Gradual loss in tumor reactivity of transferred CEA.CAR-γδ T cells in vivo; To determine the CEA.CAR-γδ T cells’ durability in maintaining tumor reactivity, single cell suspension of PBMCs, spleen and tumor tissues were cultured in the presence of CEA+ (BxPC-3) or CEA- (MIA Paca-2) tumors and Vδ2+ cells were analyzed for IFN-γ production by intracellular cytokine staining (ICS). The gene discussed is CEACAM5; the disease is neoplasm.