A) VCaP CRPC xenografts are initially sensitive to Abi/Enza, but recover tumor volume by day 30. The initial cohort was 22 mice. B) qRT-PCR of AR, AR-V7, PSA, and NKX3.1 in serial biopsies of Abi/Enza resistant VCaP xenografts. Each column represents xenografts from four mice, with qRT-PCR in technical triplicate. Bars = SEM, * = P<0.03, Mann-Whitney U. RQ = Relative Quantification C) IHC of AR, AR-V7, serine 81 phosphorylated AR (P-AR(S81)), and PSA in serial biopsies of representative tumor. D) AR Score for available Pre-Cx and CRPC data sets (Left). Bars depicting SEM are not visible due to small size. The % decrease in the AR score from Pre-Cx state (TCGA, VCaP-PreCx) to the CRPC state (SU2C, Stanbrough, FHCRC, MSKCC, NEPC-T/C/B, VCaP-CRPC, VCaP-AER) are listed (Right). TCGA –The Cancer Genome Atlas, SU2C – Stand Up 2 Cancer, Stanbrough – from Stanbrough et al. (Supplementary Reference 3), FHCRC – Fred Hutch Cancer Research Center, MSKCC – Memorial Sloan Kettering Cancer Center, NEPC-T/C/B – Neuroendocrine Prostate Cancer-Trento/Cornell/Broad.