FDA Lifts Rocket Pharmaceuticals Study Hold For Rare Disease Gene Therapy

Author: Vandana Singh | August 20, 2025 09:31am

Rocket Pharmaceuticals Inc. (NASDAQ:RCKT) stock is trading higher on Wednesday after the U.S. Food and Drug Administration (FDA) lifted the clinical hold on its pivotal Phase 2 trial of RP-A501 for Danon disease.

The hold was lifted in under three months.

Danon disease is a rare X-linked dominant genetic disorder that manifests with the clinical triad of cardiomyopathy (stiff heart muscles), skeletal myopathy (weakness), and intellectual disability.

For the unversed, in May, the company reported a patient death in the study after an acute systemic infection.

The SAE involved clinical complications related to capillary leak syndrome, where fluid and proteins leak out of tiny blood vessels (capillaries) and into the surrounding tissues.

Also Read: Rocket Refocuses Pipeline As Gene Therapy Sentiment Sours

The FDA placed a clinical hold on the trial for further evaluation. On Wednesday, the FDA confirmed that Rocket satisfactorily addressed issues outlined in the clinical hold.

The FDA authorized the pivotal study to resume first with a recalibrated dose of 3.8 x 10¹³ GC/kg of RP-A501 in three patients, treated sequentially with a minimum four-week interval between each treatment.

This adjusted dose aligns with the lower range of administered doses associated with efficacy across multiple biomarkers, echocardiographic, and clinical endpoints in the Phase 1 study. It has been determined that it will most likely confer the safety and efficacy identified in the low-dose Phase 1 cohorts.

In addition, Rocket will collaborate with investigators to implement an immunomodulatory regimen more closely reflected in the Phase 1 pediatric cohort.

The revised regimen discontinues prophylactic use of a C3 complement inhibitor, while maintaining sirolimus, rituximab, and steroids.

Additionally, the protocol will specify a lower threshold for administering a C5 inhibitor (eculizumab) in response to impending complement activation.

To date, six patients with Danon disease have been treated in the Phase 2 study with RP-A501.

Price Action: RCKT stock is up 33.68% at $3.91 during the premarket session at the last check on Wednesday.

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Posted In: RCKT