Design, synthesis, and biological evaluation of thiazole/thiadiazole carboxamide scaffold-based derivatives as potential c-Met kinase inhibitors for cancer treatment

As part of our continuous efforts to discover novel c-Met inhibitors as antitumor agents, four series of thiazole/thiadiazole carboxamide-derived analogues were designed, synthesised, and evaluated for the in vitro activity against c-Met and four human cancer cell lines. After five cycles of optimisation on structure–activity relationship, compound 51am was found to be the most promising inhibitor in both biochemical and cellular assays. Moreover, 51am exhibited potency against several c-Met mutants. Mechanistically, 51am not only induced cell cycle arrest and apoptosis in MKN-45 cells but also inhibited c-Met phosphorylation in the cell and cell-free systems. It also exhibited a good pharmacokinetic profile in BALB/c mice. Furthermore, the binding mode of 51am with both c-Met and VEGFR-2 provided novel insights for the discovery of selective c-Met inhibitors. Taken together, these results indicate that 51am could be an antitumor candidate meriting further development.