Theliatinib (HMPL-309) is a highly potent EGFR inhibitor with Ki value of 0.05 nM against the wild type EGFR and IC50 values of 3 nM and 22 nM against EGFR and EGFR T790M/L858R mutant. It demonstrats 50 fold greater selectivity for EGFR compared to 72 other kinases.
In comparison to erlotinib or gefitnib, theliatinib shows much stronger binding affinity to wild type EGFR and is more difficult to be replaced by ATP. This unique feature may result in better target engagement for theliatinib compared to erlotinib or gefitinib, leading to stronger anti-tumor activity in tumors with wild type EGFR activation due to gene amplification or protein overexpression. Theliatinib inhibits EGFR phosphorylation with an IC50 of 0.007 μM for EGF stimulated EGFR phosphorylation in A431 cells and cell survival in tumor cells with wild-type EGFR (A431, H292, FaDu cells)[1].
Theliatinib demonstrates dose-dependent anti-tumor activity in a panel of PDECX (patient-derived esophageal cancer xenograft) models with a generally good correlation between EGFR H score and tumor growth inhibition. Furthermore, aberrant activation or gene mutations of other targets such as PI3K and FGFR diminishes the anti-tumor activity of the EGFR TKIs, especially, theliatinib[1].
[1] Yongxin Ren, et al. Oncotarget. 2017, 8(31): 50832-50844.