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Test Code T790M Cell-Free DNA EGFR T790M Mutation Analysis, Blood


Ordering Guidance


This test is not a prenatal screening test.

 

This test detects only the T790M mutation in the EGFR gene. It does not detect other EGFR gene mutations in exons 18 through 21.

 

This test provides rapid detection of the EGFR T790M mutation in peripheral blood from non-small cell lung cancer patients as an alternative for EGFR analysis of tissue. For tissue testing, order EGFRS / EGFR Gene, Targeted Mutation Analysis, 51 Mutation Panel, Tumor.



Shipping Instructions


1. Samples should be transported at ambient temperature or refrigerated (4° C)

2. Samples are viable for 7 days in the Streck Black/Tan Top Tube Kit (T715)



Specimen Required


Supplies: Streck Black/Tan Top Tube Kit (T715)

Specimen Volume: Two, 10-mL Streck cell-free DNA (cfDNA) blood collection tubes

Additional Information:

1. Only blood collected in Streck cfDNA tubes will be accepted for analysis.

2. Whole blood will be processed to produce platelet-poor plasma before cfDNA isolation.


Useful For

Determination of EGFR T790M mutation status in blood specimens as an alternative to invasive tissue biopsies

 

Identification of patients with non-small cell lung cancer who harbor a T790M mutation and may benefit from specific EGFR-targeted therapies

Method Name

Droplet Digital Polymerase Chain Reaction (ddPCR)

Reporting Name

cfDNA EGFR T790M Test, Blood

Specimen Type

Whole blood

Specimen Minimum Volume

One 10 mL Streck tube

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole blood Ambient (preferred) 7 days Streck Black/Tan top
  Refrigerated  7 days Streck Black/Tan top

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Clinical Information

Epidermal growth factor receptor (EGFR)-targeted tyrosine kinase inhibitors (eg, gefitinib and erlotinib) have been approved by the US food and Drug Administration (FDA) for use in treating patients with non-small cell lung cancer (NSCLC) who previously failed to respond to traditional chemotherapy. However, the EGFR T790M mutation is associated with acquired resistance to tyrosine kinase inhibitor (TKI) therapy in about 60% of patients with disease progression after initial response to erlotinib, gefitinib, or afatinib. Recent data suggest that patients with metastatic NSCLC and the T790M mutation may benefit from osimertinib, an FDA-approved oral TKI that inhibits both EGFR-activating mutations and the T790M mutation.

Interpretation

The interpretation of molecular biomarker analysis includes an overview of the results and the associated therapeutic implications.

Cautions

Patients with a negative test result may still harbor the EGFR T790M mutation. Mutation testing of a tissue specimen for EGFR mutations should be considered for patients with a negative result with this test.

 

The limit of detection of this assay for the detection of EGFR mutations is influenced by the amount of cell-free DNA in the blood. This is a biological variable that cannot be controlled.

 

This assay was designed to detect the following T790M mutation in the EGFR gene.

 

This test has not been clinically validated for use as a tool to monitor response to therapy or for early detection of tumors.

 

This test cannot differentiate between somatic and germline alterations. Additional testing may be necessary to clarify the significance of results if there is a potential hereditary risk.

Day(s) Performed

Varies

Report Available

5 to 10 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

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

81235

LOINC Code Information

Test ID Test Order Name Order LOINC Value
T790M cfDNA EGFR T790M Test, Blood 55769-4

 

Result ID Test Result Name Result LOINC Value
113411 Result Summary 50397-9
113412 Result 55769-4
113413 Interpretation 69047-9
113414 Additional Information 48767-8
113415 Specimen 31208-2
113416 Source 31208-2
113417 Released By 18771-6

Forms

If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.

Reference Values

An interpretive report will be provided.