Rare Daily Staff

Rocket Pharmaceuticals said that the U.S. Food and Drug Administration placed a clinical hold on Rocket Pharmaceuticals’ early-stage trial for its gene therapy treatment of Danon disease, requesting additional risk mitigation methods in its trial protocol.

The notice came in the company’s first quarter earnings report. Rocket’s shares fell 25 percent on the news but were down just 15 percent at the end of the day. Rocket CEO Gaurav Shah said the company anticipates just a one quarter delay in enrollment to address FDA’s concerns.

At the same time, the company reported positive data from a phase 1 trial of low dose RP-A501 in Danon disease that demonstrate stabilization or improvements in key clinical outcomes.   

Danon disease is characterized by weakness of the heart and skeletal muscles, which leads to cognitive impairment, cardiomyopathy, and often heart transplants. The disease manifests in males, who on average, die by the time they reach 20 years of age. Rocket estimates there are between 15,000 to 30,000 people with Danon in the United States and European Union.

Rocket’s gene therapy RP-A501 is intended to restore cardiac function and early data show a decline in markers of heart failure among a small group of young adult patients.

The company said it successfully treated five patients in the low- and high-dose adult cohorts. It said that new longer-term low-dose data demonstrate durable expression and ongoing improvements in biomarkers, and evidence of a positive risk/benefit profile out to 18-months. In the two patients followed to 18-months, the company saw improvement in patient and stabilization/improvement the other, and improvement in a second one.

“These updated results increase our confidence in the low dose as a potentially viable dose for patients with Danon Disease. Safety is our top priority as we progress our gene therapy trials,” said Shah. “We are diligently working with the agency prior to initiating our low-dose pediatric cohort, which we believe has high potential as a phase 2 dose given the durable results noted in adult patients.”

Rocket said the RP-A501 Danon Disease program paused for additional risk mitigation. No new drug-related safety events have been observed in the low- or high-dose adult cohorts of the phase 1 trial. The FDA has requested the company to pause patient dosing and modify the protocol and other supporting documents with revised guidelines for patient selection and management. All follow-up study activities will continue and no additional data are requested. Rocket is continuing its dialogue with the agency to ensure safety measures are updated and harmonized adequately and anticipates additional patient treatment by the third quarter of 2021.

Rocket said it will share data updates from several other rare disease programs at the upcoming American Society of Gene & Cell Therapy meeting. The company’s shares have seen a steady rise, supported by early data from its gene therapy for Danon disease, with the company market capitalization surpassing those of established players such as Bluebird bio and UniQure.

Photo: Gaurav Shah, CEO of Rocket Pharmaceuticals

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