Deciphering the Selective Targeting of Noncovalent, Wild Type-sparing, and ATP-competitive Tyrosine Kinase Inhibitors to EGFR T790M Gatekeeper Mutant

Various tyrosine kinase inhibitors (TKIs) have been developed to target human epidermal growth factor receptor (EGFR) for cancer therapy. However, many patients treated with first-line TKIs are clinically observed to eventually establish a gatekeeper T790M mutation in the ATP-binding site of the EGFR kinase domain, which is primarily responsible for acquired drug resistance to cancers. Over the past decades, a number of noncovalent, wild-type-sparing and ATP-competitive inhibitors (NWAIs) were reported to selectively target the T790M mutant over wild-type kinase, which are independent of the traditional inhibitor classification system that categorizes EGFR TKIs into four generations. Here, we systematically investigated the intermolecular interaction of wild-type EGFR (EGFR WT ) and its T790M mutant (EGFR T790M ) with 15 existing NWAI inhibitors, paying attention to the structural and energetic responses of inhibitor ligands to the gatekeeper mutation. It was revealed that the NWAIs can be typed into three classes I, II and III, which can form S[Formula: see text] interactions, hydrophobic (van der Waals) contacts and weak hydrogen (halogen) bonding with the side-chain thioether moiety of the mutant Met790 residue, respectively, thus conferring additional affinity and specificity to inhibitor ligands upon the T790M mutation. In addition, we further performed 2D-chemical similarity search to identify new class I NWAIs, from which two Staurosporine analogs (i.e. UCN01 and ZHD0501) were identified to have a good selectivity for EGFR T790M over EGFR WT . They can be exploited as promising leading chemical scaffolds to further develop potent, selective, wild-type-sparing NWAI inhibitors of EGFR T790M gatekeeper mutant.