A gene therapy is approved to treat adults with hemophilia B  

Drug name: Hemgenix® (etranacogene dezaparvovec-drlb)
Manufacturer: CSL Behring
Condition: Hemophilia B 

Condition overview 1-7

Factor IX is a protein needed to produce blood clots to stop bleeding. Symptoms of hemophilia B, resulting from insufficient levels of Factor IX, can include prolonged or heavy bleeding after an injury, surgery, or dental procedure. Severity depends on the extent of the factor IX (FIX) deficiency. When hemophilia is severe, it can manifest as frequent spontaneous hemorrhage and abnormal bleeding from minor injuries or following trauma. Prolonged bleeding episodes can lead to serious complications, such as bleeding into joints, muscles or internal organs, including the brain.  

Most individuals who have Hemophilia B and experience symptoms are men. Estimated prevalence is 3.8 cases per 100,000 males for all severities of hemophilia B and 1.1 cases per 100,000 for severe hemophilia B.  

Hemophilia B represents about 15% of patients with hemophilia. Many women carriers of the disease have no symptoms. However, an estimated 10-25% of women carriers have mild symptoms; in rare cases, women may have moderate or severe symptoms. 

Current treatment

Recombinant Factor IX therapy is the recommended treatment for individuals with hemophilia B. Other options include plasma-derived FIX concentrates and fresh frozen plasma. Prophylactic factor replacement strategies aim to minimize time spent with low FIX plasma activity. FIX therapy can improve, but not completely stop the progression of long-term consequences.  

Hemgenix® (etranacogene dezaparvovec-drlb) overview

Etranacogene dezaparvovec is FDA approved for the treatment of adults with hemophilia B who: currently use Factor IX prophylaxis therapy, or have current or historical life-threatening hemorrhage, or have repeated, serious spontaneous bleeding episodes. 

Etranacogene dezaparvovec is a one-time gene therapy that uses an adeno-virus vector to carry the Padua gene variant of Factor IX (FIX-Padua). The therapy generates FIX proteins that are five to eight times more active than normal. Clinical trials have shown that etranacogene dezaparvovec significantly reduces the rate of annual bleeds in people with hemophilia B.1  

Etranacogene dezaparvovec is administered as a one-time intravenous (IV) infusion and cost impacts the medical benefit. Its wholesale acquisition cost (WAC) is $3.5 million per treated member. 

Date approved: November 22, 2022
Benefit/ROA: Medical benefit/Intravenous infusion 

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 References 

1.  FDA accepts CSL Behring’s biologics license application for etranacogene dezaparvovec for priority review. Accessed in September 2022 at: https://www.cslbehring.com/newsroom/2022/fda-bla-etranacogene-dezaparvovec 
2. https://www.fda.gov/news-events/press-announcements/fda-approves-first-gene-therapy-treat-adults-hemophilia-b 
3. Data on file. CSL Behring. September 2022.  
4. Hemophilia B. NORD. Accessed in September 2022 at: https://rarediseases.org/rare-diseases/hemophiliab/#:~:text=Hemophilia%20B%20is%20a%20rare,stop%20bleeding%20and%20promote%20healing .  
5. WFH guidelines for the management of hemophilia. 3 rdEdition. Accessed in September 2022 at: https://www1.wfh.org/publications/files/pdf1863.pdf  
6. Final analysis of pivotal HOPE-B Study demonstrates durable and sustained therapeutic effect of etranacogene dezaparvovec gene therapy in hemophilia B. Accessed in September 2022 at: https://www.cslbehring.com/newsroom/2022/hope-b-data-presented-at-eahad2022  
7. Von Drygalski A, Giermasz A, Castaman G, et al. Etranacogene dezaparvovec (AMT-061 phase 2b): normal/near normal FIX activity and bleed cessation in hemophilia B. Blood Adv 2019; 3(21): 3241-3247.  
8. uiQure and CSL Behring announce primary endpoint achieved in HOPE-B trial of etranacogene dezaparvovec gene therapy in patients with hemophilia B. Accessed in September 2022 at: https://www.cslbehring.com/newsroom/2021/hope-b-gene-therapy-for-hemophilia-b-toplineresults 
9. Cortellis, search term: hemophilia B. Accessed in September 2022