Wilson M, McDade C, Thiruvillakkat K, Rouse R, Sivamurthy K, Yan S. Long-term impact of the gene therapy etranacogene dezaparvovec for the treatment of hemophilia B in the United States. Poster presented at the AMCP Nexus 2023; October 17, 2023. Orlando, FL. [abstract] J Manag Care Pharm. 2023 Oct; 29(10-a Suppl):S36-7.

BACKGROUND: Etranacogene dezaparvovec (EDZ) is a gene therapy recently approved for use in people with hemophilia B (PwHB). EDZ increases FIX activity levels, reduces the risk of breakthrough bleeding episodes and eliminates the need for routine, FIX prophylaxis replacement therapy.

OBJECTIVE: To estimate long term clinical impact and cost of EDZ in the United States (US).

METHODS: A decision-analytic model was developed to evaluate the long-term impact of introducing EDZ to treat PwHB in the US over a 20-year time horizon. FIX prophylaxis comparator was a composite weighted average of different FIX prophylaxis regimens based on US market share data. We compared a scenario in which EDZ is introduced in the US versus a scenario without EDZ. Clinical inputs (annualized FIX-treated bleed rate; adverse event rates) were obtained from HOPE B phase 3 trial. EDZ durability input was sourced from a published analysis of long-term prediction of FIX activity with EDZ. EDZ has a one-time price of $3.5 million. Other medical costs (in 2022 USD), including FIX prophylaxis, disease monitoring, bleeding episode management, and adverse events were sourced from published literature. The model estimated annual and cumulative costs, treated bleeds, and joint procedures for the PwHB population over 20 years from EDZ market introduction.

RESULTS: Assuming approximately 600 PwHB were eligible for EDZ in the US, EDZ uptake was estimated to avert 11,579 bleeds and 66 joint procedures over 20 years. With the adoption of EDZ, while there was an annual incremental cost in years 1-5 (mean: $53 million annually, total $265 million), annual cost savings were achieved beginning in year 6 (mean: $177 million annually; total $2.66 billion in years 6-20). The total cumulative 20-year cost savings was $2.39 billion, with incremental cumulative cost in the first 7 years but cumulative cost savings achieved beginning in year 8.

CONCLUSIONS: Introducing EDZ to treat PwHB is expected to result in cost savings and patient benefit over 20 years. Initiating PwHB on EDZ sooner can produce greater and earlier savings and additional bleeds avoided. These results may be considered a conservative estimate of the full value delivery of EDZ to the healthcare system, as PwHB would continue to accrue savings from FIX prophylaxis use and bleeding episodes averted beyond 20 years.

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