In order to determine the optimal biologic dose for gefitinib, two identical multicentre Phase I pharmacodynamic (PD) trials were performed in patients with five tumour types known to express EGFR (NSCLC, SCCHN, ovarian, colorectal, or prostate cancer) (Baselga et al, 2002; Herbst et al, 2002). This evidence concerns the gene EGFR and prostate cancer.