OS1.1 Plasma PD-L1 levels over time differ between glioblastoma and lower-grade glioma patients

BACKGROUND Immune modulating therapies are a promising treatment approach in patients with primary brain tumors, however their clinical efficacy is still under investigation as the systemic inflammatory responses are potentially challenged by the brain’s tight immune regulatory mechanisms. Here, we aimed to investigate soluble PD-L1 (sPD-L1) in the plasma of recurrent glioblastoma (GBM) and recurrent WHO grade II - III glioma (LGG) patients over...