title: Chemotherapy options in castration-resistant prostate cancer.
abstract: BACKGROUND
  The treatment landscape for patients with metastatic castration-resistant prostate cancer (CRPC) is evolving, with recent approvals of immune therapy, novel hormonal therapy, and bone-targeted therapy. Chemotherapy remains an essential component of the armamentarium. Herein, we review current chemotherapy options for patients with CRPC and discuss future challenges.
  
  
  METHODS
  We reviewed literature for chemotherapy agents in prostate cancer, with special attention to the evidence for efficacy of the currently approved agents. We also reviewed emerging data on biomarkers of response to chemotherapy for CRPC.
  
  
  RESULTS
  Taxanes, especially docetaxel and cabazitaxel, have first- and second-line indications for CRPC, respectively, with both providing a survival benefit. Multiple attempts to improve on the single agent efficacy of docetaxel with combination therapy have not generally been successful although platinum combinations are used for resistant phenotypes. Reductions in prostate-specific antigen by ≥30% and reductions in circulating tumor cells (CTCs) to ≤ 5 are associated with improved survival on chemotherapy. Chemotherapy may continue to be effective therapy for patients with biomarkers that are associated with resistance to androgen-directed therapies (androgen receptor splice variant 7 positivity in CTCs or high CTC heterogeneity).
  
  
  CONCLUSIONS
  Chemotherapy remains an essential component of CRPC therapy, and biomarkers are being identified to define clinical scenarios where chemotherapy may be the optimal therapy choice.
authors.affiliation: Department of Oncology, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Teply
authors.affiliation: Nebraska Cancer Specialists, Omaha, NE, USA.
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: Hauke
keywords: Biomarkers; chemotherapy; prostate cancer