Comparison of dual-color in-situ hybridization and fluorescence in-situ hybridization in HER2 gene amplification in breast cancer

Validation of Dual-Color Dual In Situ Hybridization for HER2/neu Gene in Breast Cancer

CONTEXT.—

Human epidermal growth factor (HER2/neu) gene amplification, a poor prognostic factor in invasive breast cancer, has shown substantial utility as a predictive marker, with significantly improved survival following anti-HER2 therapies like trastuzumab. Dual-color dual in situ hybridization (D-DISH), a recently introduced fully automated assay for HER2/neu evaluation on light microscopy, has several advantages over fluorescence in situ hybridization (FISH).

OBJECTIVE.—

To standardize and validate the D-DISH assay using FISH as the gold standard and assess interobserver reproducibility in interpreting the D-DISH assay.

DESIGN.—

D-DISH was performed using the latest HER2 Dual ISH DNA Probe Cocktail assay (Ventana Medical Systems Inc, Tucson, Arizona) in 148 cases of invasive breast cancer. The same block was used for performing immunohistochemistry by Ventana PATHWAY anti-HER2/neu (4B5) antibody and FISH assay by ZytoLight SPEC ERBB2/CEN17 Dual Color Probe. D-DISH was separately interpreted by 4 pathologists blinded to FISH results.

RESULTS.—

Concordance of 98.65% and a Cohen κ value of 0.97 were observed between FISH and D-DISH. Intraclass correlation coefficient (0.93-0.97) and κ values (0.98-1.0) for interobserver reproducibility showed almost perfect agreement by D-DISH. Interobserver reproducibility was also evaluated for genomic heterogeneity, HER2 group categorization, and polysomy (κ values 0.42-0.74, 0.89-0.93, and 0.98-1.0, respectively).

CONCLUSIONS.—

We successfully validated the latest version of D-DISH assay as a substitute for FISH in predicting HER2 gene status with significant interobserver reproducibility, concluding that this D-DISH assay may be introduced in routine diagnostic services as a reflex test to ascertain HER2 gene status.

Detection of ERBB2 and CEN17 signals in fluorescent in situ hybridization and dual in situ hybridization for guiding breast cancer HER2 target therapy

The overexpression of the human epidermal growth factor receptor 2 (HER2) is a predictive biomarker in therapeutic effects for metastatic breast cancer. Accurate HER2 testing is critical for determining the most suitable treatment for patients. Fluorescent in situ hybridization (FISH) and dual in situ hybridization (DISH) have been recognized as FDA-approved methods to determine HER2 overexpression. However, analysis of HER2 overexpression is challenging. Firstly, the boundaries of cells are often unclear and blurry, with large variations in cell shapes and signals, making it challenging to identify the precise areas of HER2-related cells. Secondly, the use of sparsely labeled data, where some unlabeled HER2-related cells are classified as background, can significantly confuse fully supervised AI learning and result in unsatisfactory model outcomes. In this study, we present a weakly supervised Cascade R-CNN (W-CRCNN) model to automatically detect HER2 overexpression in HER2 DISH and FISH images acquired from clinical breast cancer samples. The experimental results demonstrate that the proposed W-CRCNN achieves excellent results in identification of HER2 amplification in three datasets, including two DISH datasets and a FISH dataset. For the FISH dataset, the proposed W-CRCNN achieves an accuracy of 0.970±0.022, precision of 0.974±0.028, recall of 0.917±0.065, F1-score of 0.943±0.042 and Jaccard Index of 0.899±0.073. For DISH datasets, the proposed W-CRCNN achieves an accuracy of 0.971±0.024, precision of 0.969±0.015, recall of 0.925±0.020, F1-score of 0.947±0.036 and Jaccard Index of 0.884±0.103 for dataset 1, and an accuracy of 0.978±0.011, precision of 0.975±0.011, recall of 0.918±0.038, F1-score of 0.946±0.030 and Jaccard Index of 0.884±0.052 for dataset 2, respectively. In comparison with the benchmark methods, the proposed W-CRCNN significantly outperforms all the benchmark approaches in identification of HER2 overexpression in FISH and DISH datasets (p<0.05). With the high degree of accuracy, precision and recall , the results show that the proposed method in DISH analysis for assessment of HER2 overexpression in breast cancer patients has significant potential to assist precision medicine.

HER2 Dual In Situ Hybridization: Correlations and Cautions

CONTEXT.—

Accurate HER2 testing in breast cancer is crucial for appropriate precision therapy. HER2 testing is most commonly accomplished by a combination of immunohistochemistry and in situ hybridization techniques, as gene amplification is closely tied to protein overexpression. During the last 5+ years, brightfield dual in situ hybridization (DISH) has replaced fluorescence methods (fluorescence in situ hybridization [FISH]) in some laboratories.

OBJECTIVE.—

To analyze routine HER2 DISH performance in the field.

DESIGN.—

We reviewed our experience with HER2 DISH performed at outside laboratories and referred for patient care.

