An innovative gene therapy treatment has brought transformative results for adults with hemophilia B, reducing bleeding episodes by an average of 71% after just a single infusion.
The findings come from an international Phase III clinical trial led by researchers from the University of Pennsylvania’s Perelman School of Medicine.
This promising treatment offers new hope for patients who, until now, have depended on regular infusions to manage this life-altering genetic disorder.
Understanding Hemophilia B and Its Challenges
Hemophilia is a rare genetic disorder affecting approximately 30,000 individuals in the United States, primarily males. Hemophilia B, specifically, is caused by a deficiency in clotting factor IX, a protein essential for proper blood clotting. Without it, individuals are at risk of spontaneous bleeding episodes, especially internal bleeding into joints, which can lead to painful joint damage and long-term mobility issues.
For many, managing this disorder has required frequent infusions of factor IX to prevent bleeds, an effective but burdensome process.
The new gene therapy offers an alternative to this routine, enabling patients’ bodies to produce factor IX independently.
Dr. Adam Cuker, a lead author of the study and a specialist at the Penn Blood Disorders Center, describes the impact: “What we saw from patients in this study was that within a few days of receiving the gene therapy infusion, it took root, and their bodies started making factor IX for the first time in their lives.”
While he cautions that calling it a “cure” may be premature without longer follow-up, the therapy has been “life-changing” for many patients.
A Single Infusion with Lasting Effects
Traditional treatments for hemophilia B involve prophylactic (preventive) infusions of factor IX multiple times a week. This regime, although effective, requires frequent intravenous injections, which can become a challenging part of everyday life.
In contrast, this new gene therapy requires only one infusion, after which many patients do not need additional factor IX treatments. Results from the clinical trial showed that, after at least a year of monitoring, participants had an average 71% decrease in bleeding episodes compared to the prior year under prophylactic infusions.
Remarkably, more than half of the 45 participants in the study experienced no bleeding episodes at all following the gene therapy.
The therapy, known as fidanacogene elaparvovec, was officially approved by the U.S. Food and Drug Administration (FDA) in April 2024.
This approval followed the earlier authorization of the first gene therapy for hemophilia B, etranacogene dezaparvovec-drlb, in November 2022. Both therapies represent significant milestones in hemophilia treatment, with Penn Medicine among the select medical centers nationwide offering these therapies.
Streamlined Management for Hemophilia B Patients
Dr. Cuker highlights how this therapy is not only physically beneficial but also liberating from the psychological burdens associated with hemophilia.
“We hear from people born with hemophilia that—even if their disease is well-managed—there’s this burden that’s always in the back of their mind. The frequent infusions, the cost of treatment, the need to plan for infusions when traveling, what happens if they do experience a bleed, and so on, is always there,” he shares.
For patients treated in this study, the new therapy has brought about a “hemophilia-free state of mind,” giving them a sense of freedom and relief from the constant logistics of managing their condition.
Beyond the immediate physical impact, this therapy represents a substantial improvement in quality of life. No longer constrained by the frequent need for factor IX infusions, patients are free from the routine of needles and treatments that previously dictated their schedules and lifestyle choices.
The therapy’s ability to produce lasting clotting factor IX from a single dose redefines what daily life looks like for many patients with hemophilia B.
Addressing Potential Risks and Monitoring Long-Term Effects
Despite the overwhelming positive results, the therapy is not without its risks. One of the most common adverse effects observed in the study was an immune response targeting liver cells modified by the gene therapy, a response that could potentially reduce the treatment’s effectiveness.
In these cases, patients were treated with steroids to suppress the immune reaction, ensuring that the gene therapy could continue working as intended. Penn Medicine plans to monitor all participants for at least five years to assess any long-term side effects and ensure continued safety.
Gene therapy requires specialized expertise, not only in administering the infusion but also in selecting eligible candidates and educating patients about potential risks and benefits.
Dr. Cuker and his team at Penn Medicine emphasize the importance of patient screening and education as integral components of the gene therapy process.
“Now that we have patients who were treated on this study and are essentially cured of their hemophilia, they’re telling us about realizing a new, ‘hemophilia-free state of mind,’” he notes, underscoring the transformative impact for patients and the critical role of informed care.
Future of Gene Therapy in Hemophilia Treatment
In the recent study published in the New England Journal of Medicine, the primary adverse effect observed was an immune system response targeting the liver cells affected by the gene therapy, which, if left untreated, could reduce the therapy’s effectiveness.
To manage this reaction, affected patients received steroid treatments to curb the immune response. Additionally, all participants will be monitored over the next five years to assess any potential long-term side effects.
Penn Medicine is committed to expanding access to gene therapies and is actively involved in clinical trials exploring new treatments. The institution’s expertise in screening, administering, and monitoring gene therapies offers hope to patients who may be candidates for these breakthrough treatments.
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