Disclosed are binding proteins, or fragments thereof, that specifically binds to a cancer-specific glycosylation variant of a protein and to a second epitope on the same protein, to a different protein presented on the same cell, or to a different protein presented on a different cell, such as an encoded polypeptide binding to both a cancer cell and an activated T cell. Also disclosed are polynucleotides encoding such binding proteins, including polynucleotides comprising codon-optimized coding regions and polynucleotides comprising coding regions that are not codon-optimized for expression in a particular host cell. Also disclosed are methods of making the encoded polypeptide and methods of using the polypeptide to treat, prevent or ameliorate the symptom of a disease such as cancer.