Novel substituted quinazolines for potent EGFR tyrosine kinase inhibitors

The type I receptor tyrosine kinases (RTKs) are involved in various aspects of cell growth, survival, and differentiation. Among the known RTKs, the epidermal growth factor receptor (EGFR) and ErbB-2 (HER-2) are two widely studied proteins that are prototypic members of the ErbB family which also includes ErbB-3 (Her-3) and ErbB-4 (Her-4). Overexpression of ErbB-2 and EGFR has been associated with aggressive disease and poor patient prognosis in a range of human tumour types (e.g. breast, lung, ovarian, prostate, and squamous carcinoma of head and neck). Disruption of signal transduction of these kinases has been shown to have an antiproliferative effect. Various approaches have been developed to target the ErbB signalling pathways including monoclonal antibodies (trastuzumab/Herceptin? and cetuximab/Erbitux?) directed against the receptor, and synthetic tyrosine kinase inhibitors (gefitinib/Iressa? and erlotinib/Tarceva?). Since many tumours overexpress ErbB receptors, simultaneous targeting of multiple ErbB receptors therefore becomes a promising approach to cancer treatment. Lapatinib (Tykerb?), a potent dual EGFR/ErbB-2 inhibitor, was approved for the treatment of ErbB-2-positive breast cancer. Despite years of intensive research on EGFR inhibitors, there is a surprising dearth of chemically distinct small inhibitors with a high degree of selectivity. There is also a need for new scaffolds due to the recent finding of EGFR mutations which render the kinase resistant to gefinitib and erlotinib. The structures under study will be quinazolines with different substituents. The structure-activity relationships and biological evaluation of compounds published during the last four years will be reviewed herein.