A formalin-fixed, paraffin-processed cell line standard for quality control of immunohistochemical assay of HER-2/neu expression in breast cancer

Quantitative systems pharmacology modeling of HER2-positive metastatic breast cancer for translational efficacy evaluation and combination assessment across therapeutic modalities

HER2-positive (HER2+) metastatic breast cancer (mBC) is highly aggressive and a major threat to human health. Despite the significant improvement in patients' prognosis given the drug development efforts during the past several decades, many clinical questions still remain to be addressed such as efficacy when combining different therapeutic modalities, best treatment sequences, interindividual variability as well as resistance and potential coping strategies. To better answer these questions, we developed a mechanistic quantitative systems pharmacology model of the pathophysiology of HER2+ mBC that was extensively calibrated and validated against multiscale data to quantitatively predict and characterize the signal transduction and preclinical tumor growth kinetics under different therapeutic interventions. Focusing on the second-line treatment for HER2+ mBC, e.g., antibody-drug conjugates (ADC), small molecule inhibitors/TKI and chemotherapy, the model accurately predicted the efficacy of various drug combinations and dosing regimens at the in vitro and in vivo levels. Sensitivity analyses and subsequent heterogeneous phenotype simulations revealed important insights into the design of new drug combinations to effectively overcome various resistance scenarios in HER2+ mBC treatments. In addition, the model predicted a better efficacy of the new TKI plus ADC combination which can potentially reduce drug dosage and toxicity, while it also shed light on the optimal treatment ordering of ADC versus TKI plus capecitabine regimens, and these findings were validated by new in vivo experiments. Our model is the first that mechanistically integrates multiple key drug modalities in HER2+ mBC research and it can serve as a high-throughput computational platform to guide future model-informed drug development and clinical translation.

Immunohistochemical study of mixing mineral trioxide aggregate with hyaluronic acid as a pulp-capping agent in dog teeth

Objective

The purpose of this study was to evaluate the immunohistochemical effect of hyaluronic acid (HA) on the mineralization rate of the reparative dentin when it is used as a mixing medium with mineral trioxide aggregate (MTA).

Materials and Methods

Direct pulp capping (DPC) was performed on 90 teeth from 10 dogs that had been experimentally exposed. The exposed pulps were divided into three groups according to the mixing medium with MTA: Group I: MTA + distilled water (control group), Group II: MTA + hybrid cooperative complex HA (HCC-HA), Group III: MTA + high molecular weight HA (HMW-HA). After pulp capping, all cavities were restored with final restoration. The dogs were divided randomly into five groups (two dogs each) according to the evaluation periods (7, 14, 21, 30, and 60) days. At the end of the study, the dogs were euthanized, and the sampled teeth were processed for immunohistochemical investigation.

Results

Both types of HA (HCC-HA, HMW-HA) showed an increase in the expression of alkaline phosphatase (ALP) at a higher rate than using distilled water with MTA.

Conclusions

Within the limitations of this study, HA proved to be an effective additive to MTA for DPC.

Using American Type Culture Collection Cell Lines to Evaluate Interlaboratory Variables for Estrogen Receptor and Human Epidermal Growth Factor Receptor 2 Immunostaining

CONTEXT.—

Most laboratories currently use patient tissues for validating immunohistochemical stains.

OBJECTIVE.—

To explore advantages of using cell lines with known antigenicity as a validation method.

DESIGN.—

Five American Type Culture Collection (ATCC) cell lines with known negative, low positive, and moderate to strong estrogen receptor (ER) expression as well as negative, equivocal, and positive human epidermal growth factor receptor 2 (HER2) expression were cultured and made into cell blocks. One block from each cell line was fixed in formalin and another in ethanol before cell block preparation. Two sets of paired unstained slides from each block were sent to 10 different laboratories for HER2 and ER staining to be stained on runs from different days according to each laboratory's defined protocol.

RESULTS.—

The 10 study participants evaluated 40 slides in a blinded fashion. For ER expression, all 80 interpretations for the ER strong and moderate positive cell lines had the target ER-positive result, and 74 of 80 ER-negative cell lines (92.5%) had agreement with the intended negative result. The ER low positive cell line showed varied but positive expression among all observers. The HER2 (3+)-positive cell lines yielded a target interpretation of 3+ in 65 of 80 interpretations (81.2%). For the HER2-negative cell line 69 of 78 interpretations (88.5%) were consistent with the target response (0 or 1+). No significant variation was observed between the ethanol- and non-ethanol-exposed cell lines, or between runs by the same laboratory. Variation from target results clustered within laboratories.

CONCLUSIONS.—

This study indicates that variability between laboratories can be identified by using cell lines for quantitative or semiquantitative immunohistochemistry when using cultured cell lines of known antigenicity. These cell lines could potentially play a role in aiding anatomic pathology laboratories in validating immunohistochemistry tests for formalin- and ethanol-fixed tissues.

Methods for preparing tissue microarray slides using xenografts with different levels of HER2 expression to standardize HER2 detection

Gene amplification and protein overexpression of human epidermal growth factor receptor type 2 (HER2) are specific targets for HER2-targeting drugs in breast, gastric, salivary gland, and colorectal cancers. The histopathological determination of HER2 status is crucial for treatment, highlighting the importance of improving HER2 detection accuracy in clinical practice. We prepared tissue microarray (TMA) slides for use as control slides for the standardization of gastric HER2 testing. Four human gastric cancer cell lines with HER2 scores of 3+, 2+, 1+, and 0 were xenografted in NOG mice. The TMA slides were constructed using samples from three different areas in these tumors. Staining properties were determined using six clinical kits for HER2. In TMA, HER2-positive tumors with HER2 scores of 3+ and 2+ showed good staining with all diagnostic kits, and the tissue images were similar to those of clinical samples. Xenograft tumor slides could potentially be used as external controls to standardize staining conditions for a variety of kits and may improve the accuracy of HER2 detection in clinical practice.

Molecular detection of SARS-CoV-2 in formalin-fixed, paraffin-embedded specimens

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of human coronavirus disease 2019 (COVID-19), emerged in Wuhan, China, in December 2019. The virus rapidly spread globally, resulting in a public health crisis including almost 5 million cases and 323,256 deaths as of May 21, 2020. Here, we describe the identification and evaluation of commercially available reagents and assays for the molecular detection of SARS-CoV-2 in infected FFPE cell pellets. We identified a suitable rabbit polyclonal anti-SARS-CoV spike protein antibody and a mouse monoclonal anti-SARS-CoV nucleocapsid protein (NP) antibody for cross-detection of the respective SARS-CoV-2 proteins by IHC and immunofluorescence assay (IFA). Next, we established RNAscope in situ hybridization (ISH) to detect SARS-CoV-2 RNA. Furthermore, we established a multiplex FISH (mFISH) to detect positive-sense SARS-CoV-2 RNA and negative-sense SARS-CoV-2 RNA (a replicative intermediate indicating viral replication). Finally, we developed a dual staining assay using IHC and ISH to detect SARS-CoV-2 antigen and RNA in the same FFPE section. It is hoped that these reagents and assays will accelerate COVID-19 pathogenesis studies in humans and in COVID-19 animal models.

