Cost-effectiveness model of abiraterone plus prednisone, cabazitaxel plus prednisone and enzalutamide for visceral metastatic castration resistant prostate cancer therapy after docetaxel therapy resistance

Abstract

Aims: Among patients diagnosed with prostate cancer, 10-20% will develop castration-resistant prostate cancer (CRPC) within 5 years; for 70%, CRPC will metastasize, mostly to the lungs and/or liver. We performed a cost-effectiveness model comparing abiraterone plus prednisone (ABI + PRD), cabazitaxel plus prednisone (CAB + PRD) and enzalutamide (ENZ) for visceral metastatic CRPC post-docetaxel therapy resistance. Methods: A three-state (Progression-Free, Progression, Death) lifetime Markov model was constructed to compare ABI + PRD, CAB + PRD, and ENZ from a United States healthcare payer perspective (2019 US$; discount rate 3%/yr.). Effectiveness was measured in life-years (LYs) and quality-adjusted life years (QALYs). Inputs included treatment costs, grade III/IV adverse events with incidence ≥5%, physician follow-up, lab and imaging tests. Phase III trial Kaplan-Meier curves were extrapolated to estimate overall survival and Progression-Free transition probabilities. Incremental cost-effectiveness ratios (ICERs) and utility ratios (ICURs), probabilistic sensitivity analyses (PSAs) and cost-effectiveness acceptability curves at willingness-to-pay (WTP) thresholds were estimated. Results: Models estimated 3-year overall survival rates of 1.3% for patients treated with ABI + PRD, 16.2% for CAB + PRD, and 13.2% for ENZ. Estimated Progression-Free rates at 1.5 years were 0.51% for ABI + PRD, 0.27% for CAB + PRD, and 14.47% for ENZ. LYs and QALYs were 1.20 and 0.58 respectively for ABI + PRD, 1.48 and 0.56 for CAB + PRD, and 1.58 and 0.79 for ENZ. Total treatment costs were: $115,433 for ABI + PRD, $85,337 for CAB + PRD and $109,213 for ENZ. CAB + PRD and ENZ dominated ABI + PRD due to higher LYs gained. Incremental QALYs for ENZ vs. CAB + PRD were larger than incremental LYs. The ICUR for ENZ was $103,674/QALY compared to CAB + PRD. Conclusions: This analysis found ENZ provided greater LYs and QALYs than both ABI + PRD and CAB + PRD, at a lower cost than ABI + PRD, but at a higher cost compared to CAB + PRD. For patients with visceral mCRPC after docetaxel therapy resistance, ENZ was cost-effective 92% of the time with a WTP threshold of $100,000/QALY.

Keywords: D60; D61; Metastatic disease; abiraterone; cabazitaxel; cost-effectiveness analysis; cost-utility analysis; docetaxel; economic evaluation; enzalutamide; prostate cancer.