The Raf kinases activate cellular pathways that lead to cell proliferation and can contribute to certain types of cancer. Mutations in the kinase B-Raf are involved in a wide range of cancers. In particular, the mutation B-RafV600E occurs in melanomas and other types of cancer but is poorly targeted by many inhibitors of wild type B-Raf. AZ 628 is a quinazilinone that inhibits several Raf kinases, including B-Raf, B-RafV600E, and c-Raf-1 (IC50s = 105, 34, and 29 nM in in vitro kinase assays). It also prevents activation of several tyrosine kinases, including VEGFR2, DDR2, Lyn, Flt1, and FMS. In colon and melanoma cell lines carrying B-RafV600E mutations, AZ 628 is reported to inhibit anchorage-dependent and -independent growth, induce cell cycle arrest, and cause apoptosis.
