On Monday, Rocket Pharmaceuticals, Inc. (NASDAQ:RCKT) presented long-term safety and efficacy results from the Phase 1 study of RP-A501 in male patients with Danon disease.

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.

Also Read: FDA Rejects Rocket Pharmaceuticals' Gene Therapy For Rare Immune Disorder, Asks For More Data, Stock Slides

Danon disease is caused by mutations in the LAMP2 gene, which contains instructions for the production of an enzyme called lysosomal-associated membrane protein-2 (LAMP-2). The data showed that RP-A501 was generally well tolerated.

All evaluable Danon disease patients demonstrated LAMP2 protein expression at 12 months (sustained up to 60 months) and reduction of left ventricular (LV) mass index by ≥10% at 12 months (sustained up to 54 months) after treatment.

These data were presented at the American Heart Association (AHA) Scientific Sessions 2024.

Evidence of sustained clinically meaningful improvement was observed in pediatric patients followed up to 24 months and adult/adolescent patients followed up to 60 months.

All evaluable patients in the Phase 1 trial demonstrated:

• Cardiac LAMP2 protein expression at 12 months and thereafter.
• Reduction or stabilization of Left ventricular mass index (LV mass index)– the median reduction from baseline to the most recent visit of 24%.
• Preservation of normal LV ejection fraction (LVEF).
• Reduction or stabilization of cardiac biomarkers (median cTnI and NTproBNP reductions of 84% and 57%, respectively).
• The study also showed the absence of clinical signs of heart failure in patients treated with RP-A501.

William Blair views the long-term follow-up favorably and says it supports RP-A501's durable efficacy.

Overall, the updated data from the Phase I study of RP-A501 de-risks the pivotal trial, as significant improvements in both co-primary endpoints were seen across all six treated patients.

The analyst looks forward to additional updates on the pivotal study and the company's prelaunch preparations in 2025.

"Although we continue to see RP-A501 as the main stock driver in the near term given its large total addressable market, we believe the approval of RP-L201 in leukocyte adhesion deficiency type I (LAD-I) and the completion of the rolling BLA for RP-L102 in Fanconi anemia (FA) could be incremental catalysts for Rocket in 2025," William Blair writes.

Price Action: RCKT stock is down 3.44% at $13.19 at the last check on Tuesday.

• Biogen's Outlook Dims As Analyst Projects Flat Revenue Until 2026