Breast cancer heterogeneity: evaluation of clonality in primary and metastatic lesions

Pathway Activation Analysis for Pan-Cancer Personalized Characterization Based on Riemannian Manifold

The pathogenesis of carcinoma is believed to come from the combined effect of polygenic variation, and the initiation and progression of malignant tumors are closely related to the dysregulation of biological pathways. Quantifying the alteration in pathway activation and identifying coordinated patterns of pathway dysfunction are the imperative part of understanding the malignancy process and distinguishing different tumor stages or clinical outcomes of individual patients. In this study, we have conducted in silico pathway activation analysis using Riemannian manifold (RiePath) toward pan-cancer personalized characterization, which is the first attempt to apply the Riemannian manifold theory to measure the extent of pathway dysregulation in individual patient on the tangent space of the Riemannian manifold. RiePath effectively integrates pathway and gene expression information, not only generating a relatively low-dimensional and biologically relevant representation, but also identifying a robust panel of biologically meaningful pathway signatures as biomarkers. The pan-cancer analysis across 16 cancer types reveals the capability of RiePath to evaluate pathway activation accurately and identify clinical outcome-related pathways. We believe that RiePath has the potential to provide new prospects in understanding the molecular mechanisms of complex diseases and may find broader applications in predicting biomarkers for other intricate diseases.

Imagine beyond: recent breakthroughs and next challenges in mammary gland biology and breast cancer research

On 8 December 2022 the organizing committee of the European Network for Breast Development and Cancer labs (ENBDC) held its fifth annual Think Tank meeting in Amsterdam, the Netherlands. Here, we embraced the opportunity to look back to identify the most prominent breakthroughs of the past ten years and to reflect on the main challenges that lie ahead for our field in the years to come. The outcomes of these discussions are presented in this position paper, in the hope that it will serve as a summary of the current state of affairs in mammary gland biology and breast cancer research for early career researchers and other newcomers in the field, and as inspiration for scientists and clinicians to move the field forward.

Prognosis Associated with Glycolytic Activity in Regional Lymph Nodes of Patients with Previously Untreated Metastatic Breast Cancer: A Preliminary Study

Better mechanisms of predicting prognoses in patients with metastatic breast cancer will improve the identification of patients for whom curative treatments may be the most effective. In this study, the prognostic value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) was assessed in patients with metastatic breast cancer. A retrospective analysis of women who underwent 18F-FDG PET/CT for staging of newly diagnosed metastatic breast cancer was conducted. In each patient, the maximum standardized uptake value (SUV) and total lesion glycolysis (TLG) of primary tumors and regional lymph nodes were measured and analyzed for association with survival using the Cox proportional hazards regression model. From 346 consecutive patients, 32 with metastatic invasive ductal carcinoma of the breast were included in the study. The median duration of follow-up was 22.5 months. Disease progression occurred in 26 patients, and 11 patients died. When multivariate analyses with a stepwise forward regression were applied, only the maximum SUV and TLG of regional lymph nodes showed a significant correlation with progression-free survival and overall survival, respectively. This study demonstrates that increased 18F-FDG uptake in regional lymph nodes is a strong independent predictor of survival in women with metastatic invasive ductal carcinoma of the breast.

Beyond Genetics: Metastasis as an Adaptive Response in Breast Cancer

Metastatic disease represents the primary cause of breast cancer (BC) mortality, yet it is still one of the most enigmatic processes in the biology of this tumor. Metastatic progression includes distinct phases: invasion, intravasation, hematogenous dissemination, extravasation and seeding at distant sites, micro-metastasis formation and metastatic outgrowth. Whole-genome sequencing analyses of primary BC and metastases revealed that BC metastatization is a non-genetically selected trait, rather the result of transcriptional and metabolic adaptation to the unfavorable microenvironmental conditions which cancer cells are exposed to (e.g., hypoxia, low nutrients, endoplasmic reticulum stress and chemotherapy administration). In this regard, the latest multi-omics analyses unveiled intra-tumor phenotypic heterogeneity, which determines the polyclonal nature of breast tumors and constitutes a challenge for clinicians, correlating with patient poor prognosis. The present work reviews BC classification and epidemiology, focusing on the impact of metastatic disease on patient prognosis and survival, while describing general principles and current in vitro/in vivo models of the BC metastatic cascade. The authors address here both genetic and phenotypic intrinsic heterogeneity of breast tumors, reporting the latest studies that support the role of the latter in metastatic spreading. Finally, the review illustrates the mechanisms underlying adaptive stress responses during BC metastatic progression.

Characterizing cellular mechanical phenotypes with mechano-node-pore sensing

The mechanical properties of cells change with their differentiation, chronological age, and malignant progression. Consequently, these properties may be useful label-free biomarkers of various functional or clinically relevant cell states. Here, we demonstrate mechano-node-pore sensing (mechano-NPS), a multi-parametric single-cell-analysis method that utilizes a four-terminal measurement of the current across a microfluidic channel to quantify simultaneously cell diameter, resistance to compressive deformation, transverse deformation under constant strain, and recovery time after deformation. We define a new parameter, the whole-cell deformability index (wCDI), which provides a quantitative mechanical metric of the resistance to compressive deformation that can be used to discriminate among different cell types. The wCDI and the transverse deformation under constant strain show malignant MCF-7 and A549 cell lines are mechanically distinct from non-malignant, MCF-10A and BEAS-2B cell lines, and distinguishes between cells treated or untreated with cytoskeleton-perturbing small molecules. We categorize cell recovery time, ΔT_r, as instantaneous (ΔT_r ~ 0 ms), transient (ΔT_r ≤ 40ms), or prolonged (ΔT_r > 40ms), and show that the composition of recovery types, which is a consequence of changes in cytoskeletal organization, correlates with cellular transformation. Through the wCDI and cell-recovery time, mechano-NPS discriminates between sub-lineages of normal primary human mammary epithelial cells with accuracy comparable to flow cytometry, but without antibody labeling. Mechano-NPS identifies mechanical phenotypes that distinguishes lineage, chronological age, and stage of malignant progression in human epithelial cells.

Evaluation of Discordance in Primary Tumor and Lymph Node Response After Neoadjuvant Therapy in Breast Cancer

BACKGROUND

Neoadjuvant therapy (NAT) offers a unique opportunity to assess tumor response to systemic agents. However, a discrepancy may exist between the response of the primary tumor and involved nodes. We report on the frequency of response discordance after NAT in breast cancer.

PATIENTS AND METHODS

All consecutive node-positive patients receiving NAT in our department from 2009 to 2014 were identified. Patient demographics, and radiologic and pathologic features were tabulated. Tumor response was estimated by magnetic resonance imaging of the breast. Lymph node (LN) response was estimated from pathologic treatment response measurements. Statistical analysis was performed.

RESULTS

A total of 108 node-positive patients treated with NAT were eligible for inclusion. Median age was 51.73 years (range, 20-87 years). All patients underwent axillary clearance, and 62% underwent mastectomy. A 40% mean reduction in tumor size was observed. Statistically, a positive correlation between tumor and LN response after NAT was observed (Spearman correlation coefficient, r = 0.46, P < .001). Complete pathologic response was observed in 17 patients (15.7%). However, 21 patients experienced complete LN response, with only 81% of these patients (n = 17) experiencing a complete response in tumor also. A complete response was observed in tumor in 20 patients, and this predicted complete nodal response in 85% of cases (n = 17). Fifteen percent of primary tumors with complete pathologic response had persistently positive LNs.

