title: A phase 2 trial of abiraterone acetate in Japanese men with metastatic castration-resistant prostate cancer and without prior chemotherapy (JPN-201 study).
abstract: OBJECTIVE
  Abiraterone acetate has been approved in >70 countries for chemotherapy-naïve metastatic castration-resistant prostate cancer patients. Efficacy and safety of abiraterone acetate (1000 mg/once daily) with prednisolone (5 mg/twice daily) in chemotherapy-naïve Japanese patients with metastatic castration-resistant prostate cancer was evaluated.
  
  
  METHODS
  Men, ≥20 years, with prostate-specific antigen levels of ≥5 ng/ml and evidence of progression were enrolled in this Phase 2, multicenter, open-label study. Primary efficacy endpoint was proportion of patients achieving a prostate-specific antigen decline of ≥50% from baseline (prostate-specific antigen response) after 12 week of treatment. Secondary efficacy endpoints and safety were assessed.
  
  
  RESULTS
  A confirmed prostate-specific antigen response was observed in 29/48 (60.4%) patients by week 12; lower limit of two-sided 90% confidence interval was >35% (threshold response rate), demonstrating efficacy of abiraterone acetate. Secondary efficacy endpoints: prostate-specific antigen response rate during treatment period: 62.5%; objective radiographic response, partial response: 4/18 (22.2%) patients; complete response: none; stable disease: 11/18 (61.1%) patients; median percent change in prostate-specific antigen level from baseline at Week 12: -66.62%. Median prostate-specific antigen response duration and progression-free survival were not reached, and median radiographic progression-free survival was 253 days. Of 31/48 (64.6%) patients experienced adverse events of special interest; most common was hepatic function abnormality (37.5%, Grade 3: 10.4%). One Grade 3 hypertension was the only mineralocorticoid adverse event >Grade 1/2.
  
  
  CONCLUSIONS
  Efficacy of abiraterone acetate plus prednisolone was demonstrated by decline in prostate-specific antigen levels with evidence of antitumor activity by radiography in Japanese patients with chemotherapy-naïve metastatic castration-resistant prostate cancer. Abiraterone acetate plus prednisolone had an acceptable safety profile.
  
  
  BACKGROUND
  NCT01756638.
authors.affiliation: Division of Oncology and Hematology, National Cancer Center Hospital East, Chiba nmatsuba@east.ncc.go.jp.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Matsubara
authors.affiliation: Department of Urology, Kinki University Faculty of Medicine, Osaka.
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Uemura
authors.affiliation: Department of Urology, Kitasato University School of Medicine, Kanagawa.
authors.forename: Takefumi
authors.initials: T
authors.lastname: Satoh
authors.affiliation: Department of Urology, Toho University Sakura Medical Center, Chiba.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Suzuki
authors.affiliation: Division of Urology, Department of Regenerative and Transplant Medicine, Niigata University, Graduate School of Medical and Dental Sciences, Niigata.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nishiyama
authors.affiliation: Department of Urology, Yokohama City University Graduate School of Medicine, Kanagawa.
authors.forename: Hiroji
authors.initials: H
authors.lastname: Uemura
authors.affiliation: Department of Urology, National Hospital Organization Shikoku Cancer Center, Matsuyama.
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Hashine
authors.affiliation: Janssen Pharmaceutical K.K, Tokyo.
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Imanaka
authors.affiliation: Department of Urology, Hamamatsu University School of Medicine, Shizuoka.
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Ozono
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Akaza
mesh_terms: D000069501:Abiraterone Acetate; D000368:Aged; D000369:Aged, 80 and over; D000736:Androstenes / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011239:Prednisolone / Q000008:administration & dosage; D017430:Prostate-Specific Antigen / Q000378:metabolism; D064129:Prostatic Neoplasms, Castration-Resistant / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology
chemical_list: D000736:Androstenes; D011239:Prednisolone; D017430:Prostate-Specific Antigen; D000069501:Abiraterone Acetate
keywords: abiraterone acetate; chemotherapy-naïve; metastatic castration-resistant prostate cancer; prednisolone; prostate specific antigen