The invention provides a method of targeting T-cells to tumor cells using a tumor-associated antigen (TAA) specific antibody and a T-cell specific antibody, wherein the two antibodies can bind to each other through a high affinity avidin/biotin or streptavidin/biotin connection. The invention further provides methods to target activated T-cells to different tumor types by using a T-cell specific antibody that is specific to an activated T-cell surface molecule like CTLA-4.