A 2B adenosine receptor antagonists rescue lymphocyte activity in adenosine-producing patient-derived cancer models

Abstract

Background Adenosine is a metabolite that suppresses antitumor immune response of T and NK cells via extracellular binding to the two subtypes of adenosine-2 receptors, A 2 ARs. While blockade of the A 2A ARs subtype effectively rescues lymphocyte activity, with four A 2A AR antagonists currently in anticancer clinical trials, less is known for the therapeutic potential of the other A 2B AR blockade within cancer immunotherapy. Recent studies suggest the formation of A 2A AR/A 2B AR dimers in tissues that coexpress the two receptor subtypes, where the A 2B AR plays a dominant role, suggesting it as a promising target for cancer immunotherapy. Methods We report the synthesis and functional evaluation of five potent A 2B AR antagonists and a dual A 2A AR/A 2B AR antagonist. The compounds were designed using previous pharmacological data assisted by modeling studies. Synthesis was developed using multicomponent approaches. Flow cytometry was used to evaluate the phenotype of T and NK cells on A 2B AR antagonist treatment. Functional activity of T and NK cells was tested in patient-derived tumor spheroid models. Results We provide data for six novel small molecules: five A 2B AR selective antagonists and a dual A 2A AR/A 2B AR antagonist. The growth of patient-derived breast cancer spheroids is prevented when treated with A 2B AR antagonists. To elucidate if this depends on increased lymphocyte activity, immune cells proliferation, and cytokine production, lymphocyte infiltration was evaluated and compared with the potent A 2A AR antagonist AZD-4635. We find that A 2B AR antagonists rescue T and NK cell proliferation, IFN?and perforin production, and increase tumor infiltrating lymphocytes infiltration into tumor spheroids without altering the expression of adhesion molecules. Conclusions Our results demonstrate that A 2B AR is a promising target in immunotherapy, identifying ISAM-R56A as the most potent candidate for A 2B AR blockade. Inhibition of A 2B AR signaling restores T cell function and proliferation. Furthermore, A 2B AR and dual A 2A AR/A 2B AR antagonists showed similar or better results than A 2A AR antagonist AZD-4635 reinforcing the idea of dominant role of the A 2B AR in the regulation of the immune system.