Inhibitors of tyrosine kinase

This review covers the literature on significant studies of small molecule inhibitors of the epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR), fibroblast growth factor receptor (FGFR), Flk-1, and src family tyrosine kinases from 1996 through mid-1997. During this period, there has been substantial progress in the discovery of new and highly specific tyrosine kinase inhibitors (TKIs), particularly for the EGFR family. The last 18 months saw a focused effort to discover tyrosine kinase inhibitors with increased potency, increased selectivity, better animal pharmacokinetics, and decreased toxicity. Indeed, some EGFR TKIs are now in clinical trials or are about to enter clinical trials as potential anticancer agents. Potent and selective kinase inhibitors have also been described for PDGFR, but none of these compounds have appeared to advance in the developmental process as far as kinase inhibitors for the EGFR family. Surprisingly, potent and selective inhibitors of receptors involved in neovascularization such as FGFR, Flk-1, or Flt-1 are less prevalent in the literature, and the discovery of TKIs that can inhibit angiogenesis remains a fertile area for drug discovery. Tyrosine kinases continue to remain an extremely attractive target for the design of potent and selective inhibitors that will represent an important new class of therapeutic agents for the treatment of a variety of diseases where current therapy is still insufficient.