The invention belongs to the field of tumor treatment and the field of
molecular immunology, and relates to an
antibody for resisting
human epidermal growth factor receptor 2 (HER2), as well as a medical composition and use of
antibody, in particular to the
antibody for resisting Her2 or an
antigen binding fragment of the antibody for resisting Her2. The antibody for resisting Her2 comprises a first
heavy chain and a second
heavy chain, wherein according to the first
heavy chain, a variable region of heavy chain (VH) of the first heavy chain comprises a complementarity-determining region (CDR) of which the
amino acid sequence is SEQ ID No: 1-3, and the
amino acid sequence of the CH of the first heavy chain is as shown in SEQ ID No: 7; according to the second heavy chain, a variable region of heavy chain (VH) of the second heavy chain comprises a complementarity-determining region (CDR) of which the
amino acid sequence is SEQ ID No: 4-6, and the amino acid sequence of the CH of the first heavy chain is as shown in SEQ ID No: 8. Compared with the combination of two antibodies of
trastuzumab and
pertuzumab, the antibody disclosed by the invention has higher
cell direct killing activity and higher antibody dependent cellmediated
cytotoxicity (ADCC) activity; the complement-dependentcytotoxicity (CDC) activity of the two antibodies of
trastuzumab and
pertuzumab is equivalent to that of the antibody disclosed by the invention; the antibody disclosed by the invention adopts a structure of a normal antibody; and
fucose is also knocked out, so that the ADCC activity is improved.