Hiroaki Nitta

Detection of ALK Gene Rearrangement in Non-small Cell Lung Cancer A Comparison of Fluorescence In Situ Hybridization and Chromogenic In Situ Hybridization with Correlation of ALK Protein Expression

Introduction: Accurate determination of ALK rearrangement is important in lung cancer patients, especially in determining their eligibility for crizotinib therapy. Fluorescence in situ hybridization (FISH) has been regarded as the gold standard method for detecting ALK rearrangement. However, FISH requires a fluorescence microscope, and the signals are labile and rapidly fade over time. This study evaluates the concordance between ALK gene rearrangement in non-small cell lung cancer assessed by ALK FISH and a newly developed ALK chromogenic in situ hybridization (CISH) and correlates the results with ALK protein expression assessed by immunohistochemistry. Methods: A total of 465 formalin-fixed, paraffin-embedded non-small cell lung cancer samples were analyzed by ALK FISH (PathVysion, Vysis, Abbott) and ALK CISH. For comparison, all specimens were stained by immunohistochemistry (clone 5A4, Novocastra) and interobserver reproducibility was assessed. Results: We found that agreement between the pathologists on the CISH-determined ALK status was achieved in 449 patients (96.6%), and ALK rearrangement was identified in 18 patients (4.0%) in CISH method. Among these cases, 443 cases (95.3%) had results matching the corresponding FISH results: 17 rearranged, 425 wild types, and 1 discordant case. There was high concordance in the assessment of ALK gene rearrangement between FISH and CISH techniques (&kgr; = 0.92) and between observers (&kgr; = 0.97). In addition, there was high concordance in the ALK gene status and ALK protein expression between CISH and IHC tests (&kgr; = 0.82). Conclusions: CISH is a highly reproducible and practical method to detect ALK gene rearrangement and correlated well with ALK protein expression. Here, we present a diagnostic algorithm (Chungs SNUBH ALK protocol) to detect lung cancer with ALK rearrangements using IHC, FISH and CISH. Because CISH allows a concurrent analysis of histological features of the tumors and gene rearrangement, it appears to be a useful method in determining ALK gene rearrangement.

Development of automated brightfield double In Situ hybridization (BDISH) application for HER2 gene and chromosome 17 centromere (CEN 17) for breast carcinomas and an assay performance comparison to manual dual color HER2 fluorescence In Situ hybridization (FISH)

BackgroundHuman epidermal growth factor receptor 2 (HER2) fluorescence in situ hybridization (FISH) is a quantitative assay for selecting breast cancer patients for trastuzumab therapy. However, current HER2 FISH procedures are labor intensive, manual methods that require skilled technologists and specialized fluorescence microscopy. Furthermore, FISH slides cannot be archived for long term storage and review. Our objective was to develop an automated brightfield double in situ hybridization (BDISH) application for HER2 gene and chromosome 17 centromere (CEN 17) and test the assay performance with dual color HER2 FISH evaluated breast carcinomas.MethodsThe BDISH assay was developed with the nick translated dinitrophenyl (DNP)-labeled HER2 DNA probe and DNP-labeled CEN 17 oligoprobe on the Ventana BenchMark® XT slide processing system. Detection of HER2 and CEN 17 signals was accomplished with the silver acetate, hydroquinone, and H2O2 reaction with horseradish peroxidase (HRP) and the fast red and naphthol phosphate reaction with alkaline phosphatise (AP), respectively. The BDISH specificity was optimized with formalin-fixed, paraffin-embedded xenograft tumors, MCF7 (non-amplified HER2 gene) and BT-474 (amplified HER2 gene). Then, the BDISH performance was evaluated with 94 routinely processed breast cancer tissues. Interpretation of HER2 and CEN 17 BDISH slides was conducted by 4 observers using a conventional brightfield microscope without oil immersion objectives.ResultsSequential hybridization and signal detection for HER2 and CEN 17 ISH demonstrated both DNA targets in the same cells. HER2 signals were visualized as discrete black metallic silver dots while CEN 17 signals were detected as slightly larger red dots. Our study demonstrated a high consensus concordance between HER2 FISH and BDISH results of clinical breast carcinoma cases based on the historical scoring method (98.9%, Simple Kappa = 0.9736, 95% CI = 0.9222 – 1.0000) and the ASCO/CAP scoring method with the FISH equivocal cases (95.7%, Simple Kappa = 0.8993%, 95% CI = 0.8068 – 0.9919) and without the FISH equivocal cases (100%, Simple Kappa = 1.0000%, 95% CI = 1.0000 – 1.0000).ConclusionAutomated BDISH applications for HER2 and CEN 17 targets were successfully developed and it might be able to replace manual two-color HER2 FISH methods. The application also has the potential to be used for other gene targets. The use of BDISH technology allows the simultaneous analyses of two DNA targets within the context of tissue morphological observation.

