Who Is Eligible for Roctavian or Hemgenix Gene Therapy?

One-time gene therapies for hemophilia, such as Roctavian (valoctocogene roxaparvovec) for Hemophilia A and Hemgenix (etranacogene dezaparvovec) for Hemophilia B, offer the potential to significantly reduce bleeding and the need for regular factor infusions ^[1][2]. However, it is important to understand that “one-time” refers to the infusion itself, not a guarantee of a lifelong cure. Responses to the therapy vary, factor levels may decline over time, and some patients may still need replacement factor ^[1][2].

Because of these complexities, these therapies are not suitable for everyone. Eligibility depends on FDA-approved criteria, clinical trial evidence, and careful evaluation by a specialized hemophilia treatment center.

Comparing the FDA Indications

The basic FDA requirements differ significantly depending on which type of hemophilia you have.

Note: Eligibility cannot be determined from a checklist alone. A specialized hemophilia treatment center must evaluate your specific medical history.

Age and Disease Severity

Both gene therapies are currently FDA-approved only for adults aged 18 and older ^[1][4].

• Hemophilia A (Roctavian): The FDA indication is specifically for adults with severe hemophilia A, defined as having a baseline Factor VIII level below 1 IU/dL (less than 1%) ^[1][3]. This refers to your natural baseline level, not the level measured right after a factor infusion.
• Hemophilia B (Hemgenix): The FDA indication is broader in terms of baseline levels. It is approved for adults with hemophilia B who currently use continuous factor IX prophylaxis therapy, or who have a history of life-threatening hemorrhage, or who experience repeated, serious spontaneous bleeding episodes ^[4][5].

AAV Neutralizing Antibodies

Both therapies use an adeno-associated virus (AAV5) as a microscopic delivery vehicle (or vector) to transport the functional clotting gene into your liver cells. If your immune system has been naturally exposed to this specific virus in the past, you might carry pre-existing neutralizing antibodies. These antibodies can bind to the AAV vector and reduce its delivery to the liver cells, potentially preventing the therapy from working well ^[7].

• Roctavian (Hemophilia A): Testing negative for anti-AAV5 antibodies is a strict FDA requirement for Roctavian ^[3]. Individuals with these antibodies were excluded from the pivotal clinical trials ^[1].
• Hemgenix (Hemophilia B): The clinical trials for Hemgenix included participants regardless of their pre-existing anti-AAV5 antibody status ^[6]. While the therapy showed clinical benefit in people with detectable antibodies, its effectiveness in individuals with extremely high antibody levels (titers) remains uncertain, as one trial participant with a very high titer did not respond to the treatment ^[8].

Liver Health Evaluation

Because these gene therapies target and operate inside the liver, a thorough liver health evaluation is required before treatment ^[9]. While a perfectly normal liver is not always required, certain conditions are major barriers.

To evaluate your liver, doctors will typically order laboratory blood tests, an abdominal ultrasound, and a specialized scan (like transient elastography) to measure liver stiffness or scarring (fibrosis) ^[9].

• Major Barriers: Active or uncontrolled liver infections (like Hepatitis B or C), autoimmune hepatitis, and cirrhosis or advanced liver scarring are generally considered major barriers or contraindications by expert consensus guidelines ^[9][10].
• Individualized Assessment: A successfully treated past Hepatitis C infection, mild fatty liver disease, or modestly abnormal liver enzymes may not automatically disqualify you, but will require a specialist’s judgment ^[9].

Post-Treatment Monitoring: After receiving the infusion, it is very common to experience elevated liver enzymes (such as ALT), which indicates liver stress or inflammation ^[10][2]. To manage this, your care team will monitor your blood frequently—sometimes 1 to 2 times weekly during the first year for Roctavian ^[9]. If enzymes rise, doctors may prescribe immunosuppressant medications like corticosteroids (e.g., prednisone) ^[10]. The exact monitoring schedule and steroid regimen vary by product and treatment center, and immunosuppression carries its own risks of infection that must be monitored ^[9].

History of Factor Inhibitors

Some people with hemophilia develop inhibitors—immune system antibodies that mistakenly identify infused replacement clotting factor as a threat and attack it.

• Factor VIII Inhibitors (Roctavian): People with a current or past history of Factor VIII inhibitors were entirely excluded from the pivotal Roctavian clinical trials ^[1][11]. Because researchers did not test the therapy on this group, its safety and effectiveness for patients with a history of inhibitors is not established ^[1].
• Factor IX Inhibitors (Hemgenix): Similarly, the available clinical trial summaries for Hemgenix do not establish safety or treatment outcomes for patients who have current or prior Factor IX inhibitors ^[2].

Having a history of inhibitors does not necessarily mean the FDA formally bans you from the drug, but because the therapies were not studied in these populations, treatment centers may not offer them to you. You will need to undergo current inhibitor testing to help your specialized care team make an individualized decision ^[1].