PDL1 Monoclonal Antibody-Modified mPEG–PLGA-NH₂ Nanocomposite Loaded with Heterophyllin B for the Treatment of Gastric Cancer

Immune checkpoint inhibitors (ICIs) show effectiveness in gastric cancer (GC) treatment, yet enhancing their efficacy remains challenging. We encapsulated the anticancer compound Heterophyllin B (HB) in mPEG–PLGA-NH2 nanoparticles (NPs), modified with αPDL1, forming mPEG–PLGA-NH2@HB-αPDL1 NPs. These NPs displayed low toxicity to GES-1 cells and good blood compatibility. They effectively inhibited GC cell malignant phenotypes and downregulated PD-L1 expression via the PI3K/AKT pathway. In GC allograft mice, the HB and αPDL1 combination therapy outperformed monotherapy, with the NPs showing better efficacy than free drugs. Additionally, the NPs improved the tumor immune microenvironment. H&E staining confirmed no significant toxicity to major mouse organs. Thus, mPEG–PLGA-NH2@HB-αPDL1 offers a promising strategy for optimizing ICI therapy in GC treatment.