CPI-444 is a potent adenosine A2A receptor antagonist. Upon oral administration, CPI-444 binds to adenosine A2A receptors expressed on the surface of immune cells, including T-lymphocytes, natural killer (NK) cells, macrophages and dendritic cells (DCs). This prevents tumor-released adenosine from interacting with the A2A receptors on these key immune surveillance cells, thereby abrogating adenosine-induced immunosuppression in the tumor microenvironment. MW: 407.43. Purity ≥98% by HPLC