Comparison between immunohistochemistry and chromogenic in situ hybridization in assessing HER-2 status in breast cancer

Bridging Histopathology and Radiomics Toward Prognosis of Metastasis in Early Breast Cancer

Tumor histomorphology is crucial for the prognostication of breast cancer outcomes because it contains histological, cellular, and molecular tumor heterogeneity related to metastatic potential. To enhance breast cancer prognosis, we aimed to apply radiomics analysis-traditionally used in 3D scans-to 2D histopathology slides. This study tested radiomics analysis in a cohort of 92 breast tumor specimens for outcome prognosis, addressing -omics dimensionality by comparing models with moderate and high feature counts, using least absolute shrinkage and selection operator for feature selection and machine learning for prognostic modeling. In the test folds, models with radiomics features [area under the curves (AUCs) range 0.799-0.823] significantly outperformed the benchmark model, which only included clinicopathological (CP) parameters (AUC = 0.584). The moderate-dimensionality model with 11 CP + 93 radiomics features matched the performance of the highly dimensional models with 1,208 radiomics or 11 CP + 1,208 radiomics features, showing average AUCs of 0.823, 0.799, and 0.807 and accuracies of 79.8, 79.3, and 76.6%, respectively. In conclusion, our application of deep texture radiomics analysis to 2D histopathology showed strong prognostic performance with a moderate-dimensionality model, surpassing a benchmark based on standard CP parameters, indicating that this deep texture histomics approach could potentially become a valuable prognostic tool.

HER2 Positivity Is Affected by the Papillary Structure and Has a Bidirectional Prognostic Value for Gallbladder Carcinoma

Gallbladder carcinoma (GBC) is responsible for 80%–95% of biliary tract malignancies and has a dismal prognosis. Human epidermal growth factor receptor 2 (HER2) is a promising therapeutic target of GBC. Through immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) methods, HER2 expression and gene amplification were identified on high-output tissue microarrays (TMAs) developed in 306 GBC cases to investigate its relationship with GBC and clinicopathological characteristics. Adenocarcinomas accounted for 223 (72.9%) of the cases, with 62 (27.8%) being papillary adenocarcinoma or having partial papillary structure. HER2 positivity was studied in 16.1% (36/223) of patients with adenocarcinoma and 41.9% (26/62) in adenocarcinoma with papillary structures. For 143 radically resected primary GBC cases with 24 HER2-positive tumors, survival data were valid; the median survival time was not reached, and the 5-year survival rate was 52.9%. All patients in stages 0–I survived, and the results of the HER2-positive group and the stage II HER2-negative group were similar (p = 0.354). However, in stage III, the mortality rate in the HER2-positive group was reduced (p = 0.005) and that in stage IV was higher (p = 0.005). In conclusion, HER2 positivity was significantly higher in patients with papillary GBC. The predictive value of HER2 varies by clinical stage, with no prediction in the early stages, better in stage III, and worse in stage IV.

Size and Shape Filtering of Malignant Cell Clusters within Breast Tumors Identifies Scattered Individual Epithelial Cells as the Most Valuable Histomorphological Clue in the Prognosis of Distant Metastasis Risk

Survival and life quality of breast cancer patients could be improved by more aggressive chemotherapy for those at high metastasis risk and less intense treatments for low-risk patients. Such personalized treatment cannot be currently achieved due to the insufficient reliability of metastasis risk prognosis. The purpose of this study was therefore, to identify novel histopathological prognostic markers of metastasis risk through exhaustive computational image analysis of 80 size and shape subsets of epithelial clusters in breast tumors. The group of 102 patients had a follow-up median of 12.3 years, without lymph node spread and systemic treatments. Epithelial cells were stained by the AE1/AE3 pan-cytokeratin antibody cocktail. The size and shape subsets of the stained epithelial cell clusters were defined in each image by use of the circularity and size filters and analyzed for prognostic performance. Epithelial areas with the optimal prognostic performance were uniformly small and round and could be recognized as individual epithelial cells scattered in tumor stroma. Their count achieved an area under the receiver operating characteristic curve (AUC) of 0.82, total area (AUC = 0.77), average size (AUC = 0.63), and circularity (AUC = 0.62). In conclusion, by use of computational image analysis as a hypothesis-free discovery tool, this study reveals the histomorphological marker with a high prognostic value that is simple and therefore easy to quantify by visual microscopy.

