Assessment of Quantitative and Allelic MGMT Methylation Patterns as a Prognostic Marker in Glioblastoma

J Neuropathol Exp Neurol. 2016 Mar;75(3):246-55. doi: 10.1093/jnen/nlv024. Epub 2016 Feb 16.


Methylation of the O(6)-methylguanine-DNA methyltransferase (MGMT) gene is a predictive and prognostic marker in newly diagnosed glioblastoma patients treated with temozolomide but how MGMT methylation should be assessed to ensure optimal detection accuracy is debated. We developed a novel quantitative methylation-specific PCR (qMSP) MGMT assay capable of providing allelic methylation data and analyzed 151 glioblastomas from patients receiving standard of care treatment (Stupp protocol). The samples were also analyzed by immunohistochemistry (IHC), standard bisulfite pyrosequencing, and genotyped for the rs1690252 MGMT promoter single nucleotide polymorphism. Monoallelic methylation was observed more frequently than biallelic methylation, and some cases with monoallelic methylation expressed the MGMT protein whereas others did not. The presence of MGMT methylation was associated with better overall survival (p = 0.006; qMSP and p = 0.002; standard pyrosequencing), and the presence of the protein was associated with worse overall survival (p = 0.009). Combined analyses of qMSP and standard pyrosequencing or IHC identified additional patients who benefited from temozolomide treatment. Finally, low methylation levels were also associated with better overall survival (p = 0.061; qMSP and p = 0.02; standard pyrosequencing). These data support the use of both MGMT methylation and MGMT IHC but not allelic methylation data as prognostic markers in patients with temozolomide-treated glioblastoma.

Keywords: Alkylating agents; Allele-specific; Glioblastoma; Immunohistochemistry; MGMT; Methylation; Temozolomide..

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Antineoplastic Agents, Alkylating / therapeutic use
  • Brain Neoplasms / drug therapy
  • Brain Neoplasms / genetics*
  • Brain Neoplasms / mortality
  • Brain Neoplasms / pathology
  • Chi-Square Distribution
  • DNA Methylation / genetics*
  • DNA Modification Methylases / genetics*
  • DNA Modification Methylases / metabolism
  • DNA Repair Enzymes / genetics*
  • DNA Repair Enzymes / metabolism
  • Dacarbazine / analogs & derivatives
  • Dacarbazine / therapeutic use
  • Female
  • Genetic Association Studies
  • Genotype
  • Glioblastoma / drug therapy
  • Glioblastoma / genetics*
  • Glioblastoma / mortality
  • Glioblastoma / pathology
  • Humans
  • Male
  • Middle Aged
  • Polymorphism, Single Nucleotide / genetics*
  • Promoter Regions, Genetic / genetics
  • Retrospective Studies
  • Survival Analysis
  • Temozolomide
  • Tumor Suppressor Proteins / genetics*
  • Tumor Suppressor Proteins / metabolism
  • Young Adult


  • Antineoplastic Agents, Alkylating
  • Tumor Suppressor Proteins
  • Dacarbazine
  • DNA Modification Methylases
  • MGMT protein, human
  • DNA Repair Enzymes
  • Temozolomide