In vitro and in vivo activity of MT201, a fully human monoclonal antibody for pancarcinoma treatment

Abstract In our study, a novel, fully human, recombinant monoclonal antibody of the IgG1 isotype, called MT201, was characterized for its binding properties, complement‐dependent (CDC) and antibody‐dependent cellular cytotoxicity (ADCC), as well as for its in vivo antitumor activity in a nude mouse model. MT201 was found to bind its target, the epithelial cell adhesion molecule (Ep‐CAM; also called 17‐1A antigen, KSA, EGP‐2, GA733‐2), with low affinity in a range similar to that of the clinically validated, murine monoclonal IgG2a antibody edrecolomab (Panorex®). MT201 exhibited Ep‐CAM‐specific CDC with a potency similar to that of edrecolomab. However, the efficacy of ADCC of MT201, as mediated by human immune effector cells, was by 2 orders of magnitude higher than that of edrecolomab. Addition of human serum reduced the ADCC of MT201 while it essentially abolished ADCC of edrecolomab within the concentration range tested. In a nude mouse xenograft model, growth of tumors derived from the human colon carcinoma line HT‐29 was significantly and comparably suppressed by MT201 and edrecolomab. The fully human nature and the improved ADCC of MT201 with human effector cells will make MT201 a promising candidate for the clinical development of a novel pan‐carcinoma antibody that is superior to edrecolomab. © 2002 Wiley‐Liss, Inc.