CAT and neoplasm: To solve this problem, M. Ligtenberg and his colleagues remolded T cells to co-express catalase (CAT) and tumor-specific CAR to metabolize high level H2O2 so as to improve their antioxidant capacity.32 On the one hand, these novel T cells (CAR-CAT-T cells) can significantly increase the intracellular catalase level, and at the same time reduce the accumulation amount of ROS at the tumor site no matter in the ground state or in the activated state, thus reducing oxidative stress (oxidative stress occurs when the balance between ROS production and antioxidant function is broken).