Advances in Gene Therapy: Transforming Hemophilia B Treatment
“I have seen so much progress for our community, and when I heard about a potential solution to ongoing prophylaxis treatments, I couldn’t wait to try it.”
— Chip, 74, Gene Therapy Clinical Trial Participant
In 1951, Chip was diagnosed with hemophilia B at 18 months old, during a time when no preventative or proactive treatments existed. While most kids had no worries with rough and tumble play, Chip had to be much more careful. He was excited when treatments became available to him— first fresh frozen plasma, then powdered concentrates of factor IX, followed by recombinant factor IX. While each advancement made it easier for him to manage his hemophilia B, he still had certain troubles with bleeding and experienced long-term damage to his joints.
For decades, this has been the experience of Chip and others living with hemophilia B. Even with the availability of prophylaxis treatments, the reality of frequent, lifelong preventative or on-demand infusions imposes a significant burden on the community, along with constant worry about breakthrough bleeds. In the 1990s, research progressed into gene therapy as another treatment option, and now, this innovation is providing new hope and possibilities for individuals like Chip.
Shifting Treatment Landscape Offers Long-Term Solution for People with Hemophilia B
Advancements in gene therapy have caused a seismic shift in the treatment landscape for hemophilia B, which, for the first time, offers the possibility of freedom from the constraints of continuous prophylactic infusions. Gene therapy marks a new era in hemophilia B care with the potential for sustained factor IX levels and enhanced quality of life.
Dr. Benjamin Samelson-Jones, an attending physician in the Division of Hematology at Children’s Hospital of Philadelphia (CHOP), emphasizes the importance of discussions between healthcare professionals and their patients about long-term treatment options like gene therapy.
“I’ve noticed that some individuals struggle with the frequency of prophylactic treatments,” said Dr. Samelson-Jones. “When these treatments are not administered on time, this could lead to breakthrough bleeds, particularly into joints, causing pain and long-term complications.”
HEMGENIX® (etranacogene dezaparvovec-drlb), the first ever and only currently available gene therapy for the treatment of hemophilia B, was approved in the U.S. in 2022. Through a one-time infusion, HEMGENIX introduces a working gene into the body to allow the liver to produce its own elevated and sustained factor IX levels. This offers greater bleed protection versus prophylactic treatment and can significantly reduce or eliminate the need for continuous factor IX infusions in adults with and without AAV5 neutralizing antibodies.
“I’d been following the development of gene therapy for a while and I actually proactively approached my doctor about joining the HEMGENIX clinical trial and I’m so glad I made that decision,” said Chip.
Real Life Benefits of Gene Therapy
“Gene therapy involves some initial time commitment with pre-tests and follow-up tests to check liver health and factor IX levels but that may pay off later in the form of no prophylactic infusions and bleeds,” said Dr. Samelson-Jones.
Dr. Samelson-Jones
Data from the HEMGENIX clinical trial confirms that the benefits of gene therapy are durable, with 94% of trial participants stopping factor IX prophylaxis treatment and remaining free of continuous prophylaxis through four years post-treatment. The most common side effects for HEMGENIX are liver enzyme elevations, headache, elevated levels of a certain blood enzyme, flu-like symptoms, infusion-related reactions, fatigue, nausea, and feeling unwell. “It’s truly encouraging to see the sustained durability and efficacy of gene therapy,” says Dr. Samelson-Jones. “The advancements made in recent years have been remarkable, and I believe gene therapy is an important treatment option that should be discussed with all potential eligible patients. These conversations allow us to collaborate with our patients to determine the best treatment options for them—I want to match each patient with the therapy that best suits their individual needs.”
When Domenic, now 20, was living at home, he had no problems managing his weekly infusions with the support of his family. But, after moving to college, he struggled with keeping up with his infusions, often missing them for weeks at a time. His mother learned of HEMGENIX and, after discussing it with his physician, Domenic decided to move forward with treatment. “I really just wasn’t responsible enough to do my medicine the way I was supposed to,” recalled Domenic, “but now, I haven’t needed an infusion since HEMGENIX. I never thought this would be possible for me. I can just enjoy life more without the constant worry about bleeding at the forefront of my mind. It also helps my family worry less about my health.”
Domenic was treated with HEMGENIX in 2024.
Insurance Coverage and Support Available
The durable safety and efficacy of HEMGENIX are also why this treatment offers significant potential for long-term cost savings. In the U.S., payers covering the vast majority of the population have established clear medical policies covering the cost, as it can potentially reduce annual bleed rates and the need for continuous prophylaxis treatment.
To assist those interested in receiving gene therapy and institutions in administering the treatment, HEMGENIX ConnectSM provides dedicated support teams to help each step of the way. Dr. Samelson-Jones explained, “The process of setting up our treatment facility was remarkably straightforward, although a lot of hospital committees had to give their approval, and it took some training to integrate gene therapy into our hematology practice. Between the paperwork, training, and setup, it took about a year from start to the first infusion.” He believes it was worth it to be able to offer his patients the latest advancements and the potential for an improved quality of life.
