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.

Immunohistochemistry of colorectal cancer biomarker phosphorylation requires controlled tissue fixation.

Phosphorylated signaling molecules are biomarkers of cancer pathophysiology and resistance to therapy, but because phosphoprotein analytes are often labile, poorly controlled clinical laboratory practices could prevent translation of research findings in this area from the bench to the bedside. We therefore compared multiple biomarker and phosphoprotein immunohistochemistry (IHC) results in 23 clinical colorectal carcinoma samples after either a novel, rapid tissue fixation protocol or a standard tissue fixation protocol employed by clinical laboratories, and we also investigated the effect of a defined post-operative "cold" ischemia period on these IHC results. We found that a one-hour cold ischemia interval, allowed by ASCO/CAP guidelines for certain cancer biomarker assays, is highly deleterious to certain phosphoprotein analytes, specifically the phosphorylated epidermal growth factor receptor (pEGFR), but shorter ischemic intervals (less than 17 minutes) facilitate preservation of phosphoproteins. Second, we found that a rapid 4-hour, two temperature, formalin fixation yielded superior staining in several cases with select markers (pEGFR, pBAD, pAKT) compared to a standard overnight room temperature fixation protocol, despite taking less time. These findings indicate that the future research and clinical utilities of phosphoprotein IHC for assessing colorectal carcinoma pathophysiology absolutely depend upon attention to preanalytical factors and rigorously controlled tissue fixation protocols.

BCL2 antibodies targeted at different epitopes detect varying levels of protein expression and correlate with frequent gene amplification in diffuse large B-cell lymphoma.

Patients with aggressive, BCL2 protein-positive (+) diffuse large B-cell lymphoma (DLBCL) often experience rapid disease progression that is refractory to standard therapy. However, there is potential for false-negative staining of BCL2 using the standard monoclonal mouse 124 antibody that hinders the identification of these high-risk DLBCL patients. Herein, we compare 2 alternative rabbit monoclonal antibodies (E17 and SP66) to the 124 clone in staining for BCL2 in formalin-fixed, paraffin-embedded DLBCL tissues. Overall, in 2 independent DLBCL cohorts, E17 and SP66 detected BCL2 expression more frequently than 124. In the context of MYC expression, cases identified as BCL2 (+) with SP66 demonstrated the strongest correlation with worse overall survival. The 124 clone failed to detect BCL2 expression in the majority of translocation (+), amplification (+), and activated B-cell DLBCL cases in which high levels of BCL2 protein are expected. Using dual in situ hybridization as a new tool to detect BCL2 translocation and amplification, we observed similar results as previously reported for fluorescence in situ hybridization for translocation but a higher amplification frequency, indicating that BCL2 amplification may be underreported in DLBCL. Among the discrepant cases, phosphorylation of BCL2 at T69 and/or S70 was more common than in the concordant cases and may contribute to the 124 false negatives, in addition to previously associated mutations within the epitope region. The accurate detection of BCL2 expression is important in the prognosis and treatment of DLBCL particularly with new anti-BCL2 therapies.

Childhood florid follicular hyperplasia with immunoglobulin light-chain restriction in the gastrointestinal tract.

AIMS: Immunoglobulin light-chain expression is used routinely as an indirect marker of clonality for recognizing B cell lymphoproliferative disorders. METHODS AND RESULTS: Here we describe four floral follicular hyperplasia cases in the gastrointestinal tract (appendix and rectum) of children (4 to 6 years). Immunohistochemical studies revealed lambda light-chain restriction that was associated with polyclonal IgH pattern. Clinical features and follow-up of the patients did not reveal any other systemic symptoms, laboratory abnormalities or organ alterations. CONCLUSIONS: Recognition of this phenomenon is useful in the diagnosis of nodular lymphoid hyperplasia of the gastrointestinal tract, for avoiding overdiagnosis of lymphoid malignancies, and raises concerns that the identification of light-chain restriction is not necessarily a marker of monoclonality.

Kappa and lambda light chain mRNA in situ hybridization compared to flow cytometry and immunohistochemistry in B cell lymphomas.

