Targeting of tumor growth and angiogenesis underlies the enhanced antitumor activity of lenvatinib in combination with everolimus

Abstract The combination of lenvatinib-a multiple receptor tyrosine kinase (RTK) inhibitor-plus everolimus-a mammalian target of rapamycin (mTOR) inhibitor-significantly improved clinical outcomes versus everolimus monotherapy in a phase 2 clinical study of metastatic renal cell carcinoma (RCC). Here, we investigated potential mechanisms underlying the antitumor activity of the combination treatment in preclinical RCC models. Lenvatinib plus everolimus showed greater antitumor activity than either monotherapy in 3 human RCC xenograft mouse models (A-498, Caki-1, and Caki-2). In particular, the combination led to tumor regression in the A-498 and Caki-1 models. In the A-498 model, everolimus demonstrated antiproliferative activity, whereas lenvatinib showed antiangiogenic effects. The antiangiogenic activity was potentiated by the lenvatinib plus everolimus combination in Caki-1 xenografts, where FGF-driven angiogenesis may contribute to tumor growth. The combination showed mostly additive activity in VEGF-activated, and synergistic activity against FGF-activated endothelial cells in cell proliferation and tube formation assays, as well as strongly suppressed mTOR-S6K-S6 signaling. Enhanced antitumor activities of the combination versus each monotherapy were also observed in mice bearing human pancreatic KP-1 xenografts overexpressing VEGF or FGF. Our results indicated that simultaneous targeting tumor cell growth and angiogenesis by lenvatinib plus everolimus resulted in enhanced antitumor activity. The enhanced inhibition of both VEGF- and FGF-signaling pathways by the combination underlies its superior antiangiogenic activity in human RCC xenograft models. This article is protected by copyright. All rights reserved.