ERBB2 and breast cancer: Besides GD2, further markers with a potential to target Vγ9/Vδ2 T cells specifically against breast CSCs include the human epidermal growth factor receptor 2 (HER2).44 Indeed, the HER2-specific monoclonal antibody trastuzumab was recently shown to opsonise human breast cancer xenografts and enhance the ability of γδ T cells to control tumour progression.26 The availability of approved drugs and biologics to enhance the TCR-mediated and antibody-dependent cytotoxicity of γδ T cells therefore allows a rapid translation of the present findings in the clinic.