N-(3-Ethynyl-2,4-difluorophenyl)sulfonamide Derivatives as Selective Raf Inhibitors.

A series of N-(3-ethynyl-2,4-difluorophenyl)sulfonamides were identified as new selective Raf inhibitors. The compounds potently inhibit B-Raf(V600E) with low nanomolar IC50 values and exhibit excellent target specificity in a selectivity profiling investigation against 468 kinases. They strongly suppress proliferation of a panel of human cancer cell lines and patient-derived melanoma cells with B-Raf(V600E) mutation while being significantly less potent to the cells with B-Raf(WT). The compounds also display favorable pharmacokinetic properties with a preferred example (3s) demonstrating significant in vivo antitumor efficacy in a xenograft mouse model of B-Raf(V600E) mutated Colo205 human colorectal cancer cells, supporting it as a promising lead compound for further anticancer drug discovery.