A prospective, multicenter study on the clinical effectiveness of abiraterone in metastatic castration-resistant prostate cancer in Korea: Pre- vs. post-chemotherapy.

Purpose: The proper treatment sequence for administering abiraterone acetate plus prednisolone (AAP) and chemotherapeutic agents has not yet been elucidated for metastatic castration-resistant prostate cancer (mCRPC). Hence, this study evaluated the effectiveness and safety of AAP in pre- and post-chemotherapy settings using real-world data.

Materials and methods: This prospective, multicenter, open-label, observational study included 506 patients with mCRPC. Patients were classified according to the timing of chemotherapy into pre- and post-chemotherapy groups. The effectiveness and safety of AAP were compared between the groups; the prostate-specific antigen (PSA) response, PSA progression-free survival, and radiologic progression-free survival were assessed; and adverse drug reactions were recorded.

Results: Among the included patients, 319 and 187 belonged to the pre- and post-chemotherapy groups, respectively. Risk classification was similar between the two groups. The PSA response was 61.8% in the pre-chemotherapy group and 39.0% in the post-chemotherapy group (p<0.001). The median time to PSA progression (5.00 vs. 2.93 mo, p=0.001) and radiologic progression-free survival (11.84 vs. 9.17 mo, p=0.002) were significantly longer in the pre-chemotherapy group. Chemotherapy status was associated with PSA (hazard ratio [HR] 1.39, 95% confidence interval [CI] 1.09-1.77) and radiologic progression (HR 1.66, 95% CI 1.18-2.33) during AAP treatment. Adverse drug reactions were reported at similar frequencies in both groups.

Conclusions: In this postmarketing surveillance, AAP benefited patients with mCRPC, especially in settings before chemotherapy was administered, resulting in a high PSA response and longer PSA and radiologic progression-free survival with tolerable adverse drug reactions.