CLDN18 and cancer: Similarly, CLDN18.2-TAC T cells did not exert any activity in the absence of the target antigen and—in the presence of tumor antigen—exhibited favorable pharmacology parameters, such as reacting to cancer cells expressing low CLDN18.2 levels, effective killing at low E:T ratios, clearance of tumor spheroids and in vivo xenografts, and long-lasting activity in recursive killing assays and tumor rechallenge experiments.