Very few data exist regarding the immune profile of gliomas. Our aim was to study different immunological parameters according to IDH1 mutational status and histologic grade.
Patients with grade II to IV gliomas were prospectively enrolled. Immunohistochemistry (IHC) was used to quantify CD4+ and CD8+ T cells and to study IDH1 and PDL1 (> 5%) expression on tumor cells. These parameters were correlated to mRNA expression of 20 immune-related genes (CSF1R, CTLA4, CXCL9, CXCL10, CXCL13, FOXP3, GZMA, HLADRA, IDO1, INFG, PD1, PDL1, PDL2, PRF1, STAT1, STAT3, TIGIT, TIM3, VISTA, TLR7) according to IDH1 status and histologic grade.
Between February 2017 and July 2018, 20 patients (pts) were enrolled, 14 glioblastomas (GB: 9 IDHWT, 5 IDH1MUT) and 6 lower-grade gliomas (LGG: 2 IDHWT, 4 IDHMUT). Among 18 pts: PDL1 IHC was positive (PDL1IHC+) in 10 GB (3 IDH1MUT) and 1 LGG (IDH1MUT); CD4+ T cell infiltration (intratumoral (IT)/perivascular(PV)) in 5 GB (2 IDH1MUT); CD8+ T cell infiltration in 12 GB (8 IT+PV, 3 IT, 1 PV) and 5 LGG (1 IT, 4 IT+PV). PDL1IHC+ more frequent in GB + LGGIDH1wt vs LGGIDH1mut (P = 0.06). PDL1IHC+ tumors shoed lower expression of STAT1 (P = 0.042), TIM3 (P = 0.02) and TLR7 (P = 0.06). Tumors with > 20 CD8+ T cells/HPF showed higher expression of PD1 (P = 0.03), PRF1 (P = 0.03) and STAT1 (P = 0.03).
Histologic grade and IDH1 status identify glioma groups with different immunophenotypes. This results should be confirmed in a larger sample.
Clinical trial identification
Legal entity responsible for the study
GEINO (Grupo Español de Investigación en Neuro-Oncología).
All authors have declared no conflicts of interest.