Comparison of clinical outcomes between androgen deprivation therapy with up-front abiraterone and bicalutamide for Japanese patients with LATITUDE high-risk prostate cancer in a real-world retrospective analysis.

Background: Combining abiraterone (Abi) with androgen deprivation therapy (ADT) improves overall survival, compared to ADT only, in patients with metastatic castration-sensitive prostate cancer (mCSPC). In Japan, bicalutamide (Bica) and ADT (combined androgen blockade: CAB) is frequently provided for mCSPC. Because these two treatments have not been compared, mCSPC patients who received either treatment were retrospectively analyzed.

Methods: Of 178 patients with LATITUDE high-risk mCSPC, 103 had received ADT plus upfront Abi (Abi group) and 75 had received ADT plus Bica (Bica group) in multiple institutions of the Tokai Urologic Oncology Research Seminar. Kaplan-Meir curves were used to retrospectively analyze survival and cancer recurrence. Univariate and multivariate Cox regression analyses identified potential prognostic factors for progression-free survival (PFS).

Results: Significant differences in major clinicopathological characteristics between the two groups were not observed. The rate of castration-resistant development was higher in the Bica compared to Abi group (50.6 vs. 25.2%, p < 0.001). The median PFS in the Bica group was 13.6 months {95% confidence interval [CI] 9.2-22.2}; however, in the Abi group, PFS did not reach the median {95% CI 18.5-not assessed [NA]; p < 0.001}. Time to second progression for the Abi group was superior (p = 0.07). Univariate and multivariate analyses revealed Gleason pattern 5, high alkaline phosphatase levels, and conventional CAB using Bica as significant prognostic factors for short PFS.

Conclusions: In patients with LATITUDE high-risk mCSPC, upfront use of Abi combined with ADT resulted in favorable prognostic outcomes compared with conventional ADT with Bica.