Abstract
Immune checkpoint blockade (ICB) inhibitors have shown great promise for the treatment of numerous types of cancers, including triple-negative breast cancer (TNBC), by interrupting immunosuppressive checkpoints. Herein, programmed cell death ligand 1 (PD-L1) blockade peptide-functionalized NaGdF(4) nanodots (designated as PDL1-NaGdF(4) NDs) were prepared for magnetic resonance imaging (MRI)-guided TNBC immunotherapy through covalent conjugation of the PD-L1 blockade peptide (sequence, CALNNCVRARTR) with tryptone-capped NaGdF(4) NDs (designated as Try-NaGdF(4) NDs). MDA-MB-231 tumor could be easily tracked using in vivo MRI with PDL1-NaGdF(4) ND enhancement because the as-prepared PDL1-NaGdF(4) NDs have a high longitudinal relaxivity (r (1)) value (22.8 mM(-1) S(-1)) and accumulate in the tumor site through binding with programmed cell death ligand-1 (PD-L1)-overexpressed cells. A series of in vitro/in vivo results demonstrated that the PDL1-NaGdF(4) NDs could effectively suppress MDA-MB-231 tumor growth in mice (66% volume ratio) by inhibiting migration and proliferation of tumor cells. In addition, the results of pharmacokinetic study showed that the PDL1-NaGdF(4) NDs were excreted from the body through the kidneys. These results highlight the potential of PDL1-NaGdF(4) NDs as a biocompatible nanomedicine for TNBC diagnosis and immunotherapy.