FISH in triple-negative breast cancer: a possible strategy for the future?

Abstract

Future OncologyVol. 11, No. 7 EditorialFree AccessFISH in triple-negative breast cancer: a possible strategy for the future?Elisa Rigon, Chiara Saggia, Valentina Rossi, Silvia Genestroni, Erica Gaudino, Paola Campisi, Claudia Veggiani, Renzo Luciano Boldorini & Oscar AlabisoElisa Rigon*Author for correspondence: E-mail Address: rigon.elisa@gmail.com SC Oncologia, AOU Maggiore della Caritá, Novara, ItalySearch for more papers by this author, Chiara Saggia SC Oncologia, AOU Maggiore della Caritá, Novara, ItalySearch for more papers by this author, Valentina Rossi SC Oncologia, AOU Maggiore della Caritá, Novara, ItalySearch for more papers by this author, Silvia Genestroni SC Oncologia, AOU Maggiore della Caritá, Novara, ItalySearch for more papers by this author, Erica Gaudino SC Oncologia, AOU Maggiore della Caritá, Novara, ItalySearch for more papers by this author, Paola Campisi Divisione di Anatomia Patologica, AOU Maggiore della Caritá, Novara, ItalySearch for more papers by this author, Claudia Veggiani Divisione di Anatomia Patologica, AOU Maggiore della Caritá, Novara, ItalySearch for more papers by this author, Renzo Luciano Boldorini Divisione di Anatomia Patologica, AOU Maggiore della Caritá, Novara, ItalySearch for more papers by this author & Oscar Alabiso SC Oncologia, AOU Maggiore della Caritá, Novara, ItalySearch for more papers by this authorPublished Online:25 Mar 2015https://doi.org/10.2217/fon.15.25AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinkedInReddit Keywords: FISHHER2immunohistochemistrytriple-negative breast cancerTriple-negative breast cancer (TNBC) is a specific subset of breast cancer characterized by tumors that do not express estrogen receptor or progesterone receptor, and do not overexpress HER2 [1]. This type of breast cancer, which accounts for nearly 15–20% of all breast cancer cases, often progresses to a metastatic form and is usually associated with a poor prognosis within the first 3–5 years [2].Significant heterogeneity exists within the TNBC class from the morphological and clinical point of view, and in terms of chemotherapeutic sensitivity. A recent analysis of 97 TNBCs identified six different TNBC subtypes characterized by specific gene expression profiles. In particular, two basal-like (BL1 and BL2), an immunomodulatory, a mesenchymal, a mesenchymal stem-like and a luminal androgen receptor subtype were identified [2]. In addition, a considerable overlap has been reported between TNBC and BRCA1-mutated tumors; in fact nearly 75–85% of women with BRCA1 germline mutation are expected to develop a TNBC breast cancer during their life [3].Since no specific target is available to treat this class of patients, chemotherapy is the only currently validated and potentially effective treatment. The identification of new molecular targets and the development of new target-based therapies is therefore crucial for TNBC patients, and it first requires a better understanding of the heterogenic features presented by TNBCs. One crucial point is the identification of HER2 'false negatives' among TNBCs: about 8–10% of breast cancers with HER2 amplification are misclassified as negative (immunohistochemistry [IHC] 0 or 1+), regardless of the actual presence of hormonal receptors [4]. As a consequence, these patients are denied potential benefits given by the anti-HER2 adjuvant and neoadjuvant therapies, such as trastuzumab and lapatinib [5].HER2 is an important prognostic and predictive factor for response to trastuzumab in the metastatic and adjuvant settings; the development of reliable methods for its identification is therefore of paramount importance [6]. IHC and FISH are currently the most commonly used methods to assess HER2 status: the former measures the HER2 expression, while the latter directly assesses HER2 gene amplification through a single (HER2) or double probe (HER2 and CEP17).The IHC test uses a scoring system (0, 1+, 2+, 3+) to express the amount of HER2 receptor on cell surface, taking into account the proportion of positive cells and the completeness and intensity of membrane staining. The FISH test is used when IHC results are equivocal. According to the 2013 ASCO/CAP guidelines an unequivocally positive HER2 result is obtain when IHC assay shows a complete/intense circumferential membrane staining within >10% of invasive tumor cells observed in a homogeneous and contiguous population (IHC 3+), or when the FISH assay reveals HER2 gene amplification. In single-probe assays gene amplification is defined as a mean number of HER2 copy number ≥6.0 signals per cell, while in the dual-probe assay the FISH is positive when HER2/CEP17 ratio is ≥2.0, with an average HER2 copy number ≥4.0 signals per cell; HER2/CEP17 ratio is ≥2.0, with an average HER2 copy number <4.0 signals per cell; or when HER2/CEP17 ratio is <2.0, with an average HER2 copy number ≥6.0 signals per cell [7].Tumor-negative breast cancers misclassified as HER2 negative by IHC (0 or 1+) could therefore be reclassified by FISH, with a remarkable impact on medical treatment. Adjuvant trastuzumab has significantly improved the prognosis of breast cancer patients both in terms of disease-free survival and overall survival (OS); moreover it has increased progression-free survival and OS in HER2-positive breast patients in the metastatic setting, as confirmed by a number of clinical trials [8–10].Discordance between IHC & FISHThe identification of the discordance between IHC 1+ or 0 and positive FISH is a major point to be addressed in the treatment of TNBCs, as it would help the correct selection of HER2-positive patients. Tumors classified as 0/1+ and 3+ by IHC and FISH usually show concordant results, while a higher grade of discordance is often found in cases scored 2+ by IHC that require further investigation. In a study conducted by Dybdal et al. the overall concordance rate measured between IHC and FISH assays was 82%: the HER2 amplification in the 0, 1+, 2+ and 3+ groups was observed in 3.2, 6.7, 23.9 and 89.3% of the samples, respectively. [11].A number of other studies investigated the discordance between IHC and FISH in breast cancer.Iorfida et al. conducted a prospective observational study to assess the incidence of HER2 gene amplification in 492 invasive breast carcinomas classified as IHC 1+. The FISH test was carried out in 84 cases (17%), selected according to characteristics such as: high grade, high Ki67, extensive vascular invasion, node positivity and uncertain or absent endocrine responsiveness. The results of the FISH test were positive in 13% of the patients with an IHC 1+ breast cancer, about twofold the result observed in previous studies (˜6.7%) [11]. Based on these observations the authors suggest that, in addition to the current algorithm that recommends FISH in IHC 2+ cases, the FISH test should be performed in IHC 1+ breast cancers with adverse prognostic features [12].A recent meta-analysis on 6629 patients showed that the overall discordance rate between IHC 0/1+ and FISH test for the detection of HER2 overexpression was 4%. Therefore, an IHC result of 0/1+ cannot be completely considered as negative and the execution of a valid and complementary test, such as the FISH assay, is highly recommended to better define HER2 expression [13].A study on 789 breast cancer patients showed that both patients with discordant receptor status and those with concordant TNBC had similarly unfavorable survival, probably due to an inappropriate use of targeted therapies. The authors emphasized the importance of correctly determining hormone and HER2 receptor status as a fundamental step to achieve the therapeutic effect of targeted therapies and avoid suboptimal treatment. In addition they suggest that a correlation might exist between the discordance in receptor expression and the lack of reliability of measurement methods [14].This hypothesis is further supported by a French study that compared different techniques aimed at measuring HER2 expression, concluding that the discordances reported between techniques might be due to HER2 intratumor heterogeneity, such as one tumor containing two distinct clones or tumors consisting of HER2 amplified and nonamplified subclones. The authors also suggested that the combination of IHC with FISH or Q-RT-PCR in IHC equivocal cases or even in all tumors may be a reliable and moderate-cost strategy for HER2 status assessment [15].Our experienceWe conducted a prospective experience on samples classified as TNBC, analyzed by IHC and by FISH, in order to evaluate discordant cases between IHC and FISH and to enable patients misclassified as HER2-negative to receive an appropriate anti-HER2 therapy, with the consequential prognostic advantage. We report here the preliminary findings of this analysis.Samples from 51 patients who underwent surgery for breast cancer at the Hospital Maggiore della Caritá (Novara, Italy) were collected from January 2011 to September 2014; these patients were classified as estrogen receptor, progesterone receptor and HER2-negative by IHC test. All the samples were analyzed by FISH from July 2012 to September 2014 in our molecular biology laboratory according to ASCO/CAP 2013 guidelines. A FISH-positive test was reported in 23.5% of patients; those who were classified as HER2-positive by FISH received trastuzumab in addition to the standard adjuvant therapy.On these bases, we recommend that a dedicated anatomical pathologist should be present in each laboratory as this could help reduce the discordance observed between the IHC and FISH tests.ConclusionBased on the data collected until today, we need a better definition of TNBC and a more clear understanding of its heterogeneity; this is fundamental to help develop new targeted therapies that could be effective in this population. Moreover, it is important to identify new predictive markers, as they are extremely useful to understand the mechanism of action of drugs and to identify TNBC patients who could benefit from specific therapies. Given the heterogeneity of TNBCs, more biomarkers or even entire predictive pathways might be necessary to predict the benefits from new targeted drugs [16].Oncologists and pathologists should make every effort in the identification of this small subset of patients with breast cancer, because the lack of recognition of HER2 overexpression and therefore the exclusion of anti-HER2 agents from the therapy decreases disease-free survival and OS of these patients.As a concluding remark, FISH assay in TNBCs could produce drastic changes in clinical practice; we hope that this method can soon become a standard and can be also extended to hormone-responsive breast cancers.Financial & competing interests disclosureThe authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.Editorial assistance for the preparation of this manuscript was provided by Ambra Corti, Sara Marceglia, PhD, and LucaGiacomelli, PhD, on behalf of Content Ed Net; this assistance was funded by Roche.References1 Penault-Llorca F, Viale G. Pathological and molecular diagnosis of triple negative breast cancer: a clinical perspective. Ann. Oncol. 