Sebastian M et al. – Malignant ascites is frequently found with various solid tumors, and no established treatment options exist, apart from symptomatic paracentesis. Catumaxomab, a trifunctional bispecific monoclonal antibody, has two binding specificities directed to epithelial cell adhesion molecule (EpCAM) and the T cell antigen CD3. With its Fc–fragment, catumaxomab additionally binds accessory cells, including dendritic cells, macrophages, and natural killer cells. Catumaxomab has been approved in Europe for the intraperitoneal treatment of malignant ascites in patients with EpCAM–positive epithelial tumors where standard therapy is not available or no longer feasible.