This exploratory analysis of the CHART trial (ClinicalTrials.gov: NCT03520478) investigated prostate-specific antigen (PSA) kinetics and the correlation between PSA and survival outcomes in high-volume, metastatic, hormone-sensitive prostate cancer (mHSPC). A total of 654 patients were randomized 1:1 to receive either rezvilutamide plus androgen deprivation therapy (ADT; n= 326) or bicalutamide plus ADT (n= 328). PSA kinetics were evaluated, and the correlation between survival and the achievement of undetectable PSA (≤0.2ng/mL) or ≥90% PSA reduction (PSA90) was assessed. The rezvilutamide group exhibited higher proportions of ≥50% PSA reduction (PSA50; 98.2% vs. 87.5%), PSA90 (88.7% vs. 63.1%), and undetectable PSA (38.3% vs. 17.7%) responses compared to the bicalutamide group by 3months. The rezvilutamide group demonstrated superior efficacy in delaying PSA progression compared to the bicalutamide group (hazard ratio [HR] 0.21, 95% confidence interval 0.16-0.27). The achievement of undetectable PSA and PSA90 by 6months in the rezvilutamide group was associated with prolonged overall survival (undetectable PSA, HR= 0.34; PSA90, HR= 0.22), radiographic progression-free survival (HR= 0.36, HR= 0.26), time to PSA progression (HR= 0.25, HR= 0.17), and time to castration resistance (HR= 0.34, HR= 0.23) compared to those who did not achieve these PSA milestones. Stratification by baseline PSA level revealed consistent survival improvements with rezvilutamide plus ADT across quartiles. PSA kinetics is a valuable prognostic factor in mHSPC treated with rezvilutamide plus ADT, and the achievement of undetectable PSA and PSA90 is associated with improved survival. These findings highlight the importance of monitoring PSA kinetics in the management of mHSPC. This study was funded by Jiangsu Hengrui Pharmaceuticals Co., Ltd.