Recombinant Anti-CA125 x Anti-HER2 Bispecific Antibody (Tandem scFv-Fc) is designed to be expressed as a homodimer, which has 2+2 antigen-binding valency. This format consists of one Fc region and two tandem scFv fragments, in which the anti-CA125/HER2 tandem scFv is fused to the Fc domain. The engineered fragment format is used to extend the half-life. This BsAb can bind two factors simultaneously. It is designed for the research of Breast cancer; Gastric cancer; Prostate cacncer; Ovarian cancer; Solid tumors therapy.