Hemophilia Gene Therapy Shows a Bright Future
Ultimately, gene therapy offers an exciting avenue of treatment for hemophilia B by offering the unprecedented possibility of reducing or eliminating the need for regular prophylactic infusions for years.
Innovations like HEMGENIX are changing the lives of individuals like Chip in ways they had never thought possible. Chip, who has always enjoyed traveling, often faced the daunting task of carrying his medicine and infusion equipment everywhere, having to constantly plan where and when he would infuse—in airports, on planes, etc. He was forced to make adjustments if anything changed and sometimes just finding a vein to infuse into was challenging. After treatment with HEMGENIX, he no longer needs to worry about these obstacles; he can travel with newfound ease and joy, no longer tethered to his medication. This freedom is a remarkable change for people like Chip, and it reflects a new era of possibilities for those living with hemophilia B.
About the Pivotal HOPE-B Trial
The pivotal Phase III HOPE-B trial is an ongoing, multinational, open-label, single-arm study to evaluate the safety and efficacy of HEMGENIX. Fifty-four adults classified as having moderately severe to severe hemophilia B and requiring prophylactic factor IX replacement therapy were enrolled. Participants were not excluded from the trial based on pre-existing neutralizing antibodies to AAV5. Fifty-one people completed at least four years of follow-up. HEMGENIX produced mean factor IX levels of 41.5 IU/dL (n=50) at year one, 36.7 IU/dL (n=50) at year two, 38.6 IU/dL (n=48) at year three and 37.4 IU/dL (n=47) at year four post-infusion. In addition, mean adjusted annualized bleeding rate (ABR) for all bleeds was reduced by approximately 90% from lead-in (4.16, n=54) as compared to year four (0.40, n=51). Furthermore, joint bleeds were reduced from a mean ABR of 2.34 at lead-in to 0.09 during year four. No serious treatment-related adverse reactions were reported.
IMPORTANT SAFETY INFORMATION
What is HEMGENIX?
HEMGENIX®, etranacogene dezaparvovec-drlb, is a one-time gene therapy for the treatment of adults with hemophilia B who:
- Currently use Factor IX prophylaxis therapy, or
- Have current or historical life-threatening bleeding, or
- Have repeated, serious spontaneous bleeding episodes.
HEMGENIX is administered as a single intravenous infusion and can be administered only once.
What medical testing can I expect to be given before and after administration of HEMGENIX?
To determine your eligibility to receive HEMGENIX, you will be tested for Factor IX inhibitors. If this test result is positive, a retest will be performed 2 weeks later. If both tests are positive for Factor IX inhibitors, your doctor will not administer HEMGENIX to you. If, after administration of HEMGENIX, increased Factor IX activity is not achieved, or bleeding is not controlled, a post-dose test for Factor IX inhibitors will be performed.
HEMGENIX may lead to elevations of liver enzymes in the blood; therefore, ultrasound and other testing will be performed to check on liver health before HEMGENIX can be administered. Following administration of HEMGENIX, your doctor will monitor your liver enzyme levels weekly for at least 3 months. If you have preexisting risk factors for liver cancer, regular liver health testing will continue for 5 years post-administration. Treatment for elevated liver enzymes could include corticosteroids.
What were the most common side effects of HEMGENIX in clinical trials?
In clinical trials for HEMGENIX, the most common side effects reported in more than 5% of patients were liver enzyme elevations, headache, elevated levels of a certain blood enzyme, flu-like symptoms, infusion-related reactions, fatigue, nausea, and feeling unwell. These are not the only side effects possible. Tell your healthcare provider about any side effect you may experience.
What should I watch for during infusion with HEMGENIX?
Your doctor will monitor you for infusion-related reactions during administration of HEMGENIX, as well as for at least 3 hours after the infusion is complete. Symptoms may include chest tightness, headaches, abdominal pain, lightheadedness, flu-like symptoms, shivering, flushing, rash, and elevated blood pressure. If an infusion-related reaction occurs, the doctor may slow or stop the HEMGENIX infusion, resuming at a lower infusion rate once symptoms resolve.
What should I avoid after receiving HEMGENIX?
Small amounts of HEMGENIX may be present in your blood, semen, and other excreted/secreted materials, and it is not known how long this continues. You should not donate blood, organs, tissues, or cells for transplantation after receiving HEMGENIX.
Please see full prescribing information for HEMGENIX.
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch, or call 1-800-FDA-1088.
You can also report side effects to CSL Behring’s Pharmacovigilance Department at 1-866-915-6958.
HEMGENIX is manufactured by uniQure Inc. and distributed by CSL Behring LLC.
HEMGENIX® is a registered trademark of CSL Behring LLC.
HEMGENIX ConnectSM is a service mark of CSL Behring LLC.
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