Miao et al. (2019) demonstrated that TGF-β-enriched CSCs dampened the cytotoxicity of adoptive T cells by promoting the exhaustion state through CD80-CTLA4 interaction in squamous cell carcinoma. The findings of adaptive immune resistance raised from CSCs against immunotherapy echoes with the previously proposed immunosuppressing feature of CSC, and furthermore emphases CSC as the root of tumor relapse (Tsuchiya and Shiota, 2021). Here, CTLA4 is linked to neoplasm.