Chromogenic in situ hybridization compared with other approaches to evaluate HER2/neu status in breast carcinomas

Human epidermal growth factor receptor 2 (HER2) has been evaluated in breast cancer patients to identify those most likely to benefit from herceptin-targeted therapy. HER2 amplification, detected in 20-30% of invasive breast tumors, is associated with reduced survival and metastasis. The most frequently used technique for evaluating HER2 protein status as a routine procedure is immunohistochemistry (IHC). HER2 copy number alterations have also been evaluated by fluorescence in situ hybridization (FISH) in moderate immunoexpression (IHC 2+) cases. An alternative procedure to evaluate gene amplification is chromogenic in situ hybridization (CISH), which has some advantages over FISH, including the correlation between HER2 status and morphological features. Other methodologies have also been used, such as silver-enhanced in situ hybridization (SISH) and quantitative real-time RT-PCR, to determine the number of HER2 gene copies and expression, respectively. Here we will present a short and comprehensive review of the current advances concerning HER2 evaluation in human breast cancer.

Emerging technologies for assessing HER2 amplification

Patients with human epidermal growth factor receptor-2 (HER2)+ breast cancer are eligible for trastuzumab treatment; therefore, accurate assessment of HER2 status is essential. Until recently, only 2 methods were validated for determining the HER2 status of breast tumors in the routine diagnostic setting: immunohistochemical analysis and fluorescence in situ hybridization (FISH). Recently, bright-field in situ hybridization techniques such as chromogenic in situ hybridization (CISH) and silver-enhanced in situ hybridization (SISH), which combine features of immunohistochemical analysis and FISH, have been introduced for the determination of HER2 status. These new techniques use a peroxidase enzyme-labeled probe with chromogenic detection, instead of a fluorescent-labeled probe, allowing results to be visualized by standard bright-field microscopy. Thus, the histologic features and HER2 status of a specimen can be evaluated in parallel. Moreover, signals do not decay over time. This review discusses recent publications regarding CISH and SISH testing, including results scoring and concordance between FISH and immunohistochemical analysis.

Monoplex LightCycler polymerase chain reaction quantitation of the HER2 gene for quality assurance of HER2/neu testing by immunohistochemistry and fluorescence in situ hybridization

BACKGROUND

Assessment of HER2 by immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH) is a standard practice for breast carcinomas. Testing is associated with a 20% disagreement between laboratories. The College of American Pathologists (CAP) guidelines for HER2 testing include validation of HER2 test methods by achieving 95% concordance with another validated method. Our laboratory requires IHC 3+ FISH nonamplified specimens to undergo retesting by polymerase chain reaction (PCR). A random sample of IHC 2+ cases are routinely tested by PCR. We found this practice useful for resolving discrepancies in HER2 testing.

METHODS

At clinician request, seventy-nine 3+ and one hundred forty-eight 2+ cases were tested by FISH. In 22 cases, IHC was 3+ but FISH was nonamplified. These 22 cases underwent HER2 LightCycler monoplex polymerase chain reaction (MPCR) testing. Seventeen 2+ nonamplified cases were tested by MPCR.

RESULTS

Twenty-one 3+, FISH nonamplified cases were found to be MPCR nonamplified. One IHC 3+, FISH nonamplified case was MPCR amplified. Seventeen 2+, FISH nonamplified cases were MPCR nonamplified. In all but one case, FISH and MPCR were concordant.