CONCLUSION

A significant discordance exists between the primary tumor and LN response, representing a concern for the lack of response of occult regional or systemic metastases due to potential biologic heterogeneity.

Molecular characterization of CD44+/CD24-/Ck+/CD45- cells in benign and malignant breast lesions

Breast cancer epithelial cells with the CD44⁺/CD24^-/low phenotype possess tumor-initiating cells and epithelial-mesenchymal transition (EMT) capacity. Massive parallel sequencing can be an interesting approach to deepen the molecular characterization of these cells. We characterized CD44⁺/CD24^-/cytokeratin(Ck)⁺/CD45^- cells isolated through flow cytometry from 43 biopsy and 6 mastectomy samples harboring different benign and malignant breast lesions. The Ion Torrent Ampliseq Cancer Hotspot panel v2 (CHPv2) was used for the identification of somatic mutations in the DNA extracted from isolated CD44⁺/CD24^-/Ck⁺/CD45^- cells. E-Cadherin and vimentin immunohistochemistry was performed on sections from the corresponding formalin-fixed, paraffin-embedded (FFPE) blocks. The percentage of CD44⁺/CD24^-/Ck⁺/CD45^- cells increased significantly from non-malignant to malignant lesions and in association with a significant increase in the expression of vimentin. Non-malignant lesions harbored only a single-nucleotide polymorphism (SNP). Mutations in the tumor suppressor p53 (TP53), NOTCH homolog 1 (NOTCH1), phosphatase and tensin homolog (PTEN), and v-akt murine thymoma viral oncogene homolog 1 (AKT1) genes were found in isolated CD44⁺/CD24^-/Ck⁺/CD45^- cells from ductal carcinomas in situ (DCIS). Additional mutations in the colony-stimulating factor 1 receptor (CSF1R), ret proto-oncogene (RET), and TP53 genes were also identified in invasive ductal carcinomas (IDCs). The use of massive parallel sequencing technology for this type of application revealed to be extremely effective even when using small amounts of DNA extracted from a low number of cells. Additional studies are now required using larger cohorts to design an appropriate mutational profile for this phenotype.

Proteogenomics connects somatic mutations to signalling in breast cancer

Somatic mutations have been extensively characterized in breast cancer, but the effects of these genetic alterations on the proteomic landscape remain poorly understood. We describe quantitative mass spectrometry-based proteomic and phosphoproteomic analyses of 105 genomically annotated breast cancers of which 77 provided high-quality data. Integrated analyses allowed insights into the somatic cancer genome including the consequences of chromosomal loss, such as the 5q deletion characteristic of basal-like breast cancer. The 5q trans effects were interrogated against the Library of Integrated Network-based Cellular Signatures, thereby connecting CETN3 and SKP1 loss to elevated expression of EGFR, and SKP1 loss also to increased SRC. Global proteomic data confirmed a stromal-enriched group in addition to basal and luminal clusters and pathway analysis of the phosphoproteome identified a G Protein-coupled receptor cluster that was not readily identified at the mRNA level. Besides ERBB2, other amplicon-associated, highly phosphorylated kinases were identified, including CDK12, PAK1, PTK2, RIPK2 and TLK2. We demonstrate that proteogenomic analysis of breast cancer elucidates functional consequences of somatic mutations, narrows candidate nominations for driver genes within large deletions and amplified regions, and identifies therapeutic targets.

FERAL: network-based classifier with application to breast cancer outcome prediction

MOTIVATION

Breast cancer outcome prediction based on gene expression profiles is an important strategy for personalize patient care. To improve performance and consistency of discovered markers of the initial molecular classifiers, network-based outcome prediction methods (NOPs) have been proposed. In spite of the initial claims, recent studies revealed that neither performance nor consistency can be improved using these methods. NOPs typically rely on the construction of meta-genes by averaging the expression of several genes connected in a network that encodes protein interactions or pathway information. In this article, we expose several fundamental issues in NOPs that impede on the prediction power, consistency of discovered markers and obscures biological interpretation.

RESULTS

To overcome these issues, we propose FERAL, a network-based classifier that hinges upon the Sparse Group Lasso which performs simultaneous selection of marker genes and training of the prediction model. An important feature of FERAL, and a significant departure from existing NOPs, is that it uses multiple operators to summarize genes into meta-genes. This gives the classifier the opportunity to select the most relevant meta-gene for each gene set. Extensive evaluation revealed that the discovered markers are markedly more stable across independent datasets. Moreover, interpretation of the marker genes detected by FERAL reveals valuable mechanistic insight into the etiology of breast cancer.

AVAILABILITY AND IMPLEMENTATION

All code is available for download at: http://homepage.tudelft.nl/53a60/resources/FERAL/FERAL.zip.

Network-Based Methods to Identify Highly Discriminating Subsets of Biomarkers

Complex diseases such as various types of cancer and diabetes are conjectured to be triggered and influenced by a combination of genetic and environmental factors. To integrate potential effects from interplay among underlying candidate factors, we propose a new network-based framework to identify effective biomarkers by searching for groups of synergistic risk factors with high predictive power to disease outcome. An interaction network is constructed with node weights representing individual predictive power of candidate factors and edge weights capturing pairwise synergistic interactions among factors. We then formulate this network-based biomarker identification problem as a novel graph optimization model to search for multiple cliques with maximum overall weight, which we denote as the Maximum Weighted Multiple Clique Problem (MWMCP). To achieve optimal or near optimal solutions, both an analytical algorithm based on column generation method and a fast heuristic for large-scale networks have been derived. Our algorithms for MWMCP have been implemented to analyze two biomedical data sets: a Type 1 Diabetes (T1D) data set from the Diabetes Prevention Trial-Type 1 (DPT-1) study, and a breast cancer genomics data set for metastasis prognosis. The results demonstrate that our network-based methods can identify important biomarkers with better prediction accuracy compared to the conventional feature selection that only considers individual effects.

Deformable registration for quantifying longitudinal tumor changes during neoadjuvant chemotherapy

PURPOSE

To evaluate DRAMMS, an attribute-based deformable registration algorithm, compared to other intensity-based algorithms, for longitudinal breast MRI registration, and to show its applicability in quantifying tumor changes over the course of neoadjuvant chemotherapy.

METHODS

Breast magnetic resonance images from 14 women undergoing neoadjuvant chemotherapy were analyzed. The accuracy of DRAMMS versus five intensity-based deformable registration methods was evaluated based on 2,380 landmarks independently annotated by two experts, for the entire image volume, different image subregions, and patient subgroups. The registration method with the smallest landmark error was used to quantify tumor changes, by calculating the Jacobian determinant maps of the registration deformation.

RESULTS

DRAMMS had the smallest landmark errors (6.05 ± 4.86 mm), followed by the intensity-based methods CC-FFD (8.07 ± 3.86 mm), NMI-FFD (8.21 ± 3.81 mm), SSD-FFD (9.46 ± 4.55 mm), Demons (10.76 ± 6.01 mm), and Diffeomorphic Demons (10.82 ± 6.11 mm). Results show that registration accuracy also depends on tumor versus normal tissue regions and different patient subgroups.

CONCLUSIONS

The DRAMMS deformable registration method, driven by attribute-matching and mutual-saliency, can register longitudinal breast magnetic resonance images with a higher accuracy than several intensity-matching methods included in this article. As such, it could be valuable for more accurately quantifying heterogeneous tumor changes as a marker of response to treatment.