Molecular Detection of SARS-CoV-2 in Formalin Fixed Paraffin Embedded Specimens

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of human coronavirus disease 2019 (COVID-19), emerged in Wuhan, China in December 2019. The virus rapidly spread globally, resulting in a public-health crisis including more than one million cases and tens of thousands of deaths. Here, we describe the identification and evaluation of commercially available reagents and assays for the molecular detection of SARS-CoV-2 in infected formalin fixed paraffin embedded (FFPE) cell pellets. We identified a suitable rabbit polyclonal anti-SARS-CoV spike protein antibody and a mouse monoclonal anti-SARS-CoV nucleocapsid protein (NP) antibody for cross detection of the respective SARS-CoV-2 proteins by immunohistochemistry (IHC) and immunofluorescence assay (IFA). Next, we established RNAscope in situ hybridization (ISH) to detect SARS-CoV-2 RNA. Furthermore, we established a multiplex fluorescence ISH (mFISH) to detect positive-sense SARS-CoV-2 RNA and negative-sense SARS-CoV-2 RNA (a replicative intermediate indicating viral replication). Finally, we developed a dual staining assay using IHC and ISH to detect SARS-CoV-2 antigen and RNA in the same FFPE section. These reagents and assays will accelerate COVID-19 pathogenesis studies in humans and in COVID-19 animal models.

Quantitative Assessment of Immunohistochemistry Laboratory Performance by Measuring Analytic Response Curves and Limits of Detection

Context.—

Numerous studies highlight interlaboratory performance variability in diagnostic immunohistochemistry (IHC) testing. Despite substantial improvements over the years, the inability to quantitatively and objectively assess immunostain sensitivity complicates interlaboratory standardization.

Objective.—

To quantitatively and objectively assess the sensitivity of the immunohistochemical stains for human epidermal growth factor receptor type 2 (HER2), estrogen receptor (ER), and progesterone receptor (PR) across IHC laboratories in a proficiency testing format. We measure sensitivity with parameters that are new to the field of diagnostic IHC: analytic response curves and limits of detection.

Design.—

Thirty-nine diagnostic IHC laboratories stained a set of 3 slides, one each for HER2, ER, and PR. Each slide incorporated a positive tissue section and IHControls at 5 different concentrations. The IHControls comprise cell-sized clear microbeads coated with defined concentrations of analyte (HER2, ER, and/or PR). The laboratories identified the limits of detection and then mailed the slides for quantitative assessment.

Results.—

Each commercial immunostain demonstrated a characteristic analytic response curve, reflecting strong reproducibility among IHC laboratories using the same automation and reagents prepared per current Good Manufacturing Practices. However, when comparing different commercial vendors (using different reagents), the data reveal up to 100-fold differences in analytic sensitivity. For proficiency testing purposes, quantitative assessment using analytic response curves was superior to subjective interpretation of limits of detection.

Conclusions.—

Assessment of IHC laboratory performance by quantitative measurement of analytic response curves is a powerful, objective tool for identifying outlier IHC laboratories. It uniquely evaluates immunostain performance across a range of defined analyte concentrations.

Interobserver Reproducibility of Immunohistochemical Her-2/Neu Assessment in Human Breast Cancer: An Update from INQAT round III

The clinical interest in HER-2/neu is related to trastuzumab, a drug used to treat patients with invasive breast carcinoma overexpressing the HER-2/neu protein. It is very important to correctly identify those patients who may benefit from trastuzumab by accurate assessment of the HER-2/neu status. Of the various methods available, the Dako Herceptest for immunohistochemical assay is considered the most reliable to reach this goal. The aim of this study was to investigate within a group of Italian laboratories the reproducibility of the results of HER-2/neu assessment by means of the Dako scoring system on slides stained with the Herceptest kit. This study was also conceived as the continuation of one of our previous studies, which was similar in its aims but different in the classification criteria adopted. Our results show that, whereas the intra-observer reproducibility was generally satisfactory, the interobserver reproducibility was not. Moreover, our findings confirm that the two extreme classes (0 and 3+) are more easy to identify than the other two and that the Herceptest does not allow to discriminate optimally between scoring classes 2+ and 3+. These findings are relevant in clinical practice where the treatment choice is based on categories defined by this assay, suggesting the need of adopting educational programs and/or new reference materials to improve the assay performance.

Interobserver Reproducibility of Immunohistochemical Her-2/Neu Evaluation in Human Breast Cancer: The Real-World Experience

In spite of the large number of studies on technical problems affecting the interlaboratory reproducibility of IHC HER-2/neu determination, only little is known about factors limiting the intra- and interobserver reproducibility in the actual practice of HER-2/neu expression analysis. The aim of the present INQAT study was to evaluate the intra- and interobserver reproducibility of IHC HER-2 analysis among pathologists routinely working in Italian laboratories. Twenty immunostained slides were distributed to 12 pathologists who had to report, for each slide, the semiquantitative analysis of the percentage of immunopositive cells and the qualitative evaluation of the intensity of membrane staining. The intra- and interobserver reproducibility as well as the reproducibility between each laboratory and the reference values were quantified adopting an approach based on computation of the weighted kappa statistic (Kw). Additionally, in order to evaluate the contribution of each category to the overall agreement, the kappa category-specific statistics (Kcs) were estimated for both classification criteria by jointly considering all the participating laboratories. The intraobserver analyses showed a satisfactory level of reproducibility for both the percentage of positive cells (median Kw, 0.94; range: 0.80–0.96) and membrane staining (median Kw, 0.86; range: 0.78–0.96). Similarly, a fairly good level of reproducibility for the percentage of cells (median Kw, 0.89; range, 0.73–0.96) and the intensity of membrane staining (median Kw, 0.84; range, 0.72–0.92) were observed from comparisons with reference values. When all possible pairwise comparisons were performed, a satisfactory level of interobserver reproducibility was found for most laboratories. Kw values varied between 0.51 and 0.98 (median Kw, 0.80) and between 0.61 and 0.94 (median Kw, 0.81) for semiquantitative and qualitative measurements, respectively. Analysis of the contribution of the extreme categories to the overall agreement showed a substantial or almost perfect agreement for both classification criteria. Conversely, the contribution of intermediate categories appeared to be scarce or slight for the percentage of immunostained cells and slight or fair for the intensity of membrane staining. We conclude that, overall, the interobserver reproducibility in IHC analysis of HER-2/neu expression is satisfactory, although classification of the intermediate categories is problematic, both with regard to the percentage of immunostained cells and the intensity of membrane staining.

Quality control materials for pharmacogenomic testing in the clinic

Pharmacogenomics has significantly added to our understanding of drug responses in clinical pharmacology, changing the paradigm of treatment decisions. Interrogations of both inherited and somatic variations for therapeutic purposes are increasingly being adopted in clinics, where quality control (QC) materials are required. However, for many pharmacogenomic tests, the acquisition of well-characterized QC materials is often difficult or impossible. In this review, several sources of appropriate QC materials for therapy-associated genetic testing are discussed. Among them, the novel methods for producing renewable controls that resemble patient samples are highlighted. Owing to technological complexity, more efforts are needed to develop proper controls for next-generation sequencing-based assay.