DISCUSSION

American Society of Clinical Oncology/CAP guidelines propose validation of testing procedures by showing 95% concordance with a validated test for positive and negative assays. Specific actions are not recommended to resolve discordances between tests. Our laboratory uses 3 different modalities for HER2 testing. We have found that our 2 methods for testing gene amplification status show a higher degree of concordance between themselves than either did with IHC. Review of the 3+ IHC nonamplified cases showed them to have a dark, granular circumferential staining pattern.

Changes in HER2 expression in breast cancer xenografts after therapy can be quantified using PET and (18)F-labeled affibody molecules

In vivo imaging of human epidermal growth factor receptor type 2 (HER2) expression may allow direct assessment of HER2 status in tumor tissue and provide a means to quantify changes in receptor expression after HER2-targeted therapies. This work describes the in vivo characterization of the HER2-specific N-2-(4-(18)F-fluorobenzamido)ethyl]maleimide ((18)F-FBEM)-Z(HER2:342) Affibody molecule and its application to study the effect of 17 (dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG) on HER2 expression by PET.

METHODS

To assess the correlation of signal observed by PET with receptor expression, we administered the tracer to athymic nude mice bearing subcutaneous human breast cancer xenografts with different levels of HER2 expression. To study the downregulation of HER2, we treated the mice with 4 doses (40 mg/kg) of 17-DMAG, an inhibitor of heat-shock protein 90, known to decrease HER2 expression. The animals were scanned before and after treatment. After the last scan, the mice were euthanized and tumors were frozen for receptor analysis.

RESULTS

The tracer was eliminated quickly from the blood and normal tissues, providing high tumor-to-blood and tumor-to-muscle ratios as early as 20 min after injection. The high-contrast images between normal and tumor tissue were recorded for BT474 and MCF7/clone18 tumors. Low but still detectable uptake was observed for MCF7 tumors, and none for MDA-MB-468. The signal correlated with the receptor expression as assessed by immunohistochemistry, Western blot, and enzyme-linked immunosorbent assay. The levels of HER2 expression estimated by post-treatment PET decreased 71% (P < 4 x 10(-6)) and 33% (P < 0.002), respectively, for mice bearing BT474 and MCF7/clone18 tumors. These changes were confirmed by the biodistribution studies, enzyme-linked immunosorbent assay, and Western blot.

CONCLUSION

Our results suggest that the described (18)F-FBEM-Z(HER2:342) Affibody molecule can be used to assess HER2 expression in vivo by PET and monitor possible changes of receptor expression in response to therapeutic interventions.

A negative feedback regulatory loop associates the tyrosine kinase receptor ERBB2 and the transcription factor GATA4 in breast cancer cells

Overexpression of the ERBB2 gene, linked to genomic and transcriptional amplifications, is a poor prognosis indicator in 25% to 30% of breast cancers. In contrast to some well-documented genomic amplifications, molecular mechanisms leading to ERBB2 transcriptional overexpression remain poorly characterized. Gene expression analyses of breast cancer have characterized distinct transcriptional signatures allowing a molecular classification of breast carcinoma. Coexpression of the ERBB2 and GATA4 genes was originally observed in tumors. Both genes are essential for cardiovascular development and GATA4 has been proposed to control the transcription of critical genes for the differentiation and the function of myocardium. We determined that ERBB2-targeted small interfering RNA repressed both ERBB2 and GATA4 genes, whereas GATA4-targeted small interfering RNA repressed GATA4 and activated ERBB2 transcription. Transfected GATA4-expressing construct repressed ERBB2 promoter. Phylogenetic foot printing revealed multiple putative GATA4 binding sites conserved in mammals within the ERBB2 promoter region. Chromatin immunoprecipitation showed that GATA4 binds specifically to several ERBB2 gene noncoding regions. Electrophoretic mobility shift assay revealed GATA4 binding to a well-conserved consensus motif. Site-directed mutagenesis confirmed the role of this new regulatory element for the activity of the ERBB2 gene enhancer. In agreement with a repressor role of GATA4 on ERBB2 gene expression balanced by ERBB2 activation of the GATA4 gene, a negative correlation between the relative levels of ERBB2 and GATA4 mRNA was observed in breast cancer cell lines and breast tumor samples. We propose that the negative feedback loop linking ERBB2 and GATA4 plays a role in the transcriptional dysregulation of ERBB2 gene expression in breast cancer.

