Recombinant Anti-CA72-4 x Anti-CD3 Bispecific Antibody (scDiabody-Fc) is a fusion protein of two scDiabodies with an Fc region. In single-chain Diabodies, an additional connecting linker is introduced between chains of the anti-CA72-4/anti-CD3 diabody. The scDiabody with two specificities is further fused to the Fc domain to form BsAb with 2+2 antigen-binding valency. This BsAb can retarget T cells to tumor cells. It is designed for the research of Gastrointestinal cancer; Ovarian cancer; Colon cancer; Gastric cancer; Breast cancer; Adenocarcinomas therapy.