Purpose: Vascular endothelial growth factor (VEGF)-C/VEGF-receptor 3 (VEGF-R3) signal plays a significant role in lymphangiogenesis and tumor metastasis based on its effects on lymphatic vessels. However, little is known about the effect of inhibiting VEGF-R3 on lymphangiogenesis and lymph node metastases using a small-molecule kinase inhibitor.

Experimental Design: We evaluated the effect of E7080, a potent inhibitor of both VEGF-R2 and VEGF-R3 kinase, and bevacizumab on lymphangiogenesis and angiogenesis in a mammary fat pad xenograft model of human breast cancer using MDA-MB-231 cells that express excessive amounts of VEGF-C. Lymphangiogenesis was determined by lymphatic vessel density (LVD) and angiogenesis by microvessel density (MVD).

Results: In contrast to MDA-MB-435 cells, which expressed a similar amount of VEGF to MDA-MB-231 cells with an undetectable amount of VEGF-C, only MDA-MB-231 exhibited lymphangiogenesis in the primary tumor. E7080 but not bevacizumab significantly decreased LVD within the MDA-MB-231 tumor. E7080 and bevacizumab decreased MVD in both the MDA-MB-231 and MDA-MB-435 models. E7080 significantly suppressed regional lymph nodes and distant lung metastases of MDA-MB-231, whereas bevacizumab significantly inhibited only lung metastases. E7080 also decreased both MVD and LVD within the metastatic nodules at lymph nodes after resection of the primary tumor.

Conclusions: Inhibition of VEGF-R3 kinase with E7080 effectively decreased LVD within MDA-MB-231 tumors, which express VEGF-C. Simultaneous inhibition of both VEGF-R2 and VEGF-R3 kinases by E7080 may be a promising new strategy to control regional lymph node and distant lung metastases.