Comparison of oncological outcomes of upfront androgen receptor signaling inhibitors and combined androgen blockade in Japanese patients with metastatic castration-sensitive prostate cancer.

In recent years, randomized controlled trials have demonstrated that upfront androgen receptor signaling inhibitors (ARSIs) prolong overall survival (OS) compared with androgen deprivation therapy (ADT) alone or combined androgen blockade (CAB) in patients with metastatic castration-sensitive prostate cancer (mCSPC). However, it remains unclear whether upfront ARSI is superior to CAB in Asian populations, among which the efficacy of ADT/CAB is considered relatively high. In this study, we compared the oncological outcomes of upfront ARSI and CAB in Japanese patients with mCSPC. Patients with mCSPC who underwent systemic therapy between May 2009 and October 2023 were enrolled retrospectively. Propensity score matching (PSM) was performed to compare the castration-resistant prostate cancer-free survival (CRPC-FS), cancer-specific survival (CSS), and OS between patients treated with upfront ARSI (ARSI group) and those treated with CAB (CAB group). In total, 30 and 142 patients were enrolled in the ARSI and CAB groups, respectively. After PSM (25 patients in each group), CRPC-FS was significantly longer in the ARSI group than in the CAB group (median: 36.7 vs. 12.3 months, hazard ratio: 0.44, 95% confidence interval: 0.20-0.97, p = 0.035). No significant differences were observed in CSS or OS between the two groups. In conclusion, when compared to CAB, upfront ARSI might have the potential to extend CRPC-FS among individuals in the Japanese population.