The overall goal of ongoing research is the design and characterization of recombinant immunoglobulin (Ig) forms for use in both therapeutic and diagnostic applications for a range of human cancers. Emphasis is being placed on the design and translational research of humanized CDR-grafted and CDR-modified Ig forms, domain-deleted Ig forms and single-chain fusion molecules. These studies are being conducted using a monoclonal antibody (MAb) of potential clinical utility designated CC49. This MAb has been shown to target a wide range of human tumors clinically and has demonstrated anti-tumor activity in clinical trials as a murine Ig. Studies are ongoing to identify those CDRs that are essential for antigen binding and those that may be immunogenic in humans to better define those variants that are of potential clinical utility.