CD247 and cancer: In comparison, “AND” gating CARs turned out to be technically more challenging.178 The primary CD3ζ signal was separated from the costimulatory signal, each CAR providing only one signal and each CAR recognizing a different antigen on cancer cells; full T cell activation is only provided upon simultaneous engagement of both targets.179,180 Some leakage in signaling of the CAR with signal-1, however, weakens logic gating of such dual CAR T cells.