CEACAM5 and neoplasm: Moreover, while the simpler distance and spatial correlation analyses indicated partial infiltration of the tumor bed by the TCF1-PD1+ effector CD8 T cells, the global region-based analysis also demonstrated that, in general, T cell rich and CEA+ tumor nest regions are spatially segregated from one another, and that even after immunotherapy, CEA+ tumor nests are relatively devoid of T cells.