Interestingly however, although targeting of EGFR/HER2 can suppress prostate tumor xenograft growth in in vivo models [18, 19], trials using EGFR/HER2 inhibitors such the EGFR inhibitor Gefetinib [20] or the dual EGFR/HER2 inhibitor Lapatinib [21] as single agents in patients with CRPC do not improve overall survival or decrease PSA (a surrogate marker of AR activity). This evidence concerns the gene ERBB2 and prostate neoplasm.