HER2 discordance between primary and metastatic breast cancer: assessing the clinical impact

BACKGROUND

In the setting of breast cancer relapse, treatment decisions are typically made by utilizing HER2, estrogen, and progesterone receptor expression status of the primary breast cancer. Recently, concern regarding receptor discordance has led to recommendations for rebiopsy for all cases of metastatic disease. However, whether this is an appropriate recommendation is uncertain, particularly as the clinical implications for HER2 discordance are unknown.

METHODS

We performed a literature review to identify studies assessing HER2 discordance between primary and metastatic breast cancer. These studies were then reviewed for data relating to (1) impact of clinical factors on discordance rates, (2) prognostic impact of discordance, or (3) clinical outcomes from treatment alteration due to receptor discordance. Results were analyzed qualitatively.

RESULTS

From 60 HER2 discordance studies identified, 24 contained information of interest for this review. No clear factor promoting HER2 discordance was identified. Loss of HER2 seemed to result in worse post-relapse survival and overall survival, although these data were often confounded by lack of treatment in the setting of receptor loss. Conversely, HER2 discordance was not associated with shorter DFS. Individual patients with receptor gain appear to have benefited from addition of targeted treatment, although data are limited to case reports.

CONCLUSION

Evidence of HER2 discordance leading to alterations in patient outcomes is limited, highlighting the need for further research in this area. Furthermore, lack of alteration in patient outcomes suggests that a more pragmatic approach to the decision to rebiopsy may be appropriate.

Beyond comparing means: the usefulness of analyzing interindividual variation in gene expression for identifying genes associated with cancer development

Identifying genes associated with cancer development is typically accomplished by comparing mean expression values in normal and tumor tissues, which identifies differentially expressed (DE) genes. Interindividual variation (IV) in gene expression is indirectly included in DE gene identification because given the same absolute differences in means, genes with lower variance tend to have lower p-values. We explored the direct use of IV in gene expression to identify candidate genes associated with cancer development. We focused on prostate (PCa) and lung (LC) cancers and compared IV in the expression level of genes shown to be cancer related with that in all other genes in the human genome. Compared with all those other genes, cancer-related genes tended to have greater IV in normal tissues and a greater increase in IV during the transition from normal to tumorous tissue. Genes without significantly different mean expression values between tumor and normal tissues but with greater IV in tumor than in normal tissue (note: the DE-based approach completely ignores those genes) had stronger associations with clinically important features like Gleason score in PCa or tumor histology in LC than all other genes were. Our results suggest that analyzing IV in gene expression level is useful in identifying novel candidate genes associated with cancer development.

ER, HER2, and TOP2A expression in primary tumor, synchronous axillary nodes, and asynchronous metastases in breast cancer

At recurrence of breast cancer, the therapeutic target is the metastases. However, it is current practice to base the choice of systemic treatment on the biomarker profile of the primary tumor. In the present study, confirmatory biopsies were obtained from suspected metastatic lesions and compared with the primary tumors with respect to ER, HER2, and TOP2A. In the prospective tissue-collection study, 81 patients had biopsy from a suspected relapse. Additional archived paired material was included, leaving a total of 119 patients with paired primary tumor, synchronous axillary nodes (available in 52 patients) and asyncronous metastases available for analysis. ER, HER2, and TOP2A expression of primary tumors, axillary nodes and metastases were re-analysed and determined centrally by immunohistochemistry, chromogenic in situ hybridization, and fluorescence in situ hybridization. Of the 81 patients with a biopsy from a suspected relapse, 65 (80%) were diagnosed with recurrent breast carcinoma, 3 (4%) were diagnosed with other malignancies, 6 (7%) had benign conditions, and in 7 (9%) patients the biopsy was non-representative. Discordance in ER, HER2, and TOP2A (aberration vs. normal) status between primary tumor and corresponding asynchronous metastasis was 12% (14/118), 9% (10/114), and 23% (17/75), respectively. There were no significant associations with biomarker discordance and prior adjuvant therapy, or location of biopsy. Expression of ER, HER2, and TOP2A displayed discordance with a sufficient frequency to emphasize the role of confirmatory biopsies from metastatic lesions in future management of recurrent breast cancer.

Intratumoral heterogeneity of immunohistochemical marker expression in breast carcinoma: a tissue microarray-based study

Core needle biopsies of breast carcinomas provide diagnostic, prognostic, and predictive information before neoadjuvant therapy. Possible intratumoral heterogeneity of biomarker expression questions the validity of core needle biopsy interpretation in small biopsy specimens. Using tissue microarray (TMA) technology, we studied intratumoral heterogeneity of 7 immunomarkers. Five TMAs were constructed from 44 breast carcinomas and 5 normal breast tissues, each represented by 1-mm cores in triplicate from each of 3 foci. TMAs were immunostained for monoclonal estrogen receptor (ER), monoclonal progesterone receptor (PR), polyclonal human epidermal growth factor receptor 2 (HER2), monoclonal E-cadherin (E-cad), monoclonal epidermal growth factor receptor (EGFR), monoclonal p53, and monoclonal MIB-1. Expression was quantified visually by light microscopy and by image cytometry as intensity, percentage of cells positive, and score. Using intraclass correlation coefficient, heterogeneity in the expression of the immunomarkers within subjects was compared with the overall variance. Intratumoral heterogeneity was seen with 5 immunomarkers: ER, PR, HER2, p53, and MIB-1. E-cad and EGFR failed to show intratumoral heterogeneity. Intratumoral heterogeneity in ER, PR, HER2, p53, and MIB-1 indicates their problematic interpretation in small biopsy specimens as indicative of the status of the entire tumor. A negative result does not exclude the expression of these markers in the remainder of the tumor. E-cad (positive in ductal carcinomas) and EGFR lacked heterogeneity.

Variation in hormone receptor and HER-2 status between primary and metastatic breast cancer: review of the literature

IMPORTANCE OF THE FIELD

Hormone and human epidermal growth factor receptor 2 (HER-2) receptors are two important pharmaceutical targets that affect the survival of patients with metastatic breast cancer. Discordance of hormone and HER-2 receptors were reported in a series of studies. Receptor status was reported to change in both directions, yet alteration occurs mostly in the loss of positivity for both receptors. We do not know both the exact mechanism of this process or the contribution rate of technical mistakes; a number of mechanisms might be responsible. Factors suggested include: tumor heterogeneity, clonal selection of tumor cell subpopulations, genetic instability of tumor cells, local or systemic treatments, the time interval between primary tumor and metastasis, receptor status determination techniques, and the site of metastasis.

AREAS COVERED IN THIS REVIEW

Studies of estrogen, progesterone and HER-2 receptor discordance between primary and metastasis of breast cancer are summarized. Laboratory evaluation of estrogen, progesterone and HER-2 receptors, and possible causes of receptor discordance, are summarized. Literature data are reviewed; the major shortcoming of these studies is that they are mostly retrospective.

WHAT THE READER WILL GAIN

The reader will read a concise literature review about the studies on estrogen, progesterone and HER-2 receptor discordances between primary and metastasis of breast cancer.

TAKE HOME MESSAGE

We do not know whether the changes in receptor expression account for a true biological phenomenon or may result from inconsistent measurement. However, in light of current data, for the treatment plans that target the receptors, biopsy specimen from the metastatis of breast cancer must also be evaulated for alterations in the receptor status.

