Insight into resistance mechanism of anaplastic lymphoma kinase to alectinib and JH-VIII-157-02 caused by G1202R solvent front mutation

BACKGROUND: Mutated anaplastic lymphoma kinase (ALK) drives the development of advanced non-small cell lung cancer (NSCLC). Most reported small-molecule inhibitors targeting the ALK domain do not display good inhibition of the G1202R solvent front mutation. The solvent front mutation was assumed to hinder drug binding. However, a different fact could be uncovered by the simulations reported in this study through a structural analog of alectinib (JH-VIII-157-02), which demonstrated potent effects against the G1202R mutation. METHODS: Molecular docking, conventional molecular dynamics (MD) simulations, free energy calculations, and umbrella sampling (US) simulations were carried out to make clear the principles of the binding preferences of alectinib and JH-VIII-157-02 toward ALK(WT) and the ALK G1202R (ALK(G1202R)) mutation. RESULTS: JH-VIII-157-02 has similar binding affinities to both ALK(WT) and ALK(G1202R) whereas it has has a much lower binding affinity for alectinib to ALK(G1202R). Analysis of individual energy terms indicate the major variation involves the van der Waals and entropy terms. Structural analysis reveals that the conformational change of the ATP-binding glycine-rich loop was primarily responsible for the alectinib resistance, not JH-VIII-157-02. In addition, US simulations prove JH-VIII-157-02 has similar dissociative processes from both ALK(WT) and ALK(G1202R), while alectinib is more easily dissociated from ALK(G1202R) than from ALK(WT), thus indicating lesser residence time. CONCLUSION: Both the binding affinity and the drug residence time should be emphasized in rational drug design to overcome the G1202R solvent front mutation in ALK resistance.