MUC1‐specific CARs with a combined CD28/OX40/CD3 endodomain and the HMFG2 scFv promoted proliferation and proinflammatory cytokine production in MUC1‐CAR T. Furthermore, these CAR T cells delayed tumour growth in a xenograft model bearing MDA‐MB‐435 tumour cells after a single dose of CAR‐engineered T cells was administered intraperitoneal (IP).174. Here, CD28 is linked to neoplasm.