CD4 and breast cancer: Besides that, targeting another marker antigen associated with a breast cancer stem‐like cell (BCSC) phenotype recognized as the disialoganglioside GD2 and producing novel anti‐GD2 CARs and expressing them on activated CD4 and CD8 positive T cells significantly lysed GD2‐positive breast cancer cells in vitro as well as halted local tumour progression and completely prevented lung metastasis in an orthotopic xenograft model of TNBC (MDA‐MB‐231 cell bearing rodent) in vivo.188