NT5E and neoplasm: CD73 is a member of the membrane-bound enucleotidasefamily, whichcatalyzes the extracellular hydrolysis of adenosine monophosphate(AMP) to produce anti-inflammatory and immunosuppressive adenosine.As a novel checkpoint protein, CD73 is overexpressed in the immunesystem of various tumors, where adenosine is abundantly enriched.A large number of monoclonal antibodies (mAbs), nucleotides, and non-nucleotidesas potent CD73 inhibitors are being discovered, providing opportunitiesfor novel tumor immunotherapy.