A Microfluidic Immunostaining System Enables Quality Assured and Standardized Immunohistochemical Biomarker Analysis

Immunohistochemistry (IHC) plays an important role in biomarker-driven cancer therapy. Although there has been a high demand for standardized and quality assured IHC, it has rarely been achieved due to the complexity of IHC testing and the subjective validation-based process flow of IHC quality control. We present here a microfluidic immunostaining system for the standardization of IHC by creating a microfluidic linearly graded antibody (Ab)-staining device and a reference cell microarray. Unlike conventional efforts, our system deals primarily with the screening of biomarker staining conditions for quantitative quality assurance testing in IHC. We characterized the microfluidic matching of Ab staining intensity using three HER2 Abs produced by different manufacturers. The quality of HER2 Ab was also validated using tissues of breast cancer patients, demonstrating that our system is an efficient and powerful tool for the standardization and quality assurance of IHC.

Analytic Response Curves of Clinical Breast Cancer IHC Tests

An important limitation in the field of immunohistochemistry (IHC) is the inability to correlate stain intensity with specific analyte concentrations. Clinical immunohistochemical tests are not described in terms of analytic response curves, namely, the analyte concentrations in a tissue sample at which an immunohistochemical stain (1) is first visible, (2) increases in proportion to the analyte concentration, and (3) ultimately approaches a maximum color intensity. Using a new immunostaining tool ( IHControls), we measured the analytic response curves of the major clinical immunohistochemical tests for human epidermal growth factor receptor type II (HER-2), estrogen receptor (ER), and progesterone receptor (PR). The IHControls comprise the analytes HER-2, ER, and PR at approximately log concentration intervals across the range of biological expression, from 100 to 1,000,000 molecules per test microbead. We stained IHControls of various concentrations using instruments, reagents, and protocols from three major IHC vendors. Stain intensity at each analyte concentration was measured, thereby generating an analytic response curve. We learned that for HER-2 and PR, there is significant variability in test results between clinical kits for samples with analyte concentrations of approximately 10⁴ molecules/microbead. We propose that the characterization of immunostains is an important step toward standardization.

Comparison of the types of candidate reference samples for quality control of human epidermal growth factor receptor 2 status detection

Background

Human epidermal growth factor receptor 2 (HER2) is as a target gene for trastuzumab in patients with breast cancer. Accurate determination of HER2 status and strict quality control are necessary to ensure reproducibility and accuracy of the techniques used for the determination of HER2 status.

Methods

We used three different types of samples: formalin-fixed and paraffin-embedded (FFPE) samples prepared from cell lines, agarose gel samples using cell lines, and xenograft tumor samples. One cell line for FFPE or xenografts did not overexpress HER2, while the others showed different levels of HER2 overexpression. We compared the morphology, HER2 gene amplification status, and HER2 protein expression status of these samples with those of clinical specimens.

Results

We successfully produced three kinds of samples for quality control. Cells from the cell line-sample sections were dispersed while those from the agarose gel-sample sections and xenograft tumor sample sections (prepared from the both cell lines) were concentrated in one area. The FISH results for all three kinds of samples were as expected. The IHC results of the cell line samples and xenograft tumor samples were as expected, but the staining level of the agarose gel samples, using HER2-overexpressed cell lines was weak which might be regarded as a false negative result.

Conclusions

Xenograft tumor samples might be used as an additional option for quality control in FISH and IHC. However, it might not replace the clinical specimen quality controls directly.

Electronic supplementary material

The online version of this article (doi:10.1186/s13000-016-0537-8) contains supplementary material, which is available to authorized users.

A standard tissue as a control for histochemical and immunohistochemical staining

The variable quality of histochemical and immunohistochemical staining of tissues may be attributed to pre-analytical and analytical variables. Both categories of variables frequently are undefined or inadequately controlled during specimen collection and preparation. Pre-analytical variables may alter the molecular composition of tissues, which results in variable staining; such variations may cause problems when different tissues are used as staining controls. We developed a standard tissue for use as a staining control. Our standard tissue contains five components: 1) nine combined human cell lines mixed with stroma from human spleen; 2) a squamous cancer cell line, A431; 3) fungus; 4) transverse sections of the mosquitofish and 5) normal human spleen. The first three components were embedded in HistoGel(™) and all components were processed to paraffin and used to construct a single standard paraffin block. The muscles of mosquitofish and arteries of the spleen are positive controls for eosin staining, while other tissues are useful for assessing hematoxylin staining. The mosquitofish tissues also are excellent controls for the Masson trichrome stain and all mucin-related histochemical stains that we tested. The goblet cells of the intestine and skin stained strongly with Alcian blue, pH 2.5 (AB-2.5), mucicarmine, colloidal iron, periodic acid Schiff (PAS) or PAS-hematoxylin (PASH) and combination stains such as colloidal iron-PASH. Cell lines were not useful for evaluating histochemical stains except for PASH. The splenic stroma was a useful control for AB-2.5; however, eosin and mucin stains stained cell lines poorly, probably due to their rapid growth and associated loss of some differentiated characteristics such as production of mucins. Nevertheless, the cell lines were a critical control for immunohistochemical stains. Immunostaining of specific cell lines was consistent with the presence of markers, e.g., EGFr in DU145 cells. The cell lines expressed a wide range of markers, so they were useful controls for immunohistochemical staining including EGFr, HER2, E-cadherin, cytokeratins, Ki67, PCNA, estrogen receptor, progesterone receptor, CD3, CD20 and CD45, activated (cleaved) caspase 3 and Bcl-2. The cell lines also were a control for the TUNEL stain.

RefCNV: Identification of Gene-Based Copy Number Variants Using Whole Exome Sequencing

With rapid advances in DNA sequencing technologies, whole exome sequencing (WES) has become a popular approach for detecting somatic mutations in oncology studies. The initial intent of WES was to characterize single nucleotide variants, but it was observed that the number of sequencing reads that mapped to a genomic region correlated with the DNA copy number variants (CNVs). We propose a method RefCNV that uses a reference set to estimate the distribution of the coverage for each exon. The construction of the reference set includes an evaluation of the sources of variability in the coverage distribution. We observed that the processing steps had an impact on the coverage distribution. For each exon, we compared the observed coverage with the expected normal coverage. Thresholds for determining CNVs were selected to control the false-positive error rate. RefCNV prediction correlated significantly (r = 0.96-0.86) with CNV measured by digital polymerase chain reaction for MET (7q31), EGFR (7p12), or ERBB2 (17q12) in 13 tumor cell lines. The genome-wide CNV analysis showed a good overall correlation (Spearman's coefficient = 0.82) between RefCNV estimation and publicly available CNV data in Cancer Cell Line Encyclopedia. RefCNV also showed better performance than three other CNV estimation methods in genome-wide CNV analysis.

Enhancement of antibody-dependent cell-mediated cytotoxicity by endowing IgG with FcαRI (CD89) binding

Fc effector functions such as antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cell-mediated phagocytosis (ADCP) are crucial to the efficacy of many antibody therapeutics. In addition to IgG, antibodies of the IgA isotype can also promote cell killing through engagement of myeloid lineage cells via interactions between the IgA-Fc and FcαRI (CD89). Herein, we describe a unique, tandem IgG1/IgA2 antibody format in the context of a trastuzumab variable domain that exhibits enhanced ADCC and ADCP capabilities. The IgG1/IgA2 tandem Fc format retains IgG1 FcγR binding as well as FcRn-mediated serum persistence, yet is augmented with myeloid cell-mediated effector functions via FcαRI/IgA Fc interactions. In this work, we demonstrate anti-human epidermal growth factor receptor-2 antibodies with the unique tandem IgG1/IgA2 Fc can better recruit and engage cytotoxic polymorphonuclear (PMN) cells than either the parental IgG1 or IgA2. Pharmacokinetics of IgG1/IgA2 in BALB/c mice are similar to the parental IgG, and far surpass the poor serum persistence of IgA2. The IgG1/IgA2 format is expressed at similar levels and with similar thermal stability to IgG1, and can be purified via standard protein A chromatography. The tandem IgG1/IgA2 format could potentially augment IgG-based immunotherapeutics with enhanced PMN-mediated cytotoxicity while avoiding many of the problems associated with developing IgAs.

