Catumaxomab is an anti-Ep-CAM monoclonal antibody, it has been designed to induce more efficient killing of epithelial tumor cells. More specifically, catumaxomab is a bispecific trifunctional antibody (trAb). In addition to its EpCAM recognition arm, it possesses an anti-CD3 arm that targets the T-cell antigen CD3; binding to the CD3 receptor activates T cells to release cytotoxic cytokines and to promote T cell-mediated lysis. In essence, catumaxomab consists of one half of an anti-Ep-CAM antibody and one half of an anti-CD3 antibody. The trifunctionality comes into play with an intact Fc region that selectively binds to FCg receptor-positive accessory cells, such as macrophages, dendritic cells, and natural killer (NK) cells that promote phagocytosis and antibody-dependent cell cytotoxicity. As a trAb that brings the requisite immune effector cells in close proximity to the tumor cells, catumaxomab destroys tumor cells possessing the surface antigen Ep-CAM via simultaneous activation and complex crosstalk of T cells and accessory immune cells. While it has gained approval for the intraperitoneal (i.p.) treatment of malignant ascites caused by Ep-CAM-positive metastatic epithelial-derived tumors, it is also being evaluated for the treatment of ovarian and gastric cancers.