BACKGROUND: Detection of B cell clonality is useful for assisting in the diagnosis of B cell lymphomas. Clonality assessment can be accomplished through evaluation of KAPPA and LAMBDA light chain expression. Currently, only slide based methods are available for the majority of patient biopsies and do not detect light chain protein or mRNA in many B-cell lymphomas. Herein we evaluated a new method, known as colorimetric in situ hybridization (CISH), with improved sensitivity and multiplexing capacity, for its usefulness in clonality detection in mature B cell malignancies. METHODS: The KAPPA and LAMBDA ISH was performed on a Ventana Benchmark XT utilizing two color chromogenetic detection. The probes comprised 2 haptenated riboprobes each approximately 500 base pairs long directed against the conserved regions of either KAPPA or LAMBDA mRNA. The dual colors consisted of silver deposition (black) for KAPPA light chain and a novel (pink) chromogen for LAMBDA light chain. Following optimization, CISH allowed visualization of mRNA in benign B cells in reactive tissues including germinal center, mantle zone, and post-germinal center cells. We then identified 79 cases of B cell lymphoma with formalin-fixed paraffin-embedded (FFPE) biopsies including: follicular (36 cases), mantle cell (6 cases), marginal zone (12 cases), lymphoplasmacytic (6 cases), small lymphocytic (4 cases), and diffuse large B cell (15 cases), which were selected on the basis of either prior flow cytometry or immunohistochemistry (IHC) results to serve as the predicate, "gold standard," comparator. RESULTS: 39/79 (49.4%) cases were classified as KAPPA and 29/79 (36.7%) as LAMBDA light chain restricted; while 9/79 (11.3%) cases were classified as indeterminate. Of the 70 cases with KAPPA or LAMBDA light chain restricted CISH, 69/70 (98.6%) were concordant with the reference method, while 1/70 (1.4%) was discordant. CONCLUSIONS: Optimized CISH detected lower levels of mRNA than can be visualized with current slide based methods, making clonality assessment in FFPE biopsies possible for mature B cell neoplasms. In this preliminary study, CISH was highly accurate compared to flow cytometry or IHC. CISH offers the possibility of wider applicability of light chain ISH and is likely to become a useful diagnostic tool. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1430491067123856.

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.

Mutation-specific antibody detects mutant BRAFV600E protein expression in human colon carcinomas.

BACKGROUND: A point mutation (V600E) in the BRAF oncogene is a prognostic biomarker and may predict for nonresponse to anti-EGFR antibody therapy in patients with colorectal carcinoma. BRAFV600E mutations are frequently detected in tumors with microsatellite instability and indicate a sporadic origin. We used a mutation-specific antibody to examine mutant BRAFV600E protein expression and its concordance with BRAFV600E mutation data. METHODS: Primary stage III colon carcinomas were analyzed for BRAFV600E mutations in exon 15, and 50 BRAFV600E mutation carriers and 25 wild-type tumors were selected for analysis of BRAF proteins by immunohistochemistry (IHC). IHC was performed in archival tissue specimens using a pan-BRAF antibody and a mutation-specific antibody against BRAFV600E proteins. Staining was scored by 2 pathologists who were blinded to clinical and mutation data. RESULTS: Using a pan-BRAF antibody, total BRAF protein expression was observed in the tumor cell cytoplasm in 74 of 75 colon carcinomas. A mutation-specific antibody identified diffuse cytoplasmic staining of mutant BRAFV600E proteins in 49 of 74 cancers. Analysis using a polymerase chain reaction-based assay revealed that all 49 of these cancers carried BRAFV600E mutations. In contrast, BRAFV600E staining was absent in all 25 tumors that carried wild-type copies of BRAF. CONCLUSIONS: A BRAF mutation-specific (V600E) antibody detected tumors with BRAFV600E mutations and exhibited complete concordance with a DNA-based method. These results support the use of IHC as a simplified strategy to screen colorectal cancers for BRAFV600E mutations in clinical practice.

Another look at follicular lymphoma: immunophenotypic and molecular analyses identify distinct follicular lymphoma subgroups.