Upregulation of RHOXF2 and ODF4 Expression in Breast Cancer Tissues

Objective

During the past decade, the importance of biomarker discovery has been highlighted in many aspects of cancer research. Biomarkers may have a role in early detection of cancer, prognosis and survival evaluation as well as drug response. Cancer-testis antigens (CTAs) have gained attention as cancer biomarkers because of their expression in a wide variety of tumors and restricted expression in testis. The aim of this study was to find putative biomarkers for breast cancer.

Materials and Methods

In this applied-descriptive study, the expression of 4 CTAs, namely acrosin binding protein (ACRBP), outer dense fiber 4 (ODF4), Rhox homeobox family member 2 (RHOXF2) and spermatogenesis associated 19 (SPATA19) were ana- lyzed at the transcript level in two breast cancer lines (MCF-7 and MDA-MB-231), 40 invasive ductal carcinoma samples and their adjacent normal tissues as well as 10 fibroadenoma samples by means of quantitative real-time reverse transcription polymerase chain reaction (RT-PCR).

Results

All four genes were expressed in both cell lines. Expression of ODF4 and RH- OXF2 was detected in 62.5% and 60% of breast cancer tissues but in 22.5 and 17.5% of normal tissues examined respectively. The expression of both RHOXF2 and ODF4 was upregulated in cancerous tissues compared with their normal adjacent tissues by 3.31 and 2.96-fold respectively. The expression of both genes was correlated with HER2/neu overexpression. RHOXF2 expression but not ODF4 was correlated with higher stages of tumors. However, no significant association was seen between expression patterns and estrogen and progesterone receptors status.

Conclusion

ODF4 and RHOXF2 are proposed as putative breast cancer biomarkers at the transcript level. However, their expression at protein level should be evaluated in future studies.

When tissue antigens and antibodies get along: revisiting the technical aspects of immunohistochemistry--the red, brown, and blue technique

Once focused mainly on the characterization of neoplasms, immunohistochemistry (IHC) today is used in the investigation of a broad range of disease processes with applications in diagnosis, prognostication, therapeutic decisions to tailor treatment to an individual patient, and investigations into the pathogenesis of disease. This review addresses the technical aspects of immunohistochemistry (and, to a lesser extent, immunocytochemistry) with attention to the antigen-antibody reaction, optimal fixation techniques, tissue processing considerations, antigen retrieval methods, detection systems, selection and use of an autostainer, standardization and validation of IHC tests, preparation of proper tissue and reagent controls, tissue microarrays and other high-throughput systems, quality assurance/quality control measures, interpretation of the IHC reaction, and reporting of results. It is now more important than ever, with these sophisticated applications, to standardize the entire IHC process from tissue collection through interpretation and reporting to minimize variability among laboratories and to facilitate quantification and interlaboratory comparison of IHC results.

Determining sensitivity and specificity of HER2 testing in breast cancer using a tissue micro-array approach

Introduction

Overexpression of the human epidermal growth factor receptor 2 (HER2) as a result of HER2 gene amplification is associated with a relatively poor prognosis in breast cancer and is predictive of HER2-targeting therapy response. False-positive rates of up to 20% for HER2 testing have been described. HER2-testing laboratories are therefore encouraged to participate in external quality control schemes in order to improve HER2-testing standardization.

Methods

This study investigated the feasibility of retesting large numbers of invasive breast cancers for HER2 status on tissue micro-array (TMA) as part of a quality control scheme. For this assessment different HER2 testing methods were used including HER2 detecting antibodies SP3, 4B5, Herceptest and mono color silver in situ hybridization (SISH) and dual color SISH. Final HER2 status for each tumor on the TMA was compared to the local testing result for the same tumor. Discordances between these two results were investigated further by staining whole tumor sections.

Results

For this study, 1,210 invasive breast carcinomas of patients treated in six hospitals between 2006 and 2008 were evaluated. Results from the three immunohistochemistry (IHC) and two in situ hybridization (ISH) assays performed on the TMAs were compared. The final HER2 status on TMA was determined with SP3, 4B5 and mono color SISH. Concordance between local HER2 test results and TMA retesting was 98.0%. Discordant results between local and TMA retesting were found in 20 tumors (2.0%). False positive HER2 IHC results were identified in 13 (1.3%) tumors; false negative IHC results in seven (0.7%) tumors.

Conclusions

Retesting large volumes of HER2 classified breast carcinomas was found to be feasible and can be reliably performed by staining TMAs with SP3, 4B5 and mono color SISH in combination with full-sized slides for discordant cases. The frequency of false-positive results was lower than previously reported in the literature. This method is now offered to other HER2-testing laboratories.

Defining the molecular response to trastuzumab, pertuzumab and combination therapy in ovarian cancer

BACKGROUND

Trastuzumab and pertuzumab target the Human Epidermal growth factor Receptor 2 (HER2). Combination therapy has been shown to provide enhanced antitumour activity; however, the downstream signalling to explain how these drugs mediate their response is not clearly understood.

METHODS

Transcriptome profiling was performed after 4 days of trastuzumab, pertuzumab and combination treatment in human ovarian cancer in vivo. Signalling pathways identified were validated and investigated in primary ovarian xenografts at the protein level and across a timeseries.

RESULTS

A greater number and variety of genes were differentially expressed by the combination of antibody therapies compared with either treatment alone. Protein levels of cyclin-dependent kinase inhibitors p21 and p27 were increased in response to both agents and further by the combination; pERK signalling was inhibited by all treatments; but only pertuzumab inhibited pAkt signalling. The expression of proliferation, apoptosis, cell division and cell-cycle markers was distinct in a panel of primary ovarian cancer xenografts, suggesting the heterogeneity of response in ovarian cancer and a need to establish predictive biomarkers.

CONCLUSION

This first comprehensive study of the molecular response to trastuzumab, pertuzumab and combined therapy in vivo highlights both common and distinct downstream effects to agents used alone or in combination, suggesting that complementary pathways may be involved.

Analytical Validation of a Highly Quantitative, Sensitive, Accurate, and Reproducible Assay (HERmark) for the Measurement of HER2 Total Protein and HER2 Homodimers in FFPE Breast Cancer Tumor Specimens

We report here the results of the analytical validation of assays that measure HER2 total protein (H2T) and HER2 homodimer (H2D) expression in Formalin Fixed Paraffin Embedded (FFPE) breast cancer tumors as well as cell line controls. The assays are based on the VeraTag technology platform and are commercially available through a central CAP-accredited clinical reference laboratory. The accuracy of H2T measurements spans a broad dynamic range (2-3 logs) as evaluated by comparison with cross-validating technologies. The measurement of H2T expression demonstrates a sensitivity that is approximately 7–10 times greater than conventional immunohistochemistry (IHC) (HercepTest). The HERmark assay is a quantitative assay that sensitively and reproducibly measures continuous H2T and H2D protein expression levels and therefore may have the potential to stratify patients more accurately with respect to response to HER2-targeted therapies than current methods which rely on semiquantitative protein measurements (IHC) or on indirect assessments of gene amplification (FISH).