Increased MYC gene copy number correlates with increased mRNA levels in diffuse large B-cell lymphoma

Background Translocations involving the MYC gene and increased MYC mRNA levels are associated with poor outcome in diffuse large B-cell lymphoma. However, the presence of increased MYC gene copy number and/or polysomy of chromosome 8 have not been previously described. Design and Methods Utilizing dual color chromogenic in situ hybridization, we investigated MYC gene copy and chromosome 8 centromere numbers in 52 cases of diffuse large B-cell lymphoma. Cases were divided into those with “increased” or “not increased” MYC gene copy number for comparison with MYC mRNA levels, Ki-67 values, and survival. Results Increased MYC gene copy number was present in 38% of cases. Overall, the average MYC mRNA level was 2398 (range, 342 – 9783) and the percentage of nuclei positive for Ki-67 was 57.5% (range, 20–87%). Within the group with increased MYC copy number, the MYC mRNA values ranged from 816 to 5912 (average, 2843) and the Ki-67 values ranged from 23% to 83% (average, 57%). Within the group with not increased MYC copy number, MYC mRNA values ranged from 342 to 9783 (average, 2118) and the Ki-67 values ranged from 20% to 87% (average, 58%). There was a statistically significant relationship between increased MYC gene copy number and increased MYC mRNA (P=0.034) and a trend toward a relationship between increased mRNA and higher Ki-67 values. Conclusions This is the first report that low level copy number increases are common in diffuse large B-cell lymphoma and that these changes correlate with MYC mRNA in a statistically significant manner. MYC copy number changes are an additional possible molecular mechanism that may result in increased mRNA and, likely, high proliferation and poor outcome.

Bright-Field Dual-Color Chromogenic In Situ Hybridization for Diagnosing Echinoderm Microtubule-Associated Protein-Like 4-Anaplastic Lymphoma Kinase-Positive Lung Adenocarcinomas

Introduction: A subset of lung cancers harbors an EML4-ALK (echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase) gene fusion, and detecting this subset may hold therapeutic implications. Many prior studies used fluorescence in situ hybridization (FISH) analysis for this detection, but FISH may have disadvantages including signal decay and dark-field examination that may obscure tissue architecture. In this study, we explored the potential of the ALK-break-apart chromogenic in situ hybridization (CISH) method to detect ALK-rearranged lung cancer. Methods: We examined 15 lung adenocarcinomas with reverse-transcriptase polymerase chain reaction-proven EML4-ALK fusion transcripts and 30 ALK-negative cases. One hundred tumor cells were evaluated by CISH and FISH for each case, and a detailed signal profile was recorded and compared. Results: CISH preserved tissue architecture and cytomorphology considerably and facilitated the signal evaluation using a routine light microscope. Positive rearrangement signals (splits or isolated 3′ signals) were identified in 13 to 78% (mean ± SD, 41% ± 19%) of tumor cells in the ALK-positive cohort and in 0 to 15% (mean ± SD, 6% ± 4%) of cells in the ALK-negative cohort. The two groups were best separated by a cutoff value of 20%, with a sensitivity of 93% and a specificity of 100%. The only false-negative tumor having only 13% CISH-positive cells displayed predominantly (76%) isolated 5′ signals unaccompanied by 3′ signals. FISH showed largely similar signal profiles, and the results were completely concordant with CISH. Conclusions: We have successfully introduced CISH for diagnosing EML4-ALK-positive lung adenocarcinoma. This method allows simultaneous visualization of genetics and tumor cytomorphology and facilitates the molecular evaluation and could be applicable in clinical practice to detect lung cancer that may be responsive to ALK inhibitors.

