O6-methylguanine Methyltransferase Promoter Methylation Research Articles

Significance of O6-methyl guanine methyltransferase promoter methylation in high grade glioma patients: optimal cutoff point, CpG locus, and genetic assay.

To evaluate O6-methyl guanine methyltransferase (MGMT) promoter methylation status in high grade glioma patients and to identify the best cutoff point as well as the most predictive CpG loci for patients survival. Consecutive high grade glioma patients treated with surgical gross total resection followed by concomitant radiochemotherapy and adjuvant chemotherapy were included in this retrospective observational study. Methylation status of MGMT promoter CpG island of resected tumor tissue were evaluated using next generation sequencing assay. The outcomes were grouped as CpG 70-78, CpG 79-83, CpG 84-87, CpG 70-87, and whole promoter. Quantitative analyses were dichotomized as methylated or unmethylated based on the cutoff points set to %10, and methylation was further graded as <%10 unmethylated, %10-30 low-methylated, and %30-100 high-methylated. Total of 95 patients with the mean age of 51.50 ± 12.36 years were included in the study. Overall survival (OS) and progression free survival (PFS) were 14.53 ± 1.92 (95% CI 10.77-18.30) and 10.90 ± 2.05 (95% CI 6.89-14.92) months, respectively. MGMT promoter was methylated in 38.2% of cases and high-methylated in 10.5% of cases. Methylation status of MGMT promoter was recognized as a very powerful predictor of OS and PFS. In particular, high-methylation of CpG 79-83 and CpG 84-87 islands at promoter region were strongly associated with better survival outcomes (p < 0.05). Our outcomes support the prognostic value of MGMT promoter methylation in patients with high grade glioma. Sequencing of whole promoter CpG islands demonstrated that methylation of particular CpG sites might predict clinical outcomes more precisely.

Glioblastoma multiforme: a review of where we have been and where we are going

Malignant gliomas such as glioblastoma multiforme (GBM) present some of the greatest challenges in the management of cancer patients worldwide, despite notable recent achievements in oncology. Even with aggressive surgical resections using state-of-the-art preoperative and intraoperative neuroimaging, along with recent advances in radiotherapy and chemotherapy, the prognosis for GBM patients remains dismal: median survival after diagnosis is about 14 months. Established good prognostic factors are limited, but include young age, high Karnofsky Performance Status (KPS), high mini-mental status examination score, O6-methylguanine methyltransferase promoter methylation, and resection of > 98% of the tumor. Standard treatment includes resection, followed by concurrent chemotherapy and radiotherapy. GBM research is being conducted worldwide at a remarkable pace, with some of the more recent promising studies focused on identification of aberrant genetic events and signaling pathways, tumor stem cell identification and characterization, modulation of tumor immunological responses, combination therapies, and understanding of the rare long-term survivors. Past treatment strategies have failed for various reasons; however, newer strategies in trials today and on the horizon encourage optimism. To help illustrate ‘where we have been’ with this fatal disease and ‘where we are going’ with contemporary studies, we include in this review a detailed history of Phase III clinical trials for GBM, with a final emphasis on exciting new treatment strategies that offer hope for future GBM therapy.

Glioblastoma multiforme: a review of therapeutic targets

Glioblastoma is the commonest primary brain tumor, as well as the deadliest. Malignant gliomas such as glioblastoma multiforme (GBM) present some of the greatest challenges in the management of cancer patients worldwide, despite notable recent achievements in oncology. Even with aggressive surgical resections using state-of-the-art preoperative and intraoperative neuroimaging, along with recent advances in radiotherapy and chemotherapy, the prognosis for GBM patients remains dismal: survival after diagnosis is about 1 year. Established prognostic factors are limited, but include age, Karnofsky performance status, mini-mental status examination score, O6-methylguanine methyltransferase promoter methylation and extent of surgery. Standard treatment includes resection of > 95% of the tumor, followed by concurrent chemotherapy and radiotherapy. Nevertheless, GBM research is being conducted worldwide at a remarkable pace, in the laboratory and at the bedside, with some of the more recent promising studies focused on identification of aberrant genetic events and signaling pathways to develop molecular-based targeted therapies, tumor stem cell identification and characterization, modulation of tumor immunological responses and understanding of the rare long-term survivors. With this universally fatal disease, any small breakthrough will have a significant impact on survival and provide hope to the thousands of patients who receive this diagnosis annually. This review describes the epidemiology, clinical presentation, pathology and tumor immunology, with a focus on understanding the molecular biology that underlies the current targeted therapeutics being tested.