NCI-N87 gastric tumor bearing mice were treated intravenously with a single injection of anti-Her2 position 1-ADC (1, 3 or 5 mg/kg) or anti-Her2 position 2-ADC (1, 3 or 5 mg/kg), anti-Her2 Cys-ADC (1, 3 or 5 mg/kg), the anti-CD22 position 1-ADC at 5 mg/kg or vehicle control (5% Dextrose), when the average tumor size reached approximately 200 mm3. The gene discussed is CD22; the disease is gastric neoplasm.