Background: Despite recent therapeutic advances for patients with breast, colorectal and gastroesophageal cancers with HER2 overexpression, there is still a significant unmet medical need for better treatment options for HER2-positive solid tumors, especially those with low or intermediate HER2 expression (1+ and 2+ by immunohistochemistry (IHC)). The T Cell Antigen-Coupler (TAC) technology is a novel way to genetically modify T cells and to redirect these T cells to target cancer antigens and to activate T cells naturally by co-opting the natural T cell Receptor (TCR).