The present invention relates to novel therapeutic antibodies directed against HER2 (ErbB2), as well as recombinant polyclonal anti-HER2 antibody compositions, and use of the antibodies and antibody composition for treatment of cancers. The antibody composition comprises at least three recombinant antibodies that bind distinct epitopes of HER2. Two of the antibodies bind to HER2 on the surface of a cell such that they generate a cross-linked antibody-receptor lattice on the cell surface and thereby result in HER2 receptor internalization. The third antibody in the composition binds HER2 such that it blocks heterodimerization between HER2 and HER3.
