Adenosine receptor antagonist 6 is an orally active, selective (S)-enantiomer compound that acts as an A2A adenosine receptor (A2AAR) antagonist. It binds to the A2A adenosine receptor with a Ki value of 19.18 nM. This antagonist inhibits cAMP production mediated by 5’-N-ethylcarboxamide adenosine (NECA) with an IC50 value of 0.089 μM and reduces immunosuppression, while enhancing the secretion of IL-2 and IFN-γ. It counteracts adenosine-induced immunosuppression in T cell activation and cytokine release and inhibits tumor growth in CT26/MC38 xenograft models, making it applicable for colorectal cancer research.

Adenosine receptor antagonist 6 (Compound 11a) exhibits selective binding to A1, A2B, and A3 adenosine receptors with Ki values of 392.23 nM, 2129 nM, and 9036 nM, respectively. In activated primary human peripheral blood mononuclear cells (PBMCs), it dose-dependently inhibits NECA-mediated cAMP production with an IC50 of 0.089 μM. This compound also counteracts adenosine's immunosuppressive effects on T cell activation and cytokine release at concentrations ranging from 0.1 to 10 μM. Additionally, it mitigates NECA-mediated immunosuppression, restoring IL-2 and IFN-γ secretion at concentrations between 0.03 and 3 μM. Adenosine receptor antagonist 6 suppresses cell proliferation in HCT116 cells (IC50 = 17.21 μM), MDA-MB-231 cells (IC50 = 53.77 μM), MC38 cells (IC50 = 18.91 μM), and CT26 cells (IC50 = 19.36 μM) over 48 hours at concentrations of 0.8125 to 50 μM. The compound demonstrates low metabolic clearance involving CYP450 enzymes, with CYP1A2 playing a key role in its stereoselective metabolism.

Administered orally once daily at a dosage of 15-25 mg/kg for 19-21 days, Adenosine receptor antagonist 6 (Compound 11a) effectively inhibits tumor growth in CT26/MC38 xenograft models, whether used alone or combined with a PD-L1 monoclonal antibody.