Gefitinib

Gefitinib (ZD-1839, Iressa) is a novel potent EGFR tyrosine kinase inhibitor with an IC50 of 0.40nM.Gefitinib (ZD-1839,Iressa) selectively inhibited EGF-stimulated growth of HUVECs (IC50 = 0.03 - 0.1 µM) compared with FGF- or VEGF-stimulated growth (IC50 = 1 - 3 µM for both).Gefitinib is a competitive inhibitor with respect to ATP (Ki = 2.1 nM) when the peptide substrate concentration was fixed at 2 mM (6-fold higher than the Km) and the ATP concentration was varied. Gefitinib showed noncompetitive kinetics (Ki = 15.0 nM) when the ATP concentration was 50 µM (6-fold higher than the Km) and the peptide concentration was varied.