AIMS: The aim of this study was to analyse the immunophenotypic and molecular features of a large series of follicular lymphomas, focusing in particular on atypical cases that fail to express CD10 and/or bcl-2. Such cases present diagnostic pitfalls, especially with regard to the differential diagnosis from follicular hyperplasia and marginal zone B-cell lymphoma. Therefore, we also included an immunohistochemical evaluation of stathmin, which is strongly expressed by germinal centre B cells, as a putative new marker for follicular lymphomas, particularly those with an atypical phenotype. METHODS AND RESULTS: Two hundred and five follicular lymphomas were investigated with immunohistochemistry and fluorescence in-situ hybridization (FISH). The use of three distinct anti-bcl-2 antibodies together with CD10 expression data and FISH analysis for bcl-2 and bcl-6 rearrangements allowed subclassification of follicular lymphoma into four distinct subgroups: (i) CD10-positive/bcl-2-positive, (ii) CD10-positive/bcl-2-negative, (iii) CD10-negative/bcl-2-positive, and (iv) CD10-negative/bcl-2-negative. All cases were bcl-6-positive. STMN1 (stathmin) was shown to be helpful in diagnosing bcl-2-negative and/or CD10-negative follicular lymphomas, and in their distinction from marginal zone B-cell lymphoma. CONCLUSIONS: Combined immunohistological and molecular analyses reveal that follicular lymphomas showing an atypical immunophenotypic and molecular profile exist, and we demonstrate that STMN1 represents a novel useful diagnostic marker for these.

Bright-field in situ hybridization methods to discover gene amplifications and rearrangements in clinical samples.

Brightfield in situ hybridization (BISH) applications have significant advantages over traditional fluorescence in situ hybridization (FISH). BISH slides can be analyzed using a regular microscope while FISH slides require the use of a specialized fluorescence microscope. BISH slides allow observers for correlating the gene status (gene amplifications, gene rearrangements, and gene deletions) and tissue morphology better than FISH slides. Also, BISH slides are ideal for the permanent preservation of gene signals. Furthermore, BISH applications can be optimized using an automated tissue slide processing system. BISH applications are becoming a popular method for clinical examination of gene status for selecting cancer treatments.

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.

Concurrent expression of MYC and BCL2 in diffuse large B-cell lymphoma treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone.

PURPOSE: Diffuse large B-cell lymphoma (DLBCL) is curable in 60% of patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). MYC translocations, with or without BCL2 translocations, have been associated with inferior survival in DLBCL. We investigated whether expression of MYC protein, with or without BCL2 protein expression, could risk-stratify patients at diagnosis. PATIENTS AND METHODS: We determined the correlation between presence of MYC and BCL2 proteins by immunohistochemistry (IHC) with survival in two independent cohorts of patients with DLBCL treated with R-CHOP. We further determined if MYC protein expression correlated with high MYC mRNA and/or presence of MYC translocation. RESULTS: In the training cohort (n = 167), MYC and BCL2 proteins were detected in 29% and 44% of patients, respectively. Concurrent expression (MYC positive/BCL2 positive) was present in 21% of patients. MYC protein correlated with presence of high MYC mRNA and MYC translocation (both P < .001), but the latter was less frequent (both 11%). MYC protein expression was only associated with inferior overall and progression-free survival when BCL2 protein was coexpressed (P < .001). Importantly, the poor prognostic effect of MYC positive/BCL2 positive was validated in an independent cohort of 140 patients with DLBCL and remained significant (P < .05) after adjusting for presence of high-risk features in a multivariable model that included elevated international prognostic index score, activated B-cell molecular subtype, and presence of concurrent MYC and BCL2 translocations. CONCLUSION: Assessment of MYC and BCL2 expression by IHC represents a robust, rapid, and inexpensive approach to risk-stratify patients with DLBCL at diagnosis.

A gene-protein assay for human epidermal growth factor receptor 2 (HER2): brightfield tricolor visualization of HER2 protein, the HER2 gene, and chromosome 17 centromere (CEN17) in formalin-fixed, paraffin-embedded breast cancer tissue sections.

