Comparison of abiraterone acetate plus prednisolone and combined androgen blockade in high-risk metastatic hormone-sensitive prostate cancer

Abiraterone acetate plus prednisone/prednisolone (AAP) and androgen deprivation therapy (ADT) was approved for the treatment of high-risk metastatic hormone-sensitive prostate cancer (mHSPC) in Japan in 2018. We investigated 22 patients with mHSPC showing ≥2 of 3 high-risk factors (Gleason score ≥8, ≥3 bone lesions or measurable visceral metastases) who received AAP plus ADT at our hospital between March 2018 and October 2019. We compared outcomes between the propensity-score matched AAP plus ADT group and the combined androgen blockade (CAB) group (19 matched pairs, 38 patients) to evaluate the efficacy and safety of AAP plus ADT. Prostate-specific antigen progression-free survival (PSA-PFS) was significantly longer in the AAP group than in the CAB group (not reached vs 15.1 months, p = 0.014). Time to achievement of serum PSA ≤0.2 ng/ml and ≤0.1 ng/ml was shorter in the AAP group than in the CAB group (6.4 months vs not reached, p = 0.001 and 11.0 months vs not reached, p = 0.004, respectively). Although no significant intergroup difference was observed in the overall survival rates and PSA-PFS2 (PSA-PFS on subsequent anticancer therapy) owing to the shorter follow-up in the AAP group, our data suggest that the clinical efficacy of AAP is better than that of CAB in patients with mHSPC.