CEACAM5 and colon carcinoma: A previous study by our group demonstrated that the MC38-CEA murine colon carcinoma and the 4T1 murine TNBC models have differential response to PD-L1 blockade.7 PD-L1 treatment resulted in only 1/8 mice (12.5%) cured in the MC38-CEA model and 0/20 mice (0%) cured in the 4T1 model.