Kinase experiment:

The vanadate (Vi)-sensitive ATPase activity of ABCG2 in the membrane of High Five insect cells is measured. Briefly, membrane (2 μg/0.06 mL) are incubated in ATPase assay buffer with or without 0.4 mM vanadate at 37℃ for 5 min and then incubated with varying concentrations of telatinib at 37℃ for 5 min. The ATPase reaction is started by the addition of 4 mM Mg-ATP. After incubating at 37℃ for 10 min, the reactions are stopped by adding 0.05 mL of 10% SDS solution. The liberated inorganic phosphate is measured[4].

Animal experiment:

Mice: The mice are randomized into four groups and treated with one of the following regimens: (a) vehicle (10% N-methyl-pyrrolidinone, 90% polyethylene glycol 300) (q3d×6), (b) DOX (1.8 mg/kg, i.p., q3d×6), (c) telatinib dissolved in 10% N-methyl-pyrrolidinone, 90% polyethylene glycol 300 (15 mg/kg, p.o., every 2nd and 3rd day; total 12 times), and (d) DOX (1.8 mg/kg, i.p., q3d×6) + telatinib (15 mg/kg, p.o., every 2nd and 3rd day, given 1 h before giving DOX; total 12 times). DOX for injection is prepared by dissolving in saline. Tumor volume is measured using calipers and body weights are recorded[4].

Telatinib (BAY 57-9352) is a selective inhibitor of VEGFR2, VEGFR3, c-Kit and PDGFRα with IC50 value of 6 nM, 4 nM, 1 nM and 15 nM, respectively [1].

Vascular endothelial growth factor receptor (VEGFR) is the receptor of VEGF and plays an important role in stimulating vasculogenesis and angiogenesis. Platelet-derived growth factor (PDGF) is a member of growth factors and involves in blood vessel formation. C-Kit is the receptor of a growth factor. Many studies have shown that abnormal of VEGFR, c-Kit and PDGFR are correlated with a variety of tumors [1, 2, 3].

Telatinib is a potent VEGFR2/3, c-Kit and PDGFRα inhibitor. When tested with a panel of tumor cell lines (MDA-MB-231 breast caicinoma, Colo-205 colon carcinoma, DLD-1 colon carcinoma and H460 non-small cell lung carcinoma), Telatinib treatment exhibited inhibition on VEGFR-2 autophosphorylation and PDGF-βwhich involved in the angiogenic process [2].

Telatinib has been used in clinical trails to a variety of cancers treatment and has achieved promising results [2-4].

It is also reported that Telatinib restores tumor cells sensitivity to anticancer drugs and significantly reduced cellular viability by inhibiting ABCG2 expression [3].

References:
[1].  Steeghs, N., et al., Hypertension and rarefaction during treatment with telatinib, a small molecule angiogenesis inhibitor. Clin Cancer Res, 2008. 14(11): p. 3470-6.
[2].  Strumberg, D., et al., Phase I dose escalation study of telatinib (BAY 57-9352) in patients with advanced solid tumours. Br J Cancer, 2008. 99(10): p. 1579-85.
[3].  Sodani, K., et al., Telatinib reverses chemotherapeutic multidrug resistance mediated by ABCG2 efflux transporter in vitro and in vivo. Biochem Pharmacol, 2014. 89(1): p. 52-61.
[4].   Eskens, F.A., et al., Phase I dose escalation study of telatinib, a tyrosine kinase inhibitor of vascular endothelial growth factor receptor 2 and 3, platelet-derived growth factor receptor beta, and c-Kit, in patients with advanced or metastatic solid tumors. J Clin Oncol, 2009. 27(25): p. 4169-76.