The O2‐consuming PDT procedure can worsen the hypoxia degree, possibly causing the tumor metastasis and resistance to many therapeutic modalities such as PDT, RT, chemotherapy, and catalytic medicine.[84, 85] Versatile nanotechnology‐enabled O2‐supplying strategies have been developed for alleviating tumor hypoxia, among which the direct conversion of tumor‐overexpressed H2O2 into O2 has been mostly explored, including the typical use of catalase and Mn‐based nanocatalysts.[86, 87, 88, 89] The intrinsically low H2O2 level in tumor, however, severely limits the O2‐production efficacy. This evidence concerns the gene CAT and neoplasm.