Levels And Enzyme Activity Of Cd73 In Primary Samples From Cancer Patients

CD73 is an ectonucleotidase that converts extracellular AMP to Adenosine. Within the tumor microenvironment, adenosine produced by CD73 is believed to have an immunosuppressive effect upon anti-tumor immunity. CD73 is found on lymphoid and myeloid cells, and blockade of this enzyme has been shown to alter the suppressive capacity of cells. Expression of surface CD73 as well as soluble CD73(sCD73) levels were measured in serum, peripheral blood mononuclear cells, and tumor samples from healthy and cancer patient donors. Enzymatic activity of both surface CD73 and sCD73 was determined and differences in levels across varying tumor types and disease status were quantified. In addition, CD73 levels and activity were measured after incubation or treatment with anti-CD73 antibody, MEDI9447. These studies suggest a potential role of surface and sCD73 as a pharmacodynamic and/ or predictive biomarker of anti-CD73 immunotherapy. Citation Format: Qihui Huang, Nicholas M. Durham, Erin Sult, Yuling Wu, Jenny Liu, Nicholas Holoweckyj, Laurie Iciek, Robert Hollingsworth, Brett Hall, Ronald Herbst, Ching Ching Leow, Kris Sachsenmeier. Levels and enzyme activity of CD73 in primary samples from cancer patients. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1538. doi:10.1158/1538-7445.AM2015-1538