Number needed to treat (NNT) and cost of preventing an event (COPE) of enzalutamide vs. abiraterone acetate plus prednisone for the treatment of metastatic castration-resistant prostate cancer (mCRPC) patients who failed androgen deprivation therapy (A

Abstract

Objective: The aim of this study was to estimate the NNT and COPE of enzalutamide (ENZ) in comparison with abiraterone acetate+prednisone (AA+P) over a 12-month and 24-month period from the Supplementary Health System perspective in metastatic castration-resistant prostate cancer patients who are chemotherapy naïve (MCRPC). Methods: The NNT is calculated by the inverse of the absolute risk reduction of an intervention vs. control; additionally, COPE represents the NNT multiplied by total cost of treatment in a pre-defined period. The absolute risk of ENZ and AA+P, and their respective control treatments, were obtained from the Kaplan Meier curves for the co-primary end points of radiographic progression free survival (rPFS) and overall survival (OS) from the clinical studies PREVAIL and COU-AA-302, respectively. Mean treatment duration was estimated utilizing the area under curve (AUC) technique from the respective intervention rPFS curves. The results analyzed ENZ or AA+P versus its respective placebo at 12 and 24 months for NNT and COPE. Total treatment cost consisted of drug cost, monitoring cost and adverse event (>=1% incidence and special interest adverse events) related cost. Results: The 12 month analysis resulted in NNTOS/ENZ= 12.79; NNTrPFS/ENZ= 2.59; NNTOS/AA+P= 116.28; NNTrPFS/AA+P= 4.72 and COPEOS/ENZ= BRL 1,626,583; COPErPFS/ENZ= BRL 329,701; COPEOS/AA+P= BRL 15,144,886; COPErPFS/AA+P= BRL 614,368. For the 24-month analysis, the results were: NNTOS/ENZ= 11.00; NNTrPFS/ENZ= 3.58; NNTOS/AA+P=16.56; NNTrPFS/AA+P= 5.00 and COPEOS/ENZ= BRL 1,965,454; COPErPFS/ENZ= BRL 639,327; COPEOS/ AA+P= BRL 2,833,580; COPErPFS/AA+P= BRL 855,741. Conclusion: Across the 12- and 24-month time horizons, the NNT and COPE was favorable for ENZ vs. AA+P in patients with MCRPC.