Anticancer effects of ZD6474, a VEGF receptor tyrosine kinase inhibitor, in gefitinib ("Iressa")-sensitive and resistant xenograft models.

Abstract

ZD6474 is a novel, orally available inhibitor of vascular endothelial growth factor (VEGF) receptor-2 (KDR) tyrosine kinase, with additional activity against epidermal growth factor receptor (EGFR) tyrosine kinase. ZD6474 has been shown to inhibit angiogenesis and tumor growth in a range of tumor models. Gefitinib ("Iressa") is an selective EGFR tyrosine kinase inhibitor (TKI) that blocks signal transduction pathways. We examined the antitumor activity of ZD6474 in the gefitinib-sensitive lung adenocarcinoma cell line, PC-9, and a gefitinib-resistant variant (PC-9/ZD). PC-9/ZD cells showed cross-resistance to ZD6474 in an in vitro dye formation assay. In addition, ZD6474 showed dose-dependent inhibition of EGFR phosphorylation in PC-9 cells, but inhibition was only partial in PC-9/ZD cells. ZD6474-mediated inhibition of tyrosine residue phosphorylation (Tyr992 and Tyr1045) on EGFR was greater in PC-9 cells than in PC-9/ZD cells. These findings suggest that the inhibition of EGFR phosphorylation by ZD6474 can contribute a significant, direct growth-inhibitory effect in tumor cell lines dependent on EGFR signaling for growth and/or survival. The effect of ZD6474 (12.5-50 mg/kg/day p.o. for 21 days) on the growth of PC-9 and PC-9/ZD tumor xenografts in athymic mice was also investigated. The greatest effect was seen in gefitinib-sensitive PC-9 tumors, where ZD6474 treatment (>12.5 mg/kg/day) resulted in tumor regression. Dose-dependent growth inhibition, but not tumor regression, was seen in ZD6474-treated PC-9/ZD tumors. These studies demonstrate that the additional EGFR TKI activity may contribute significantly to the antitumor efficacy of ZD6474, in particular in those tumors that are dependent on continued EGFR-signaling for proliferation or survival. In addition, these results provide a preclinical rationale for further investigation of ZD6474 as a potential treatment option for both EGFR-TKI-sensitive and EGFR-TKI-resistant tumors.

• Authors: Fumiko Taguchi, Yasuhiro Koh, Fumiaki Koizumi, Tomohide Tamura, Nagahiro Saijo, Kazuto Nishio
• Journal: Cancer science (Cancer Sci) Vol. 95 Issue 12 Pg. 984-9 (Dec 2004) ISSN: 1347-9032 [Print] England
• PMID: 15596048 (Publication Type: Journal Article)

Chemical References

• Antineoplastic Agents
• Enzyme Inhibitors
• Piperidines
• Quinazolines
• Tyrosine
• Receptors, Vascular Endothelial Growth Factor
• Gefitinib
• vandetanib

Topics

• Adenocarcinoma (drug therapy)
• Animals
• Antineoplastic Agents (therapeutic use)
• Apoptosis (drug effects)
• Carcinoma, Non-Small-Cell Lung (drug therapy)
• Cell Proliferation (drug effects)
• Drug Resistance, Neoplasm
• Enzyme Inhibitors (therapeutic use)
• Female
• Gefitinib
• Lung Neoplasms (drug therapy)
• Mice
• Mice, Nude
• Neovascularization, Pathologic (drug therapy)
• Phosphorylation (drug effects)
• Piperidines (therapeutic use)
• Quinazolines (therapeutic use)
• Receptors, Vascular Endothelial Growth Factor (antagonists & inhibitors)
• Tumor Cells, Cultured
• Tyrosine (metabolism)
• Xenograft Model Antitumor Assays