A new class of potent farnesyltransferase inhibitors based on a 1,4-diazepane scaffold was synthesized with protein farnesyltransferase inhibition potencies in the low nanomolar range. The compounds block the growth on two hormone-resistant tumor prostatic cell lines (DU145 and PC3). The advanced cellular evaluation of the more potent farnesyltransferase inhibitors was explored and revealed a disorganization of tubulin in PC3 cells.