Jennifer Nguyen

Background: Metastatic castration-resistant prostate cancer (mCRPC) treatment commonly includes first-line (1L) androgen receptor pathway inhibitors (ARPIs) followed by second-line (2L) taxane-based chemotherapy. Adverse events (AEs) may lead to early taxane discontinuation, which can negatively affect outcomes and costs. This retrospective observational study assessed real-world outcomes, AEs, and costs of 2L taxane therapy by number of cycles among patients with mCRPC previously treated with a 1L ARPI; outcomes were compared with patients receiving 2L ARPI. Methods: Overall survival (OS; overall and by number of taxane cycles received) was determined for 2L taxane and compared with 2L ARPI using the Flatiron Health electronic health record database (Jul 1, 2012, to Jun 30, 2020). Taxane-related AEs and associated costs were estimated using the IQVIA PharMetrics® Plus claims database (Jan 1, 2013, to Aug 31, 2021). Results: Overall, 2L ARPI ( n = 473) vs. taxane ( n = 214) was associated with longer median OS (15.4 vs. 13.6 months). Patients receiving > 8 ( n = 48) vs. ≤ 8 taxane cycles ( n = 166) had longer median OS (18.4 vs. 11.9 months; p = 0.006). Patients receiving > 8 vs. ≤ 8 taxane cycles were also more likely to experience an AE (95% vs. 88%) but had lower mean AE-related total healthcare costs per patient per month ($3,429 vs. $6,334). Conclusion: Patients who received > 8 cycles of 2L taxane had longer observed survival. However, these results are subject to selection bias and immortal time bias. Prospective or time-adjusted analyses are needed.