Canadian Association of Pathologists-Association canadienne des pathologistes National Standards Committee/Immunohistochemistry: best practice recommendations for standardization of immunohistochemistry tests

Immunohistochemical and immunocytochemical assays are highly complex diagnostic analyses used to aid in the accurate identification and biologic characterization of tissue types in neoplastic and nonneoplastic diseases. Immunohistochemical tests are applied mainly to the diagnosis of neoplasms. Some immunohistochemical tests provide information of important prognostic and predictive value in selected human neoplasms and, as such, are often critical for the appropriate and effective treatment of patients. This document provides recommendations and opinions of the Canadian Association of Pathologists-Association canadienne des pathologistes National Standards Committee/Immunohistochemistry relevant to clinical immunohistochemical terminology, classification of immunohistochemical tests based on risk assessment, and quality control and quality assurance and summarizes matters to be considered for appropriate immunohistochemical/immunocytochemical test development, performance, and interpretation in diagnostic pathology and laboratory medicine.

Molecular mechanisms of antigen retrieval: antigen retrieval reverses steric interference caused by formalin-induced cross-links

The overwhelming majority of antibodies useful for formalin fixed, paraffin embedded (FFPE) tissues require antigen retrieval to reverse the effect of formalin fixation and re-establish immunoreactivity. How this reversal happens is poorly understood. We developed a new experimental model for studying the mechanism of formalin fixation and antigen retrieval. Epitope mapping studies on nine antibodies useful for FFPE tissues revealed that each consisted of a contiguous stretch of amino acids in the native protein (linear epitope). Small peptides representing the epitopes of antibodies to human epidermal growth factor receptor type (HER2), estrogen, and progesterone receptors were attached covalently to glass microscope slides in a peptide array. Most peptides retained immunoreactivity after formalin fixation. Immunoreactivity was completely abrogated for all peptides, however, if an irrelevant large protein was present during formalin-induced cross-linking. We hypothesize that cross-linking the irrelevant protein to the peptide epitopes sterically blocked antibodies from binding. Antigen retrieval dissociates irrelevant proteins and restores immunoreactivity. Because the epitopes for clinical antibodies require only primary protein structure, the fact that antigen retrieval probably denatures the secondary and tertiary structure of the protein is irrelevant. The same mechanism may occur in tissue samples subjected to formalin fixation and antigen retrieval.

Comparison of Pathvysion and Poseidon HER2 FISH assays in measuring HER2 amplification in breast cancer: a validation study

Aims

The current study was done as a validation study prior to setting up a clinical HER2 testing service using the new commercial Poseidon HER2 fluorescence in situ hybridisation (FISH) assay. However, it was felt that the experience of the authors of this study may be of interest to other laboratories when considering setting up a HER2 diagnostic facility.

Methods

122 patients who had been diagnosed with invasive breast cancer were selected. Immunolabelling with HercepTest, PathVysion and Poseidon FISH assays were carried out using tissue microarray blocks.

Results

Concordance correlation coefficients showed near perfect agreement in average HER2 and centromere specific signal counts per cell and in the HER2/CEP17 ratios between the PathVysion and the Poseidon FISH assays. In addition, the κ measure showed perfect agreement (κ 0.9441, p<0.0001), and if only 2+ cases were considered there was substantial agreement (κ 0.7671, p=0.0006), between the two assays. The sensitivity and the specificity of the Poseidon FISH kit were calculated to be 95.2% and 100%, respectively, whereas the positive predictive value (PPV) and negative predictive value (NPV) were 100% and 99%, respectively. With regard to the ability to presume HER2 polysomy, the Poseidon FISH kit had a sensitivity of 93.3% and a specificity of 99.1%, with PPV and NPV of 93.3% and 99.1%, respectively, as assessed with PathVysion classification as the reference.

Conclusions

Statistical analysis confirmed that the two FISH assays are comparable in terms of detection of HER2 gene amplification. Proceeding from these findings, the genetic diagnoses obtained with the Poseidon kit can be considered to be as valuable as the results from the Food and Drug Administration approved PathVysion assay, and its utilisation in routine HER2 diagnostics is proposed.

Immunodetection of DNA repair endonuclease ERCC1-XPF in human tissue

The high incidence of resistance to DNA-damaging chemotherapeutic drugs and severe side effects of chemotherapy have led to a search for biomarkers able to predict which patients are most likely to respond to therapy. ERCC1-XPF nuclease is required for nucleotide excision repair of helix-distorting DNA damage and the repair of DNA interstrand crosslinks. Thus, it is essential for several pathways of repair of DNA damage by cisplatin and related drugs, which are widely used in the treatment of non-small cell lung carcinoma and other late-stage tumors. Consequently, there is tremendous interest in measuring ERCC1-XPF expression in tumor samples. Many immunohistochemistry studies have been done, but the antibodies for ERCC1-XPF were not rigorously tested for antigen specificity. Herein, we survey a battery of antibodies raised against human ERCC1 or XPF for their specificity using ERCC1-XPF-deficient cells as a negative control. Antibodies were tested for the following applications: immunoblotting, immunoprecipitation from cell extracts, immunofluorescence detection in fixed cells, colocalization of ERCC1-XPF with UV radiation-induced DNA damage in fixed cells, and immunohistochemistry in paraffin-embedded samples. Although several commercially available antibodies are suitable for immunodetection of ERCC1-XPF in some applications, only a select subset is appropriate for detection of this repair complex in fixed specimens. The most commonly used antibody, 8F1, is not suitable for immunodetection in tissue. The results with validated antibodies reveal marked differences in ERCC1-XPF protein levels between samples and cell types.

Tissue Microarray: A rapidly evolving diagnostic and research tool

Tissue microarray is a recent innovation in the field of pathology. A microarray contains many small representative tissue samples from hundreds of different cases assembled on a single histologic slide, and therefore allows high throughput analysis of multiple specimens at the same time. Tissue microarrays are paraffin blocks produced by extracting cylindrical tissue cores from different paraffin donor blocks and re-embedding these into a single recipient (microarray) block at defined array coordinates. Using this technique, up to 1000 or more tissue samples can be arrayed into a single paraffin block. It can permit simultaneous analysis of molecular targets at the DNA, mRNA, and protein levels under identical, standardized conditions on a single glass slide, and also provide maximal preservation and use of limited and irreplaceable archival tissue samples. This versatile technique, in which data analysis is automated, facilitates retrospective and prospective human tissue studies. It is a practical and effective tool for high-throughput molecular analysis of tissues that is helping to identify new diagnostic and prognostic markers and targets in human cancers, and has a range of potential applications in basic research, prognostic oncology and drug discovery. This article summarizes the technical aspects of tissue microarray construction and sectioning, advantages, application, and limitations.

