| CPC C07K 16/2881 (2013.01) [A61P 35/00 (2018.01); C07K 16/2863 (2013.01); C07K 2317/31 (2013.01); C07K 2317/34 (2013.01); C07K 2317/55 (2013.01); C07K 2317/92 (2013.01)] | 10 Claims | 
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               1. A bispecific antibody or a bispecific antibody fragment thereof, comprising: 
            an IgG portion that binds to a transferrin receptor (TfR) and an N-terminal side polypeptide that binds to a cell surface antigen, 
                wherein the IgG portion includes VH having CDRs 1 to 3 containing the amino acid sequences represented by SEQ ID NOs: 32 to 34, respectively, and VL having CDRs 1 to 3 containing the amino acid sequences represented by SEQ ID NOs: 17 to 19, respectively, 
                wherein the N-terminal side polypeptide is Fab of an antibody against EGFR, and the antibody includes VH having CDRs 1 to 3 containing the amino acid sequences represented by SEQ ID NOs: 65 to 67, respectively, and VL having CDRs 1 to 3 containing the amino acid sequences represented by SEQ ID NOs: 17 to 19, respectively, 
                wherein the bispecific antibody or the bispecific antibody fragment thereof binds to TfR and the cell surface antigen, 
                wherein the N-terminal side polypeptide binds directly or through a linker to the N terminus of a heavy chain of the IgG portion. 
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