The present invention concerns compositions and methods of use of antibodies or antibody fragments that bind to an epitope located within the second cysteine rich domain (Cys2 amino acid residues 1575 1725) of MUC5AC. The antibodies bind with high specificity and selectivity to pancreatic cancer and are of use for therapy detection and/or diagnosis of pancreatic cancer. In preferred embodiments therapeutic antibody may be conjugated to at least one therapeutic agent such as Y. Both and detection of pancreatic cancer may be performed with the subject methods and compositions. Specific dosages of radiolabeled antibody and/or gemcitabine of use in human pancreatic cancer patients are disclosed herein.
