Budget Impact of Enzalutamide for Nonmetastatic Castration-Resistant Prostate Cancer

Prostate cancer is the most common cancer and second-leading cause of cancer death among men in the United States. Prostate cancer poses a large economic burden, which increases with progression from localized to metastatic disease. Newly approved treatments for non-metastatic castration-resistant prostate cancer (nmCRPC) delay disease progression and reduce the risk of metastatic disease. Quantifying the potential budget impact of these new treatments is of interest to health care decision makers.

To estimate the budget impact of enzalutamide for the treatment of patients with nmCRPC in the United States over a 3-year time horizon.

An Excel-based model was developed to estimate the budget impact to a U.S. health plan of enzalutamide, a second-generation antiandrogen, as an add-on to androgen deprivation therapy (ADT) for the treatment of high-risk nmCRPC patients (prostate-specific antigen doubling time of ≤ 10 months). Comparators include apalutamide + ADT, bicalutamide + ADT, and ADT only. The analysis includes treatment costs for nmCRPC and for treatment after progression to metastatic castration-resistant prostate cancer (mCRPC). The treated population size was estimated from epidemiological data and literature. Dosing, duration of therapy, and adverse event rates were based on package inserts and pivotal studies. RED BOOK, Centers for Medicare & Medicaid Services fee schedules, and literature were used to obtain costs of drugs, adverse events, and health care visits. Market shares were estimated for each comparator before and after enzalutamide adoption. A 1-way sensitivity analysis was performed to quantify the impact of parameter uncertainty.

In a hypothetical 1-million-member plan with 3% annual growth, it was estimated that there would be approximately 19 eligible incident nmCRPC patients in year 1, increasing to 20 eligible incident patients in year 3. With an assumed market share of approximately 6% for enzalutamide in year 1, the budget impact would be $106,074 ($0.009 per member per month [PMPM]). With a 26% enzalutamide share in year 3, the budget impact would be $632,729 ($0.048 PMPM). Cumulative budget impact to the health plan over 3 years is estimated to be $1,082,095 ($0.028 PMPM). The increased cost of the treatment regimen is partly offset by reduced postprogression costs.

Treatment of nmCRPC patients with enzalutamide has a modest budget impact that is partly offset by delaying progression to mCRPC.

This research was sponsored by Astellas Pharma and Pfizer, the codevelopers of enzalutamide. All authors contributed to the development of the manuscript and maintained control over the final content. Schultz is employed by Astellas Pharma and owns stock in Gilead Sciences and Shire. O'Day and Sugarman are employees of Xcenda, which received consultancy fees from Astellas Pharma. Ramaswamy is employed by Pfizer. A synopsis of the current study was presented in poster format at the AMCP Managed Care & Specialty Pharmacy Annual Meeting 2019, in San Diego, CA, on March 25-28, 2019.