BIOM-32. DNA METHYLATION SUBCLASSES PREDICT THE BENEFIT FROM GROSS TOTAL TUMOR RESECTION IN IDH-WILDTYPE GLIOBLASTOMA PATIENTS

DNA methylation-based tumor classification allows an enhanced distinction into subgroups of glioblastoma. However, the clinical benefit of DNA methylation-based stratification of glioblastomas remains inconclusive. We performed a multicentric cohort study including 430 patients with newly diagnosed glioblastoma whose tumors were subjected to DNA methylation profiling. The primary outcome was overall survival (OS) and progression-free survival (PFS). Secondary outcomes were the prognostic relevance of EOR and MGMTpromoter methylation status as well as surgical benefit for recurrent glioblastoma. After stratifying patients in accordance with their DNA methylation subclasses RTK I, RTK II, and mesenchymal (MES), outcome analyses revealed no significant differences between these three methylation subclasses (p = 0.06). RTK I or RTK II tumors who underwent gross-total resection (GTR) or near GTR had a longer OS and PFS than partially resected patients (p < 0.01). In the MES subclass, no survival benefit for a maximized EOR was found (p = 0.33). In multivariate analysis, the therapy response-predictive value of MGMT promoter methylation was evident for RTK I (p < 0.01) and RTK II (p = 0.02) but failed to be an independent factor in the MES subclass (p= 0.06). For local recurrence, re-resection conveyed a progression-to-overall survival (POS) benefit (p < 0.01), which was evident in the RTK I (p = 0.03) and RTK II (p < 0.01) subclasses, but not in the MES subclass (p = 0.33).This study demonstrates a survival benefit from maximized EOR at surgery for newly diagnosed and recurrent glioblastomas of the RTK I and RTK II subclass but not the MES subclass. Hence, it needs to be carefully considered whether the MES subclass should be treated with maximal surgical resection, especially when located in eloquent areas and at time of recurrence.

CD74 regulates complexity of tumor cell HLA class II peptidome in brain metastasis and is a positive prognostic marker for patient survival

Despite multidisciplinary local and systemic therapeutic approaches, the prognosis for most patients with brain metastases is still dismal. The role of adaptive and innate anti-tumor response including the Human Leukocyte Antigen (HLA) machinery of antigen presentation is still unclear. We present data on the HLA class II-chaperone molecule CD74 in brain metastases and its impact on the HLA peptidome complexity.We analyzed CD74 and HLA class II expression on tumor cells in a subset of 236 human brain metastases, primary tumors and peripheral metastases of different entities in association with clinical data including overall survival. Additionally, we assessed whole DNA methylome profiles including CD74 promoter methylation and differential methylation in 21 brain metastases. We analyzed the effects of a siRNA mediated CD74 knockdown on HLA-expression and HLA peptidome composition in a brain metastatic melanoma cell line.We observed that CD74 expression on tumor cells is a strong positive prognostic marker in brain metastasis patients and positively associated with tumor-infiltrating T-lymphocytes (TILs). Whole DNA methylome analysis suggested that CD74 tumor cell expression might be regulated epigenetically via CD74 promoter methylation. CD74high and TILhigh tumors displayed a differential DNA methylation pattern with highest enrichment scores for antigen processing and presentation. Furthermore, CD74 knockdown in vitro lead to a reduction of HLA class II peptidome complexity, while HLA class I peptidome remained unaffected.In summary, our results demonstrate that a functional HLA class II processing machinery in brain metastatic tumor cells, reflected by a high expression of CD74 and a complex tumor cell HLA peptidome, seems to be crucial for better patient prognosis.

The influence of preoperative anticoagulation on outcome and quality of life after surgical treatment of chronic subdural hematoma

The main aim of this study was to investigate the influence of perioperative anticoagulation on the clinical course and outcome of 144 patients who underwent surgery for chronic subdural hematoma (CSDH). The outcome was categorized according to the modified Rankin Scale (mRS), Barthel Index and postoperative quality of life (QoL) scale. There was a significant correlation between preoperative aspirin medication and reoperation (Mann-Whitney U-test, p<0.05). Moreover, dosage and duration of postoperative low-molecular-weight heparin (LMWH) administration were associated with a higher risk of reoperation (Mann-Whitney U-test, p<0.01) and a worse outcome on the mRS (Mann-Whitney U-test, p<0.05). Intraoperative treatment with prothrombin complex concentrate led to a poor outcome on the mRS (Craddock-Flood test, p<0.05). Reoperation is the strongest predictive factor of a poor QoL after surgical treatment of CSDH. Both preoperative and postoperative anticoagulation treatment may affect reoperation rate and, thus, postoperative QoL.