Rocket Pharmaceuticals (NASDAQ:RCKT) shares rose 8% on Tuesday after the company said it reached alignment with the US Food and Drug Administration on the pivotal Phase 2 trial of RP-A501 for Danon disease.
The FDA confirmed a pivotal efficacy population of 12 patients, including the first three patients treated under the study’s modified protocol, according to Rocket. The agency also supported continued enrolment and dosing at the recalibrated dose.
Rocket said the FDA confirmed the established 12-month co-primary endpoints intended to support a potential accelerated approval application.
First Three Patients Included in Pivotal Population
The FDA reviewed initial safety data from the first three patients treated under the modified protocol, the company said. All three had completed at least four weeks of follow-up and had been discharged following the observation period specified by the protocol.
According to Rocket, no clinical or laboratory evidence of thrombotic microangiopathy or capillary leak syndrome had been observed in those patients at the time of the update.
The pivotal population will comprise 12 male patients receiving RP-A501 at a recalibrated dose of 3.8 × 10¹³ genome copies per kilogram using commercial-grade product.
The first three patients treated at that dose will count towards the pivotal population, leaving nine additional patients to be enrolled and treated. Rocket expects to complete dosing of the remaining patients by mid-2027.
Primary Assessment Planned at 12 Months
The study’s primary assessment will take place at 12 months and use two co-primary endpoints: myocardial LAMP2 protein expression and a 10% reduction from baseline in left ventricular mass index.
The modified protocol includes the recalibrated RP-A501 dose and an immunomodulatory regimen comprising rituximab, sirolimus and corticosteroids. It also incorporates revised eligibility criteria, safety monitoring and risk-mitigation measures.
RP-A501 remains an investigational therapy, and alignment with the FDA on the trial design does not constitute regulatory approval.
Rocket Pharmaceuticals plans to provide a broader update on its Danon disease programme during a virtual investor webinar on October 6, 2026.
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