MSLN and cancer: Mesothelin (MSLN) is highly expressed ina variety of cancers includingcolorectal cancer, with limited expression in normal tissues,4,21 making it a promising target for therapy.2,22 Antibody-dependenttherapies targeting MSLN, including antibody drug conjugates (ADC)are being evaluated in clinical trials; however, they have had minimalimprovements in therapeutic outcomes.6−10 The long circulation time and limited tumor penetration of full-lengthantibodies contribute to the limited therapeutic response.