23(6), vi19–vi22 (2012).Crossref, Medline, Google Scholar2 Criscitiello C, Azim HA Jr, Schouten PC, Linn SC, Sotiriou C. Understanding of biology of triple negative breast cancer. Ann. Oncol. 23(6), 13–18 (2012).Crossref, Google Scholar3 Eiermann W, Vallis KA. Locoregional treatments for triple negative breast cancer. Ann. Oncol. 23(6), 30–34 (2012).Crossref, Google Scholar4 Press MF, Finn RS, Cameron D et al. HER-2 gene amplification, HER-2 and epidermal growth factor receptor mRNA and protein expression, and lapatinib efficacy in women with metastatic breast cancer. Clin. Cancer Res. 14(23), 7861–7870 (2008).Crossref, Medline, CAS, Google Scholar5 Ross JS. Human epidermal growth factor receptor 2 testing in 2010: does chromosome 17 centromere copy number make any difference? J. Clin. Oncol. 28(28), 4293–4295 (2010).Crossref, Medline, Google Scholar6 Perez EA, Press MF, Dueck AC et al. Immunohistochemistry and fluorescence in situ hybridization assessment of HER2 in clinical trials of adjuvant therapy for breast cancer (NCCTG N9831, BCIRG 006, and BCIRG 005). Breast Cancer Res. Treat. 138, 99–108 (2013).Crossref, Medline, CAS, Google Scholar7 Wolff AC, Hammond ME, Hicks DG et al. Recommendation for human epidermal growth factor receptor 2 testing in breast cancer: American Society of Clinical Oncology/College of American Pathologists clinical practice guideline update. J. Clin. Oncol. 31(31), 3997–4013 (2013).Crossref, Medline, Google Scholar8 Piccart-Gebhart MJ, Procter M, Leyland-Jones B et al. Trastuzumab after adjuvant chemotherapy in HER2-positive breast cancer? N. Engl. J. Med. 353, 1659–1672 (2005).Crossref, Medline, CAS, Google Scholar9 Smith I, Procter M, Gelber RD et al. 2 year follow-up of trastuzumab after adjuvant chemotherapy in HER2-positive breast cancer: a randomised controlled trial. Lancet 369, 29–36 (2007).Crossref, Medline, CAS, Google Scholar10 Perez EA, Romond EH, Suman VJ et al. Trastuzumab plus adjuvant chemotherapy for human epidermal growth factor receptor 2-positive breast cancer: planned joint analysis of overall survival from NSABP B-31 and NCCTG N9831. J. Clin. Oncol. 32(33), 3744–3752 (2014).Crossref, Medline, CAS, Google Scholar11 Dybdal N, Leiberman G, Anderson S et al. Determination of HER2 gene amplification by fluorescence in situ hybridization and concordance with the clinical trials immunohistochemical assay in women with metastatic breast cancer evaluated for treatment with trastuzumab. Breast Cancer Res. Treat. 93, 3–11 (2005).Crossref, Medline, CAS, Google Scholar12 Iorfida M, Dellapasqua S, Bagnardi V et al. Her-2 negative (1+) breast cancer with unfavorable prognostic features: to FISH or not to FISH? Ann. Oncol. 23, 1371–1372 (2012).Crossref, Medline, CAS, Google Scholar13 Bahreini F, Soltanian AR, Mehdipour P. A meta-analysis on concordance between immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) to detect HER2 gene overexpression in breast cancer. Breast Cancer doi:10.1007/s12282-014-0528-0 (2014) (Epub ahead of print).Medline, Google Scholar14 Liedtke C, Broglio K, Moulder S et al. Prognostic impact of discordance between triple receptor measurements in primary and recurrent breast cancer. Ann. Oncol. 20, 1953–1958 (2009).Crossref, Medline, CAS, Google Scholar15 Lehmann-Che J, Amira-Bouhidel F, Turpin E et al. Immunohistochemical and molecular analyses of HER2 status in breast cancer are highly concordant and complementary approaches. Br. J. Cancer 104, 1739–1946 (2011).Crossref, Medline, CAS, Google Scholar16 Bayraktar S, Glück S. Molecularly targeted therapies for metastatic triple negative breast cancer. Breast Cancer Res. Treat. 138, 21–35 (2013).Crossref, Medline, CAS, Google ScholarFiguresReferencesRelatedDetailsCited ByBreast cancer prevention in premenopausal women: role of the Mediterranean diet and its components1 October 2019 | Nutrition Research Reviews, Vol. 33, No. 1Impact of biomarkers and genetic profiling on breast cancer prognostication: A comparative analysis of the 8th edition of breast cancer staging system13 June 2019 | The Breast Journal, Vol. 25, No. 5 Vol. 11, No. 7 eToC Sign up Follow us on social media for the latest updates Metrics History Published online 25 March 2015 Published in print April 2015 Information© Future Medicine LtdKeywordsFISHHER2immunohistochemistrytriple-negative breast cancerFinancial & competing interests disclosureThe authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.Editorial assistance for the preparation of this manuscript was provided by Ambra Corti, Sara Marceglia, PhD, and LucaGiacomelli, PhD, on behalf of Content Ed Net; this assistance was funded by Roche.PDF download