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

Inhibition of the adenosine 2A receptor (A2AR) is recognized
as a promising immunotherapeutic strategy but is challenged by the
ubiquity of A2AR 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 A2AR 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
A2AR engagement and downstream signaling was done in a
human blood translational assay, clearly showcasing the potential
of A2AR allosteric modulation as a novel approach for efficient
and safer cancer immunotherapies.