Test Id : ROS1F

This test includes a charge for the probe application, analysis, and professional interpretation of results for one probe set (2 individual fluorescence in situ hybridization probes). No analysis charges will be incurred if an insufficient number of representative cells are available for analysis.

Appropriate ancillary probes may be performed at consultant discretion to render comprehensive assessment. Any additional probes will have the results included within the final report and will be performed at an additional charge.

This test does not include a pathology consultation. If a pathology consultation is requested, order PATHC / Pathology Consultation, and appropriate testing will be added at the discretion of the pathologist and performed at an additional charge.

Multiple oncology (cancer) gene panels are also available. For more information see Hematology, Oncology, and Hereditary Test Selection Guide

Confirmation testing for the presence of a possible ROS1 fusion transcript by next generation sequencing to resolve atypical or unbalanced fluorescence in situ hybridization results is available, order MCLNR / MayoComplete Lung Rearrangements, Rapid Test, Tumor.

Advise Express Mail or equivalent if not on courier service.

1. A pathology report is required for testing to be performed. If not provided, appropriate testing and/or interpretation may be compromised or delayed. Acceptable pathology reports include working drafts, preliminary pathology, or surgical pathology reports.

The following information must be included in the report provided.?

1. Patient name

2. Block number - must be on all blocks, slides, and paperwork

3. Date of collection

4. Tissue Source

3. A reason for testing must be provided. If this information is not provided, an appropriate indication for testing may be entered by Mayo Clinic Laboratories.

Submit only 1 of the following specimens:

Preferred

Specimen Type: Tissue block

Collection Instructions: Submit a formalin-fixed, paraffin-embedded tumor tissue block. Blocks prepared with alternative fixation methods will be attempted but are less favorable for successful results by FISH testing; provide fixation method used.

Additional Information:

1. Paraffin-embedded specimens can be from any anatomic location (skin, soft tissue, lymph node, etc).

2. Bone specimens that have been decalcified will be attempted for testing, but the success rate is approximately 50%.

Acceptable

Specimen Type: Tissue slides

Slides: 1 Hematoxylin and eosin stained and 4 unstained

Collection Instructions: Submit 4 consecutive unstained, positively charged, unbaked slides with 5 micron-thick sections of the tumor tissue and 1 slide stained with hematoxylin and eosin.

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

Slides: 1 Hematoxylin and eosin stained and 2 unstained

Fluorescence in situ hybridization (FISH) testing for ROS1 allows for the detection of most ROS1 rearrangements, therefore, is useful for identifying tumors that may be sensitive to directed therapy

ROS1 FISH testing may also support the diagnosis of inflammatory myofibroblastic tumor, certain cutaneous melanocytic tumors, or other neoplasms when used in conjunction with pathologic assessment

This test includes a charge for the probe application, analysis, and professional interpretation of results for one probe set (2 individual fluorescence in situ hybridization probes). No analysis charges will be incurred if an insufficient number of representative cells are available for analysis.

Appropriate ancillary probes may be performed at consultant discretion to render comprehensive assessment. Any additional probes will have the results included within the final report and will be performed at an additional charge.

The ROS1 gene at 6q22 encodes a tyrosine kinase receptor. Chromosomal rearrangements resulting in fusion of the 3’ aspect of the ROS1 gene with the 5’ aspect of various partner genes was first identified in non-small cell carcinomas of the lung. ROS1 fusions have since been identified in various other neoplasms including but not limited to inflammatory myofibroblastic tumors and cutaneous melanocytic tumors.

Clinical data has shown that tumors harboring ROS1 fusions may be sensitive to directed tyrosine kinase inhibitor therapy.

An interpretive report will be provided.

A result is considered positive when the percent of cells separation of the ROS1 FISH probes exceeds the normal cutoff for the ROS1 FISH probe set.

A positive result is consistent with rearrangement of the ROS1 gene and likely reflects ROS1 fusion with a partner gene. The significance of this finding is dependent on the clinical and pathologic features.

A positive result suggests that the tumor may be responsive to directed therapy in the proper clinical and pathologic context. While results may indicate the potential response to directed tyrosine kinase inhibitors, selection of treatment remains a clinical decision.

A positive result may support a certain diagnosis in a particular clinical and pathologic context.

A negative result does not exclude the presence of a ROS1 fusion or exclude the possible sensitivity to targeted therapy.

This test is not approved by the U.S. Food and Drug Administration, and it is best used as an adjunct to existing clinical and pathologic information.

This fluorescence in situ hybridization (FISH) assay does not rule out other chromosome abnormalities.

Fixatives other than formalin (eg, Prefer, Bouin's) may not be successful for FISH assays. Non-formalin fixed specimens will not be rejected.

Paraffin-embedded tissues that have been decalcified may not be successful for FISH analysis. The success rate of FISH studies on decalcified tissue is approximately 50%.

FISH studies will be attempted if sufficient tumor is present for analysis. The pathologist reviewing the hematoxylin and eosin-stained slide may find it necessary to cancel testing if insufficient tissue/tumor is available for testing.

If no FISH signals are observed post-hybridization, the case will be released indicating a lack of FISH results.

1. Cui M, Han Y, Li P, et al. Molecular and clinicopathological characteristics of ROS1-rearranged non-small-cell lung cancers identified by next-generation sequencing. Molecular Oncology. 2020;14(11):2787-95

2. Bergethon K, Shaw AT, Ou SH, et al. ROS1 rearrangements define a unique molecular class of lung cancers. J Clin Oncol. 2012;30(8):863-870. doi:10.1200/JCO.2011.35.6345

3. Antonescu CR, Suurmeijer AJ, Zhang L, et al. Molecular characterization of inflammatory myofibroblastic tumors with frequent ALK and ROS1 gene fusions and rare novel RET rearrangement. Am J Surg Pathol. 2015;39(7):957-967

4. Wiesner T, He J, Yelensky R, et al. Kinase fusions are frequent in Spitz tumours and spitzoid melanomas. Nature communications. 2014;5(1):3116

5. Shaw AT, Ou SH, Bang YJ, et al. Crizotinib in ROS1-rearranged non-small-cell lung cancer. N Engl J Med. 2014;371(21):1963-1971

The test is performed using a laboratory-developed ROS1 (6q22) dual-color, break-apart strategy probe (BAP). Paraffin-embedded tissue samples are cut at 5 microns and mounted on positively charged glass slides. The selection of tissue and the identification of target areas on the hematoxylin and eosin (H and E)-stained slide are performed by a pathologist. Using the H and E-stained slide as a reference, target areas are etched with a diamond-tipped engraving tool on the back of the unstained slide to be assayed. The probe set is hybridized to the appropriate target areas, and 2 technologists each independently analyze 50 interphase nuclei (100 total) with the results expressed as the percent of abnormal nuclei.(Unpublished Mayo method)

Monday through Friday

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• Prospective clients should contact their account representative. For assistance, contact Customer Service.

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.

88271x2, 88291-DNA probe, each (first probe set), Interpretation and report

88271x2-DNA probe, each; each additional probe set (if appropriate)

88271x1-DNA probe, each; coverage for sets containing 3 probes (if appropriate)

88271x2-DNA probe, each; coverage for sets containing 4 probes (if appropriate)

88271x3-DNA probe, each; coverage for sets containing 5 probes (if appropriate)

88274 w/modifier 52-Interphase in situ hybridization, <25 cells, each probe set (if appropriate)

88274-Interphase in situ hybridization, 25 to 99 cells, each probe set (if appropriate)