In a clinic trial using TCR-engineered T cells targeting metastatic colorectal cancer and a high avidity CEA-reactive TCR, all three patients developed severe transient inflammatory colitis due to the TCR reacting to CEA-expressing normal colon epithelium cells (Although one patient had an objective regression of cancer metastatic to the lung and liver) (Parkhurst et al., 2011). Here, CEACAM5 is linked to cancer.