Identification of diagnostic subnetwork markers for cancer in human protein-protein interaction network

Background

Finding reliable gene markers for accurate disease classification is very challenging due to a number of reasons, including the small sample size of typical clinical data, high noise in gene expression measurements, and the heterogeneity across patients. In fact, gene markers identified in independent studies often do not coincide with each other, suggesting that many of the predicted markers may have no biological significance and may be simply artifacts of the analyzed dataset. To find more reliable and reproducible diagnostic markers, several studies proposed to analyze the gene expression data at the level of groups of functionally related genes, such as pathways. Studies have shown that pathway markers tend to be more robust and yield more accurate classification results. One practical problem of the pathway-based approach is the limited coverage of genes by currently known pathways. As a result, potentially important genes that play critical roles in cancer development may be excluded. To overcome this problem, we propose a novel method for identifying reliable subnetwork markers in a human protein-protein interaction (PPI) network.

Results

In this method, we overlay the gene expression data with the PPI network and look for the most discriminative linear paths that consist of discriminative genes that are highly correlated to each other. The overlapping linear paths are then optimally combined into subnetworks that can potentially serve as effective diagnostic markers. We tested our method on two independent large-scale breast cancer datasets and compared the effectiveness and reproducibility of the identified subnetwork markers with gene-based and pathway-based markers. We also compared the proposed method with an existing subnetwork-based method.

Conclusions

The proposed method can efficiently find reliable subnetwork markers that outperform the gene-based and pathway-based markers in terms of discriminative power, reproducibility and classification performance. Subnetwork markers found by our method are highly enriched in common GO terms, and they can more accurately classify breast cancer metastasis compared to markers found by a previous method.

A comparison of HER2/neu gene amplification and its protein overexpression between primary breast cancer and metastatic lymph nodes

OBJECTIVE

Breast cancer is a heterogeneous disease. The aim of this prospective study, in which fluorescence in situ hybridization was used to determine human epidermal growth factor receptor 2 status in primary breast cancers and in the lymph node metastases, was to verify the stability of human epidermal growth factor receptor 2 status in the following steps of neoplastic progression of breast cancer, which is fundamental for an appropriate therapeutic approach.

METHODS

From patients with primary breast cancer, for whom, after January 2003, surgery was performed and involved metastatic lymph nodes were found, we randomly selected four groups of 15 patients, whose human epidermal growth factor receptor 2 score by immunohistochemistry was either 0, 1+, 2+ or 3+, respectively, totaling to 60. For each of those patients, their primary tumors and all of the metastatic lymph nodes were examined. Primary tumors and metastatic lymph nodes in each patient were examined by fluorescence in situ hybridization.

RESULTS

Of 18 patients with fluorescence in situ hybridization-positive primary tumors, 15 (83.3%) were fluorescence in situ hybridization-positive and 2 (11.1%) were fluorescence in situ hybridization-negative in all of their metastatic lymph nodes, and 1 (5.5%) patient had mixed (fluorescence in situ hybridization-positive or -negative) metastatic lymph nodes. Of 42 patients with fluorescence in situ hybridization-negative primary tumors, 40 (95%) were fluorescence in situ hybridization-negative and 2 (5%) fluorescence in situ hybridization-positive in all of their metastatic lymph nodes.

CONCLUSIONS

This study revealed that fluorescence in situ hybridization resulted in a high concordance of 83.3% between the human epidermal growth factor receptor 2 manifestation (fluorescence in situ hybridization-positive status) in primary tumors and that in metastatic lymph nodes, demonstrating that it is appropriate to determine whether and how to apply treatment by trastuzumab based on the results of evaluation of human epidermal growth factor receptor 2 expression.

Hormone receptor and c-ERBB2 status in distant metastatic and locally recurrent breast cancer. Pathologic correlations and clinical significance

Estrogen receptor (ER), progesterone receptor (PR), and c-ERBB2 (HER2/neu) are therapeutically and prognostically important markers in the management of breast carcinoma. They are not always analyzed in distant metastatic and locally recurrent breast cancers. We compared immunohistochemical expression in a series of primary breast carcinomas with their distant metastases (n = 72) and local recurrences (n = 45) and analyzed the impact of any changes on survival. Discordance rates between primary and metastatic and between primary and locally recurrent lesions, respectively, were 18% (13/72) and 13% (6/45) for ER, 42% (30/72) and 33% (15/45) for PR, and 7% (5/72) and 2% (1/45) for c-ERBB2. There was statistically significant discordance between primary and metastatic PR status (P = .017; kappa = 0.201). Among locally recurrent tumors, 15 (33%) of 45 revealed discordance for PR (P = .006; kappa = 0.366). We observed a trend for shorter survival among women with ER- metastatic and locally recurrent tumors regardless of the primary tumor ER status. Our findings suggest a benefit for routine evaluation of ER, PR, and c-ERBB2 status in distant metastatic and locally recurrent breast cancer for therapeutic and prognostic purposes.

Gene expression profiles identify inflammatory signatures in dendritic cells

Dendritic cells (DCs) constitute a heterogeneous group of antigen-presenting leukocytes important in activation of both innate and adaptive immunity. We studied the gene expression patterns of DCs incubated with reagents inducing their activation or inhibition. Total RNA was isolated from DCs and gene expression profiling was performed with oligonucleotide microarrays. Using a supervised learning algorithm based on Random Forest, we generated a molecular signature of inflammation from a training set of 77 samples. We then validated this molecular signature in a testing set of 38 samples. Supervised analysis identified a set of 44 genes that distinguished very accurately between inflammatory and non inflammatory samples. The diagnostic performance of the signature genes was assessed against an independent set of samples, by qRT-PCR. Our findings suggest that the gene expression signature of DCs can provide a molecular classification for use in the selection of anti-inflammatory or adjuvant molecules with specific effects on DC activity.

Prognostic impact of discordance between triple-receptor measurements in primary and recurrent breast cancer

BACKGROUND

We evaluated discordance in expression measurements for estrogen receptor (ER), progesterone receptor (PR), and HER2 between primary and recurrent tumors in patients with recurrent breast cancer and its effect on prognosis.

METHODS

A total of 789 patients with recurrent breast cancer were studied. ER, PR, and HER2 status were determined by immunohistochemistry (IHC) and/or FISH. Repeat markers for ER, PR, and HER2 were available in 28.9%, 27.6%, and 70.0%, respectively. Primary and recurrent tumors were classified as triple receptor-negative breast cancer (TNBC) or receptor-positive breast cancer (RPBC, i.e. expressing at least one receptor). Discordance was correlated with clinical/pathological parameters.

RESULTS

Discordance for ER, PR, and HER2 was 18.4%, 40.3%, and 13.6%, respectively. Patients with concordant RPBC had significantly better post-recurrence survival (PRS) than discordant cases; patients with discordant receptor status had similarly unfavorable survival as patients with concordant TNBC. IHC scores for ER and PR showed weak concordance between primary and recurrent tumors. Concordance of HER2-FISH scores was higher.

CONCLUSIONS

Concordance of quantitative hormone receptor measurements between primary and recurrent tumors is modest consistent with suboptimal reproducibility of measurement methods, particularly for IHC. Discordant cases have poor survival probably due to inappropriate use of targeted therapies. However, biological change in clinical phenotype cannot be completely excluded.

