FIGURE 6.

Overcoming the upregulation of immunosuppressive pathways. (A) Schematic illustration of the preparation of polyethylene glycol‐coated cancer cell membrane‐based nanoparticles and the combinational therapeutic strategy of immune checkpoint blockade and nanoparticles. Reproduced with permission.^{[ 129 ]} Copyright 2018, Elsevier Ltd. (B) Schematic illustration of the structure of tumor cell membrane‐coated nanoparticles loaded with toll‐like receptor 7 agonists and how these treatment systems regulate anti‐tumor immunity in vivo. Reproduced with permission.^{[ 130 ]} Copyright 2018, American Chemical Society. (C) Anti‐CD19 CAR‐T cells with PD‐1 deficiency had great anti‐tumor activity against subcutaneous CD19+ PD‐L1+ tumor xenografts. Reproduced with permission.^{[ 132 ]} Copyright 2017, The Author(s)