Whereas genomic studies of metastatic prostate cancer have demonstrated genomic alterations in AR and its pathway, the genomic characterization of paired biopsy samples from living patients with CRPC before secondary ADT initiation and at the time of resistance have been limited as a result of the logistical challenges of obtaining repeated tumor biopsies and tumor heterogeneity in metastatic prostate cancer. This evidence concerns the gene AR and metastatic prostate carcinoma.