Evt801: Standalone Cancer Immunotherapy In Vegfr3(+) Tumors And Combination With Immune Checkpoint Therapies In Vegfr3(-) Tumors

In collaboration with Sanofi, we previously showed that inhibition of the VEGFR3 pathway by SAR131675 leads to reduction of tumor growth by acting on the tumor microenvironment. We have identified a new drug candidate, EVT801, and evaluated its activity on tumor models expressing VEGFR3. For proof-of-concept, we transfected the mouse BNL hepatoma cell line with VEGFR3. EVT801 displayed a strong therapeutic activity by acting on both VEGFR3 + tumor cells and on the Tumor Microenvironment (TME). By deciphering the mechanism of action of the compounds we showed that EVT801 strongly decreased tumor-associated immunosuppression by decreasing MDSCs (Myeloid Derived Suppressor cells) and CD4 + regulatory T cells and by increasing macrophages with a M1 phenotype inside the tumor. As a consequence the T-cell:MDSC ratios were increased in the TME and also in peripheral blood. In addition to its immunomodulatory properties, EVT801 decreased angiogenesis without increasing hypoxia. We have evaluated EVT801 therapeutic activity in syngeneic tumor mouse models which are not expressing VEGFR3 such as 4T1 mammary carcinoma and CT26 colon carcinoma models. As expected, we observed an intermediate therapeutic activity of the compound on both tumor models. Positive modulation of the TME was equivalent to what we observed with the VEGFR3 + tumor model. With this unique mechanism of action of EVT801 on the TME, we evaluated its ability to increase therapeutic activity of standard Immune Checkpoint Therapies (ICT) such as anti-CTLA-4 and anti-PD-1 mAbs. Strong additive therapeutic activities were observed with EVT801 in combination with these ICT as illustrated by the development of long-term tumor-specific memory CD8 + T cell responses. Toxicological data show that EVT801 has a favorable pharmacological profile consistent with its entry into pre-clinical development. Taken together, these results indicate that EVT801 represents an innovative drug for cancer Immunotherapy which provide a favorable microenvironment to promote tumor regression. In addition, EVT801 may improve the frequency of response to ICT. Citation Format: Michael Esquerre, Pierre Fons, Gaelle Badet, Pauline Barron, Jeremy Kagan, Antoine Alam, Jerome Meneyrol, Isabelle Blanc, Roselyne Broussy, Florence Gaujarengues, Joanna Lisztwan, Michael Paillasse, Mark Whittaker, Francoise Bono. EVT801: Standalone cancer immunotherapy in VEGFR3 + tumors and combination with immune checkpoint therapies in VEGFR3 - tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2634. doi:10.1158/1538-7445.AM2017-2634