Rocket Pharma's Gene Therapy for Rare Pediatric Disease Faces Delay in FDA Approval

Last Friday, Rocket Pharma announced that the US health regulatory agency had not approved its investigational gene therapy for a rare and severe pediatric disease that significantly impacts the patients' immune system function. This news led to a significant over 12% drop in the company's stock price in early trading.

According to reports, the US Food and Drug Administration (FDA) responded with a detailed letter, requesting Rocket to provide limited additional information on certain processes for its gene therapy candidate named Kresladi, in order to complete a comprehensive review. Rocket is seeking the FDA's first approval for this therapy to treat severe Leukocyte Adhesion Deficiency-I (LAD-I) patients, with an estimated 800 to 1,000 patients affected in the US and Europe.

In these patients, a mutation in the protein encoded by the ITGB2 gene prevents white blood cells from properly adhering to the vessel walls at sites of infection, potentially leading to severe immune dysfunction and recurrent infections. Rocket stated that it has met with the FDA and discussed the required information to expedite the approval process.

The marketing authorization application is based on early to mid-stage clinical trial data, where all 9 patients treated survived at least 12 months post-treatment. However, in February this year, the FDA extended the review timeline for certain process data related to this gene therapy.

Analyst Tyler Van Buren from TD Cowen commented that this delay appears to be related to internal bandwidth issues at the FDA, rather than any issues with Rocket itself. He also noted that while Kresladi represents a relatively smaller market opportunity for Rocket, a successful approval would strongly validate the company's lentiviral platform, which is working to provide other treatment options for more patient populations.

Currently, the only treatment option for this disease is bone marrow transplantation, which is often difficult to obtain and carries significant risks.