Evaluating the Cost-Effectiveness of Etranacogene Dezaparvovec Gene Therapy for Hemophilia B Treatment in the USA.

Background: Hemophilia B, a severe genetic disorder, involves substantial treatment costs and frequent interventions. Etranacogene dezaparvovec (EDZ) is a recently approved gene therapy for hemophilia B.

Objective: This study evaluates the cost-effectiveness of EDZ compared with conventional factor IX (FIX) prophylaxis.

Methods: A semi-Markov model simulated a cohort of adult males with severe hemophilia B to assess the economic impact of EDZ versus FIX prophylaxis over a lifetime horizon from a health system perspective in the USA. Inputs derived from clinical trials included therapy durability and transition probabilities based on Pettersson Scores. Scenario analyses incorporated frameworks suggested by the Institute for Clinical and Economic Review for single or short-term transformative therapies.

Results: Base-case analysis showed that at a cost of US$3.5 million, EDZ led to lifetime cost savings of US$11 million and an additional 0.64 quality-adjusted life years (QALYs) compared with FIX. However, FIX has extremely high annual costs. When annual cost offsets attributed to EDZ were capped at US$150,000, EDZ was found to have a threshold price of US$3.1 million at a willingness-to-pay of US$150,000 per QALY.

Conclusion: EDZ proved to be a dominant strategy over FIX prophylaxis in the base-case scenario, providing large cost savings and slightly better outcomes. The substantial costs associated with FIX are a primary driver behind these results. The introduction of cost-offset caps significantly affects the value-based price of EDZ. Using caps on cost offsets in considering price can help to balance affordability and value in the health system.