More importantly, besides our phenotypic monitoring, we demonstrated that the impaired cytotoxic capacity of all T cell subsets within TIL and TAL against autologous high‐grade serous ovarian tumor cells expressing HER‐2 can be efficiently enhanced by the application of bsscFv [HER2xCD3] and tribody [(HER2)2xVγ9] in vitro. Here, ERBB2 is linked to ovarian serous tumor.