Long-Term Study Confirms Gene Therapy Works for Haemophilia B Patients

New Delhi: A study by UK-based scientists has confirmed that a gene transfer approach to treating haemophilia B remains safe and effective over the long term.

Published in The New England Journal of Medicine, the study presents 13 years of follow-up data and shows an almost 10-fold reduction in annualised bleeding rates among patients treated with a one-time gene therapy. The results support the long-term viability of gene therapy for managing the rare genetic bleeding disorder.

Haemophilia B is caused by insufficient levels of factor IX, a protein that helps blood clot. The disorder is X-linked and affects approximately 1 in 25,000 male births. While severity varies, patients with the condition are prone to spontaneous bleeding and potentially life-threatening haemorrhages.

Scientists from St. Jude Children’s Research Hospital and University College London conducted the study, which included 10 adult males with severe haemophilia B. These patients received a single dose of a gene therapy drug between March 2010 and November 2012.

"The key benefit is that gene therapy is a one-time, simple intravenous infusion that's very straightforward to do and potentially has positive effects for a lifetime," said Andrew Davidoff, Chair of the St. Jude Department of Surgery.

After an initial report of success in 2014, the study followed the same group of patients for another decade. All participants maintained stable levels of factor IX and continued to show significant reduction in bleeding.

"For these 10 patients, the factor levels are stable and have been at the same level across these 13 years," said principal investigator Ulrike Reiss from the St. Jude Department of Haematology. "Further, we have not seen any side effects or toxic events in the long-term follow-up."

The gene therapy primarily targets the liver. Although a mild liver inflammation was observed shortly after administration, it was effectively managed with steroids and did not recur.

The findings offer reassurance about the durability, safety, and long-term outcomes of gene therapy for haemophilia B and may influence how the disease is treated in the future.