Mgmt promoter status in idh1/2 mutant anaplastic astrocytoma patients assessed by dna methylation profiling and qms-pcr: a report from the eortc brain tumor group

Abstract BACKGROUND Temozolomide efficacy in high-grade glioma is related to MGMTp methylation. We compared the prognostic and predictive effect of MGMTp between DNA methylation profiling (MGMT-STP27 model) and qMS-PCR in IDH1/2mt anaplastic astrocytoma patients. METHODS The 2x2 factorial design phase III CATNON trial randomized 751 adult patients with newly diagnosed 1p/19q non-codeleted anaplastic glioma to 59.4Gy radiotherapy, radiotherapy with concurrent temozolomide, radiotherapy with 12 cycles of adjuvant temozolomide, or radiotherapy with concurrent and adjuvant temozolomide. MGMTp methylation status was assessed with the MGMT-STP27 model using 850k EPIC data, and qMS-PCR. IDH1/2 mutation status was determined with next-generation sequencing. OS was measured from randomization date. RESULTS We identified 444 IDH1/2mt anaplastic astrocytoma patients. MGMTp was methylated in 365/440 patients (83.0%) with MGMT-STP27 data, and 168/361 patients (46.5%) with qMS-PCR data. The agreement between both modalities is 59.9% (Cohen’s Kappa score 0.229). At database lock, 289 patients with MGMT-STP27 data were alive and 236 patients with qMS-PCR data. The median OS of MGMTp methylated glioma patients was 9.1 yrs [95%CI 7.5-not reached] for the MGMT-STP27 model, and not reached [95%CI 9.1-not reached] for qMS-PCR. For MGMTp unmethylated glioma patients, the median OS was 6.9 yrs [95%CI 6.2-not reached] for the MGMT-STP27 model, and 6.8 yrs [95%CI 6.2-9.7] for qMS-PCR. The HR for OS based on MGMTp methylation was 0.88 [95%CI 0.58-1.31] for the MGMT-STP27 model, and 0.72 [95%CI 0.50-1.03]) for qMS-PCR. The HR for OS after radiotherapy with any temozolomide vs radiotherapy alone for the MGMT-STP27 model was 0.53 [95%CI 0.37-0.78] for MGMTp methylated, and 0.54 [95%CI 0.25-1.18] for MGMTp unmethylated glioma patients; and for MS-PCR was 0.34 [95%CI 0.19-0.61] for MGMTp methylated, and 0.53 [95%CI 0.33-0.85] for MGMTp unmethylated glioma patients. CONCLUSION MGMTp methylation, regardless of assay, was neither prognostic nor predictive for outcome to temozolomide in IDH1/2mt anaplastic astrocytoma patients.