MSLN and neoplasm: Mesothelin (MSLN) contributes to the malignant and invasive phenotype in ovarian cancer,3 4 and has limited expression in healthy cells,5 making it a candidate target6 Studies targeting MSLN with monoclonal antibodies,7 vaccination8 and chimeric antigen receptor (CAR)-expressing T cells9 have shown modest anti-tumor activity, validating MSLN as a viable target antigen.