CEACAM5 and colon carcinoma: MC38-CEA is a murine model of colon carcinoma transduced to express carcinoembryonic antigen (CEA), a well-established self and tumor-associated antigen.17 Previous work completed by our group has demonstrated that the MC38-CEA colon carcinoma model is minimally responsive to monotherapy anti-PD-L1, with objective response rates of 12.5%.18 We therefore sought to identify rationally designed combination treatments in this model.