An open-label phase Ib dose escalation study to evaluate the safety, tolerability, pharmacokinetics, immunogenicity, and maximum tolerated dose of anetumab ravtansine in combination with pegylated liposomal doxorubicin 30 mg/m2 given every 3 weeks in subjects with mesothelin-expressing platinum-resistant recurrent ovarian, fallopian tube, or primary peritoneal cancer. The gene discussed is MSLN; the disease is peritoneum cancer.