Suppression of the negative regulator LRIG1 contributes to ErbB2 overexpression in breast cancer

The ErbB2 receptor tyrosine kinase is overexpressed in approximately 25% of breast tumors and contributes to poor patient prognosis and therapeutic resistance. Here, we examine the role of the recently discovered ErbB negative regulator LRIG1 in ErbB2(+) breast cancer. We observe that LRIG1 protein levels are significantly suppressed in ErbB2-induced mammary tumors in transgenic mice as well as in the majority of ErbB2(+) human breast tumors. These observations raise the possibility that LRIG1 loss could contribute to the initiation or growth of ErbB2(+) breast tumors. RNA interference-mediated knockdown of endogenous LRIG1 in the ErbB2-overexpressing breast tumor cell lines MDA-MB-453 and BT474 further elevates ErbB2 in these cells and augments cellular proliferation. In contrast, ectopic expression of LRIG1 reverses these trends. Interestingly, we observe that LRIG1 protein levels are suppressed in response to ErbB receptor activation in breast tumor cells but are unaffected by ErbB activation in immortalized nontransformed breast epithelial cells. Our observations indicate that the suppression of LRIG1 protein levels is a common feature of breast tumors. Moreover, our observations point to the existence of a feed-forward regulatory loop in breast tumor cells where aberrant ErbB2 signaling suppresses LRIG1 protein levels, which in turn contributes to ErbB2 overexpression.

FOXP3 is an X-linked breast cancer suppressor gene and an important repressor of the HER-2/ErbB2 oncogene

The X-linked Foxp3 is a member of the forkhead/winged helix transcription factor family. Germline mutations cause lethal autoimmune diseases in males. Serendipitously, we observed that female mice heterozygous for the "scurfin" mutation of the Foxp3 gene (Foxp3(sf/+)) developed cancer at a high rate. The majority of the cancers were mammary carcinomas in which the wild-type Foxp3 allele was inactivated and HER-2/ErbB2 was overexpressed. Foxp3 bound and repressed the HER-2/ErbB2 promoter. Deletion, functionally significant somatic mutations, and downregulation of the FOXP3 gene were commonly found in human breast cancer samples and correlated significantly with HER-2/ErbB2 overexpression, regardless of the status of HER-2 amplification. Our data demonstrate that FOXP3 is an X-linked breast cancer suppressor gene and an important regulator of the HER-2/ErbB2 oncogene.

Prognostic value of HER2 gene amplification detected by chromogenic in situ hybridization (CISH) in metastatic breast cancer

After so many years of research, clinical value of HER2 (Human epidermal growth factor receptor 2) is unclear. Perhaps the main reason is variability of testing methods that produce controversial results. There is a lack of studies regarding prognostic value of CISH especially in metastatic breast cancer (MBC) when risk evaluation is based on different parameters than for primary breast cancer. Aim of this study was to compare prognostic relevance of HER2 status in MBC tested by two different methods i.e. immunohistochemistry (IHC) and chromogenic in situ hybridization (CISH). HER2 status of the same group of 107 MBC patients was determined by IHC (protein overexpression) and by CISH (gene amplification). HER2 results obtained by IHC and CISH showed significant correlation, beside the existence of discrepancies. Beside the significant correlation in two methods, there was a difference in prognostic values of compared methods during the course of metastatic disease. There was a significant difference in progression-free interval (PFI) between HER2 non-amplified and HER2 amplified cases determined by CISH, in postmenopausal subgroup and node-positive subgroup, but no significant difference for IHC stratified MBC patients. CISH seems to be accurate and more informative method than IHC regarding prognostic value of HER2 in metastatic breast cancer.

