A heterodimeric bispecific immunoglobulin molecule includes a first Fab or scFv fragment which specifically binds to EGFR, and a second Fab or scFv fragment which specifically binds to c-MET, and an antibody hinge region, an antibody CH2 domain and an antibody CH3 domain including a hybrid protein-protein interaction interface domain. Each of the interaction interface domains is formed by an amino acid segment of the CH3 domain of a first member and an amino acid segment of the CH3 domain of a second member. The hybrid protein-protein interface domain of the first chain is interacting with the protein-protein-interface of the second chain by homodimerization of a corresponding amino acid segment of the same member of the immunoglobulin superfamily within interaction domains.
