Definition

A monoclonal antibody directed against the cell surface receptor CD39 (cluster of differentiation 39; ectonucleoside triphosphate diphosphohydrolase-1; NTPDase1; ENTPD1), with potential immunomodulating and antineoplastic activities. Upon administration, anti-CD39 monoclonal antibody IPH5201 specifically targets and binds to the CD39 antigen, thereby preventing the conversion and degradation of the immune-stimulatory adenosine triphosphate (ATP) to adenosine monophosphate (AMP). This leads to an increase in the extracellular levels of ATP and a decrease in the levels of immunosuppressive adenosine within the tumor microenvironment (TME). A high level of ATP increases pro-inflammatory cytokine levels and promotes both T-cell proliferation and the stimulation of dendritic cells (DCs) and other myeloid-derived cells that are necessary for innate and adaptive immunity. CD39, a cell surface ectonucleosidase, is upregulated on tumor cells as an immune evasion strategy. Blocking its action may improve anti-tumor immune responses.