Li et al. revealed that designing Meso‐CAR‐T with co‐stimulation domains including CD28, 4‐1BB, and CD3 detected potent cytotoxicity in breast cancer MDA‐MB‐231‐Luc and MCF‐7‐Luc cell lines by releasing cytokines, perforin, and granzyme B as well as inhibition of tumour growth at a late stage in mice bearing MDA‐MB‐231 TNBC xenografts.191. Here, GZMB is linked to breast cancer.