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A groundbreaking 13-year follow-up study has demonstrated that gene therapy for hemophilia B remains safe and effective over the long term, offering new hope for patients with this rare and debilitating genetic disorder. The research, conducted by scientists from St. Jude Children’s Research Hospital and University College London, is the longest reported follow-up for any gene therapy targeting hemophilia B.
Hemophilia B is an X-linked genetic disorder affecting approximately one in 25,000 male births, characterized by insufficient levels of the blood-clotting protein factor IX. The disease can cause frequent spontaneous bleeding and life-threatening hemorrhages, with traditional treatment requiring lifelong, expensive infusions of factor IX protein.
The study involved 10 adults with severe hemophilia B who received a one-time intravenous infusion of gene therapy between 2010 and 2012. Over the following 13 years, researchers monitored the patients for safety, efficacy, and the durability of treatment effects. The results, published in The New England Journal of Medicine, revealed that all patients maintained stable levels of factor IX and experienced a dramatic reduction in bleeding episodes.
Specifically, the annualized bleeding rate dropped from an average of 14 episodes per year to just 1.5 episodes—an almost tenfold reduction. While factor IX levels did not reach the normal range, patients saw significant improvements in quality of life and a reduced need for supplemental factor IX infusions.
Notably, the therapy was well tolerated, with no long-term toxic effects observed. A minor, transient liver inflammation was noted shortly after treatment in some patients, but this was managed with steroids and did not recur. The vast majority of the gene therapy vector was targeted to the liver, where it remained effective and stable.
“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 co-investigator Dr. Andrew Davidoff, chair of the St. Jude Department of Surgery.
The study’s findings address longstanding questions about the durability and stability of gene therapy for hemophilia B and offer profound hope for patients and their families. “It’s incredibly rewarding to see the sustained safety and efficacy, which truly validates the potential of gene therapy as a one-time treatment for this condition,” said Dr. Amit Nathwani, the study’s chief investigator.
Disclaimer:
This article is based on information from scientific studies and press releases. It is intended for informational purposes only and should not be considered medical advice. Consult a qualified healthcare professional for diagnosis and treatment options for hemophilia B or any other medical condition. The results described may not be representative of all patients, and individual outcomes may vary.
