Effect of gelonin immunoconjugate with monoclonal antibody MSN-1 to endometrial adenocarcinoma on antigen-producing tumor cells in vivo.

Missile therapy, which destroys cancer cells specifically, has been advocated as an effective modality for the treatment of carcinoma. We have developed an immunoconjugate consisting of the monoclonal antibody MSN-1 (IgM), which reacts strongly with endometrial adenocarcinomas, combined with a plant hemitoxin named gelonin via a disulfide bond using N-succinimidyl-3-(2-pyridyldithio) propionate and 2-iminothiolane, and examined its selective cytotoxicity in athymic mice. The reductions in resected weights of target tumor cells, at the local site of MSN-1-gelonin immunoconjugate treatment, were 96% with local administration and 75% with caudal vein administration, as compared with the untreated group. There was no weight loss in treated mice. Our results suggest that this MSN-1-gelonin immunoconjugate has potential clinical applications in the treatment of endometrial adenocarcinomas.