A fully human IgG1 monoclonal antibody directed against the cell surface glycoprotein mesothelin and conjugated to the maytansinoid DM4 with potential antineoplastic activity. The monoclonal antibody moiety of anetumab ravtansine targets and binds to the tumor associated antigen mesothelin; upon internalization, the DM4 moiety binds to tubulin and disrupts microtubule assembly/disassembly dynamics, resulting in inhibition of cell division and cell growth of mesothelin-expressing tumor cells. Mesothelin is overexpressed on all mesotheliomas as well as many ovarian and pancreatic cancers while minimally expressed on normal tissue.