The MSLN-directed antibody–drug conjugate, anetumab ravtansine, which consists of a human anti-MSLN antibody conjugated to the maytansinoid tubulin inhibitor, DM4, via a disulfide-containing linker, was found to be active against malignant mesothelioma and ovarian cancer with high MSLN expression [13]. The gene discussed is MSLN; the disease is ovarian cancer.