Figure 1: Schema demonstrating immune activation and the role of
immune suppression and checkpoints. Glioblastoma exerts profound
immunosuppressive effects via multiple, redundant mechanisms, including
the TGF-β/VEGF signalling pathway, IL-2Rα/CD25-mediated IL-
2 deprivation, CTLA-4/PD-1/PD-L1 immune checkpoint interaction,
STAT3 activation, as well as by IDO/Arg-1 enzymatic suppression. All of
these mechanisms have been investigated as potential therapeutic targets
for glioblastoma treatment in various clinical and preclinical trials.