P17.33.A BLOOD GROUP 0 ATTRIBUTES TO PROLONGED PFS, OS AND FIVE-YEAR SURVIVAL IN IDH-WILDTYPE GLIOBLASTOMA PATIENTS WITH MGMT PROMOTER METHYLATION

Abstract BACKGROUND Glioblastoma (GBM) is the most common malignant primary brain tumour in adult patients. Despite multimodal therapeutic approaches there is still no possibility of curing. The identification of factors that improve prognosis and prolong life is gaining increased relevance. This study focussed on the impact of the AB0 blood group system on progression-free (PFS), overall survival (OS), and long-term survival in a large cohort of IDH-wildtype (wt) patients diagnosed with glioblastoma. MATERIAL AND METHODS 716 patients diagnosed with GBM between January 2009, and December 2020, who were treated at the Department of Neurosurgery, Münster University Hospital, a large tertiary brain tumour centre, at any stage of their condition were included. Data acquisition was done retrospectively. The study cohort was divided into two collectives based on their blood group: those with blood group 0 and those with blood group Non-0. Patient characteristics and treatment regimens were compared between these groups. Univariate and multivariate analysis was performed regarding patients´ overall survival, progression free survival, and five-year survival via log-rank tests and Cox proportional hazards regressions, respectively. RESULTS AB0 blood group information was available in 554 patients. No fundamental differences between blood group 0 and blood group Non-0 were found regarding their clinical characteristics. In contrast, an increased PFS, OS, and five-year survival in both univariable and multivariable analyses was identified for blood group 0 compared to patients with blood group Non-0. This difference was even stronger in patients with MGMT promoter methylated tumours who received standardised radiochemotherapy (OS blood group 0 24.6 months (95%CI 17.8-31.4) versus Non-0 17.7 months (14.1-21.3), p=0.015 log-rank analysis, hazard ratio 0.70 (95%CI 0.53-0.94)). Inversely, this correlation did not appear when the MGMT promoter was unmethylated or in patients without (standardised) adjuvant therapy. CONCLUSION This study assessed a new independent favourable prognostic marker in GBM IDH-wt patients: Blood group 0 in conjunction with a MGMT promoter methylation (including weak methylation) in patients receiving standardised radiochemotherapy prolongs prognosis exceptionally. Based on this data, a more precise risk-benefit analysis can be derived, resulting in improved personalized treatment options. Moreover, our finding suggests an interplay between the downregulation of a DNA repair protein via MGMT promoter methylation and the absence of a functional blood cell surface glycosyltransferase, as in blood group 0.