Treatment strategies and outcomes in a long‐term registry study of patients with high‐risk metastatic hormone‐naïve prostate cancer in Japan: An interim analysis of the J‐ROCK study

OBJECTIVE: The prognosis of high‐risk metastatic hormone‐naïve prostate cancer is poor, and real‐world evidence of therapeutic options and sequences is lacking. The J‐ROCK study aimed to evaluate the outcomes in a real‐world setting in Japan. METHODS: Patients with high‐risk metastatic hormone‐naïve prostate cancer diagnosed after May 2019 were eligible. Based on their treatment within 3 months after diagnosis, patients were allocated to either cohort 1 (androgen deprivation therapy alone or combined androgen blockade with bicalutamide) or cohort 2 (androgen deprivation therapy with abiraterone acetate+prednisolone, docetaxel, enzalutamide, or apalutamide). RESULTS: In this first interim analysis (cut‐off January 2021), 410 patients were enrolled, including 163 patients in cohort 1 and 247 in cohort 2. The median follow‐up period was 7.6 (range 0.1–20.5) months. A higher proportion of patients in cohort 2 (42.5%) achieved nadir prostate‐specific antigen levels ≤0.2 ng/ml within a year, compared with cohort 1 (22.1%). Prostate‐specific antigen‐progression‐free survival was also more favorable in cohort 2 (adjusted hazard ratio 0.629 [95% confidence interval 0.345–1.147]). CONCLUSIONS: The higher proportion of cohort 2 suggest a paradigm shift has occurred in the real‐world treatment of high‐risk metastatic hormone‐naïve prostate cancer in Japan. Some factors including prostate‐specific antigen may affect treatment selection but need further observation. Most patients in cohort 2 received abiraterone acetate+prednisolone. The proportion of patients in cohort 1 receiving combined androgen blockade was lower than previously reported in Japan. This analysis suggest that more intensive therapy tends to prolong prostate‐specific antigen‐progression‐free survival in patients with high‐risk metastatic hormone‐naïve prostate cancer.