The definitive value of active-specific immunotherapy for experimental carcinoma of the colon.

Active-specific immunotherapy with concanavalin A or with neuraminidase-modified syngeneic tumor cells has been studied in an experimental model of colon cancer. Systemic immunotherapy with concanavalin A-modified tumor cells or with neuraminidase-modified tumor cells has resulted in up to 70 percent cure of rats receiving a lethal inoculum of tumor in a model tumor system which otherwise proved 80 percent lethal to untreated hosts. The possible mechanisms whereby neuraminidase or concanavalin A are effective cell-surface modifiers for active-specific immunotherapy are discussed. In vitro studies suggest markedly heightened antigenic recognition following immunization with concanvalin A-modified syngeneic tumor cells. These studies represent the first apparent evidence for the definitive value of systemic active-specific immunotherapy for the adjuvant treatment of large bowel cancer.