Abstract 1485: Sunitinib enhances the antitumor responses of agonistic CD40-antibody by reducing MDSCs and synergistically improving endothelial activation and T-cell recruitment

Abstract

Abstract CD40-activating immunotherapy has potent anti-tumor effects due to its ability to activate dendritic cells and induce cytotoxic T-cell responses. However, its efficacy is limited by accumulation of immunosuppressive cells in the tumor and by endothelial anergy induced by pro-angiogenic growth factors. Here, we show that combining agonistic CD40 monoclonal antibody (mAb) therapy with vascular targeting using the tyrosine kinase inhibitor sunitinib significantly decrease tumor growth and improve survival in B16.F10 melanoma and T241 fibrosarcoma. Treatment of tumor-bearing mice with anti-CD40 mAb lead to increased activation of CD11c+ dendritic cells in the tumor draining lymph node, as evidenced by enhanced CD86 expression, while sunitinib treatment reduced vessel density. CD11b+Gr1+ myeloid derived suppressor cells accumulated in the tumor draining lymph nodes after anti-CD40 mAb treatment. This effect was reversed by co-treatment with sunitinib. Tumor endothelial expression of ICAM1 and VCAM1 adhesion molecules were increased only when anti-CD40 mAb treatment was combined with sunitinib. This was associated with enhanced tumoral infiltration of CD8+ T-lymphocytes. Our results show that combining CD40-stimulating immunotherapy with sunitinib treatment exert potent complementary antitumor effects mediated by dendritic cell activation, reduction in myeloid derived suppressor cells and increased endothelial activation, resulting in enhanced recruitment of cytotoxic T cells. Citation Format: Luuk van Hooren, Maria Georganaki, Hua Huang, Sara Mangsbo, Anna Dimberg. Sunitinib enhances the antitumor responses of agonistic CD40-antibody by reducing MDSCs and synergistically improving endothelial activation and T-cell recruitment. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1485.