Incorporation of a rigid 1,3-diketone-containing fragment led to significantly improved AXL inhibitory activity: design, synthesis, and SAR of the anilinopyrimidine AXL inhibitors

Overexpressed AXL kinase is involved in various human malignancies, which incurs tumor progression, poor prognosis, and drug resistance. Suppression of the aberrant AXL axis with genetic tools or small-molecule inhibitors has achieved valid antitumor efficacies in both preclinical studies and clinical antitumor campaigns. Herein we will report the design, synthesis, and structure–activity relationship (SAR) exploration of a series of anilinopyrimidine type II AXL inhibitors. Among these inhibitors, 4l exhibited the enzymatic AXL and cellular BaF3/TEL-AXL IC₅₀ values of 0.5 nM and less than 0.2 nM, respectively. Western blot analysis displayed that 4l dose-dependently inhibited the phosphorylation of AXL and its downstream cascade Akt, which was better than that of the reference control R428. Moreover, 4l markedly suppressed the AXL/GAS6-mediated migration in NCI-H1299 cells.