CAT and neoplasm: Rapid proliferation of tumor cells and their abnormal vascular structures often created a hypoxic microenvironment, and the host can repair damaged DNA induced from RT especially at a low concentration of oxygen available in such a tumor microenvironment to diminish the antitumor effect from RT.[175] It is a sagacious way to relieve hypoxia by co‐delivery of oxygen suppliers, such as catalase, to decompose over‐produced hydrogen peroxide to oxygen.[176] Chen et al. designed multifunctional PLGA NPs to load catalase in its aqueous cavity and imiquimod (R837) in its shell for RT (Figure 11a).