Combotope antibody libraries

The invention provides specific antibodies, antibody libraries and methods for identifying specific antibodies, which target Tn- and/or STn- glycosylation sites of any glycoprotein of choice, especially glycoproteins of cancer cell targets. The antibodies identified by the new concept proposed herein have combined specificity towards both the sugar epitope as well as the peptide epitope of the glycoprotein of the cancer cell.