Characterization of PSA dynamics and oncological outcomes in patients with metastatic hormone-sensitive prostate cancer treated with androgen receptor signaling inhibitors

BackgroundThis study investigated the characteristics of prostate-specific antigen (PSA) dynamics when androgen receptor signaling inhibitor (ARSI), or vintage agent (bicalutamide) was used for patients with metastatic hormone-sensitive prostate cancer (mHSPC).Patients and methodsA total of 213 mHSPC patients from each of the ARSI and bicalutamide groups treated between 2015 and 2022 were selected from multiple institutions using propensity score-matched analysis to align backgrounds. PSA progression-free survival (PFS) and overall survival (OS) were assessed. PSA level at 3 months, PSA nadir level, and time to PSA nadir were examined to analyze of PSA kinetics.ResultsARSI treatment significantly improved PSA PFS compared to bicalutamide (P = 0.0063), although no significant difference in OS was seen (P = 0.3134). No significant differences were observed between treatment groups in median PSA levels at 3 months (1.47 vs 0.52 ng/ml, P = 0.3042) or PSA nadir levels (0.263 vs 0.1345 ng/ml, P = 0.1228). Bicalutamide treatment demonstrated longer time to nadir than ARSI in progression-free cases (median: 243 vs 213.5 days, P = 0.0003). Survival tree analysis found that PSA nadir <= 1.5 ng/ml and time to nadir >= 145 days were the optimal cut-offs for best stratifying OS with bicalutamide, while PSA nadir <= 0.45 ng/ml and time to nadir >= 70 days were optimal with ARSI.ConclusionNo significant differences in PSA response was seen between groups; however, distinct optimal cut-offs were demonstrated for PSA nadir and time to nadir. The present findings will be useful for optimal PSA monitoring for mHSPC patients and for early identification of poor-prognosis populations.