STAT3 and cancer: As for drugs loaded in NPs, considering the immunosuppression and metastasis of cancer associated with the overexpression of programmed cell death ligand 1 (PD-L1) induced by constitutive activation of STAT3, NSC74859 (NSC, N), a signal transducer activator of transcription 3 (STAT3) inhibitor targeting Src Homology 2 (SH2) domain, was used to delay the growth of HNSCC in our previous works [34].