The PathVysion HER-2 DNA Probe Kit is one of the first examples of what is recognized as genomic disease management, or personalized medicine. This means that the test helps enable the accurate assessment of a patient's HER-2 status at the DNA level with a high degree of accuracy and helps guide doctors to make the most appropriate therapy decisions based on the patient's own genetic profile. PathVysion is one of the preferred tests for assessing HER-2 status:

• FISH is considered the gold standard for HER-2 testing^{1, 2, 3}
• Studies indicate FISH to accurately and reproducibly assess tumors for HER-2 status⁴
• PathVysion exhibits better concordance than IHC between local and central laboratories¹
• The Chromosome 17 probe acts as an internal control and corrects for polysomy (identifies gene amplification versus chromosome 17 polysomy) and nuclear truncation1
• FDA approved automated result scanning is available for PathVysion^5,6

PathVysion direct labeled FISH probes yield definitive results at the molecular level. The test uses fluorescent probes to "paint" the HER-2 genes in the tumor cell nucleus, to see if the number of gene copies is normal or not. Interpretation is objective - results are obtained by counting the fluorescent signals (dots). In addition, because this test measures genetic material, which is very stable, tissue preparation has very little effect on test outcome.

Probe Design

HER-2/neu, also known as ERBB2 or HER-2, is a gene that has been shown to play a key role in the regulation of cell growth. The gene codes for a 185 kd transmembrane cell surface receptor that is a member of the tyrosine kinase family. HER-2 has been shown to be amplified in human breast, ovarian, and other cancers. 

The PathVysion HER-2 DNA Probe Kit consists of two labeled DNA probes. The LSI HER-2 probe that spans the entire HER-2 gene is labeled in SpectrumOrange. The CEP 17 probe is labeled in SpectrumGreen and hybridizes to the alpha satellite DNA located at the centromere of chromosome 17 (17p11.1-q11.1). Inclusion of the CEP 17 probe allows for the relative copy number of the HER-2 gene to be determined.

Indications and Limitations of Use

Intended Use

The PathVysion HER-2 DNA Probe Kit (PathVysion Kit) is designed to detect amplification of the HER-2/neu gene via fluorescence in situ hybridization (FISH) in formalin-fixed, paraffin-embedded human breast cancer tissue specimens. Results from the PathVysion Kit are intended for use as an adjunct to existing clinical and pathologic information currently used as prognostic factors in stage II, node-positive breast cancer patients. The PathVysion Kit is further indicated as an aid to predict disease-free and overall survival in patients with stage II, node-positive breast cancer treated with adjuvant cyclophosphamide, doxorubicin and 5-fluorouracil (CAF) chemotherapy.

The PathVysion Kit is indicated as an aid in the assessment of patients for whom HERCEPTIN^® (Trastuzumab) treatment is being considered (see HERCEPTIN package insert).

Warning

HERCEPTIN therapy selection

NOTE: All of the patients in the HERCEPTIN clinical trials were selected using an investigational immunohistochemical assay (CTA). None of the patients in those trials were selected using the PathVysion assay. The PathVysion assay was compared to the CTA on a subset of clinical trial samples and found to provide acceptably concordant results. The actual correlation of the PathVysion assay to HERCEPTIN clinical outcome in prospective clinical trials has not been established.

Adjuvant therapy selection

The PathVysion Kit is not intended for use to screen for or diagnose breast cancer. It is intended to be used as an adjunct to other prognostic factors currently used to predict disease-free and overall survival in stage II, node-positive breast cancer patients and no treatment decision for stage II, node-positive breast cancer patients should be based on HER-2/neu gene amplification status alone.

Selected patients with breast cancers shown to lack amplification of HER-2/neu may still benefit from CAF (cyclophosphamide, doxorubicin, 5-fluorouracil) adjuvant therapy on the basis of other prognostic factors that predict poor outcome (eg, tumor size, number of involved lymph nodes, and hormone receptor status). Conversely, selected patients with breast cancers shown to contain gene amplification may not be candidates for CAF therapy due to preexisting or intercurrent medical illnesses.

Required Training

Abbott Molecular will provide training in specimen preparation, assay procedure, and interpretation of FISH testing of the HER-2 gene for inexperienced users. It is also recommended that a laboratory that has previously received training but now has new personnel performing the assay request training for the new users.

Limitations

1. The PathVysion Kit has been optimized only for identifying and quantifying chromosome 17 and the HER-2/neu gene in interphase nuclei from formalin-fixed, paraffin-embedded human breast tissue specimens. Other types of specimens or fixatives should not be used.
2. The performance of the PathVysion Kit was validated using the procedures provided in this package insert only. Modifications to these procedures may alter the performance of the assay.
3. Performance characteristics of the PathVysion Kit have been established only for node positive patients receiving the designated regimens of CAF and for metastatic breast cancer patients being considered for HERCEPTIN therapy. Performance with other treatment regimens has not been established.
4. The clinical interpretation of any test results should be evaluated within the context of the patient’s medical history and other diagnostic laboratory test results.
5. FISH assay results may not be informative if the specimen quality and/or specimen slide preparation is inadequate.
6. Technologists performing the FISH signal enumeration must be capable of visually distinguishing between the orange and green signals.

CAUTION: United States Federal law restricts this device to sale and distribution to or on the order of a physician or to a clinical laboratory; use is restricted to, by, or on the order of a physician.

References

1. Sauter G, et al. Guidelines for Human Epidermal Growth Factor Receptor 2 Testing: Biologic and Methodologic Considerations. J Clin Oncol 27:1323-1333, 2009.  
2. Mass R, et al. Evaluation of Clinical Outcomes According to HER-2 Detection by Fluorescence in situ Hybridization in Women with Metastatic Breast Cancer Treated with Trastuzumab. Clinical Breast Cancer, Vol 6, No. 3, 240-246, 2005.  
3. Allison M, The HER2 testing conundrum. Nature Biotechnology 28 (2): 117-119, 2010.
4. Press M, et al. Diagnostic Evaluation of Her-2 as a Molecular Target: An Assessment of Accuracy and Reproducibility of Laboratory Testing in Large, Prospective Randomized Clinical Trials, Clinical Cancer Research 2005; 11(18) September 15, 2005.
5. http://www.accessdata.fda.gov/cdrh_docs/pdf6/k061602.pdf BioView Duet approval for PathVysion
6. http://www.accessdata.fda.gov/cdrh_docs/pdf8/k080909.pdf Ikonisys approval for PathVysion