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

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, AARs. While blockade of the AARs subtype effectively rescues lymphocyte activity, with four AAR antagonists currently in anticancer clinical trials, less is known for the therapeutic potential of the other AAR blockade within cancer immunotherapy. Recent studies suggest the formation of AAR/AAR dimers in tissues that coexpress the two receptor subtypes, where the AAR plays a dominant role, suggesting it as a promising target for cancer immunotherapy.

METHODS

We report the synthesis and functional evaluation of five potent AAR antagonists and a dual AAR/AAR 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 AAR 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 AAR selective antagonists and a dual AAR/AAR antagonist. The growth of patient-derived breast cancer spheroids is prevented when treated with AAR 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 AAR antagonist AZD-4635. We find that AAR antagonists rescue T and NK cell proliferation, IFNγ and perforin production, and increase tumor infiltrating lymphocytes infiltration into tumor spheroids without altering the expression of adhesion molecules.

CONCLUSIONS

Our results demonstrate that AAR is a promising target in immunotherapy, identifying ISAM-R56A as the most potent candidate for AAR blockade. Inhibition of AAR signaling restores T cell function and proliferation. Furthermore, AAR and dual AAR/AAR antagonists showed similar or better results than AAR antagonist AZD-4635 reinforcing the idea of dominant role of the AAR in the regulation of the immune system.