Molecular Simulation Studies on the Binding Selectivity of Type-I Inhibitors in the Complexes with ROS1 versus ALK.

ROS1 and ALK are promising targets of anticancer drugs for non-small-cell lung cancer. Since they have 49% amide acid sequence homology in the kinases domain and 77% identity at the ATP binding area, some ALK inhibitors also showed some significant responses for ROS1 in the clinical trial, such as the type-I binding inhibitor crizotinib and PF-06463922. As a newly therapeutic target, the selective ROS1 inhibitor is relatively rare. Moreover, the molecular basis for the selectivity of ROS1 versus ALK still remains unclear. In order to disclose the binding preference toward ROS1 over ALK and to aid the design of selective ROS1 inhibitors, the specific interactions and difference of conformational changes in the dual and selective ROS1/ALK inhibitors systems were investigated by molecular dynamics (MD) simulation and principle component analysis (PCA) in our work. Afterward, binding free energies (MM/GBSA) and binding free energies decomposition analysis indicated that the dominating effect of Van der Waals interaction drives the specific binding process of the type-I inhibitor, and residues of the P-loop and the DFG motif would play an important role in selectivity. On the basis of the modeling results, the new designed compound 14c was verified as a selective ROS1 inhibitor versus ALK, and SMU-B was a dual ROS1/ALK inhibitor by the kinase inhibitory study. These results are expected to facilitate the discovery and rational design of novel and specific ROS1 inhibitors.