The aim was to evaluate the efficacy and safety of abiraterone acetate plus prednisolone in patients with chemotherapy-naïve early metastatic castration-resistant prostate cancer who failed first-line androgen deprivation therapy.
Patients with early metastatic castration-resistant prostate cancer with confirmed prostate-specific antigen progression within 1-year or prostate-specific antigen progression without having normal prostate-specific antigen level (<4.0 ng/mL) during first-line androgen deprivation therapy were enrolled and administered abiraterone acetate (1000 mg) plus prednisolone (10 mg). A minimum of 48 patients were required according to Simon's minimax design. The primary endpoint was prostate-specific antigen response rate (≥50% prostate-specific antigen decline by 12 weeks), secondary endpoints included prostate-specific antigen progression-free survival and overall survival. Safety parameters were also assessed.
For efficacy, 49/50 patients were evaluable. Median age was 73 (range: 55-86) years. The median duration of initial androgen deprivation therapy was 32.4 (range: 13.4-84.1) weeks and 48 patients experienced prostate-specific antigen progression within 1-year after initiation of androgen deprivation therapy. prostate-specific antigen response rate was 55.1% (95% confidence interval: 40.2%-69.3%), median prostate-specific antigen-progression-free survival was 24.1 weeks, and median overall survival was 102.9 weeks (95% confidence interval: 64.86 not estimable [NE]). Most common adverse event was nasopharyngitis (15/50 patients, 30.0%). The most common ≥grade 3 adverse event was alanine aminotransferase increased (6/50 patients, 12.0%).
Abiraterone acetate plus prednisolone demonstrated a high prostate-specific antigen response rate of 55.1%, suggesting tumor growth still depends on androgen synthesis in patients with early metastatic castration-resistant prostate cancer. However, prostate-specific antigen-progression-free survival was shorter than that reported in previous studies. Considering the benefit-risk profile, abiraterone acetate plus prednisolone would be a beneficial treatment option for patients with chemotherapy-naive metastatic prostate cancer who show early castration resistance.
Japanese journal of clinical oncology. 2020 Dec 15 [Epub ahead of print]
K Kobayashi, N Okuno, G Arai, H Nakatsu, A Maniwa, N Kamiya, T Satoh, H Kikukawa, Y Nasu, H Uemura, T Nakashima, K Mikami, M Iinuma, K Tanabe, J Furukawa, H Kobayashi
Department of Urology, Federation of National Public Service Personnel Mutual Aid Associations Yokosuka Kyosai Hospital, Kanagawa, Japan., Department of Urology, Independent Administrative Institution National Hospital Organization Sagamihara Hospital, Kanagawa, Japan., Department of Urology, Dokkyo Medical University Saitama Medical Center, Saitama, Japan., Department of Urology, Asahi General Hospital, Chiba, Japan., Department of Urology, Independent Administrative Institution National Hospital Organization Shizuoka Medical Center, Shizuoka, Japan., Department of Urology, Toho University Sakura Medical Center, Chiba, Japan., Department of Urology, Kitasato University School of Medicine, Kanagawa, Japan., Department of Urology, Independent Administrative Institution National Hospital Organization Kumamoto Medical Center, Kumamoto, Japan., Department of Urology, Japan Organization of Occupational Health and Safety Okayama Rosai Hospital, Okayama, Japan., Department of Urology and Renal Transplantation, Yokohama City University Medical Center, Kanagawa, Japan., Department of Urology, Ishikawa Prefectural Central Hospital, Ishikawa, Japan., Department of Urology, Chibaken Saiseikai Narashino Hospital, Chiba, Japan., Department of Urology, Independent Administrative Institution National Hospital Organization Mito Medical Center, Ibaraki, Japan., Department of Urology, Tokyo Women's Medical University Hospital, Tokyo, Japan., Department of Urology, National University Corporation Kobe University Hospital, Hyogo, Japan., Janssen Pharmaceutical K.K., Tokyo, Japan.