Controversies in the assessment of HER-2: more questions than answers

Human epidermal growth factor receptor 2 (HER-2) is over-expressed in 15% to 30% of breast cancers and is a poor prognostic marker in node-positive patients. HER-2 expression is an indicator of greater sensitivity to anthracycline-based chemotherapy and is the major criterion for selection for treatment with the anti-HER-2 antibody trastuzumab (Herceptin). Fluorescence in situ hybridization and immunohistochemistry (IHC) are the 2 most commonly used methods for detection of the gene and protein, respectively. Criticisms have been levied at the IHC method of identifying HER-2 overexpression but convenience and costs of this technique cannot be overlooked. Modifications to the IHC technique and scoring accommodate for many of the problems that derive from variables in preanalytical and analytic factors that influence results but standardization is currently impossible to attain. Deficiencies in fluorescence in situ hybridization assay also exist and alternative molecular methods of assay are explored in this review.

HER-2 DNA quantification of paraffin-embedded breast carcinomas with LightCycler real-time PCR in comparison to immunohistochemistry and chromogenic in situ hybridization

OBJECTIVES

To compare the detection of HER-2 status by real-time PCR, on paraffin-embedded breast carcinomas, in respect to immunohistochemistry (IHC) and chromogenic in situ hybridization (CISH).

DESIGN AND METHODS

Paraffin-embedded breast carcinomas collected from 85 patients diagnosed with early stage breast cancer were analyzed for HER-2 gene amplification by real-time PCR and CISH, as well as for HER-2 protein expression by IHC.

RESULTS

HER-2 gene amplification was observed in 19 (22.4%) of 85 breast cancer patients by real-time PCR and in 19 (22.4%) of 85 patients by CISH. Strong (3+) HER-2 protein over-expression was observed in 13 (15.3%) out of 85 patients. Moreover, there were 4 out of 85 (4.7%) patients that had moderate (2+) HER-2 protein over-expression, while 68 out of 85 (80%) patients had no HER-2 protein over-expression by IHC. There were strong concordance rates between real-time PCR and IHC (79/85, 92.9%, p<0.0001) and real-time PCR and CISH (77/85, 90.6%, p<0.0001). The concordance rate between the three methods was 90.6% (p<0.0001).

CONCLUSIONS

Our data show that the results obtained for amplification of HER-2 by real-time PCR on the LightCycler are comparable to those obtained by IHC and CISH.

Simultaneous imaging of membrane antigen and the corresponding chromosomal locus in pathology archives

A new procedure for the simultaneous staining of membranous antigens, such as tyrosine kinase-type cell surface receptor HER2 (c-erbB2), and the corresponding chromosome (chromosome 17 for c-erbB2) in the same cell for use in examining pathology archives is presented. A multistep procedure involving microwave-assisted fluorescence in situ hybridization and immunofluorescence yielded cell images having c-erbB2 on the membrane and genomic signals from the chromosome 17 centromere and the c-erbB2 locus. Furthermore, a combination of microwave-assisted chromogenic in situ hybridization and immunohistochemistry found colorized signals from both chromosome 17 centromere in the nuclei and c-erbB2 on the membranes of individual cells. Quantitative image analysis further confirmed the presence of a significantly stronger c-erbB2 immunoreactivity on cells containing three or more signals from chromosome 17 than from those with less than three signals. It was possible to extend the constellation of cell surface markers and corresponding chromosomes or locus-specific makers to several other genes including CDH1. In this case, the disappearances of CDH1 expression, a CDH1 locus signal, and a centromere enumeration probe (CEP) 16 signal were simultaneously demonstrated in the less-adhesive tumor cells. Thus, it is believed that this procedure might pave the way for exploiting pathology archives for the genotype-phenotype analysis of individual cells.