RESULTS.—

Of 273 identified retrospective DISH results, 55 had repeated FISH testing at our institution; 7 (13%) were discordant. Additional cases had technical flaws hampering appropriate scoring. In 23 cases (42%), HER2 DISH was performed without immunohistochemistry. Slide review of a prospective cohort of 42 consecutive DISH cases revealed 14 (33%) with technical or interpretative limitations potentially jeopardizing results. Commonly identified problems include lack of or weak signals in most tumor cells, and silver precipitate or red signals outside of nuclei, resulting in false-negative or false-positive interpretations, respectively. Further, 44% (24 of 55) of DISH reports lacked complete data, specifically average HER2 signals/cell.

CONCLUSIONS.—

While HER2 DISH can be an efficient and effective alternative to FISH, we illustrate pitfalls and reinforce that careful attention to slide quality and technical parameters are critically important. HER2 DISH cotesting with immunohistochemistry could help minimize false-negative or false-positive HER2 results.

HER2 expression and relevant clinicopathological features in esophageal squamous cell carcinoma in a Chinese population

Background

Despite great progress in surgery and other treatments, the prognosis of patients with esophageal squamous cell carcinoma (ESCC) is still very poor. HER2 has strong therapeutic implications in certain cancers, such as breast cancer and gastric cancer. However, literature on the frequency of HER2 expression in ESCC is scarce. In the present study, HER2 protein expression, HER2 gene amplification and the relationship between HER2 status and clinicopathological characteristics were evaluated in a large cohort of Chinese ESCC patients.

Methods

A total of 857 consecutive ESCC patients who received radical esophagectomy without neoadjuvant therapy between January 2014 and October 2015 were included in this retrospective study. HER2 protein expression was analyzed by immunohistochemistry (IHC), and its correlation with clinicopathological parameters was assessed. In addition, 65 cases, including 13 HER2 overexpression (3+) cases and 52 HER2 equivocal (2+) cases from the 857-case cohort, and another 104 ESCC cases, including 1 HER2 overexpression (3+) case, 3 HER2 equivocal (2+) cases and 100 HER2 negative (1+/0) cases, were selected to construct tissue microarrays (TMAs). Dual-color in situ hybridization (DISH) was performed on the TMAs to assess HER2 gene amplification and the relationship with clinicopathological parameters.

Results

We found HER2 overexpression (3+) status in 1.5% (13/857) of cases and HER2 equivocal (2+) status in 6.1% (52/857) of cases. HER2 IHC expression was significantly associated with gender (P = 0.028). However, there were no significant correlations between HER2 IHC expression and age, tumor differentiation, pT stage, pN stage, pM stage and pTNM stage (P > 0.05). Regarding the 169 cases analyzed by DISH, 14 (of 14, 100%) HER2 overexpression (3+) cases, 10 (of 55, 18.2%) HER2 equivocal (2+) cases, and 0 (of 100, 0%) HER2 negative (1+/0) cases showed HER2 gene amplification. HER2 gene amplification was not significantly associated with clinicopathological characteristics such as age, gender, tumor differentiation, pT stage, pN stage, pM stage and pTNM stage (P > 0.05).

Conclusions

Approximately 1.5% of the Chinese ESCC patients had HER2 overexpression based on IHC. IHC and DISH had a high concordance rate. These results provide valuable insight for the future treatment of ESCC.

Comparison of HER2 testing among laboratories: Our experience with review cases retested at Moffitt Cancer Center in a two-year period

Determination of human epidermal receptor protein-2 (HER2) is a crucial step in the treatment of patients diagnosed with invasive breast carcinoma. HER2 status is an independent clinical prognostic factor and a predictive factor of tumor response to chemotherapeutic agents such as trastuzumab. Accurate testing is necessary to offer adequate therapy to patients. To evaluate the variation in HER2 testing results, we analyzed our data from review cases in which HER2 testing was repeated at our institution from January 2013 to December 2014. For the study, the reason for repeating the test, the testing methodology used, and the tests results were collected. Concordance between outside and in-house HER2 results was compared. Discrepancies were classified as major and minor. A total of 173 cases were retested during this period. One-hundred and twenty-eight cases met the inclusion criteria. Sixteen cases were originally tested at large reference laboratories and two in international laboratories. In the 110 remaining cases, the test was performed at small community laboratories or the testing facility was not available. Forty-one (32%) discrepancies were identified. Of these, 15 (12% of 128 total) were major and 26 (20% of 128 total) were considered minor discrepancies. Our study confirms that significant discrepancies in HER2 results persist even after stricter and well-developed testing guidelines have been embraced.

Progress in the clinical detection of heterogeneity in breast cancer

Breast cancer is currently the most common form of cancer and the second‐leading cause of death from cancer in women. Though considerable progress has been made in the treatment of breast cancer, the heterogeneity of tumors (both inter‐ and intratumor) remains a considerable diagnostic and prognostic challenge. From clinical observation to genetic mutations, the history of understanding the heterogeneity of breast cancer is lengthy and detailed. Effectively detecting heterogeneity in breast cancer is important during treatment. Various methods of depicting this heterogeneity are now available and include genetic, pathologic, and imaging analysis. These methods allow characterization of the heterogeneity of breast cancer on a genetic level, providing greater insight during the process of establishing an effective therapeutic plan. This study reviews how the understanding of tumor heterogeneity in breast cancer evolved, and further summarizes recent advances in the detection and monitoring of this heterogeneity in patients with breast cancer.