BACKGROUND: The eligibility of breast cancer patients for human epidermal growth factor receptor 2 (HER2)-directed therapies is determined by the HER2 gene amplification and/or HER2 protein overexpression status of the breast tumor as determined by in situ hybridization (ISH) or immunohistochemistry (IHC), respectively. Our objective was to combine the US Food and Drug Administration (FDA)-approved HER2 & chromosome 17 centromere (CEN17) brightfield ISH (BISH) and HER2 IHC assays into a single automated HER2 gene-protein assay allowing simultaneous detection of all three targets in a single tissue section. METHODS: The HER2 gene-protein assay was optimized using formalin-fixed, paraffin-embedded (FFPE) samples of the xenograft tumors MCF7 [HER2 negative (non-amplified gene, protein negative)] and Calu-3 [HER2 positive (amplified gene, protein positive)]. HER2 IHC was performed using a rabbit monoclonal anti-HER2 antibody (clone 4B5) and a conventional 3,3'-diaminobenzidine IHC detection. The HER2 & CEN17 BISH signals were visualized using horseradish peroxidase-based silver and alkaline phosphatase-based red detection systems, respectively with a cocktail of 2,4-dinitrophenyl-labeled HER2 and digoxigenin-labeled CEN17 probes. The performance of the gene-protein assay on tissue microarray slides containing 189 randomly selected FFPE clinical breast cancer tissue cores was compared to that of the separate HER2 IHC and HER2 & CEN17 BISH assays. RESULTS: HER2 protein detection was optimal when the HER2 IHC protocol was used before (rather than after) the BISH protocol. The sequential use of HER2 IHC and HER2 & CEN17 BISH detection steps on FFPE xenograft tumor sections appropriately co-localized the HER2 protein, HER2 gene, and CEN17 signals after mitigating the silver background staining by using a naphthol phosphate-containing hybridization buffer for the hybridization step. The HER2 protein and HER2 gene status obtained using the multiplex HER2 gene-protein assay demonstrated high concordance with those obtained using the separate HER2 IHC and HER2 & CEN17 BISH assays, respectively. CONCLUSIONS: We have developed a protocol that allows simultaneous visualization of the HER2 IHC and HER2 & CEN17 BISH targets. This automated protocol facilitated the determination of HER2 protein and HER2 gene status in randomly selected breast cancer samples, particularly in cases that were equivocal or exhibited tumor heterogeneity. The HER2 gene-protein assay produced results virtually equivalent to those of the single FDA-approved HER2 IHC and HER2 & CEN17 BISH assays. VIRTUAL SLIDES: The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2041964038705297.

Partial plasma cell differentiation as a mechanism of lost major histocompatibility complex class II expression in diffuse large B-cell lymphoma.

Loss of major histocompatibility complex class II (MHC II) expression is associated with poor patient outcome in diffuse large B-cell lymphoma (DLBCL). As MHC II molecules are lost with plasmacytic differentiation in normal cells, we asked whether MHC II loss in DLBCL is associated with an altered differentiation state. We used gene expression profiling, quantum dots, and immunohistochemistry to study the relationship between MHC II and plasma cell markers in DLBCL and plasmablastic lymphoma (PBL). Results demonstrate that MHC II(-) DLBCL immunophenotypically overlap with PBL and demonstrate an inverse correlation between MHC II and plasma cell markers MUM1, PRDM1/Blimp1, and XBP1s. In addition, MHC II expression is significantly higher in germinal center-DLBCL than activated B cell-DLBCL. A minor subset of cases with an unusual pattern of mislocalized punctate MHC II staining and intermediate levels of mRNA is also described. Finally, we show that PBL is negative for MHC II. The results imply a spectrum of MHC II expression that is more frequently diminished in tumors derived from B cells at the later stages of differentiation (with complete loss in PBL). Our observations provide a possible unifying concept that may contribute to the poor outcome reported in all MHC II(-) B-cell tumors.

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.

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 (κ = 0.92) and between observers (κ = 0.97). In addition, there was high concordance in the ALK gene status and ALK protein expression between CISH and IHC tests (κ = 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 (Chung's 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.

The pre-B-cell receptor associated protein VpreB3 is a useful diagnostic marker for identifying c-MYC translocated lymphomas.