The HER-2 receptor and breast cancer: ten years of targeted anti-HER-2 therapy and personalized medicine

The human epidermal growth factor receptor (HER-2) oncogene encodes a transmembrane tyrosine kinase receptor that has evolved as a major classifier of invasive breast cancer and target of therapy for the disease. The validation of the general prognostic significance of HER-2 gene amplification and protein overexpression in the absence of anti-HER-2 targeted therapy is discussed in a study of 107 published studies involving 39,730 patients, which produced an overall HER-2-positive rate of 22.2% and a mean relative risk for overall survival (OS) of 2.74. The issue of HER-2 status in primary versus metastatic breast cancer is considered along with a section on the features of metastatic HER-2-positive disease. The major marketed slide-based HER-2 testing approaches, immunohistochemistry, fluorescence in situ hybridization, and chromogenic in situ hybridization, are presented and contrasted in detail against the background of the published American Society of Clinical Oncology-College of American Pathologists guidelines for HER-2 testing. Testing issues, such as the impact of chromosome 17 polysomy and local versus central HER-2 testing, are also discussed. Emerging novel HER-2 testing techniques, including mRNA-based testing by real-time polymerase chain reaction and DNA microarray methods, HER-2 receptor dimerization, phosphorylated HER-2 receptors, and HER-2 status in circulating tumor cells, are also considered. A series of biomarkers potentially associated with resistance to trastuzumab is discussed with emphasis on the phosphatase and tensin homologue deleted on chromosome ten/Akt and insulin-like growth factor receptor pathways. The efficacy results for the more recently approved small molecule HER-1/HER-2 kinase inhibitor lapatinib are also presented along with a more limited review of markers of resistance for this agent. Additional topics in this section include combinations of both anti-HER-2 targeted therapies together as well as with novel agents including bevacizumab, everolimus, and tenespimycin. A series of novel HER-2-targeting agents is also presented, including pertuzumab, ertumaxomab, HER-2 vaccines, and recently discovered tyrosine kinase inhibitors. Biomarkers predictive of HER-2 targeted therapy toxicity are included, and the review concludes with a consideration of HER-2 status in the prediction of response to non-HER-2 targeted treatments including hormonal therapy, anthracyclines, and taxanes.

Inferring pathway activity toward precise disease classification

The advent of microarray technology has made it possible to classify disease states based on gene expression profiles of patients. Typically, marker genes are selected by measuring the power of their expression profiles to discriminate among patients of different disease states. However, expression-based classification can be challenging in complex diseases due to factors such as cellular heterogeneity within a tissue sample and genetic heterogeneity across patients. A promising technique for coping with these challenges is to incorporate pathway information into the disease classification procedure in order to classify disease based on the activity of entire signaling pathways or protein complexes rather than on the expression levels of individual genes or proteins. We propose a new classification method based on pathway activities inferred for each patient. For each pathway, an activity level is summarized from the gene expression levels of its condition-responsive genes (CORGs), defined as the subset of genes in the pathway whose combined expression delivers optimal discriminative power for the disease phenotype. We show that classifiers using pathway activity achieve better performance than classifiers based on individual gene expression, for both simple and complex case-control studies including differentiation of perturbed from non-perturbed cells and subtyping of several different kinds of cancer. Moreover, the new method outperforms several previous approaches that use a static (i.e., non-conditional) definition of pathways. Within a pathway, the identified CORGs may facilitate the development of better diagnostic markers and the discovery of core alterations in human disease.

Micrometastatic spread in breast cancer: detection, molecular characterization and clinical relevance

Immunocytochemical or molecular assays allow the detection of single disseminated tumor cells (DTCs) in the bone marrow (BM) or the peripheral blood in 10% to 60% of breast cancer patients without signs of metastasis. Results from recently reported studies suggest that circulating tumor cell (CTC) levels may serve as a prognostic marker and be used for early assessment of therapeutic response in patients with metastatic breast cancer. In early stage breast cancer, however, the impact of CTCs is less well established than that of DTCs in BM, where several clinical studies demonstrated that such cells are an independent prognostic factor at primary diagnosis. The characterization of DTCs/CTCs has already shed new light on the complex process underlying early tumor cell dissemination and metastatic progression in cancer patients. Characterization of DTCs should help to identify novel targets for biological therapies aimed to prevent metastatic relapse. In addition, understanding tumor 'dormancy' and identifying metastatic stem cells might result in the development of new therapeutic concepts.

Network-based classification of breast cancer metastasis

Mapping the pathways that give rise to metastasis is one of the key challenges of breast cancer research. Recently, several large-scale studies have shed light on this problem through analysis of gene expression profiles to identify markers correlated with metastasis. Here, we apply a protein-network-based approach that identifies markers not as individual genes but as subnetworks extracted from protein interaction databases. The resulting subnetworks provide novel hypotheses for pathways involved in tumor progression. Although genes with known breast cancer mutations are typically not detected through analysis of differential expression, they play a central role in the protein network by interconnecting many differentially expressed genes. We find that the subnetwork markers are more reproducible than individual marker genes selected without network information, and that they achieve higher accuracy in the classification of metastatic versus non-metastatic tumors.

Bystander killing of breast cancer MCF-7 cells by MDA-MB-231 cells exposed to 5-fluorouracil is mediated via Fas

The major drawback with cancer therapy is the development of resistant cells within tumors due to their heterogeneous nature and due to inadequate drug delivery during chemotherapy. Therefore, the propagation of injury ("bystander effect" (BE)) from directly damaged cells to other cells may have great implications in cancer chemotherapy. The general advantage of the bystander cell killing phenomenon is the large therapeutic index that can be achieved. Experiments suggest that this phenomenon is detected in radiation therapy as well as in gene therapy in conjunction with chemotherapy. In the present study, we developed an original in vitro model dedicated to the exploration of bystander cytotoxicity induced during breast carcinoma chemotherapy. In brief, we investigated this perpetuation of injury on untreated bystander MCF-7 breast cancer cells which were coplated with 5-fluorouracil (5-FU)-treated MDA-MB-231 breast cancer cells. To achieve this goal, a specific in vitro coculture model which involved mixing of aggressive MDA-MB-231 breast cancer cells with enhanced green fluorescent protein (EGFP) expressing stable clone of non-metastatic MCF-7 breast cancer cells (MCF-EGFP), was used. A bystander killing effect was observed in MCF-EGFP cells cocultured with MDA-MB-231 cells pretreated with 5-FU. The striking decrease in MCF-EGFP cells, as detected by assaying for total GFP intensity, is mediated by activation of Fas/FasL system. The implication of Fas in MCF-EGFP cell death was confirmed by using antagonistic anti-FasL antibody that reverses bystander cell death by blocking FasL on MDA-MB-231 cells. In addition, inhibition of CD95/Fas receptor on the cell surface of MCF-EGFP cells by treatment with Pifithrin-alpha, a p53 specific transactivation inhibitor, partially abrogated the sensitivity of bystander MCF-EGFP cells. Our data, therefore, demonstrates that the Fas/FasL system could be considered as a new determinant for chemotherapy-induced bystander cell death in breast cancers.

