The antibody SC-1 is a human IGM molecule, which binds to a tumor specific receptor. This SC-1 receptor is detectable on biopsies, it is present in about 50% of gastric cancers. After binding of the antibody to the receptor the tumor cells go into apoptosis. 50 patients expressing the SC-1 receptor on their tumors have been treated with SC-1 prior to gastrectomy. In 80% of cases apoptosis induction could be demonstrated in the tumors. The only side effect of the SC-1 therapy was a reversible episode of fever during antibody infusion in 8% of our patients.