Key unresolved questions include: (1) Whether interindividual variability in gut microbiota composition affects the polysaccharide-autophagy-PD-L1 axis; (2) Long-term safety of microbial interventions (e.g., SCFA overproduction-induced intestinal barrier dysfunction); (3) Relationship between autophagy activation thresholds and tumor types; (4) Systematic analysis of polysaccharide structure–activity relationships (molecular weight, glycosidic bonds). The gene discussed is CD274; the disease is neoplasm.