A prodrug nanoparticle synthesized by conjugating PD-L1Pep-2 with doxorubicin via cathepsin B-cleavable peptide linker (FRRG) inhibited tumor progression in the 4T1 mouse breast tumor model by inducing doxorubicin-mediated immunogenic cell death and blocking PD-L1 through PD-L1Pep-2102. This evidence concerns the gene CD274 and neoplasm.