Budget Impact of Adaptive Abiraterone Therapy for Castration-Resistant Prostate Cancer.

Background: The use of a novel strategy known as adaptive abiraterone therapy based on mathematical modeling of evolutionary dynamics of tumor subpopulations was shown in a clinical trial to extend the time to disease progression in patients with metastatic castration-resistant prostate cancer (CRPC) and reduced the use of abiraterone therapy. Although the clinical impact of adaptive abiraterone treatment is clear, the economic impact of this strategy has not been investigated.

Objective: To compare the cost of care with adaptive abiraterone therapy versus standard continuous abiraterone therapy in patients with metastatic CRPC, using patient billing data.

Methods: We performed a retrospective review of billing data for patients with metastatic CRPC who received abiraterone treatment at a large cancer center between June 1, 2012, and August 31, 2018. Patients were divided into 2 groups based on whether they received adaptive abiraterone therapy (N = 15) or continuous abiraterone therapy (N = 21). All patients with refractory, metastatic prostate cancer after castration that was indicated for abiraterone therapy were eligible for this study. Each patient in the adaptive abiraterone therapy cohort received abiraterone plus prednisone treatment until the patient reached a target threshold of 50% or more reduction in prostate-specific antigen (PSA) level compared with his PSA level before abiraterone therapy; treatment was then suspended until the PSA level rose above the 50% of PSA before abiraterone therapy target threshold. The continuous therapy cohort received abiraterone plus prednisone daily until radiographic progression. The primary outcomes were the mean annual cost of care per patient, including and excluding the cost of abiraterone, and the cost of care, by clinical category.

Results: The median time to disease progression was 25.8 months for patients who received adaptive abiraterone therapy compared with 12.1 months for patients who received continuous abiraterone therapy. Overall, the mean total, including the cost of drug, annual cost per patient who received adaptive abiraterone therapy was $79,093 compared with $146,782 for patients who received continuous abiraterone therapy (P <.0001). The annual cost of care per patient, excluding the cost of abiraterone, was $13,883 for those who received adaptive therapy versus $22,322 for those who received continuous abiraterone therapy (P = .2757), which was not statistically significant.

Conclusion: Practical precision medicine strategies, such as adaptive abiraterone treatment or pharmacogenomics-targeted dosing, can use known biomarkers, such as PSA, to tailor therapy, generate improved outcomes, and reduce costs without the need for novel drug and diagnostic discovery and development. The results of this study suggest that a large clinical study of adaptive abiraterone therapy is warranted to validate the potential of this strategy to extend the time to disease progression and reduce costs of treatment of metastatic CRPC.