Antibody humanization is the process by which animal species’ antibodies (usually murine) are engineered to more closely resemble human antibodies so that they are less likely to elicit anti-drug antibody responses when used clinically. The process involves selection of human antibody acceptor templates, followed by the identification of amino acids from the murine sequence that should be retained in the humanized sequence in order to preserve antigen binding; these amino acids comprise CDR residues plus additional framework resides important for maintaining the overall structure of the CDRs. Further consideration is also given to the physicochemical characteristics of the antibody and how these can be optimized during the humanization process.