Pre-vaccination promote baseline immunity, significantly increase expression of INF-γ, Fms-related tyrosine kinase 3 ligand (FLT3L) and granulocyte–macrophage colony-stimulating factor(GM-CSF), and help “cold” tumor, such as glioblastoma and pancreatic ductal carcinoma, respond to ICIs (65, 66, 71). Here, FLT3LG is linked to pancreatic ductal adenocarcinoma.