Figure 3.

A hypothetic schematic for how advanced aging decreases immunotherapeutic efficacy in subjects with glioblastoma (GBM). There is a basal level of IDO-mediated immunosuppression by GBM cells (red) that does not change between (A) young and (B) elderly (as defined by ≥65 years of age) individuals. In contrast, there is additional immunosuppression in the elderly brain due to the accumulation of brain-resident IDO-expressing dendritic cells (green), which synergize with the GBM cell IDO to suppress the anti-GBM immune response facilitated by combination radiation, anti-PD-1 mAb, and IDO enzyme inhibitor treatment (middle box).