New Methods for ALK Status Diagnosis in Non–Small-Cell Lung Cancer: An Improved ALK Immunohistochemical Assay and a New, Brightfield, Dual ALK IHC–In Situ Hybridization Assay

Introduction: The demonstration of anaplastic lymphoma kinase (ALK) positivity in non–small-cell lung cancer (NSCLC) has been hindered by the technical complexity and interpretative challenges of fluorescence in situ hybridization methods for detection of ALK gene rearrangement and by the inadequate sensitivity of existing immunohistochemistry (IHC) methods for ALK protein detection. In this study, we sought to increase the sensitivity of ALK IHC detection and to develop a brightfield assay for concurrent detection of ALK protein expression and ALK gene rearrangement. Methods: We developed a horseradish peroxidase–based IHC detection system using the novel, nonendogenous hapten 3-hydroxy-2-quinoxaline (HQ) and tyramide. We also developed a dual gene protein ALK assay combining a brightfield break-apart in situ hybridization ALK assay with another sensitive IHC method using the novel, nonendogenous hapten 5-nitro-3-pyrazole. We examined the sensitivity and accuracy of these methods using surgically resected NSCLC cases examined with ALK fluorescence in situ hybridization. Results: The new HQ-tyramide IHC detection system offered readily interpretable staining with substantially greater sensitivity than conventional ALK IHC, and produced heterogeneous and homogeneous patterns of ALK protein staining among ALK-positive NSCLC surgical cases. The new 5-nitro-3-pyrazole–based IHC detection system was similar in ALK detection sensitivity to the HQ-tyramide IHC system and was compatible with the brightfield in situ hybridization assay. Conclusion: The new HQ-tyramide IHC reagent system allows more sensitive assessment of ALK protein status in NSCLC cases. The new ALK gene-protein assay allows the concurrent visualization of ALK gene and ALK protein status in single cells, allowing more accurate ALK status determination even in heterogeneous specimens.

Application of automated mRNA in situ hybridization for formalin-fixed, paraffin-embedded mouse skin sections: effects of heat and enzyme pretreatment on mRNA signal detection.

Recently, an automated mRNA in situ hybridization application was introduced for the Ventana Discovery instrument. The application was designed so that all necessary steps from baking through signal detection were completed within 1 day on the instrument. We applied this technology for visualizing the expression site of versican in formalin-fixed mouse skin paraffin tissue sections. Our focus of this study was to demonstrate the effects of protease digestion or heating pretreatment, termed cell conditioning, on the hybridization signal using a well characterized versican antisense riboprobe. Paraffin sections were automatically deparaffinized, fixed, and acid-treated. Then, the tissue sections were subjected to protease digestion alone (3 strengths), cell conditioning alone, or the combination of cell conditioning and protease digestion. Hybridization was performed with digoxigenin-labeled versican antisense probe (20 ng/slide) for 6 hours, and the signal was detected using a Nitro blue Tetrazolium chloride 5-Bromo-4-cloro-3-indolyl phosphate toluidine salt (NBT/BCLIP) substrate solution for 3 hours on the instrument. Cell conditioning alone did not produce any signal, whereas the highest strength of protease digestion produced noticeable background staining. However, when cell conditioning and mild protease digestion were combined, the signal for versican mRNA was clearly demonstrated in the hair papilla region. Thus, we demonstrated the effects of the cell conditioning step followed by mild protease digestion for enhancing the mRNA target staining compared with protease digestion or the cell conditioning step alone. We verified that the automated in situ hybridization process was applicable for formalin-fixed mouse skin paraffin sections and that the automated 1-day protocol is simple and reproducible. The precise control of automation allows fine tuning of temperature and enzyme dose to find the optimized assay condition for the signal to noise ratio and morphology.

Epidermal growth factor receptor mutation-specific immunohistochemical antibodies in lung adenocarcinoma

We investigated the sensitivity and specificity of two novel Epidermal growth factor receptor (EGFR) mutation‐specific antibodies in the detection of the most common EGFR mutations in lung adenocarcinoma.

