Protein tyrosine kinase (PTK) inhibitors are potential antiproliferative agents for diseases caused by the hyperactivity of PTKs. Tyrphostins are a class of antiproliferative compounds which act as PTK blockers. PTK inhibitors specific for platelet-derived growth factor (PDGF) receptor kinase could help in the treatment of atherosclerosis, restenosis, pulmonary fibrosis, and gliomas. AG-1295 is a quinoxaline-type tyrphostin that acts as a potent and selective inhibitor of PDGF receptor kinase in vitro and in Swiss 3T3 cells (IC50s range from 0.3-1 μM). It inhibits PDGF-stimulated DNA synthesis with an IC50 value of 2.5 μM without affecting activity of the EGF receptor.
