Discovery of 6-(difluoro(6-(4-fluorophenyl)-[1,2,4]triazolo[4,3-b][1,2,4]triazin-3-yl)methyl)quinoline as a highly potent and selective c-Met inhibitor.

c-Met/HGF overexpression has been detected in many human malignancies including tumors which are resistant to anticancer therapy. Disrupting the aberrant c-Met/HGF axis has enjoyed significant progress in both preclinical and clinical antitumor campaign. To eliminate the OCH2-related metabolic deficiency of our previously reported triazolotriazine 2, we synthesized a series of CH2-/CF2-linked triazolotriazines and assessed their c-Met activities, leading to the highly potent compound 23 with IC50 values of 0.24 nM of enzymatic activity in c-Met and 0.85 nM of cellular activity in EBC-1 cancer cell line, as well as with complete tumor regression in EBC-1 xenograft mice model at dose of 25 mg/kg via oral administration. Based on its potent anti-proliferative activities and favorable pharmacokinetic properties, 23 has been selected as a drug candidate for preclinical investigation.