A human immunoglobulin G1 (IgG1) monoclonal antibody directed against the carbohydrate antigen sialyl Lewis A (carbohydrate antigen 19-9; CA19-9), with potential antineoplastic activity. Upon administration, anti-CA19-9 monoclonal antibody BNT321 targets and binds to CA19-9, and kills CA19-9-expressing tumor cells through the induction of both complement-dependent cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC). CA19-9 is overexpressed on a number of different tumor cell types, and plays a key role in tumor cell survival and metastasis.