In a groundbreaking study, researchers have designed probiotic-colonized tumor, thereby enhancing CAR T cell immunotherapy. This two-step method involves modifying a strain of non-pathogenic E. coli to deliver synthetic antigens to the tumor microenvironment and "tag" the tumor. Subsequently, CAR T cells are generated, and programmed to recognize these synthetic antigen tags. Upon administration of the E. coli probiotics, the CAR T cells are guided to the solid tumor, orchestrating the eradication of tumor cells in both breast and colon cancer experimental models.