Gene therapy cures patients with hemophilia B

Gianna Melillo
·2 min read

Story at a glance

  • Hemophilia B occurs when patients lack sufficient levels of the blood protein factor IX.

  • Some current treatments for the condition involve repeated infusions of the protein.

  • But new research shows a one-time gene therapy could offer long-term efficacy for patients.

Hemophilia B is a rare condition that prevents patients’ blood from sufficiently clotting, heightening the risks of prolonged bleeding.

However, new trial results published today led researchers to claim the majority of adults with the disorder could be cured within the next three years.

This is thanks to FLT180a (verbrinacogene setparvovec), a gene therapy that functions to normalize levels of factor IX, a blood protein that is insufficient in patients with the condition. Findings of the multicenter trial, which included 10 patients with severe or moderately severe hemophilia B, were published in The New England Journal of Medicine.

After 26 weeks of receiving different doses of FLT180a, patients were enrolled in a longer follow-up study. After 27 months, all patients but one exhibited sustained levels of factor IX.

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Around 10 percent of adverse events reported throughout the study period were associated with the treatment while around a quarter were due to immunosuppression, resulting from use of glucocorticoids with or without tacrolimus – a substance used to help the body prevent rejection of a transplanted organ.

Questions about FLT180a remain, including how long its benefits will last in patients, with some estimates projecting it could remain effective for at least a decade.

Gene therapies have been making waves in the medical field due to their lasting efficacy, while current trials are underway to study the treatments’ effects in a variety of diseases, ranging from cancer to glaucoma.

These therapies work by introducing a new or replacement gene to the patient through a viral vector administered via an infusion. Despite the seemingly long-term efficacy seen with these therapies, they are often expensive and the majority must be delivered in an in-patient setting. But for some, including FLT180a, only a single treatment is needed for patients to reap the benefits.

Only a handful of gene therapies are approved in the United States, including a treatment for spinal muscular atrophy (SMA) and elapsed acute lymphoblastic leukemia. Zolgensma, the treatment approved for SMA, currently costs 2.1 million U.S. dollars for a one-time infusion, making it the most expensive drug in the country as of 2021.

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