title: The current role and limitations of surrogate endpoints in advanced prostate cancer.
abstract: OBJECTIVE
  The identification of appropriate surrogate endpoints for evaluating cancer therapeutics has been of ongoing interest across various tumor types. Metastatic castrate-resistant prostate cancer (mCRPC) has been a particularly challenging area. As more targeted and novel therapies are being developed in this disease space, an urgent need exists to identify surrogate endpoints in mCRPC. The ability to discern patient benefit in the absence of patient death or other complications would facilitate both drug development and more appropriate patient care.
  
  
  METHODS
  We reviewed the available literature and guidelines used in the development and approval of recent agents for mCRPC.
  
  
  RESULTS
  The majority of regulatory approvals of new medications have relied on overall survival (OS) or prevention of complications such as skeletal related events (SRE's). Progression-free survival measures, such as bone scans, computed tomography scans, and prostate-specific antigen related changes, have not been validated nor uniformly accepted as outcome surrogates. All of the successful recent pivotal Phase III trials designed to achieve regulatory approval in mCRPC have used either OS or SRE's as the primary endpoint.
  
  
  CONCLUSIONS
  There are significant problematic issues that exist associated with defining and implementing surrogate markers in mCRPC beyond survival and complications. Suggestions are made as to how the current situation might be improved.
authors: Department of Urology, Kimmel Cancer Center, Thomas Jefferson University Philadelphia, PA. Electronic address: leonard.gomella@jefferson.edu.
authors: Leonard G
authors: LG
authors: Gomella
authors: Department of Medicine, Section of Hematology and Medical Oncology and Urology Tulane University Health Sciences Center in New Orleans, LA.
authors: A
authors: A
authors: Oliver Sartor
mesh_terms: D015415:Biomarkers; D014408:Biomarkers, Tumor / Q000097:blood; D002986:Clinical Trials as Topic; D018450:Disease Progression; D018572:Disease-Free Survival; D006801:Humans; D007167:Immunotherapy; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000628:therapy*; D012107:Research Design; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States; D014486:United States Food and Drug Administration
chemical_list: D015415:Biomarkers; D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen
keywords: Metastatic castrate-resistant prostate cancer; Prostate cancer endpoints