Abstract 1367: The dual selective VEGFR-FGFR kinases inhibitor E-3810 decreases tumor perfusion and inhibits tumor growth: an analysis using dynamic contrast-enhanced magnetic resonance imaging

Background: E-3810 is a potent VEGFR1, 2 and 3 and FGFR 1 kinases inhibitor showing potent anti-angiogenic and antitumor activity in several in vitro and in vivo mouse models (Proceedings AACR-EORTC-NCI Meeting, Boston, November 2009; Abstracts No. 252 and 257). The aim of this study was to investigate, in a rat model, the antitumor activity of E-3810 and its anti-angiogenic effects by using DCE-MRI and to correlate the response with a panel of biological markers. Methods: Nude rats were subcutaneously xenografted with human Calu-6 lung cancer cells and treated orally once daily for 14 consecutive days, either with E-3810 − 10 mpk (dose chosen on the basis of a preliminary study in the same model) or Sorafenib − 100 mpk. Tumor growth and parameters reflecting tumor vascular permeability/perfusion (Ktrans) were evaluated by T2-weighted MRI and by T1-weighted DCE-MRI using Gd-DTPA (Magnevist®) as contrast agent at D-1, D1, D3, D7 and D14. The number, maturity and functionality of tumor vessels were assessed using CD31/α-SMA colocalisation by IHC and injection of Hoechst fluorescent dye on D1, D3, D7 and D14. On the same days, the level of circulating endothelial cells (CEC) and collagen IV were measured by FACS and ELISA assays. Results: In comparison to vehicle-treated animals, a marked tumor growth inhibition was observed in E-3810-treated rats (max T/C 21%) with no remarkable signs of toxicity. In the same animals, Ktrans value in the tumor rim was significantly decreased (up to 49% on D14). This DCE-MRI finding was supported by the significant decrease in the Hoechst stained area observed at D1 (−97%), D7 (−96%) and D14 (−75%). In addition, the number of tumor vessels (both CD31 and colocalized CD31/α-SMA) was significantly decreased at D3 (−72%), D7 (−68%) and D14 (−86%) in E-3810-treated rats. Always in comparison to vehicle group, no significant changes in CEC were observed after treatment with E-3810, whereas collagen IV levels significantly increased at D14 (+38). Similar effects on all the above mentioned parameters were observed in Sorafenib treated animals. Conclusions: E-3810 displayed a marked antitumor activity in the model of Calu-6 tumor bearing nude rats. The antitumor effect is coupled with a strong antiangiogenic activity, as indicated by decrease in vascular permeability/perfusion and decrease of microvessels density that occur early on and are maintained throughout the treatment period. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1367.