Soluble PD-L1 is associated with local and systemic inflammation markers in primary and secondary brain tumours

BackgroundImmune-modulatory treatments have so far shown limited clinical activity in primary brain tumours. We aimed to investigate soluble programmed death receptor ligand 1 (sPD-L1) as systemic inflammation parameter in patients with brain tumour.MethodsEDTA plasma was collected from 81 glioma (55 glioblastoma (GBM), 26 lower-grade glioma (LGG)), 17 meningioma and 44 brain metastasis (BM) patients and 24 controls. sPD-L1 concentrations were determined by ELISA. Correlations with the local tumour microenvironment were assessed by immunohistochemical analysis for PD-L1, CD3 and CD8.ResultssPD-L1 was detected in 62 out of 166 (37.7%) patients (glioma: 41/81, 50.6%; meningioma: 5/17, 29.4%; BM: 7/44, 15.9%; controls: 9/24, 37.5%; p=0.002). sPD-L1 concentrations were lower in BM than in LGG (p=0.003) or GBM (p