To overcome the problem of the persistently suppressed CAR T-cell activity by myeloid-derived suppressor cells (MDSCs) within the TME of BRCA, the authors prepared a MUC1-targeting CAR T-cell using a new chimeric costimulatory receptor targeting the TNF-associated apoptosis-inducing ligand receptor 2 (TR2) distributed in MDSCs. This evidence concerns the gene MUC1 and invasive breast carcinoma.