title: Retreatment of men with metastatic castrate-resistant prostate cancer with abiraterone.
abstract: BACKGROUND
  Abiraterone acetate (AA), oral CYP17 inhibitor, is an active agent in the treatment of metastatic castrate-resistant prostate cancer (mCRPC).
  
  
  METHODS
  We (R.L.A and N.A) retrospectively evaluated outcome in 12 men who were re-treated with AA following prior treatment with AA at the Princess Margaret Cancer Centre.
  
  
  RESULTS
  All men were heavily pre-treated for mCRPC with a median of four prior lines of therapy, one of which was AA (given either pre- or post-chemotherapy). Eleven out of 12 (92%) men stopped their first treatment course of AA due to progression and one stopped for financial reasons. Seven men had a PSA decrease ≥50% following their first AA treatment, of which three (46%) had a PSA decrease ≥50% to AA re-treatment. The responses to AA re-treatment were generally short-lived with a median biochemical progression-free survival of 2.3 months and median treatment duration of 3.2 months. No PSA responses to AA re-treatment were seen in five men who did not have an initial PSA response to AA.
  
  
  CONCLUSIONS
  Our data suggest that AA re-challenge may have limited benefit in select men with mCRPC, and warrants further formal research.
authors.affiliation: Department of Medical Oncology and Hematology, Princess Margaret Cancer Center, University Health Network, Toronto, Canada.
authors.forename: Raya
authors.initials: R
authors.lastname: Leibowitz-Amit
authors.forename: Nimira
authors.initials: N
authors.lastname: Alimohamed
authors.forename: Francisco E
authors.initials: FE
authors.lastname: Vera-Badillo
authors.forename: Jo-An
authors.initials: JA
authors.lastname: Seah
authors.forename: Arnoud J
authors.initials: AJ
authors.lastname: Templeton
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Knox
authors.forename: Ian F
authors.initials: IF
authors.lastname: Tannock
authors.forename: Srikala S
authors.initials: SS
authors.lastname: Sridhar
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Joshua
mesh_terms: D000069501:Abiraterone Acetate; D000368:Aged; D000369:Aged, 80 and over; D000730:Androstadienes / Q000627:therapeutic use*; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D064129:Prostatic Neoplasms, Castration-Resistant / Q000188:drug therapy* / Q000201:enzymology; D012189:Retrospective Studies; D013254:Steroid 17-alpha-Hydroxylase / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000730:Androstadienes; D004791:Enzyme Inhibitors; D013254:Steroid 17-alpha-Hydroxylase; D000069501:Abiraterone Acetate
keywords: abiraterone; mCRPC; re-challenge