Theliatinib (HMPL-309)

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].

A431 cells (1 × 10⁴ cells/well) in exponential phase are seeded in duplicates in DMEM containing 10% FBS and incubated at 37°C and 5% CO2 overnight. Then, 10 μL of test compounds (theliatinib, gefitinib and erlotinib) at tested concentrations (10~0.005 μM, 3 fold gradient dilution) are added into each well with the final concentration of DMSO at 0.5%. The cells are incubated for 48 h followed by further incubation for 1h after adding 10 μL/well CCK-8 solution. Cell survival is determined by measuring the optical density at 450 nm.

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].