Reactivity of a humanized antibody (hPankoMab) towards a tumor-related MUC1 epitope (TA-MUC1) with various human carcinomas

Humanized antibodies against tumor-related antigens are now established reagents for in vivo diagnostics and for therapeutic approaches, and are increasingly developed. Humanized PankoMab (hPankoMab), a humanized form of PankoMab directed against a novel tumor-related MUC1 epitope (TA-MUC1), was recently developed for clinical application. In the present study, the reactivity of hPankoMab with various human cancers was systematically studied by immunohistochemistry on 137 surgical specimens, including lung, breast, gastric, colorectal, liver, cervical, kidney, thyroid, and other carcinomas, as well as on several non-epithelial malignancies. The study was performed on paraffin sections without antigen retrieval. hPankoMab reacted strongly with carcinomas originating from glandular or squamous epithelia, weakly with hepatocellular carcinomas, and not with sarcomas. The binding sites of hPankoMab in carcinomas were found around the whole cell surface and, in most cases, also in the cytoplasm of cancer cells.