Researchers from the Children’s Hospital of Philadelphia (CHOP) and Royal Prince Alfred Hospital in Sydney have released findings from a long-term study on the gene therapy fidanacogene elaparvovec for hemophilia B treatment. The study, which is the longest follow-up study to date for this gene therapy, was published in the New England Journal of Medicine. Hemophilia B is caused by a deficiency in coagulation factor IX (FIX), leading to severe bleeding issues. Current treatment involves regular FIX infusions to manage and prevent bleeding episodes.
Fidanacogene elaparvovec, a gene therapy using a recombinant adeno-associated virus vector, has shown promise as a potentially transformative one-time treatment option. It includes a high-activity FIX transgene known as FIX-Padua, which significantly boosts the efficiency of FIX production, requiring much lower doses than traditional treatments.
The study, led by Dr. Lindsey George from CHOP, followed 14 male participants aged 18 and over for 3 to 6 years, with 8 participants still ongoing. According to Dr. Benjamin J. Samelson-Jones, an attending physician at CHOP, “Our findings mark the longest-ever follow-up for patients with hemophilia B who received gene therapy with FIX-Padua.” The study shows sustained FIX activity levels, fewer bleeding episodes, and improved mobility among participants.
No major adverse events linked to the therapy were reported, with only mild and manageable liver enzyme elevations in some cases. The study suggests that gene therapy can reduce dependence on FIX infusions and associated healthcare costs, potentially changing the standard care for hemophilia B.
The work received support from Pfizer and is documented in the New England Journal of Medicine article titled “Fidanacogene Elaparvovec for Hemophilia B: A Multi-Year Follow-Up Study,” authored by Rasko, Samelson-Jones, and others.
