Rocket Pharmaceuticals (NASDAQ: RCKT) announced it has reached alignment with the U.S. Food and Drug Administration (FDA) on the design of a global pivotal Phase 2 trial for its gene therapy RP-A501 in Danon Disease. This marks an important milestone on the path to delivering a potentially transformative treatment for this devastating inherited cardiomyopathy.
Danon Disease is caused by genetic mutations in the LAMP2 gene leading to fatal heart failure. There are currently no approved therapies. The disease affects an estimated 15,000 to 30,000 patients in the U.S. and Europe, taking the lives of most males by age 20 and females by 40. RP-A501 aims to be the first-ever therapy to change the course of Danon Disease.
The news sent Rocket’s stock price soaring 34% to $20.46 in after-hours trading on Tuesday, as investors welcomed the positive regulatory update.
The planned Phase 2 pivotal trial will be a global, single-arm, open label study enrolling 12 Danon Disease patients. This includes a pediatric safety lead-in of 2 patients. All participants will receive a dose of 6.7 x 1013 GC/kg of RP-A501 delivered through intravenous infusion.
To support potential accelerated approval by the FDA, the co-primary efficacy endpoints at 12 months are LAMP2 protein expression and reduction in left ventricular mass, a key measure of heart damage. Expression of LAMP2, which is deficient in Danon patients, and decreased cardiac hypertrophy would signal RP-A501 is restoring cardiac function at its root genetic cause.
Secondary trial endpoints consist of the biomarker troponin, heart failure questionnaires, functional classification, event-free survival, and safety. These could support eventual full approval. A concurrent global natural history study will provide an external control arm for comparison.
According to Rocket CEO Dr. Gaurav Shah, “RP-A501 has the potential to restore normal cardiac function and provide a lifetime of benefit to patients with Danon Disease who have no other viable treatment options.” The company believes this pivotal trial design sets the most rapid path to deliver RP-A501 to patients in dire need.
Rocket’s gene therapy approach involves using an engineered virus called AAV9 to deliver a functional LAMP2 gene into patients’ heart cells. The gene insert encodes LAMP2B, a key protein involved in the cellular recycling process called autophagy. Restoring LAMP2B in the heart could potentially halt the accumulation of cellular debris and improve cardiac structure and function.
The company has already manufactured sufficient high-quality RP-A501 drug product at its in-house cGMP facility to supply the full pivotal Phase 2 trial. Qualified potency assays are also in place to support quality control and regulatory compliance.
Looking ahead, Rocket plans to file a Clinical Trial Application in the EU in Q3 2023 to initiate study activities abroad. The company also recently secured an ICD-10 code from the Centers for Medicare and Medicaid Services for LAMP2 deficiency, which will support diagnostic efforts.
This alignment with the FDA represents a major achievement for both Rocket and the Danon Disease community. RP-A501 would be the first-ever approved treatment for this deadly cardiovascular condition. The gene therapy aims to be a one-time curative infusion that could provide transformative and lifelong benefits to affected patients.
Beyond Danon Disease, Rocket believes this program paves the way for developing genetic medicines against other inherited heart diseases. Cardiac gene therapy has long faced hurdles, but the company is forging a new path for treating genetic cardiovascular conditions at their root.
With the pivotal Phase 2 trial design now locked in, Rocket can move full speed ahead on enrolling patients and gathering data to support potential approval. The company expects to release initial results from the trial evaluating RP-A501 in 2024. This could lead to a approved treatment for Danon Disease in the not too distant future—bringing tremendous hope to patients and families affected by this devastating illness.