Borderline HER‐2 breast cancer cases: Histochemical versus real‐time PCR analysis and impact of different cut‐off values

Seventy-one cases that had resulted borderline for HER-2 protein expression at conventional immunohistochemical assay (2+) were assessed for HER-2 gene amplification by real-time PCR and by FISH in accordance with the manufacturer's recommendations (gene amplification with ratio >or=2 in both methods). Thirty-three out of 71 cases (47%) resulted amplified at real-time PCR analysis, whereas 15 cases resulted positive at FISH (21%). Apparently, PCR was more sensitive than FISH in HER-2 determination, only 10 cases resulting amplified in both tests. When the mean ratio value obtained in all PCR experiments was adopted as threshold in determining HER-2 gene amplification, the apparent sensitivity of PCR was reduced but correlation between PCR and FISH results was dramatically increased. Furthermore, when the mean PCR ratio value observed in the FISH-positive group was chosen as threshold, the best agreement between PCR and FISH results was achieved. Therefore, we found that the proposed threshold ratio value of >or=2 is not accurate in separating HER-2 amplified and non-amplified cases. We suggest that the threshold ratio value in PCR tests should be determined in each laboratory using FISH controlled cases. Finally, above certain in-lab generated threshold values, PCR might be proposed as a highly predictive positive test in HER-2 assessment.

Experimental validation of peptide immunohistochemistry controls

Peptide immunohistochemistry (IHC) controls are a new quality control format for verifying proper IHC assay performance, offering advantages in high throughput automated manufacture and standardization. We previously demonstrated that formalin-fixed peptide epitopes, covalently attached to glass microscope slides, behaved (immunochemically) in a similar fashion to the native protein in tissue sections. To convert this promising idea into a practical clinical laboratory quality control tool, we tested the hypothesis that the quality assurance information provided by peptide IHC controls accurately reflects IHC staining performance among a diverse group of clinical laboratories. To test the hypothesis, we first designed and built an instrument for reproducibly printing the controls on microscope slides and a simple software program to measure the color intensity of stained controls. Automated printing of peptide spots was reproducible, with coefficients of variation of 4% to 8%. Moreover, the peptide controls were stable at <or=4 degrees C for at least 7 months, the longest time duration we tested. A national study of 109 participating clinical laboratories demonstrated a good correlation between a laboratory's ability to properly stain formalin-fixed peptide controls to their ability in properly staining a 3+ HER-2 formalin-fixed tissue section mounted on the same slide (r=0.87). Therefore, peptide IHC controls accurately reflect the analytical component of an IHC stain, including antigen retrieval. Besides its use in proficiency survey testing, we also demonstrate the feasibility of applying peptide IHC controls for verifying intralaboratory IHC staining consistency, using Levy-Jennings charting.

Cell lines as candidate reference materials for quality control of ERBB2 amplification and expression assays in breast cancer

BACKGROUND

Human epidermal growth factor receptor 2 (HER2) is an important biomarker whose status plays a pivotal role in therapeutic decision-making for breast cancer patients and in determining their clinical outcomes. Ensuring the accuracy and reproducibility of HER2 assays by immunohistochemistry (IHC) and by fluorescence in situ hybridization (FISH) requires a reliable standard for monitoring assay sensitivity and specificity, and for assessing methodologic variation. A prior NIST workshop addressed this need by reaching a consensus to create cell lines as reference materials for HER2 testing.

METHODS

Breast carcinoma cell lines SK-BR-3 and MCF-7 were characterized quantitatively by IHC with chicken anti-HER2 IgY antibody and by FISH with biotinylated bacterial artificial chromosome DNA probes; both assays used quantum dots as detectors. Formalin-fixed and paraffin-embedded (FFPE) cell blocks were prepared and tested for suitability as candidate reference materials by IHC and FISH with commercially available reagents. IHC and FISH results were also compared with those obtained by laser-scanning cytometry and real-time PCR, respectively.

RESULTS

MCF-7 cells had typical numbers of gene copies and very low production of HER2 protein, whereas SK-BR-3 cells contained approximately 10-fold more copies of the gene and exhibited approximately 15-fold higher amounts of HER2 protein than MCF-7 cells. FFPE SK-BR-3 cells showed results similar to those for fresh SK-BR-3 cells.

CONCLUSIONS

SK-BR-3 and MCF-7 are suitable as candidate reference materials in QC of HER2 testing. Coupled with the associated assay platforms, they provide valuable controls for quantitative measurement of HER2 amplification and production in breast cancer samples, irrespective of the antibody/probe or detector used.

Tissue Microarray: A rapidly evolving diagnostic and research tool

Tissue microarray is a recent innovation in the field of pathology. A microarray contains many small representative tissue samples from hundreds of different cases assembled on a single histologic slide, and therefore allows high throughput analysis of multiple specimens at the same time. Tissue microarrays are paraffin blocks produced by extracting cylindrical tissue cores from different paraffin donor blocks and re-embedding these into a single recipient (microarray) block at defined array coordinates. Using this technique, up to 1000 or more tissue samples can be arrayed into a single paraffin block. It can permit simultaneous analysis of molecular targets at the DNA, mRNA, and protein levels under identical, standardized conditions on a single glass slide, and also provide maximal preservation and use of limited and irreplaceable archival tissue samples. This versatile technique, in which data analysis is automated, facilitates retrospective and prospective human tissue studies. It is a practical and effective tool for high-throughput molecular analysis of tissues that is helping to identify new diagnostic and prognostic markers and targets in human cancers, and has a range of potential applications in basic research, prognostic oncology and drug discovery. This article summarizes the technical aspects of tissue microarray construction and sectioning, advantages, application, and limitations.

Human breast cancer tumor models: molecular imaging of drug susceptibility and dosing during HER2/neu-targeted therapy

PURPOSE

To use near-infrared (NIR) optical imaging to assess the therapeutic susceptibility and drug dosing of orthotopic human breast cancers implanted in mice treated with molecularly targeted therapy.

MATERIALS AND METHODS

This study was approved by the institutional animal care and use committee. Imaging probes were synthesized by conjugating the human epidermal growth factor receptor type 2 (HER2)-specific antibody trastuzumab with fluorescent dyes. In vitro probe binding was assessed with flow cytometry. HER2-normal and HER2-overexpressing human breast cancer cells were orthotopically implanted in nude mice. Intravital laser scanning fluorescence microscopy was used to evaluate the in vivo association of the probe with the tumor cells. Mice bearing 3-5-mm-diameter tumors were intravenously injected with 0.4 nmol of HER2 probe before or after treatment. A total of 123 mice were used for all in vivo tumor growth and imaging experiments. Tumor fluorescence intensity was assessed, and standard fluorescence values were determined. Statistical significance was determined by performing standard analysis of variance across the imaging cohorts.

RESULTS

HER2 probe enabled differentiation between HER2-normal and HER2-overexpressing human breast cancer cells in vitro and in vivo, with binding levels correlating with tumor trastuzumab susceptibility. Serial imaging before and during trastuzumab therapy revealed a significant reduction (P < .05) in probe binding with treatment and thus provided early evidence of successful HER2 inhibition days before the overall reduction in tumor growth was apparent.

CONCLUSION

NIR imaging with HER2-specific imaging probes enables evaluation of the therapeutic susceptibility of human mammary tumors and of drug dosing during HER2-targeted therapy with trastuzumab. This approach, combined with tomographic imaging techniques, has potential in the clinical setting for determining patient eligibility for and adequate drug dosing in molecularly targeted cancer therapies.

