Subtle Structural Changes across the Boundary between AR/AR Dual Antagonism and AR Antagonism: A Novel Class of 2-Aminopyrimidine-Based Derivatives.

Aberrantly elevated adenosine in the tumor microenvironment exerts its immunosuppressive functions through adenosine receptors AR and AR. Antagonism of AR and AR has the potential to suppress tumor growth. Herein, we report a systemic assessment of the effects of an indole modification at position 4, 5, 6, or 7 on both AR/AR activity and selectivity of novel 2-aminopyrimidine compounds. Substituting indole at the 4-/5-position produced potent AR/AR dual antagonism, whereas the 6-position of indole substitution gave highly selective AR antagonism. Molecular dynamics simulation showed that the 5-cyano compound had a lower binding free energy than the 6-cyano compound due to water-bridged hydrogen bond interactions with E169 or F168 in AR. Of note, dual AR/AR antagonism by compound can profoundly promote the activation and cytotoxic function of T cells. This work provided a strategy for obtaining novel dual AR/AR or AR antagonists by fine-tuning structural modification.