a comprehensive Danon disease program update in the second half of 2026.