Suggested Guidelines for Immunohistochemical Techniques in Veterinary Diagnostic Laboratories

This document is the consensus of the American Association of Veterinary Laboratory Diagnosticians (AAVLD) Subcommittee on Standardization of Immunohistochemistry on a set of guidelines for immunohistochemistry (IHC) testing in veterinary laboratories. Immunohistochemistry is a powerful ancillary methodology frequently used in many veterinary laboratories for both diagnostic and research purposes. However, neither standardization nor validation of IHC tests has been completely achieved in veterinary medicine. This document addresses both issues. Topics covered include antibody selection, fixation, antigen retrieval, antibody incubation, antibody dilutions, tissue and reagent controls, buffers, and detection systems. The validation of an IHC test is addressed for both infectious diseases and neoplastic processes. In addition, storage and handling of IHC reagents, interpretation, quality control and assurance, and troubleshooting are also discussed. Proper standardization and validation of IHC will improve the quality of diagnostics in veterinary laboratories.

National HER2 proficiency test results using standardized quantitative controls: characterization of laboratory failures

CONTEXT

An important component in fostering test standardization for HER2 testing by immunohistochemistry is an appropriate positive control. We developed a new standardized, quantitative immunohistochemical HER2 control using a HER2 peptide covalently attached to glass microscope slides. The peptide controls can be formalin fixed or unfixed, providing the new capability of distinguishing errors associated with antigen retrieval from errors associated with the staining process itself.

OBJECTIVE

To investigate the causes of variability in HER2 immunohistochemistry staining performance. By comparing laboratory performance with both formalin-fixed and unfixed analyte controls, we aimed to distinguish problems associated with antigen retrieval from reagent or staining protocol deficiencies.

DESIGN

HER2 peptide analyte controls were printed on 2 slides that also contained unstained sections of invasive breast carcinomas and were mailed with the College of American Pathologists' 2006 HER2-B proficiency testing survey. Laboratory participants were asked to stain the 2 slides and return them for central review and quantification. This study is unique in combining central review with new quantitative HER2 controls.

RESULTS

Of 109 participants who returned evaluable stained slides, staining was suboptimal in 20 (18.3%) as judged by quantification of the peptide analyte controls and review of tissue sections. Of those, 35% failed due to antigen retrieval errors, 20% failed due solely to antibody or staining protocol problems, and the remainder failed due to a combination of the two.

CONCLUSIONS

In practice, errors in HER2 testing are caused by variables associated with antigen retrieval and the reagents and staining protocol, as well as interpretive error. Analyte controls help distinguish these different causes.

Protein kinase Calpha determines HER2 fate in breast carcinoma cells with HER2 protein overexpression without gene amplification

In some HER2-positive breast tumors, cell surface overexpression of HER2 is not associated with gene amplification but may instead rest in altered gene transcription, half-life, or recycling of the oncoprotein. Here, we show that HER2 overexpression in HER2 2+ carcinomas is associated with neither an increase in gene transcription nor a deregulation in the ubiquitin-dependent pathways, but instead seems to be regulated by protein kinase Calpha (PKCalpha) activity. The stimulation of PKCalpha up-regulated HER2 expression, whereas PKCalpha inhibition by pharmacologic treatments and PKCalpha-specific small interfering RNA led to a dramatic down-regulation of HER2 levels only in breast cancer cells HER2 2+. Consistent with the in vitro data, our biochemical analysis of HER2 2+ human primary breast specimens revealed significantly higher levels of phosphorylated PKCalpha compared with HER2-negative tumors. Inhibition of HER2 activation by the tyrosine kinase inhibitor lapatinib led to decreased levels of PKCalpha phosphorylation, clearly indicating a cross-talk between PKCalpha and HER2 molecules. These data suggest that HER2 overexpression in HER2 2+ carcinomas is due to an accumulation of the recycled oncoprotein to the cell surface induced by activated PKCalpha.

Quantification of immunohistochemistry--issues concerning methods, utility and semiquantitative assessment II

Immunohistochemistry is entering its fourth decade of use on formalin-fixed paraffin-embedded tissues. Over this period the method has evolved to become a major part of the practice of diagnostic surgical pathology worldwide. From the beginning immunohistochemistry has been adapted to provide a range of markers of cell lineage and tissue type, with particular application to the diagnosis and classification of tumours. In this modality immunohistochemical methods were employed simply as 'special stains', the results of which were evaluated qualitatively by the pathologist, as for any other stain. More recently, attention has shifted to the demonstration of prognostic markers in tumour cells, driven by the advent of molecular biology and the discovery of numerous regulatory molecules, coupled with manufacture of the corresponding specific antibodies. Immunohistochemistry has rapidly adapted to this new use, but in so doing the demand for quantification has become paramount; it is no longer enough that the 'stain' is there; rather it is a question of 'How much is there?'. This review explores the limitations of immunohistochemistry when employed in a semiquantitative mode, and explores the possibility of fulfilling the full potential of immunohistochemistry, as a true quantitative immunoassay applied in a tissue section environment.

Transformed diffuse large B-cell lymphomas with gains of the discontinuous 12q12-14 amplicon display concurrent deregulation of CDK2, CDK4 and GADD153 genes

Transformation of the indolent follicular lymphoma (FL) to the aggressive diffuse large B-cell lymphoma (DLBCL) results in resistance to therapy with shortened survival. It has been demonstrated that the 12q12-14 region was mainly amplified in DLBCL cases but not in their FL counterparts. Therefore, we examined the DNA copy number and protein expression profiles for CDK2, CDK4 and GADD153, three genes that map to 12q12-14, in a set of 44 paired FL/DLBCL samples from 22 patients. The concordant amplification of these genes occurred in seven of 22 (32%) of FL cases, compared with 15 of 22 (68%) of DLBCL cases. At the protein level, 15 of 22 of the DLBCL samples (68%) showed strong staining for the CDK2 protein, compared with five of 21 of FL samples (24%). The majority of the DLBCL samples (16/22, 72%) expressed the CDK4 protein, whereas the majority of the FL samples (12/21, 57%) showed no expression of this protein. Except for one DLBCL case, no expression of the GADD153 protein could be detected. The deregulation of the CDK2 and CDK4 genes at the genetic and protein levels suggest a functional role for these genes in the transformation process and could potentially provide targets for prognostic tests or therapeutic interventions.

Comparison of multiplex ligation dependent probe amplification to immunohistochemistry for assessing HER-2/neu amplification in invasive breast cancer

The HER-2/neu transmembrane tyrosine kinase receptor is both a prognostic marker and a therapeutic target for breast cancer. Accurate determination of HER-2/neu status is a prerequisite for selecting breast tumors for HER-2/neu immunotherapy or for taxan based chemotherapy. Unfortunately, there is no consensus concerning how this determination should be reached. We compared assessment of HER-2/neu status using Multiplex ligation-dependent probe amplification (MLPA) and immunohistochemistry (IHC). The patient group comprised 60 Indonesian breast cancers patients. IHC was performed on paraffin sections using the CB11 antibody from Novocastra. Results were scored according to the Hercept test. For MLPA, DNA was extracted from frozen samples, PCR amplified with a probe set containing three hemi-primer sets for the HER-2 locus and another nine control probes spread over chromosome 17 and other chromosomes, and analyzed on a gene scanner. A ratio above two for at least two HER-2 locus probes compared to the control probes was regarded as amplification. IHC for HER-2/neu was negative in 36 cases, and 24 cases (40%) showed expression. Seven, eight and nine of the latter cases were 1+, 2+ and 3+ positive, respectively. Forty-seven cases showed no amplification by MLPA, and 13 cases (22%) were amplified. Comparison of IHC and MPLA showed that none of the 36 IHC-negative or seven IHC 1+ cases was amplified. Five of the eight (63%) 2+ cases were amplified, and eight of nine (89%) of the IHC 3+ tumors showed gene amplification by MLPA assay. For HER-2/neu, there is a good correlation between gene amplification detected by MLPA and overexpression by IHC in invasive breast cancer. It appears that MLPA can detect the HER-2 amplified cases in the IHC 2+ class. Because MLPA is quick and inexpensive, it is an attractive method for detecting HER-2/neu amplification in daily laboratory practice.