HER2 gene amplification in patients with prostate cancer: Evaluating a CISH-based method

Prostate cancer (PCa) is one of the most widespread malignancies in the world. The role of the human epidermal growth factor receptor 2 (HER2) in the pathogenesis and progression of human PCa remains poorly understood. In contradiction with breast cancer, studies on HER2 overexpression and gene amplification in PCa have produced varying results, although the HER2 oncogene has been implicated in the biology of numerous tumor types, and serves as a prognostic marker and therapeutic target in breast cancer. Technical challenges are considered the main reasons for data discrepancies. Amplification of the HER2 gene has previously been reported in PCa, in which it was associated with tumor progression. The present study aimed to evaluate the prevalence and clinical significance of HER2 amplification in PCa. A total of 32 biopsy samples obtained from human prostate adenocarcinomas were evaluated by chromogenic in situ hybridization (CISH) to determine the frequency of patients with HER2 gene amplifications. High copy numbers of HER2 were detected in 19 of the prostate tumors analyzed. The results of the present study suggested that, in patients without amplification of HER2, high levels of prostate-specific antigen or a high Gleason score were not significantly correlated with a high pathologic stage. Furthermore, amplification levels of the HER2 gene were directly associated with pathologic stage in patients with PCa. Therefore, the potential use of HER2 as a prognostic factor or therapeutic target for PCa warrants further study.

Optimal Scoring of Brightfield Dual-Color In Situ Hybridization for Evaluation of HER2 Amplification in Breast Carcinoma: How Many Cells Are Enough?

OBJECTIVES

The purpose of this study was to determine the optimum number of cells that should be counted when scoring human epidermal growth factor receptor 2 (HER2) brightfield dual-color in situ hybridization (BDISH), including cases with HER2/chromosome 17 (Chr17) ratios in the 1.80 to 2.20 range.

METHODS IN TOTAL,

131 cases of breast carcinoma with HER2 immunohistochemistry and BDISH were included. For cases with a HER2/Chr17 ratio of less than 1.80 or more than 2.20 (n = 115), BDISH scoring was performed for 60 cells using three tumor fields, and for cases with a HER2/Chr17 ratio of 1.80 to 2.20 (n = 16), scoring was performed for 120 cells using six tumor fields. Mean HER2/Chr17 ratio and HER2 copy number were calculated for cumulative cell counts.

RESULTS

The HER2 status as determined by the HER2/Chr17 ratio or HER2 copy number was unchanged following counting of additional cells in 100% of cases with ratio of less than 1.80 or more than 2.20. The HER2 status of two cases with ratios of 1.80 to 2.20 changed from positive to negative following counting of 120 cells.

CONCLUSIONS

Our findings support recommendations to score 20 nuclei in conjunction with careful assessment of immunohistochemistry and scan of the BDISH slide to identify areas of heterogeneity. Scoring of additional cells/fields is likely not of benefit and might be a disadvantage since the scorer moves out of the area of strongest signal.

Biomarker testing for breast, lung, and gastroesophageal cancers at NCI designated cancer centers

BACKGROUND

Molecular biomarkers, a cornerstone of precision oncology, are critical in breast, gastroesophageal, and non-small cell lung cancer management (BC, GEC, NSCLC). Testing practices are intensely debated, impacting diagnostic quality and affecting pathologists, oncologists and patients. However, little is known about testing approaches used in practice. Our study described biomarker practices in BC, GEC, and NSCLC at the leading US cancer centers.

METHODS

We conducted a survey of the National Cancer Institute (NCI) designated centers on BC, GEC, and NSCLC biomarker testing. We used simple frequencies to describe practices, two-sided Fisher's exact test and two-sided McNemar's test for cross-cancer comparison. All statistical tests were two-sided.

RESULTS

For BC human epidermal growth factor receptor 2 (HER2), 39% of centers combine guidelines by using in situ hybridization (ISH) and immunohistochemistry (IHC) concurrently, and 21% reflex-test beyond guideline-recommended IHC2+. For GEC HER2, 44% use ISH and IHC concurrently, and 28% reflex-test beyond IHC2+. In NSCLC, the use of IHC is limited to 4% for epidermal growth factor receptor (EGFR) and 7% for anaplastic lymphoma kinase (ALK). 43.5% test NSCLC biomarkers on oncologist order; 34.5% run all biomarkers upfront, and 22% use a sequential protocol. NSCLC external testing is statistically significantly higher than BC (P < .0001) and GEC (P < .0001). NSCLC internally developed tests are statistically significantly more common than BC (P < .0001) and GEC (P < .0001).

CONCLUSIONS

At the NCI cancer centers, biomarker testing practices vary, but exceeding guidelines is a common practice for established biomarkers and emerging practice for newer biomarkers. Use of internally developed tests declines as biomarkers mature. Implementation of multibiomarker protocols is lagging. Our study represents a step toward developing a biomarker testing practice landscape.