A recombinant disulfide stabilized anti-Lewis Y IgG immunotoxin containing a 38 KD toxic element derived from the Pseudomonas aeruginosa exotoxin A and a monoclonal antibody fragment, designed to target adenocarcinomas expressing Lewis Y. LMB-9 immunotoxin attaches to tumor cells, facilitating he entry of the exotoxin. The exotoxin moiety induces caspase-mediated apoptosis of tumor cells via a mechanism involving mitochondrial damage; it also catalyzes the transfer of ADP ribose from nicotinamide adenine dinucleotide (NAD) to elongation factor-2 in eukaryotic cells, thereby inactivating elongation factor 2 and inhibiting protein synthesis.