Effect of a farnesyl transferase inhibitor (R115777) on ductal carcinoma in situ of the breast in a human xenograft model and on breast and ovarian cancer cell growth in vitro and in vivo

Introduction

The ras pathway is essential for cell growth and proliferation. The effects of R115777, a farnesyl transferase inhibitor, were investigated in cancer cell lines expressing varying levels of growth factor receptors and with differing ras status. Effects on tumour xenografts and human ductal carcinoma in situ (DCIS) of the breast in a xenograft mouse model were also tested.

Method

In vitro, the concentrations required to reduce cell numbers by 50% (50% inhibitory concentration) were established (MDA-MB231, MCF-7, MCF-7/HER2-18, BT-474, SK-BR3 and SKOV3). Human DCIS was implanted in nude mice or, in separate experiments, cultured cells were injected (MDA-MB231, MCF-7/HER2-18, SKOV3) and allowed to form tumours. Proliferation and apoptosis were determined by immunohistochemistry in xenografts and cell tumours.

Results

The 50% inhibitory concentrations varied a hundred-fold, from 39 nmol/l (± 26 nmol/l) for SKBR3 to 5.9 μmol/l(± 0.8 μmol/l) for MDA-MB231. In MCF-7/HER2-18 and SKOV3 cells the levels of tumour growth inhibition were approximately 85% and 40%, respectively. There was a significant decrease in the cell turnover index (CTI; proliferation/apoptosis). In MDA-MB 231 with activated k-ras no inhibition was observed. In treated DCIS xenografts proliferation decreased and apoptosis increased. The CTI ratio between the start and 1 and 2 weeks of treatment were 1.99 and 1.50, respectively, for controls and 0.85 (P = 0.005) and 0.75 (P = 0.08) for treated xenografts.

Conclusion

Treatment with the farnesyl transferase inhibitor reduced cell growth in vitro and cell tumour growth in vivo. In DCIS treatment resulted in a reduced CTI. R115777 is a promising treatment for breast cancer but the relation between effect and growth factor receptor and ras status has to be established.

Technology insight: Identification of biomarkers with tissue microarray technology

High-throughput technologies have been developed in the hope of increasing the pace of biomedical research, and accelerating the rate of translation from bench to bedside. Using such technology in target discovery has resulted in the need for systematic validation of the targets in an equally rapid manner. For example, gene expression microarrays have highlighted many potential targets in cancer, and tissue microarrays have emerged as a powerful tool to validate these targets by measuring tumor-specific protein expression and linking it to clinical outcome. Automated quantitative analysis of the tissue microarray 'spots' is beginning to take the technology a step further, removing observer bias, and providing standards for quality control and the potential for high-throughput analysis. The validation required for translation of tissue biomarkers from the research lab to the clinical lab will probably rely heavily on the combination of tissue microarray technology with automated quantitative analysis.

Standardized on-slide control for quality assurance in the immunohistochemical assessment of therapeutic target molecules in breast cancer

Individualization and optimization of risk-adapted therapy in breast cancer requires molecular profiling of individual cancer specimens. In tissues of heterogeneous cellular composition, such as mammary tissue, cancer prognostic markers and potential therapeutic target molecules are preferentially detected by in situ techniques such as immunohistochemistry. The more therapy decisions are based on immunohistochemical findings, the more histopathologists are confronted with the demand to establish standardized procedures that enable reproducible evaluation independent from the investigating laboratory. Disappointing results of recent national and international immunohistochemistry trials for steroid receptor and HER-2 analysis in breast cancer underline the need to act now beyond recommendations and well-formulated guidelines for standardization. In order to ensure staining quality in every individual immunohistochemical analysis, we have developed an on-slide control with standardized samples which are placed on every slide of a therapy-decisive stain together with the tissue of interest. Novel mini tissue microarrays were constructed comprising cell lines as standardized controls, indicating the sensitivity and reliability of the staining procedure. Standardized control material on the same slide as the patient's specimen require neither additional reagents nor time and are automatically archived on the diagnostic slide to prove the quality of staining even after years.

Simultaneous detection of HER2/neu gene amplification and protein overexpression in paraffin-embedded breast cancer

The determination of HER2/neu status in breast carcinomas has become essential for the selection of breast cancer patients for Herceptin therapy. Herceptin treatment is used in patients with metastatic breast carcinoma with HER2/neu protein overexpression detected by immunohistochemistry (IHC) or gene amplification analysed by fluorescence in situ hybridization (FISH). A multiparametric fluorescent approach based on the simultaneous detection of HER2/neu gene amplification and protein expression was established to increase the accuracy, and to improve the reproducibility, of HER2/neu diagnostics. Based on four paraffin-embedded breast cancer cell lines, a combined fluorescent immunostaining (FIHC) and FISH method was developed by using the PathVysion HER2 DNA Probe Kit (VYSIS) and the polyclonal antibody from the HercepTest (DAKO). Diagnostic applicability was documented on 215 formalin-fixed primary breast carcinomas. Criteria for immunofluorescence quantification were chosen by analogy with the FDA-approved HercepTest scoring, ranging from 0 to 3+. There was 97.7% concordance between conventional IHC and fluorescence IHC. The FISH data resulting from the multiparametric approach did not differ from conventional FISH. Breast carcinomas with HER2/neu protein overexpression and simultaneous gene amplification were detected with 100% sensitivity. In addition, five of the 215 cases (2.3%) had HER2/neu gene amplification without protein overexpression. The main advantage of this novel approach is that polysomy, aneuploidy, gene amplification, and protein content can be analysed simultaneously in the same cell.

Estrogen receptor analysis for breast cancer: current issues and keys to increasing testing accuracy

The estrogen receptor (ER) is a regulator of cellular growth, proliferation, and differentiation. In addition to having prognostic value, ER is the most important biologic marker of therapeutic response in breast cancer. Some level of measurable ER protein is expressed in 70-80% of human breast. Immunohistochemistry is the current method of choice for ER assessment, and its predictive value has been shown to be superior to that of biochemically based assays. Although accurate ER protein assessment is critical for optimal treatment of patients with breast cancer, studies have demonstrated inter-laboratory variability in ER detection. False-negative results for tumors with low ER protein levels have been a subject of recent concern. Lack of standardization for immunohistochemistry between laboratories is thought to be the major reason for testing errors, although variability in scoring methods and reporting practices, which can affect results, also plays a role. In this article, we review studies addressing interlaboratory variability and recommend optimal testing techniques and reporting procedures for ER testing, with the goal of increasing interlaboratory standardization for ER analysis by immunohistochemistry. We additionally highlight recent biologic, molecular, and gene expression profiling data related to ER in breast cancer.