CD73 is highly expressed in tumors and is an ectonucleotidase that drives the conversion of AMP to immunosuppressive adenosine. PM1015 is a potentially best-in-class antagonist of CD73 that differentiates from other competitor agents by blocking membranous and soluble CD73 to maximal levels without hook effects. The reduction of adenosine levels by inhibiting CD73 removes a major pro-tumor pathway for improving treatment of cancer patients.