2-Azabicyclo[3.2.1]octane-based ALK inhibitors inspired by aconitine scaffold remodeling: design, synthesis, and biological evaluation

Abstract

Building on a previously reported aconitine-inspired 2-azabicyclo[3.2.1]octane scaffold, a series of derivatives was designed and synthesized as ALK-directed leads. Compound 14n showed the lowest measured biochemical ALK IC₅₀ in the present series (0.73 nM) and a biochemical preference for ALK within the tested kinase panel. It retained inhibitory activity against ALK L1196M and G1202R, with IC₅₀ values of 10.5 and 88.7 nM, respectively. Compound 14n exhibited antiproliferative activity in two ALK-positive cell lines, NCI-H2228 and Karpas-299, with IC₅₀ values of 0.06 and 0.69 μM, respectively. In NCI-H2228 cells, 14n reduced ALK, AKT, and ERK phosphorylation, induced G0/G1-phase cell-cycle arrest and apoptosis, and reduced wound closure and Transwell migration. In an NCI-H2228 xenograft model, 14n produced dose-dependent tumor growth inhibition. At 30 mg/kg, its antitumor effect was similar in magnitude to that of ceritinib at the same dose, with no overt toxicity observed under the tested conditions. Molecular docking and molecular dynamics simulations suggested a plausible binding mode within the ALK ATP-binding pocket. These findings identify 14n as an ALK-directed lead for further optimization.