Structural insights into dual-antagonize mechanism of AB928 on adenosine A₂receptors

Abstract The adenosine subfamily G protein-coupled receptors A 2A R and A 2B R were identified as promising candidates for cancer immunotherapy within recent years. One of the A 2A R/A 2B R dual antagonist, AB928, has progressed to phase II clinic trial for the treatment of rectal cancer. However, the precise mechanism underlying its dual-antagonistic properties remains elusive. Herein, we report crystal structures of A 2A R in complex with AB928 and a selective A 2A R antagonist, 2-118. The structures reveal a common binding mode on A 2A R, wherein the ligands establish extensive interactions with residues from both the orthosteric pocket and the secondary pocket. Conversely, the cAMP assay together with molecular dynamics simulations conducted on both A 2A R and A 2B R indicate that the ligands adopt distinct binding modes on A 2B R. Detailed analysis of their chemical structures suggests that AB928 can readily adapt to the A 2B R pocket, while 2-118 cannot due to its intrinsic differences. This disparity potentially accounts for their divergent inhibitory efficacies between A 2B R and A 2A R. The findings from this study can serve as valuable structural templates for future development of selective or dual inhibitors targeting A 2A R/A 2B R in the context of cancer therapy.