B3(Fv)-PE38KDEL, a single-chain immunotoxin that causes complete regression of a human carcinoma in mice.

The genes encoding the heavy- and light-chain Fv regions of the monoclonal murine antibody B3, which recognizes a carbohydrate antigen on the surface of many human carcinomas, were cloned by PCR techniques and used to generate single-chain immunotoxins containing Pseudomonas exotoxin (PE). The light and heavy chains were connected by a flexible linker to form a single-chain antigen-binding protein, B3(Fv), which was in turn fused to truncated...