Test Id : MGMTD
MGMT Promoter Methylation Analysis, Tumor
Useful For
Suggests clinical disorders or settings where the test may be helpful
Prognostication of newly diagnosed patients with glioblastoma
Identification of newly diagnosed glioblastoma patients that may derive benefit from alkylating chemotherapy (ie, temozolomide)
Therapy selection for newly diagnosed glioblastoma in older patients (>60-65 years)
Highlights
MGMT promoter methylation status has prognostic and predictive value for patients with glioblastoma.
Additional Tests
Lists tests that are always performed, at an additional charge, with the initial tests.
| Test Id | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| SLIRV | Slide Review in MG | No, (Bill Only) | Yes |
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
When this test is ordered, slide review will always be performed at an additional charge.
Method Name
A short description of the method used to perform the test
Droplet Digital Polymerase Chain Reaction (ddPCR)
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
Glioblastoma
GBM
Droplet Digital PCR
MGMT
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
When this test is ordered, slide review will always be performed at an additional charge.
Specimen Type
Describes the specimen type validated for testing
Varies
Necessary Information
A pathology report (final or preliminary), containing the following information, is required and must accompany specimen for testing to be performed:
1. Patient name
2. Block number-must be on all blocks, slides, and paperwork (can be handwritten on the paperwork)
3. Tissue collection date
4. Source of the tissue
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
This assay requires at least 20% tumor nuclei.
-Preferred amount of tumor area with sufficient percent tumor nuclei: tissue 144 mm(2) tissue (4 x 6 mm x 6 mm areas)
-Minimum amount of tumor area: 36 mm(2) tissue (1 x 6 mm x 6 mm area)
-These amounts are cumulative over up to 10 unstained slides and must have adequate percent tumor nuclei.
-Tissue fixation: formalin-fixed paraffin-embedded (FFPE), non-decalcified
Submit only 1 of the following specimens:
Specimen Type: Tissue block
Collection Instructions: Submit a formalin-fixed non-decalcified, paraffin-embedded tissue block.
Specimen Type: Tissue slide
Slides: 1 Stained and 10 unstained
Collection Instructions: Submit 1 slide stained with hematoxylin and eosin and 10 unstained, nonbaked slides with 5-micron thick sections of the tumor tissue.
Note: The total amount of required tumor nuclei can be obtained by scraping up to 10 slides from the same block.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
5 unstained slides at 5-microns thickness
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Specimens that have been decalcified (all methods) Specimens that have not been formalin-fixed, paraffin-embedded Extracted nucleic acid (DNA/RNA) | Reject |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Ambient (preferred) | ||
| Refrigerated | |||
Useful For
Suggests clinical disorders or settings where the test may be helpful
Prognostication of newly diagnosed patients with glioblastoma
Identification of newly diagnosed glioblastoma patients that may derive benefit from alkylating chemotherapy (ie, temozolomide)
Therapy selection for newly diagnosed glioblastoma in older patients (>60-65 years)
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
When this test is ordered, slide review will always be performed at an additional charge.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
MGMT (O[6]-methylguanine-DNA methyltransferase) encodes a DNA repair enzyme. This enzyme rescues tumor cells from alkylating agent-induced damage and confers tumor resistance to chemotherapy with alkylating agents. Epigenetic silencing of MGMT by increased methylation of CpG sites within the promoter region results in decreased MGMT expression and reduces MGMT-mediated DNA repair of alkylating agent-induced DNA damage in tumor cells, increasing tumor sensitivity and response to alkylating chemotherapy.
MGMT promoter methylation status is a molecular biomarker for glioblastoma, which is the most frequent malignant primary central nervous system (CNS) adult-type tumor. In newly diagnosed patients with glioblastoma, MGMT promoter "methylated" status indicating increased levels of methylation is an independent favorable prognostic biomarker and a strong predictor of response to alkylating chemotherapy. Current standard of care treatment for glioblastoma patients consists of surgical resection followed by radiotherapy and alkylating chemotherapy with temozolomide. Older patients (>60-65 years) often have decreased tolerance for combined chemoradiation. For this group of patients, MGMT promoter methylation status guides treatment decision between monotherapy with the alkylating agent temozolomide versus radiotherapy alone.
Glioblastoma was originally defined solely based on histological features. Based on the 2021 World Health Organization (WHO) classification of CNS tumors, the original glioblastoma is now divided in "glioblastoma, IDH-wildtype, CNS WHO grade 4" (most cases) and "astrocytoma, IDH-mutant, CNS WHO grade 4".(1) In isocitrate dehydrogenase (IDH)-mutant diffuse gliomas, MGMT promoter "methylated" status is frequent and strongly associated with the IDH mutation-induced glioma CpG island methylator phenotype (G-CIMP), except for the uncommon infratentorial IDH-mutant astrocytomas. Therefore, the clinical significance of MGMT promoter methylation status in the context of IDH-mutant diffuse gliomas is less firmly established.
MGMT promoter methylation status may be evaluated by multiple methods, and the testing platform with most prospective clinical trial validation is methylation-specific polymerase chain reaction evaluating downstream CpG sites.
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
An interpretive report will be provided.
Interpretation
Provides information to assist in interpretation of the test results
The interpretation of molecular biomarker analysis includes an overview of the results and the associated diagnostic, prognostic, and therapeutic implications.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Test results should be interpreted in context of clinical findings, tumor sampling, and other laboratory data. If results obtained do not match other clinical or laboratory findings, contact the laboratory for possible interpretation. Misinterpretation of results may occur if the information provided is inaccurate or incomplete.
Reliable results are dependent on adequate specimen collection and processing. This test has been validated on formalin-fixed, paraffin-embedded tissues; other types of fixatives are discouraged.
