title: Enzalutamide treatment in patients with metastatic castration-resistant prostate cancer progressing after chemotherapy and abiraterone acetate.
abstract: OBJECTIVE
  The aim of this study was to record prostate-specific antigen (PSA) response and overall survival (OS) for a group of metastatic castration-resistant prostate cancer (mCRPC) patients treated with enzalutamide following progression after abiraterone treatment in the post-chemotherapy setting.
  
  
  METHODS
  Twenty-four mCRPC patients with progression after abiraterone treatment following primary docetaxel therapy received enzalutamide 160 mg/day. The percentage PSA response was recorded following first line docetaxel, abiraterone and enzalutamide treatment. Fischer's exact test, Mann-Whitney U test and linear regression model were used to test for differences in PSA response.
  
  
  RESULTS
  All patients had a follow-up of at least 3 months. The median PSA response following 1 month of enzalutamide was -12% (range -56% to 76%), while the median best PSA response was -22% (-76% to 76%). Forty-six percent had a greater than 30% decrease in PSA. The PSA response to enzalutamide did not correlate with the number of prior cancer treatments (p = 0.57), time from diagnosis to mCRPC (p = 0.11) or prior response to docetaxel (p = 0.67). However, patients treated with second line cabazitaxel had an inferior PSA response to enzalutamide (p = 0.03), and there was a trend for the PSA response to abiraterone to correlate with the PSA response to the succeeding enzalutamide (B = 0.22, p = 0.05). The median OS was 4.8 months.
  
  
  CONCLUSIONS
  Previous abiraterone therapy is associated with a less marked fall in PSA following enzalutamide therapy in post-chemotherapy mCRPC patients compared with reported results in randomized trials. Larger prospective studies of sequencing are warranted.
authors.affiliation: Department of Urology, Copenhagen Prostate Cancer Center, Rigshospitalet, Copenhagen University Hospital , Copenhagen , Denmark ; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark.
authors.forename: Frederik Birkebaek
authors.initials: FB
authors.lastname: Thomsen
authors.forename: Martin Andreas
authors.initials: MA
authors.lastname: Røder
authors.forename: Per
authors.initials: P
authors.lastname: Rathenborg
authors.forename: Klaus
authors.initials: K
authors.lastname: Brasso
authors.forename: Michael
authors.initials: M
authors.lastname: Borre
authors.forename: Peter
authors.initials: P
authors.lastname: Iversen
mesh_terms: D000069501:Abiraterone Acetate; D000368:Aged; D000730:Androstadienes / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001549:Benzamides; D015331:Cohort Studies; D057176:Compassionate Use Trials; D018572:Disease-Free Survival; D000077143:Docetaxel; D006801:Humans; D007610:Kallikreins / Q000378:metabolism*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009570:Nitriles; D010669:Phenylthiohydantoin / Q000031:analogs & derivatives* / Q000627:therapeutic use; D017430:Prostate-Specific Antigen / Q000378:metabolism*; D064129:Prostatic Neoplasms, Castration-Resistant / Q000188:drug therapy*; D043823:Taxoids / Q000627:therapeutic use; D017211:Treatment Failure; D016896:Treatment Outcome
chemical_list: D000730:Androstadienes; D000970:Antineoplastic Agents; D001549:Benzamides; D009570:Nitriles; D043823:Taxoids; D000077143:Docetaxel; D010669:Phenylthiohydantoin; C552428:cabazitaxel; C540278:enzalutamide; C549870:KLK3 protein, human; D007610:Kallikreins; D017430:Prostate-Specific Antigen; D000069501:Abiraterone Acetate
keywords: abiraterone; castration-resistant prostate cancer; enzalutamide; post-chemotherapy; sequencing