Intratumoral Heterogeneity of HER2/neu in Breast Cancer?A Rare Event

HER2/neu is overexpressed in about 20% of invasive breast carcinomas. Numerous studies have shown that there is high level of concordance between the HER2/neu status of the primary breast cancer and the metastases of a given patient. Recently, changes in HER2/neu status with tumor progression have been reported, suggesting the possibility of an emerging different tumor clone. Little is known about intratumoral heterogeneity with regard to HER2/neu oncoprotein overexpression. We identified nine cases of invasive ductal carcinoma that showed intratumoral variation in HER2/neu oncoprotein expression by immunohistochemistry. This was confirmed by the intratumoral variation in the amplification status of the HER2/neu gene by fluorescence in situ hybridization and by chromogenic in situ hybridization. The results of this study suggest that some cases of primary breast carcinoma are heterogeneous in regard to HER2/neu gene amplification or protein overexpression. Heterogeneity of HER2/neu status in a tumor may be a rare event or underestimated. This phenomenon should be examined as it may contribute to a better understanding of the variation in therapeutic responses and the conflicting data in studies about the prognostic and predictive role of HER2/neu status in subsets of breast cancer patients.

HER2 testing: a review of detection methodologies and their clinical performance

The ERBB2 proto-oncogene, commonly referred to as the human epidermal growth factor receptor-2 (HER2) gene, encodes a 185 kd receptor tyrosine kinase. Overexpression of the protein leads to constitutive activity of the HER2 receptor and breast tumor development through enhanced cell proliferation, survival, motility and adhesion. Overabundance of the HER2 receptor, typically caused by amplification of the HER2 gene, is present in approximately 10-30% of invasive breast cancers, and is associated with an aggressive disease course and decreased disease-free and overall survival in node-positive patients. Tratuzumab, a humanized murine monoclonal antibody, offers a targeted treatment modality for tumors that over express the HER2 protein. Tratuzumab, shown to be effective and initially approved for treatment of metastatic breast cancer, has recently been shown to be very effective in the adjuvant setting. Thus, to offer prognostic information and to direct appropriate treatment it is important to provide accurate laboratory assessment of the status of HER2. This article provides an overview of the methods currently used to assess HER2.

Disseminated tumor cells in breast cancer: detection, characterization and clinical relevance

Hematogenous distant metastasis is the leading cause of cancer-related death in breast cancer and other solid tumors. By applying sensitive immunocytochemical or molecular assays, disseminated tumor cells (DTCs) in bone marrow can be detected in 20–40% of breast cancer patients without any clinical or even histopathological signs of metastasis. The detection of DTCs provides prognostic information and might help to identify patients who need adjuvant therapy, and to monitor the efficacy of adjuvant therapy. Within the last few years, various efforts have led to an increased sensitivity in the detection of DTC. This review will summarize the most important methods for DTC detection in bone marrow and for circulating tumor cells in the blood of breast cancer patients, the clinical relevance of DTCs and, finally, provide an outlook on clinical implications.

Prognostic gene expression signatures can be measured in tissues collected in RNAlater preservative

Gene expression signatures have the ability to serve in both prognostic and predictive capacities in patient management. The use of RNA as the starting material and the lability of this analyte, however, dictate that tissues must be snap-frozen or stored in a solution that can maintain the integrity of the RNA. We compared pairs of snap-frozen and RNAlater preservative-suspended tissue from 30 such paired lymph node-negative breast tumors and 21 such paired Dukes' B colon tumors. We assessed the correlation of gene expression profiles and prediction of recurrence based on two prognostic algorithms. Tissues stored in RNAlater preservative generated expression profiles with excellent correlation (average Pearson correlation coefficients of 0.97 and 0.94 for the breast and colon tumor pairs, respectively) compared to those produced by tissues that were snap-frozen. The correlation in the prediction of recurrence was 97% and 95% for the breast and colon tumor pairs, respectively, between these two types of tissue handling protocols. This novel finding demonstrates that prognostic signatures can be obtained from RNAlater preservative-suspended tissues, an important step in bringing gene expression signatures to the clinic.

Intratumoral DNA stem-line heterogeneity in superficial spreading melanoma

BACKGROUND

In primary melanomas, data on the degree of intratumoral heterogeneity to date have been lacking.

OBJECTIVE

Our purpose was to investigate intratumoral DNA stem-line heterogeneity in superficial spreading melanoma (SSM).

METHODS

Multiple measuring fields of 54 SSMs (tumor thickness median 1.60 mm) were studied by DNA image cytometry to obtain data on the number of DNA stem lines per tumor, their ploidy characteristics, and intratumoral distribution. Results were compared with standard histopathological criteria.

RESULTS

Twenty-three of 54 SSMs were found to have two or three distinct proliferating tumor cell stem lines (1.46 +/- 0.57 per tumor). Stem lines appeared spatially separated in 22 of 23 SMMs. At least 3 measuring fields per tumor were necessary to identify all stem lines with a likelihood of 95%. DNA heterogeneity correlated with tumor thickness, but occurred in 5 of 19 cases of pT1 melanoma.

CONCLUSIONS

Primary SSMs can be regarded as potentially clonally unstable with a tendency for spatial separation of tumor cell stem lines.

Clonal origin of lymph node metastases in bladder carcinoma

BACKGROUND

Evidence of genetic heterogeneity within urothelial carcinomas of the bladder has raised questions about the clonal origin of urothelial carcinoma and its metastases. High-grade urothelial carcinoma of the bladder frequently metastasizes to multiple regional lymph nodes in the pelvis. Whether or not these multiple lymph node metastases originate from the same tumor clone is uncertain. Molecular analysis of microsatellite alterations and X-chromosome inactivation status of distinct tumor cell populations from the same patient may further our understanding of the genetic basis of carcinoma progression and metastasis.

METHODS

The authors examined 24 patients who underwent radical cystectomy for urothelial carcinoma. All patients had multiple (from two to four) lymph node metastases. Genomic DNA samples were prepared from formalin fixed, paraffin embedded tissue sections using laser-assisted microdissection. Loss of heterozygosity (LOH) assays for 3 microsatellite polymorphic markers on chromosome 9p21 (D9S171, region of putative tumor suppressor gene p16), 9q32 (D9S177, putative tumor suppressor gene involved in urothelial carcinoma tumorigenesis), and 17p13 (TP53, the p53 locus) were performed. In addition, X-chromosome inactivation analysis was performed in primary tumors and metastases from 10 female patients.

RESULTS

In total, 79 tumors were analyzed. The overall frequency of allelic loss was 67% (16 of 24 tumors) in the primary urothelial carcinomas and 79% (19 of 24 tumors) in the metastatic carcinomas. The primary urothelial carcinoma showed LOH at the D9S171, D9S177, and TP53 loci in 39% (9 of 23 tumors), 30% (6 of 20 tumors), and 30% (7 of 23 tumors) of informative samples, respectively. LOH in > or = 1 lymph node metastases was seen at the D9S171, D9S177, and TP53 loci in 35% (8 of 23 tumors), 45% (9 of 20 tumors), and 48% (11 of 23 tumors) of informative samples, respectively. Eleven tumors demonstrated identical allelic loss patterns at all DNA loci both in the primary carcinoma and in all corresponding lymph node metastases. Three tumors showed allelic loss in the metastatic carcinoma but not in its matched primary carcinoma. Six tumors demonstrated a different LOH pattern in each of its lymph node metastases. Clonality analysis showed the same pattern of nonrandom X-chromosome inactivation both in the primary urothelial carcinoma and in all of the lymph node metastases in five of nine informative tumors studied. Four tumors showed a random pattern of X-chromosome inactivation in both the primary carcinoma and in the metastases.