BACKGROUND: During B-cell development, precursor B cells transiently express the pre-B-cell receptor composed of µ heavy chain complexed with VpreB and λ5 surrogate light chain polypeptides. Recent profiling studies unexpectedly revealed abundant transcripts of one member of the VpreB family, VpreB3, in a subset of mature B cells and Burkitt lymphoma. DESIGN AND METHODS: Here we used a novel antibody to investigate the normal expression pattern of VpreB3 protein in human hematopoietic and lymphoid tissues, and to determine whether VpreB3 could serve as a useful diagnostic biomarker for select B-cell lymphomas. RESULTS: We found that VpreB3 protein is normally expressed by precursor B cells in bone marrow and by a subset of normal germinal center B cells in secondary lymphoid organs. Among lymphoid malignancies, we found an association between VpreB3 expression and B-cell tumors with c-MYC abnormalities. VpreB3 was highly expressed in all cases of Burkitt lymphoma, whether of endemic or sporadic origin (44/44 cases, 100%), all cases of B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma (5/5 cases, 100%), and the majority of diffuse large B-cell lymphomas harboring a c-MYC translocation (15/18 cases, 83%). The expression of VpreB3 in diffuse large B-cell lymphomas without a c-MYC translocation was associated with c-MYC polysomy in 25/75 cases (33%) but only rarely observed in diffuse large B-cell lymphomas lacking a c-MYC abnormality (9/98 cases, 9%). CONCLUSIONS: We conclude that for B-cell tumors with features suggesting a possible c-MYC translocation, such as intermediate to large cell size and high proliferation rate, the presence of VpreB3 should prompt subsequent confirmatory genetic testing, whereas the absence of VpreB3 is virtually always associated with wild-type c-MYC alleles.

The impact of pre-analytical processing on staining quality for H&E, dual hapten, dual color in situ hybridization and fluorescent in situ hybridization assays.

With the advent of personalized medicine, anatomic pathology-based molecular assays, including in situ hybridization (ISH) and mRNA detection tests, are performed routinely in many laboratories and have increased in their clinical importance and complexity. These assays require appropriately fixed tissue samples that preserve both nucleic acid targets and histomorphology to ensure reliable test results for determining patient treatment options. However, all aspects of tissue processing, including time until tissue fixation, type of fixative, duration of fixation, post-fixation treatments, and sectioning of the sample, impact the staining results. ASCO/CAP has issued pre-analytical guidelines to standardize tissue processing for HER2 testing in breast carcinoma specimens: 10% neutral-buffered formalin (NBF) with a fixation time from at least 6 to 48h [1]. Often, this recommendation is not followed to the detriment of staining results [2]. In this paper, we used a human breast carcinoma cell line (MCF7) generated as xenograft tumors as a model system to analyze the effects of different pre-analytical conditions on ISH staining. We performed H&E, FISH and dual colorimetric HER2 ISH assays using specimens fixed across a range of times in six different commonly used fixatives. Additionally, we investigated the effects of varying tissue section thickness, which also impacted the quality of ISH staining. Finally, we evaluated the effects of three different decalcifying solutions on human breast specimens, typically a treatment that occurs post-fixation for evaluating metastases to bone. The results indicate that time and type of fixation treatment, as well as appropriate tissue thickness and post-fixation treatment, all contribute to the quality of ISH staining results. Our data support the ASCO/CAP recommendations for standardized tissue processing (at least 6h in formalin-based fixatives and 4µm section thickness) and indicate that certain fixatives and post-fixative treatments are detrimental to molecular staining results.

Automated brightfield break-apart in situ hybridization (ba-ISH) application: ALK and MALT1 genes as models.

Cancer diagnosis can be a complex process, which takes consideration of histopathological, clinical, immunophenotypic, and genetic features. Since non-random chromosomal translocations are specifically involved in the development of various cancers, the detection of these gene aberrations becomes increasingly important. In recent years, break-apart (or split-signal) fluorescence in situ hybridization (FISH) has emerged as an advantageous technique to detect gene translocations on tissue sections. However, FISH assays are technically challenging and require specialized fluorescence microscopes. Furthermore, the FISH signal is not stable for long term archiving due to photo bleaching. Our objective was to demonstrate the feasibility of brightfield break-apart in situ hybridization (ba-ISH) for anaplastic lymphoma kinase (ALK) and mucosa-associated lymphoid tissue translocation protein 1 (MALT1) genes as models. ALK or MALT1 break-apart probes were labeled with digoxigenin (DIG) or 2,4-dinitrophenyl (DNP) on both sides of a known gene breakpoint region and the hybridization sites were visualized with the combination of alkaline phosphatase (AP)-based blue and red detection. Therefore, normal genes are detected as purple dots by mixing blue and red colors while translocated genes are detected as isolated blue or red dots. Formalin-fixed, paraffin-embedded tonsil was used as control for the co-localized 5' and 3' probes. Gene translocations of ALK or MALT1 were detected as separate blue and red dots on ALCL and MALT lymphoma cases. Thus, ISH analyses of gene translocations can be conducted with a regular light microscope and the long term archiving of break-apart ISH slides can be achieved.

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.