A phase 2 study of abiraterone acetate in Japanese men with metastatic castration-resistant prostate cancer who had received docetaxel-based chemotherapy

Takefumi Satoh, Hiroji Uemura, Kazunari Tanabe, Tsutomu Nishiyama, Akito Terai, Akira Yokomizo, Tatsuya Nakatani, Keiichiro Imanaka, Seiichiro Ozono, Hideyuki Akaza

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Abstract

Objective: In this Phase 2 multicenter study the efficacy and safety of oral abiraterone acetate (1000 mg/once daily) plus prednisolone (5 mg/twice daily) was evaluated in metastatic castration-resistant prostate cancer patients from Japan who had previously received docetaxelbased chemotherapy. Methods: Men (aged ≥20 years) with metastatic castration-resistant prostate cancer (prostate-specific antigen levels: ≥5 ng/ml), who had received 1 or 2 cytotoxic chemotherapies (with ≥1 regimen being docetaxel) for prostate cancer, were enrolled in this open-label, single-arm study. Primary efficacy endpoint was proportion of patients achieving a ≥50% prostate-specific antigen decline from baseline (prostate-specific antigen response rate) after 12-week treatment. Safety and pharmacokinetics were also assessed. Results: Confirmed prostate-specific antigen response rate byWeek 12 was 28.3% (90% confidence interval: 17.6%; 41.1%) or 13 out of 46 (full analysis set) treated patients. However, total prostate-specific antigen response rate including confirmed and unconfirmed responses was 34.8% (90% confidence interval: 23.2%; 47.9%). Secondary efficacy endpoints and outcomes were: improvement in Eastern Cooperative Oncology Group performance status score by ≥1 unit: 7/16 patients (43.8%); objective radiographic response: complete response, partial response and stable disease in 0, 1/22 (4.5%) and 9/22 (40.9%) patients, respectively; pain palliation response: 9/16 (56.3%) patients. The most common adverse events (>20% patients) were upper respiratory tract infection (13/47, 27.7% patients) and hepatic function abnormal (10/47, 21.3% patients, Grade 3: 8.5%). All mineralocorticoid-related toxicities were Grade 1/2. Conclusions: Abiraterone acetate plus prednisolone showed favorable efficacy in metastatic castration-resistant prostate cancer Japanese patients who had received chemotherapy. Abiraterone acetate plus prednisolone had an acceptable safety profile.

Original languageEnglish
Pages (from-to)1206-1215
Number of pages10
JournalJapanese journal of clinical oncology
Volume44
Issue number12
DOIs
Publication statusPublished - Dec 1 2014

All Science Journal Classification (ASJC) codes

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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    Satoh, T., Uemura, H., Tanabe, K., Nishiyama, T., Terai, A., Yokomizo, A., Nakatani, T., Imanaka, K., Ozono, S., & Akaza, H. (2014). A phase 2 study of abiraterone acetate in Japanese men with metastatic castration-resistant prostate cancer who had received docetaxel-based chemotherapy. Japanese journal of clinical oncology, 44(12), 1206-1215. https://doi.org/10.1093/jjco/hyu148