Improper treatment of tissues, such as decalcification, may cause polymerase chain reaction failure.
Rare polymorphisms exist that could lead to false-negative or false-positive results.
This test evaluates for the presence of increased levels of methylation of downstream CpG sites 75-80 and 84-87. Analytical validation studies showed that this assay requires at least 25 methylated copies for a positive result. Retrospective clinical validation study of approximately 200 patients with integrated diagnosis of glioblastoma, IDH-wildtype with grade 4 histological features who were treated with standard of care regiment including temozolomide established the cutoff of 6.50% fraction abundance to distinguish two groups of patients with statistically different overall survival rates. Using the combined cutoff of at least 25 methylated copies and 6.50% fraction abundance to define positive for increased promoter methylation ("methylated") status, patients with tumors positive for increased MGMT promoter methylation ("methylated") status have shown improved survival when compared to patients with tumors negative for increased MGMT promoter methylation ("unmethylated") status.
Negative results do not exclude the possibility that increased levels of methylation may be present but below the cut-offs for this assay due to low tumor purity. This assay requires at least 20% tumor.
Negative results do not exclude the presence of increased levels of methylation in other CpG sites.
Supportive Data
Analytical validation studies demonstrated limit of quantitation for the assay to be 25 methylated copies. Fraction abundance (FA) threshold of 6.50% was above the estimated upper confidence interval limit of the 95th% quantile of the 95% confidence interval of values for non-neoplastic brain tissue. Clinical validation studies showed that this FA threshold favored identifying both low and high levels of methylation as positive for increased levels of methylation/"methylated" status, so that a negative result is more likely to indicate a truly negative result for increased levels of methylation/"unmethylated" status. Both values for methylated copies and FA will be used to determine if a sample is positive or negative for increased MGMT promoter methylation. A minimum of 360 unmethylated copies is required for a sample to be confidently resulted as negative.
Concordance between this test and the prior Mayo Clinic methylation-specific polymerase chain reaction and methylation array methods for detection of MGMT promoter methylation were 95% (194/205) and 97% (38/39), respectively.
The minimum viable tumor percent and DNA input required for testing are 20% and 25 ng, respectively.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. WHO Classification of Tumours Editorial Board. Central Nervous System Tumours. 5th ed. IARC Press; 2021. WHO Classification of Tumours, Vol 6
2. Hegi ME, Diserens AC, Gorlia T, et al. MGMT gene silencing and benefit from temozolomide in glioblastoma. N Engl J Med. 2005;352(10):997-1003
3. Stupp R, Hegi ME, Mason WP, et al. Effects of radiotherapy with concomitant and adjuvant temozolomide versus radiotherapy alone on survival in glioblastoma in a randomised phase III study: 5-year analysis of the EORTC-NCIC trial. Lancet Oncol. 2009;10(5):459-66
4. Wick W, Platten M, Meisner C, et al. Temozolomide chemotherapy alone versus radiotherapy alone for malignant astrocytoma in the elderly: The NOA-08 randomised, phase 3 trial. Lancet Oncol. 2012;13(7):707-715
5. Malmstrom A, Gronberg BH, Marosi C, et al. Temozolomide versus standard 6-week radiotherapy versus hypofractionated radiotherapy in patients older than 60 years with glioblastoma: the Nordic randomised, phase 3 trial. Lancet Oncol. 2012;13(9):916-926
6. Hegi ME, Genbrugge E, Gorlia T, et al. MGMT promoter methylation cutoff with safety margin for selecting glioblastoma patients into trials omitting temozolomide: A pooled analysis of four clinical trials. Clin Cancer Res. 2019;25(6):1809-1816
7. Mansouri A, Hachem LD, Mansouri S, et al. MGMT promoter methylation status testing to guide therapy for glioblastoma: refining the approach based on emerging evidence and current challenges. Neuro Oncol. 2019;21(2):167-178
8. Wen PY, Weller M, Lee EQ, et al. Glioblastoma in adults: a Society for Neuro-Oncology (SNO) and European Society of Neuro-Oncology (EANO) consensus review on current management and future directions. Neuro Oncol. 2020;22(8):1073-1113
9. Brat DJ, Aldape K, Bridge JA, et al. Molecular biomarker testing for the diagnosis of diffuse gliomas. Arch Pathol Lab Med. 2022;146(5):547-574
10. Hegi ME, Oppong FB, Perry JR, et al. No benefit from TMZ treatment in glioblastoma with truly unmethylated MGMT promoter: Reanalysis of the CE.6 and the pooled Nordic/NOA-08 trials in elderly glioblastoma patients. Neuro Oncol. 2024;26(10):1867-1875
Method Description
Describes how the test is performed and provides a method-specific reference
Droplet digital polymerase chain reaction using a TaqMan assay is performed on bisulfite converted DNA to evaluate for the presence of increased levels of methylation involving CpG sites 75-80 and 84-87 within the promoter region of the MGMT gene.(Unpublished Mayo method)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Varies
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their account representative. For assistance, contact Customer Service.
Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
81287
88381-Microdissection manual
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| MGMTD | MGMT Promoter Methylation Analysis | 60252-4 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| 621859 | Result Summary | 50397-9 |
| 621860 | Result | 60252-4 |
| 621861 | Interpretation | 69047-9 |
| 621862 | Additional Information | 48767-8 |
| 621863 | Specimen | 31208-2 |
| 621864 | Source | 31208-2 |
| 621865 | Tissue ID | 80398-1 |
| 621866 | Method | 85069-3 |
| 621867 | Disclaimer | 62364-5 |
| 621868 | Released by | 18771-6 |