It was also observed that inhibitory cytokines such as IL‐10 and TGF‐β that are mainly secreted by MDSCs, M2 TAMs, and Treg were considerably reduced in both serum (Figure 5E,F) and tumor tissues (Figure S23, Supporting Information) after HBO treatment, indicating it is HBO, not PD‐1 Ab, that reprograms TME from being immunosuppressive to immunostimulatory. Here, TGFB1 is linked to neoplasm.