In comparison with nonselective HDAC inhibitors, our newly designed HDAC1/2/6 inhibitor, SDFZ‐8, not only demonstrated more potent T cell activation and improved antigen presenting ability but also contributed to alleviating the immunosuppressive tumor environment by promoting macrophage polarization and negatively regulating PD‐1 expression (Figure 7). Here, HDAC1 is linked to neoplasm.