Tesevatinib (XL-647) is an orally available, multi-target tyrosine kinase inhibitor (IC50s: 0.3, 16, 1.5, 8.7, and 1.4 nM for EGFR, ErbB2, KDR, Flt4, and EphB4).

Tesevatinib was inactive against a panel of 10 tyrosine kinases (including the insulin and the insulin-like growth factor-1 receptor) and 55 serine-threonine kinases (including cyclin-dependent kinases, stress-activated protein kinases, and protein kinase C isoforms). Tesevatinib inhibits cellular proliferation and EGFR pathway activation in the erlotinib-resistant H1975 cell line that harbors a double mutation (L858R and T790M) in the EGFR gene. In A431 cells, Tesevatinib reduces cell viability (IC50: 13 nM).

Growth inhibition of H1975 and A431 cells by increasing concentrations of Tesevatinib is determined by seeding 5000 cells per well in 96-well plates. The following day, cells are washed once with low-serum RPMI 1640 (0.1% fetal bovine serum, 1% nonessential amino acids, and 1% penicillin/streptomycin), after which 90 μL of the low-serum RPMI 1640 is added. Tesevatinib is diluted to 10 times the test concentrations and 10 μL are added to triplicate wells for a 72-h incubation. Cell viability is determined.

Tumor-bearing mice are given either Tesevatinib, erlotinib, or gefitinib at 100 mg/kg and tumors are harvested 1 to 72 h later. Half an hour before the respective time point, EGF (50 μg/mouse) is given via i.v. bolus injection with tumors dissected 30 min later and tumor extracts are prepared by homogenization in 10 volumes of ice-cold lysis buffer. Lysates are clarified by centrifugation and EGFR tyrosine phosphorylation levels are determined by ELISA.