A humanized IgG1 monoclonal antibody directed against human mesothelin with potential antineoplastic activity. Amatuximab binds to mesothelin, triggering an antibody dependent cellular cytotoxicity (ADCC)-mediated host immune response against mesothelin-expressing tumor cells, which may result in tumor cell lysis. Mesothelin, a 40kDa cell surface glycoprotein, is overexpressed in several human tumors, including mesothelioma and ovarian and pancreatic adenocarcinomas. or A substance being studied in the treatment of mesothelioma. Amatuximab binds to a protein called mesothelin, which is found on some cancer cells. Amatuximab may help the immune system kill cancer cells. It is a type of monoclonal antibody. Also called anti-mesothelin monoclonal antibody MORAb-009 and MORAb-009.