Test Catalog

Test ID: NTRK    
NTRK Gene Fusion Panel, Tumor

Useful For Suggests clinical disorders or settings where the test may be helpful

Identifying solid tumors that may respond to targeted therapies by simultaneously assessing for rearrangements involving the NTRK1, NTRK2, and NTRK3 genes resulting in fusion transcripts

 

This test is not useful for hematologic malignancies.

Genetics Test Information Provides information that may help with selection of the correct genetic test or proper submission of the test request

This test uses next-generation sequencing to identify rearrangements (fusions) involving the NTRK1, NTRK2, and NTRK3 genes.

 

The assay was designed to detect the most common NTRK gene fusions and novel gene fusion partners in the targeted gene regions. See NTRK RNA Targeted Gene Fusions table in Special Instructions for details.

 

Of note, this test is performed to evaluate rearrangements (fusions) within solid tumor samples. This test is not intended for use for hematological malignancies.

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

Targeted cancer therapies are defined as antibody or small molecule drugs that block the growth and spread of cancer by interfering with specific cell molecules involved in tumor growth and progression. Multiple targeted therapies have been approved by the FDA for treatment of specific cancers. Molecular genetic profiling is often needed to identify targets amenable to targeted therapies and to minimize treatment costs and therapy-associated risks.

 

Fusions involving the NTRK1, NTRK2, or NTRK3 genes (ie, NTRK gene fusions) form through intra- and interchromosomal rearrangements. NTRK gene fusions lead to activation of downstream MAPK, PIK, and STAT3 signaling pathways and act as oncogenic drivers of multiple types of pediatric and adult solid tumors. In solid tumors, the presence of an NTRK gene fusion is a biomarker for response to tropomyosin receptor kinase (TRK) inhibitor therapy.

 

This test assesses for fusions involving the NTRK1, NTRK2, and NTRK3 genes. The results of this test can be useful in guiding treatment of individuals with advanced solid tumors.

 

See the NTRK RNA Targeted Gene Fusions table in Special Instructions for details regarding the targeted gene regions evaluated by this test.

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

An interpretive report will be provided.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

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

 

A negative (wild-type) result does not rule out the presence of a rearrangement (fusion) that may be present but below the limits of detection of this assay. The analytical sensitivity of this assay is a minimum coverage of 10 targeted fusion reads with 5 unique fusion molecules in a sample with 10% or greater tumor content.

 

Only gene rearrangements (fusions) involving targeted breakpoints in NTRK1, NTRK2, and NTRK3 genes will be detected. This test does not detect point mutations, insertion/deletion mutations, large single or multiexon deletions or duplications, or genomic copy number variants in any of the genes tested.

 

Rare polymorphisms may be present that could lead to false-negative or false-positive results. Test results should be interpreted in the 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 updated 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 cytology slides and formalin-fixed, paraffin-embedded tissues; other types of fixatives are discouraged. Improper treatment of tissues, such as decalcification, may cause PCR failure.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Drilon A, Laetsch TW, Kummar S: Efficacy of Larotrectinib in TRK Fusion-Positive Cancers in Adults and Children. N Engl J Med 2018 Feb 22;378(8):731-739 doi: 10.1056/NEJMoa1714448

2. Cocco E, Scaltriti M, Drilon A: NTRK fusion-positive cancers and TRK inhibitor therapy. Nat Rev Clin Oncol 2018 Dec;15(12):731-747 doi: 10.1038/s41571-018-0113-0

Special Instructions Library of PDFs including pertinent information and forms related to the test