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Here, we report on a patient presenting with two histopathologically distinct gliomas. At the age of 42, the patient underwent initial resection of a right temporal oligodendroglioma IDH mutated 1p/19q co-deleted WHO Grade II followed by adjuvant radiochemotherapy with temozolomide. 15 months after initial diagnosis, the patient showed right hemispheric tumor progression and an additional new left frontal contrast enhancement in the subsequent imaging. A re-resection of the right-sided tumor and resection of the left frontal tumor were conducted. Neuropathological work-up showed recurrence of the right-sided oligodendroglioma with features of an anaplastic oligodendroglioma WHO Grade III, but a glioblastoma WHO grade IV for the left frontal lesion. In depth molecular profiling revealed two independent brain tumors with distinct molecular profiles of anaplastic oligodendroglioma IDH mutated 1p/19q co-deleted WHO Grade III and glioblastoma IDH wildtype WHO grade IV. This unique and rare case of a patient with two independent brain tumors revealed by in-depth molecular work-up and epigenomic profiling emphasizes the importance of integrated work-up of brain tumors including methylome profiling for advanced patient care. [ABSTRACT FROM AUTHOR]

Purpose: Gliomas are the most frequent primary brain tumors of adults. Despite intensive research, there are still no targeted therapies available. Here, we performed an integrated analysis of glioma and programmed cell death ligand 1 (PD-L1) in 90 samples including 58 glioma and 32 control brain tissues. Methods: To identify PD-L1 expression in glioma, we performed immunohistochemical analysis of PD-L1 tumor proportion score (TPS) using the clinically valid PD-L1 22C3 antibody on 90 samples including controls and WHO grade I–IV gliomas. Results: We found that PD-L1 is highly expressed in a subfraction of glioma cells. Analysis of PD-L1 levels in different glioma subtypes revealed a strong intertumoral variation of PD-L1 protein. Furthermore, we correlated PD-L1 expression with molecular glioma hallmarks such as MGMT-promoter methylation, IDH1/2 mutations, TERT promoter mutations and LOH1p/19q. Conclusion: In summary, we found that PD-L1 is highly expressed in a subfraction of glioma, indicating PD-L1 as a potential new marker in glioma assessment opening up novel therapeutic approaches. [ABSTRACT FROM AUTHOR]