Discovery of Novel Benzo[4,5]imidazo[1,2-]pyrazin-1-amine-3-amide-one Derivatives as Anticancer Human A Adenosine Receptor Antagonists.

The blockade of A adenosine receptor (AAR) activates immunostimulatory response through regulating signaling in tumor microenvironment. Thus, AAR has been proposed as a promising target for cancer immunotherapy. In this work, we designed a new series of benzo[4,5]imidazo[1,2-]pyrazin-1-amine derivatives bearing an amide substitution at 3-position to obtain potent antitumor antagonist . The structure-activity relationship studies were performed by molecular modeling and radioactive assay. The anticancer activities were evaluated by 3',5'-cyclic adenosine monophosphate (cAMP) functional and T cell activation assay. The most potent compound showed much higher affinity toward AAR ( = 0.08 nM) and exhibited more significant immunostimulatory anticancer activity than clinical antagonist AZD4635. More importantly, significantly inhibited the growth of triple-negative breast cancer by reversing immunosuppressive tumor microenvironment in the xenograft mouse model without severe toxicity at the testing dose. These results make a promising immunotherapy anticancer drug candidate.