HER2 assessment by silver in situ hybridization: where are we now?

Human epidermal growth factor receptor 2/neu expression in urothelial carcinomas

Introduction

Urothelial carcinomas of the bladder are more common in males, making them the sixth-most common cancer in men and the tenth-most common cancer overall, worldwide. Current guidelines do not recommend routine testing for human epidermal growth factor receptor (HER2/neu) expression on the biopsy specimens of patients with urothelial carcinoma. This study was aimed at determining the expression pattern of HER2/neu and its usefulness in muscle-invasive and nonmuscle-invasive urothelial carcinoma.

Methods

HER2/neu expression was assessed in 89 specimens of urothelial cancer by immunohistochemistry (IHC), and equivocal cases were subjected to fluorescent in situ hybridization (FISH).

Results

On IHC for HER2/neu, 17.9% (7/39) of the muscle-invasive bladder cancers (MIBCs) showed a 3+ expression, whereas 22% (11/50) of the non-muscle invasive cancers were positive with a score of 3+. A significant correlation between HER2/neu status and muscle invasion could not be established in the current study (P = 0.74, Fisher's exact test). Three cases of muscle-invasive (7.7%) and 2 cases (4%) among nonmuscle invasive cancers showed equivocal expression. All the cases with equivocal (2+) expression on IHC were subjected to FISH and none showed gene amplification on hybridization and were considered as negative.

Conclusion

Overexpression of HER-2/neu was seen in 17.9% of MIBCs and 22% of non-MIBCs. There are no norms for routine testing of HER2/neu expression in the biopsy specimens of urothelial carcinoma. There is an unmet need to establish guidelines for HER2/neu scoring, similar to that for breast and gastric cancers, to determine the proportion of positive cases and help in identification of those who may benefit from targeted therapies.

HER2 Expression in Bladder Cancer: A Focused View on Its Diagnostic, Prognostic, and Predictive Role

Bladder cancer (BC) is a heterogeneous disease from a molecular, morphological, and clinical standpoint. HER2 is a known oncogene involved in bladder carcinogenesis. Assessing HER2 overexpression as a result of its molecular changes in a routine pathology practice using immunohistochemistry might be a useful adjunct in several scenarios, namely (1) to correctly identify flat urothelial lesions and inverted urothelial lesions in the diagnostic setting; (2) to provide prognostic hints in both non-muscle invasive (NMI) and muscle invasive (MI) tumors, thus supplementing risk stratification tools, especially when evaluating higher-risk tumors such as those with variant morphology; (3) to improve antibody panels as a surrogate marker of BC molecular subtyping. Furthermore, the potential of HER2 as a therapeutic target has been only partly explored so far, in light of the ongoing development of novel target therapies.

Impact of chromosome 17 centromere copy number increase on patient survival and human epidermal growth factor receptor 2 expression in gastric adenocarcinoma

The accurate evaluation of human epidermal growth factor receptor 2 (HER2) status is essential for the appropriate use of targeted therapies. An increased number of chromosome 17 centromere enumeration probe (CEP17) signals may underrate fluorescence in situ hybridization (FISH) outcomes, resulting in false-negative or a false-equivocal HER2 status assessment. The aim of the present study was to assess the frequency of CEP17 copy number increase (CNI), its effects on HER2 protein expression (and the subsequent effects on tumor cells), and the survival outcomes of patients with gastric cancer. Archival primary tumor samples from 244 patients that underwent gastric resection for adenocarcinoma were retrieved for both HER2 protein expression analysis (using immunochemistry) and HER2 gene amplification (using FISH). The associations between HER2 status, CEP17 CNI and multiple clinicopathological parameters (including survival outcome), were assessed. The relationship between CEP17 CNI and HER2 protein upregulation was also investigated. CEP17 CNI was detected in 17.2% of cases, and a strong association between CEP17 CNI and HER2 upregulation was revealed. The impact of CEP17 CNI on survival did not reach statistical significance. Consequently, CEP17 CNI was discovered to be strongly associated with HER2 upregulation in tumor cells, which may characterize a critical issue in HER2 testing. Therefore, the eligibility for HER2-targeted agents in CEP17 CNI-positive patients warrants further recognition.

Building Up a High-throughput Screening Platform to Assess the Heterogeneity of HER2 Gene Amplification in Breast Cancers

Targeted therapies against the human epidermal growth factor receptor 2 (HER2) have radically changed the outcome of patients with HER2-positive breast cancers. However, a minority of cases displays a heterogeneous distribution of HER2-positive cells, which generates major clinical challenges. To date, no reliable and standardized protocols for the characterization and quantification of HER2 heterogeneous gene amplification in large cohorts have been proposed. Here, we present a high-throughput methodology to simultaneously assess the HER2 status across different topographic areas of multiple breast cancers. In particular, we illustrate the laboratory procedure to construct enhanced tissue microarrays (TMAs) incorporating a targeted mapping of the tumors. All TMA parameters have been specifically optimized for the silver in situ hybridization (SISH) of formalin-fixed paraffin-embedded (FFPE) breast tissues. Immunohistochemical analysis of the prognostic and predictive biomarkers (i.e., ER, PR, Ki67, and HER2) should be performed using automated procedures. A customized SISH protocol has been implemented to allow a high-quality molecular analysis across multiple tissues that underwent different fixation, processing, and storage procedures. In this study, we provide a proof-of-principle that specific DNA sequences could be localized simultaneously in distinct topographic areas of multiple and heterogeneously processed breast cancers using an efficient and cost-effective method.