Discovery of the First Efficacious Adenosine 2A Receptor Negative Allosteric Modulators for High Adenosine Cancer Immunotherapies

Inhibition of the adenosine 2A receptor (A_2AR) is recognized as a promising immunotherapeutic strategy but is challenged by the ubiquity of A_2AR function in the immune system. To develop a safe yet efficacious immunotherapy, the discovery of a novel negative allosteric modulator (NAM) was preferred. Leveraging an in-house, sensitive, high-throughput screening cellular assay, novel A_2AR NAM scaffolds were identified, followed by an extensive structure-activity relationship (SAR) study, leading to the discovery of potent 2-amino-3,5-dicyanopyridine derivatives. The allosteric mode of action of active compounds was confirmed by progressive fold-shift assay, nonlinearity of the Schild plot analysis, biophysical measurements, and retained satisfactory potencies in high-adenosine concentrations. Further correlation of A_2AR engagement and downstream signaling was done in a human blood translational assay, clearly showcasing the potential of A_2AR allosteric modulation as a novel approach for efficient and safer Cancer immunotherapies.