Abstract 4140: Discovery and characterization of novel highly potent A2A adenosine receptor antagonists for cancerimmunotherapy

Abstract

Introduction: Extracellular adenosine produced at high concentrations within the tumor micro-environment (TME) and suppresses immune function via inhibition of immune cell activation. Targeting adenosine receptors has emerged as a novel method to activate anti-tumor immunity. In particular, A2A adenosine receptor (A2AR), one of the G-protein-coupled-receptors, exhibits immunosuppressive functions. Herein, we suggest novel A2AR antagonist lead compounds as a highly potent antagonist of A2AR for immunotherapy. Materials and Methods: Novel A2AR antagonist lead compounds were designed using CADD and synthesized as the active biologic inhibitory compound. The protein preparation and molecular docking were performed using Glide (Schrodinger). A radioligand binding assay was performed to evaluate the affinities of A2AR Antagonists for the human adenosine A2AR. The potencie of A2AR antagonists were determined by cAMP assay in HEK293-hA2AR cells and cAMP-mediated pCREB assay in human CD8+ T cells from whole blood. In vivo CT26 and MC38 syngeneic tumor models were used to assess the therapeutic effect of A2AR antagonists. Results: A2AR antagonist lead compounds showed strong binding affinities toward human A2AR. They also potently inhibited the NECA-mediated production of intracellular cAMP in HEK293 cells expressing human A2AR. Elevated intracellular cAMP following A2AR activation results in the phosphorylation of CREB (cAMP response element-binding protein). A2AR antagonist lead compounds treatment inhibited pCREB in NECA-stimulated HEK293-hA2AR and human CD8+ T cells. A2AR antagonist lead compounds inhibited tumor growth of mouse syngeneic tumor models as a single agent and combination with anti-PD-L1. In combination with anti-PD-L1, A2AR antagonist lead compounds had remarkable antitumor activities in multiple mouse tumor models, including restoration of immune responses in models that incompletely responded to anti-PD-L1 monotherapy. Conclusion: These results showed the potencies of A2AR antagonist lead compounds with high capability of A2AR inhibition. Blockade of the adenosine signaling pathway may be vital for enhancing anti-tumor responses in solid tumors that show an incomplete response to anti-PD-L1 therapy. A2AR antagonist lead compounds demonstrate a novel approach to anti-cancer immunotherapy. Citation Format: Kyungik Lee, Seungah Jun, EunYoung Byun, Hosun Lee, Yongtaek Lee, MiJin Moon, Yu-Yon Kim, Hyun Jeong Kang, YoungGil Ahn, YoungHoon Kim, Kwee Hyun Suh. Discovery and characterization of novel highly potent A2A adenosine receptor antagonists for cancerimmunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4140.