IgG-scFv is a type of appended IgGs, which are IgG based molecules with additional antigen-binding units. In the format of IgG(H)-scFvs, two scFvs from the same parental antibody are linked to the C terminus of IgG HC. IgG-scFvs belong to symmetric bispecific IgG-like molecules and there is no chain-mispairing problem during antibody expression. IgG-scFv is bispecifc and tetravalent, 2+2 antigen-binding valency. In some conditions, each Fab and scFv can have different specificity, which will result in tetravalent, trispecific (2+1+1 antigen-binding valency) or tetraspecific (1+1+1+1 antigen-binding valency) molecules. And such molecules can be custom-tailored to meet customers’ specific requirements.