Insulin-like growth factor-1 receptor protein expression and gene copy number alterations in non–small cell lung carcinomas

Insulin-like growth factor-1 receptor (IGF-1R) is a tyrosine kinase receptor implicated in the pathogenesis of several malignancies and is potentially an attractive target for anticancer treatment. In this study, we included 379 patients who underwent surgical resection (179 diagnosed as having adenocarcinoma [ADC]; 150, squamous cell carcinoma [SCC]; 41, sarcomatoid carcinoma and 9, large cell carcinoma). IGF-1R expression and gene copy number were assessed by immunohistochemistry and bright-field in situ hybridization (BISH), respectively. IGF-1R expression in non-small cell lung carcinoma was observed in 41.4% of samples and was more prevalent in SCC (69.3%) than in ADC (25.1%), large cell carcinoma (33.3%), and sarcomatoid carcinoma (12.2%) (P < .001). Among ADCs, most mucinous ADCs (75%) showed strong membranous staining with the IGF-1R antibody. Compared with protein expression, IGF-1R gene alteration was rare (8.4%). A statistically significant correlation between IGF-1R expression and positive IGF-1R BISH was observed (γ = 0.762, P < .001). IGF-1R-positive tumors were more common in smokers (P = .004), and these tumors were larger (P = .006) than the IGF-1R-negative tumors. IGF-1R BISH positivity was not correlated with any clinicopathologic factor. IGF-1R expression and IGF-1R BISH positivity were not correlated with overall survival. IGF-1R is highly expressed in SCC and mucinous ADC, although copy number alterations in the IGF-1R gene were rare. These findings may have important implications for future anti-IGF-1R therapeutic approaches.

The assessment of HER2 status in breast cancer: the past, the present, and the future

Humanized monoclonal anti‐human growth factor receptor 2 (HER2) antibody trastuzumab was approved for HER2 positive breast cancer patient treatment 11 years after the demonstration of HER2 gene amplification associated with the HER2 protein overexpression in breast cancer in 1987. HER2 positive status of breast cancer patients is assessed by HER2 gene amplification with in situ hybridization (ISH) and/or HER2 protein overexpression with immunohistochemistry (IHC). Because the discordance between quantitative HER2 ISH and subjective, semi‐quantitative HER2 IHC assay results is a well‐recognized issue of HER2 testing, we developed an assay combining HER2 ISH and HER2 IHC assays (HER2 gene‐protein assay; HER2 GPA) as one test on the same tissue section. HER2 GPA allows pathologists to score the HER2 gene and HER2 protein status simultaneously at the individual cell level. The possibility that HER2 GPA may become the next generation of HER2 testing is discussed, particularly for cases in which it is difficult to assess the HER2 status of breast cancer patients due to the HER2 heterogeneity.

HER2 intratumoral heterogeneity analyses by concurrent HER2 gene and protein assessment for the prognosis of HER2 negative invasive breast cancer patients

HER2 gene-protein assay (GPA) is a new method for the simultaneous evaluation of HER2 immunohistochemistry (IHC) and HER2 dual in situ hybridization (DISH) on single tissue sections of breast cancer. We investigated the presence of HER2 gene and protein discrepancy and HER2-heterogeneity using HER2-GPA. HER2 status was analyzed for the correlation between the presence of HER2-heterogeneity and patient prognosis. Consecutive 280 invasive breast cancer were examined. Statuses of HER2 protein and gene were evaluated in whole tumor sections of HER2 GPA slides. HER2 protein and gene combination patterns were classified to six phenotypic and genotypic types for each case, as well as at individual cell levels: (A) IHC and DISH positive; (B) IHC positive and DISH negative; (C) IHC equivocal and DISH positive; (D) IHC equivocal and DISH negative; (E) IHC negative and DISH positive; and (F) IHC and DISH negative. The presence of HER2-heterogeneity was determined by the existence of at least two of six types within one tumor. HER2-IHC positive patients had significantly worse survival than IHC negative patients and HER2-DISH positive patients had significantly worse survival than DISH negative patients. HER2 IHC negative and DISH positive patients had significantly worse recurrence-free survival than IHC and DISH negative patients. In the HER2 IHC and DISH negative group, the HER2 heterogeneous group had significantly worse survival than the nonheterogeneous group. Notably, among triple negative breast cancer (TNBC), the HER2 heterogeneous group had significantly worse survival than the nonheterogeneous group. Our study suggests that the presence of HER2-heterogeneity might be a prognostic factor in HER2 negative breast cancer patients, especially in TNBC.