CAT and cancer: These metals offer several key benefits: (1) they can directly and effectively deplete GSH via high-valence states [34]; (2) they can also mimic catalase activity to catalyze the decomposition of the higher concentrations of H2O2 found in cancer cells into O2, which not only mitigates hypoxia in cancerous tissues but also facilitates the generation of 1O2 [35]; (3) upon reduction, they can react with the high concentrations of H2O2 within cancer cells to yield hydroxyl radicals—potent oxidants that markedly augment the therapeutic potential of ROS-based treatments (Figure 1) [36].