Via genetic engineering, EcN was modified to be responsive to ionizing radiation and to produce a single-chain variable fragment (scFv) directed against TREM2 (Triggering Receptor Expressed on Myeloid Cells 2), thereby modulating macrophages, and synergizing with the ICIs αPD-L1 to enhance the radioimmunotherapy effect for low rectal cancer (Figure 3C). Here, TREM2 is linked to rectal cancer.