CSF2 and neoplasm: Briefly, CCL21a and ExoGM‐CSF+Ce6 (tumor cell‐derived exosomes with granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) mRNA encapsulated inside and sonosensitizer chlorin e6 (Ce6) incorporated in the surface) are mixed with nanoclay and gelatin methacryloyl, forming the hydrogel designated as CCL21a/ExoGM‐CSF+Ce6@nanoGel.