Real-world outcomes in patients with metastatic castration-resistant prostate cancer beyond progression after upfront androgen receptor signaling inhibitor

BackgroundUpfront androgen receptor signaling inhibitor (ARSI) along with androgen deprivation therapy is the current standard of care for metastatic castration-sensitive prostate cancer. However, evidence on second-line therapy after upfront ARSI is scarce. We aimed to evaluate the oncological outcome of ARSI versus docetaxel (DOC) after upfront ARSI therapy in a real-world clinical practice.MethodsSubjects were metastatic castration-resistant prostate cancer (mCRPC) patients who had progressed within 2 years of upfront ARSI therapy and received ARSI (ARSI group) or DOC (DOC group) as a second-line therapy. Second-line progression-free survival (second-line PFS), and second-line overall survival (second-line OS) were assessed. Propensity score matching (PSM) was used to adjust the clinicopathological features and treatment patterns.ResultsA total of 101 mCRPC patients, 68 in the ARSI group, and 33 in the DOC group, were included in this analysis. Median second-line PFS was 6.3 months in the ARSI group and 4.9 months in the DOC group (p = 0.21). Median second-line OS was 25.0 months in the ARSI group and 14.2 months in the DOC group (p = 0.06). Prostate-specific antigen nadir <= 0.2 ng/ml during upfront ARSI therapy was significantly associated with improved second-line PFS. After PSM, no significant difference in second-line PFS and second-line OS were observed between the two groups.ConclusionARSI or DOC has comparable oncologic outcomes in terms of second-line PFS and second-line OS. Further prospective research with longer follow-ups will be needed to identify the optimal treatment after upfront ARSI therapy.