Also here, Siglec-E deletion synergized with anti-PD-1/PD-L1 treatment to improve antitumor efficacy, again indicating that Siglec-9 is an immune-checkpoint molecule on macrophages that can be targeted to repolarize macrophages to enhance anti-PD-1/PD-L1 therapeutic efficacy of difficult-to-treat cancers, like glioblastoma multiforme and PDAC. The gene discussed is CD274; the disease is glioblastoma.