CONCLUSIONS

LOH and X-chromosome inactivation assays showed that multiple lymph node metastases and matched primary urothelial carcinomas of the bladder had the same clonal origin, suggesting that the capability for metastasis often arises in only a single clonal population in the primary tumor. The variable LOH patterns observed in some of the tumors likely reflect genetic divergence during the clonal evolution of urothelial carcinoma.

Sensitivity of Lewis lung carcinoma to cisplatin undergoes considerable variations during growth and metastasizing

Growth and metastasizing of Lewis lung carcinoma were accompanied by complex changes in tumor sensitivity to cisplatin. On day 17 of growth, tumor sensitivity was much lower than immediately after transplantation. Further growth of Lewis lung carcinoma was accompanied by a progressive increase in its sensitivity to cytostatic treatment. The study of migration activity of the tumor and dynamics of metastasizing showed that metastatically active carcinoma cells dominated on day 17 of tumor growth, but then the number of these cells progressively decreased to the 29th day of tumor growth. Growth-related changes in the sensitivity of Lewis lung carcinoma were probably due to complex variations in the number of metastatically active tumor cells with high resistance to cisplatin.

Comparison ofHER-2 status determined by fluorescence in situ hybridization in primary and metastatic breast carcinoma

BACKGROUND

Accurate assessment of HER-2 status is necessary prior to anti-HER-2 antibody (trastuzumab) therapy for metastatic breast carcinoma. However, controversy exists regarding whether to assess HER-2 status in the primary tumor or in metastatic lesions. It is also unclear whether HER-2 status can change during disease progression or after chemotherapy.

METHODS

Breast carcinoma samples from 60 women with known HER-2 status in both primary tumors and paired metastases (locoregional disease, n = 43 patients; distant disease, n = 17 patients) were reviewed retrospectively. Thirty-two patients underwent chemotherapy before their metastatic lesions were sampled, including 18 patients who received neoadjuvant chemotherapy and 14 patients who received adjuvant chemotherapy. The HER-2 gene was examined by fluorescence in situ hybridization either in paraffin-embedded tissue samples (48 primary tumors and 9 metastatic tumors) or in fine-needle aspirates (12 primary tumors and 51 metastatic tumors). HER-2 gene amplification was defined as a HER-2:chromosome 17 signal ratio >/= 2.0.

RESULTS

The HER-2 status of primary and metastatic tumors agreed in 58 of 60 patients (97%), including 18 (30%) amplified tumors and 40 (67%) nonamplified tumors. A discrepancy in HER-2 status was observed in specimens from two patients in which HER-2 amplification was detected in the primary tumor but not the metastatic tumors. In one patient, three foci of tumor nodules were found in the same breast; the HER-2 status was assessed in only one of them, which showed amplification; however, HER-2 amplification was not detected in the axillary lymph node metastasis. In another patient, the HER-2 gene was amplified in the primary tumor but not in the liver metastasis. No metastases showed HER-2 amplification without amplification in the primary tumor. Locoregional and distant metastases demonstrated similar concordance rates with their corresponding primary tumors (98% and 94%, respectively). Complete concordance of HER-2 status was found between primary tumors prior to chemotherapy and metastases that were sampled after chemotherapy.

CONCLUSIONS

The HER-2 status in breast carcinoma generally was stable during metastasis, whether to locoregional or distant sites. Chemotherapy did not modify the HER-2 status in metastatic lesions. Therefore, HER-2 amplification can be evaluated reliably in material from either primary or metastatic tumors in most patients. Further study with larger series is warranted to elucidate the significance of discordant results.

Validation of a tissue microarray to study differential protein expression in inflammatory and non-inflammatory breast cancer

AIMS

Inflammatory breast cancer (IBC) is an aggressive subtype of breast cancer with poor prognosis. The mechanisms responsible for the aggressive clinical evolution are incompletely understood. We constructed a tissue microarray (TMA) and validated its use in translational IBC research. Differential expression of proteins that might play a role in causing the IBC phenotype was studied.

METHODS AND RESULTS

A TMA containing 34 IBC and 41 non-stage matched non-IBC tumours was constructed. Five core biopsies were taken for each IBC and three cores for each non-IBC tumour. The TMA was validated using three approaches: (1) the excellent concordance between immunohistochemical results of the initial pathological examination and the results obtained with the TMA for ER, PR and HER2/neu (kappa > 0.74); (2) the known differential expression between IBC and non-IBC for four bio-markers in IBC (ER, PR, p53 and HER2/neu) was confirmed ( p < 0.01); (3) the HER2/neu status using three different antibodies (CB11, TAB250 and HercepTest) was highly concordant (kappa > 0.75). Furthermore, the overexpression of E-Cadherin and RhoC GTPase in IBC ( p < 0.05) was confirmed. We did not find a differential expression pattern for carbonic anhydrase IX (CA IX) and EGFR.

CONCLUSIONS

Using different approaches, we have validated the use of our TMA for studying differential protein expression in IBC and non-IBC. We confirm the overexpression of E-Cadherin and RhoC GTPase in IBC. The lack of differential expression for CA IX and EGFR might suggest the pathways are equally utilised in both types of breast cancer.

HER-2/neu (c-erbB-2) Evaluation in Primary Breast Carcinoma by Fluorescent In Situ Hybridization and Immunohistochemistry With Special Focus on Intratumor Heterogeneity and Comparison of Invasive and In Situ Components

We have studied the intratumor HER-2/neu heterogeneity in 78 consecutive and population-based primary invasive breast carcinomas. Within the invasive component, heterogeneity was detected in only 1 of 78 tumors. In 48 tumors (62%), we found both in situ and invasive components in analyzed tissue sections. Twelve of these 48 tumors had a difference of at least 2 arbitrary units in the in situ compared with the invasive part of the tumor with regard to the HER-2/neu status analyzed by HercepTest (immunohistochemistry). Eight of these 12 tumors were reanalyzed with fluorescent in situ hybridization and immunohistochemistry with and without a new Automated Cellular Imaging System. In this limited material, immunohistochemistry in combination with the Automated Cellular Imaging System seemed to have a better correlation with fluorescent in situ hybridization than immunostaining analyzed manually. In conclusion, HER-2/neu expression is not seldom heterogeneous in invasive compared with in situ components within a tumor. This finding should be considered in the choice of evaluation method. To avoid heterogeneity as a confounding factor in HER-2/neu analyses, detection methods such as immunohistochemistry and fluorescent in situ hybridization, which can provide evaluation in a preserved tissue architecture, should be used. Perhaps the intratumor HER-2/neu heterogeneity can explain some of the unexpected failures of trastuzumab therapy.

