Multi-specific antigen-binding constructs that target immunotherapeutics are described. The multi-specific antigen-binding constructs comprise a first antigen-binding polypeptide construct that binds to an immunotherapeutic (such as a CAR-T cell or a bispecific T-cell engager), and a second antigen binding polypeptide construct that binds to a tumour-associated antigen. Also described are methods of using the multi-specific antigen-binding constructs to re-direct or enhance the binding of the immunotherapeutic to a tumour cell, and methods of treating patients who have relapsed from or failed treatment with the immunotherapeutic.
