BACKGROUND: Enasidenib was recently approved in the United States (US) for patients with relapsed or refractory (R/R) acute myeloid leukemia (AML) with an isocitrate dehydrogenase-2 (IDH2) mutation.
OBJECTIVE: To estimate the budgetary impact of adding enasidenib to the formulary of a hypothetical third-party payer with 5,000,000 covered lives in the US over a 5-year time horizon.
METHODS: A decision-analytic model was developed in Microsoft Excel to estimate drug acquisition, administration, transfusion, diagnostic testing, and adverse event (AE) costs associated with enasidenib and standard high- and low-intensity chemotherapies for R/R AML. Eligible patients, market shares, and treatment duration were estimated from published epidemiologic studies and market research. Regimen dosing information and AE incidence data were taken from published clinical studies and product labels. Transfusion-related data were extracted from enasidenib clinical data and a published Medicare study for comparators. Drug costs were set to wholesale acquisition costs, while other medical costs were estimated from standard US sources. Per member per month (PMPM) and total costs were calculated for two market scenarios; one without enasidenib and one with enasidenib. The difference between the scenarios results in the budget impact of adding enasidenib to formulary. Sensitivity analyses were performed around enasidenib drug acquisition cost, market share uptake, and duration of treatment.
RESULTS: The model estimated approximately 15 patients in the hypothetical health plan would have an IDH2 mutation and be eligible for R/R AML treatment during a calendar year. Overall, with the introduction of enasidenib to formulary, costs for administration, transfusions, and AEs were calculated to slightly decrease, while costs for drug acquisition and diagnostic testing would increase. Additional PMPM costs were estimated to be $0.002 in the first-year post-introduction of enasidenib, $0.006 in the second year, and plateaued at $0.011 in the third-year. Total cost differences post-introduction ranged from approximately $103,000 in the first year to $686,000 in the fifth year. Sensitivity analyses (+/-10% of base-case) showed PMPM to increase from a minimum of $0.001 to a maximum of $0.013 across the 5 years analyzed.
CONCLUSIONS: Adding enasidenib to the formulary for IDH2-mutated, R/R AML patients has a minimal impact on the PMPM cost of a US health plan while providing physicians with another treatment for patients in a disease with limited modern therapies.
