Abstract 2654: Differential effect of MGMT methylation between moderate or high vascular profile in IDH wild-type glioblastoma

A significant association between MGMT methylation and prolonged overall survival (OS) was observed for patients with glioblastoma (GB) that present moderately relative cerebral blood volume (rCBV) 1. However, that study should be updated to the current glioma WHO classification. In the current study we assess the combined effect of rCBV and MGMT methylation combined on OS in patients with IDH wild-type GB. An independent cohort of 95 IDH wild-type GB patients with OS>30 days and with tumor resection was included for this study. The rCBV values of the highest angiogenic tumor regions were automatically calculated using ONCOhabitats analysis services2. Finally, the whole cohort was divided into moderately and highly vascularized GB by the median of the previously calculated rCBVs (rCBVmedian=9.56). We observed a significant association between MGMT methylation and prolonged OS for the whole cohort (p = 0.003, HR = 0.49), as well as for patients with moderate rCBV (p = 0.002, AUC = 0.30). The difference in OS between patients with MGMT methylated and patients with MGMT unmethylated was 4 times higher in the group with moderate rCBV than for the group with high rCBV (205 vs. 42 days). Finally, no association was found between MGMT methylation and OS in patients with high rCBV (p > 0.05) (Table below). Our results highlight the combined prognostic effect of MGMT methylation and moderate vascularity in IDH wild-type GB patients. As demonstrated, non-invasive MRI perfusion markers may identify those patients who will mostly benefit in terms of prolonged OS owing to their MGMT methylation status. 1: doi.org/10.1007/s00330-020-07297-4 2: doi.org/10.1016/j.ijmedinf.2019.05.002 Number of patientsMedian OS (days)ResultsStatistical resultsTotalMeth MGMTUnmethMGMTMeth MGMTUnmethMGMTΔOSHR [95% CI]pAUCAll9551445894501390.49 [0.30-0.78]0.0028*0.61Moderate rCBV4221216534482050.30 [0.14-0.64]0.0020*0.72High rCBV533023493451420.68 [0.37-1.26]0.21800.52 Citation Format: Maria del Mar Álvarez-Torres, Elies Fuster-García, Javier Juan-Albarracín, Josep Puig, Carmen Balaña, Jaume Capellades, Kyrre Eeg Emblem, Juan Miguel García-Gómez. Differential effect of MGMT methylation between moderate or high vascular profile in IDH wild-type glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2654.