Alpha v integrin inhibitors and cancer therapy.

Recent gene disruption experiments have suggested that targeting the alpha v integrins (cell surface adhesion and signaling receptors) to prevent tumor progression can result in different outcomes depending on the strategy. Nevertheless, two alpha v binding antagonists have made their way to the clinic in the oncology field; both Vitaxin, a humanized antibody, and cilengitide, a cyclic peptide mimicking the RGD ligand recognition peptidic domain common to alpha v integrin ligands, are in phase II clinical trials. This year, development of another peptidic inhibitor was initiated. This review questions whether companies are reluctant to propose small synthetic heterocyclic inhibitors as successors to peptide-derived agents with better pharmacokinetics and oral bioavailability. Is this class of compounds immediably flawed like the platelet alpha IIb beta 3 oral antagonists? Tentative answers are provided in this review following description of the lead compounds and the rationale for their use as cancer treatments, imaging agents or drug targeting vectors.