We have developed new agents for the treatment of cancer by genetically modifying Pseudomonas exotoxin. We have deleted the cell-binding region of Pseudomonas exotoxin and replaced it with various growth factors or the combining regions of antibodies in a single chain form. These new recombinant molecules are called recombinant toxins. Several different types of recombinant toxins have been produced. B3(Fv)-PE38KDEL is a recombinant toxin that kills many different adenocarcinomas and epidermoid carcinomas. The molecule is now undergoing preclinical development.