Targeted therapy in breast cancer: the HER-2/neu gene and protein

The HER-2/neu oncogene, a member of the epidermal growth factor receptor or erb gene family, encodes a transmembrane tyrosine kinase receptor that has been linked to prognosis and response to therapy with the anti-HER-2-humanized monoclonal antibody, trastuzumab (Herceptin, Genentech, South San Francisco, CA) in patients with advanced metastatic breast cancer. HER-2/neu status has also been tested for its ability to predict the response of breast cancer to other therapies including hormonal therapies, topoisomerase inhibitors, and anthracyclines. This review includes an analysis of 80 published studies encompassing more than 25,000 patients designed to consider the relative advantages and disadvantages of the various methods of measuring HER-2/neu in clinical breast cancer specimens. Southern blotting, PCR amplification detection, and fluorescence in situ hybridization assays designed to detect HER-2/neu gene amplification are compared with HER-2/neu protein overexpression assays performed by immunohistochemical techniques applied to frozen and paraffin-embedded tissues and enzyme immunoassays performed on tumor cytosols. The significance of HER-2/neu overexpression in ductal carcinoma in situ and the HER-2/neu status in uncommon female breast conditions and male breast cancer are also considered. The role of HER-2/neu testing for the prediction of response to trastuzumab therapy in breast cancer is reviewed along with the current studies designed to test whether HER-2/neu status can predict the response to standard and newer hormonal therapies, cytotoxic chemotherapy, and radiation. The review will also evaluate the status of serum-based testing for circulating HER-2/neu receptor protein and its ability to predict disease outcome and therapy response.

Cyclin-Dependent Kinase 6 Inhibits Proliferation of Human Mammary Epithelial Cells

Many defects in cancer cells are in molecules regulating G1-phase cyclin-dependent kinases (cdks), which are responsible for modulating the activities of Rb family growth-suppressing proteins. Models for understanding how such defects affect proliferation assume that cdks are responsible for sequentially phosphorylating, and hence inactivating, the growth-suppressing functions of Rb family proteins, thus promoting cell cycle progression. However, cdks also play a role in formation of growth-suppressing forms of pRb family molecules, including the “hypophosphorylated” species of pRb itself. Here, it is shown that normal human mammary epithelial cells have a high amount of cdk6 protein and activity, but all breast tumor-derived cell lines analyzed had reduced levels, with several having little or no cdk6. Immunohistochemical studies showed reduced levels of cdk6 in breast tumor cells as compared with normal breast tissue in vivo. Cdk6 levels in two breast tumor cell lines were restored to those characteristic of normal human mammary epithelial cells by DNA transfection. The cells had a reduced growth rate compared with parental tumor cells; cells that lost ectopic expression of cdk6 reverted to the faster growth rate of parental cells. Cell lines with restored cdk6 levels accumulated higher amounts of the Rb family protein p130 as well as E2F4, a suppressing member of the E2F family of transcription factors, in their nuclei. The results suggest that cdk6 restrains rather than stimulates breast epithelial cell proliferation and that its loss or down-regulation could play a role in breast tumor development.

HER-2/neu amplification by fluorescence in situ hybridization in cytologic samples from distant metastatic sites of breast carcinoma

BACKGROUND

Amplification of the HER-2/neu oncogene has been proposed as a target for antibody-based therapies and as a predictor of chemoresponsiveness in advanced breast carcinoma. Few studies have concentrated on HER-2/neu gene evaluation by fluorescence in situ hybridization (FISH) on distant metastatic sites and none have been performed on cytologic samples. The current study evaluated HER-2/neu amplification by FISH on cytologic samples obtained from distant metastatic lesions of breast carcinoma to update HER-2/neu characterization through a safe and easier procedure than biopsy.

METHODS

Twenty-two cytologic samples from distant metastases (12 hepatic samples, 4 skin samples, 3 pleural samples, and 3 peritoneal samples) were submitted to HER-2/neu evaluation by FISH. Seventeen corresponding primary breast tumors also were evaluated by FISH on paraffin histologic sections or on destained archival cytologic smears.

RESULTS

Seven of the 22 metastases (32%) were amplified. Amplification was observed in 4 of the 12 liver metastases, in 1of the 3 ascitic fluid specimens, and in 2 of the 4 skin metastases. In all the three pleural fluid specimens, HER-2/neu was unamplified. Matched results from primary and metastatic lesions were obtained in 14 cases (5 were amplified and 9 were unamplified on both primary and metastatic tumors).

CONCLUSIONS

The results of the current study emphasized the feasibility and advantages of two rapid and very informative techniques, such as fine-needle aspiration biopsy and FISH. Both procedures were performed to ascertain the malignant nature of a suspicious lesion and to obtain predictive markers for response. Since the advent of trastuzumab, the characterization of the molecular profile in metastatic breast disease has become increasingly important for targeted therapy selection.

Comparison of topoisomerase-IIalpha gene status between primary breast cancer and corresponding distant metastatic sites

BACKGROUND

Topoisomerase-IIalpha (topo-IIalpha) is a key enzyme in DNA replication and a molecular target for anticancer drugs called topoisomerase-II inhibitors, such as anthracyclines. Its value as a predictive marker of responsiveness to these cytotoxic drugs is currently being evaluated with promising results. However, even in the metastatic setting, the choice of treatment is based on the biologic characteristics of the primary tumor. Few data are available regarding the expression of biological markers between the primary tumor and the corresponding distant metastases.

METHODS

Topo-IIalpha gene status was evaluated in 29 breast cancer patients in which a primary tumor sample and a corresponding metastatic sample were both available. Fluorescent in situ hybridization (FISH) with the Vysis triple probe (Vysis multi-color topo-IIalpha spectrum orange, Her-2 spectrum green and CEP17 spectrum aqua probe) was used, which allowed the concomitant evaluation of HER-2 gene status.

RESULTS

As previously reported, topo-IIalpha gene aberrations are always associated with HER-2 gene amplification; indeed no topo-IIalpha gene aberrations have been observed in the HER-2 negative tumors. Conversely, 38.5% (five patients) of the HER-2 positive primary breast tumors (13 patients) were topo-IIalpha amplified, while 61.5% (eight patients) had a normal topo-IIalpha gene. No topo-IIalpha gene deletion was found in our series. Topo-IIalpha gene amplification in the primary tumor was always associated with amplification in the corresponding metastases, and no metastases with topo-IIalpha gene amplification were seen without amplification in the primary tumor. Furthermore, the amplification level of topo-IIalpha (i.e., ratio topo-IIalpha:CEP17) remained unchanged in primary and metastatic sites.

CONCLUSION

Despite the low number of patients, our results seem to indicate that topo-IIalpha gene status evaluation in the primary breast tumor accurately reflects its status in the corresponding distant metastases.

The Her-2/neu gene and protein in breast cancer 2003: biomarker and target of therapy

The HER-2/neu oncogene encodes a transmembrane tyrosine kinase receptor with extensive homology to the epidermal growth factor receptor. In this review, the association of HER-2/neu gene and protein abnormalities with prognosis and response to therapy with trastuzumab and to other therapies in breast cancer is presented. By considering a series of 80 published studies encompassing more than 25,000 patients, the relative advantages and disadvantages of Southern blotting, polymerase chain reaction amplification, and fluorescence in situ hybridization assays designed to detect HER-2/neu gene amplification are compared with HER-2/neu protein overexpression assays performed by immunohistochemical techniques applied to frozen and paraffin-embedded tissues and enzyme immunoassays performed on tumor cytosols. The significance of HER-2/neu overexpression in ductal carcinoma in situ and the HER-2/neu status in uncommon female breast conditions and male breast cancer are also considered. The role of HER-2/neu testing for the prediction of response to trastuzumab therapy in breast cancer is presented as well as its potential impact on responses to standard and newer hormonal therapies, cytotoxic chemotherapy, and radiation. The review also evaluates the status of serum-based testing for circulating HER-2/neu receptor protein and its ability to predict disease outcome and therapy response.

Comparison of HER-2 status between primary breast cancer and corresponding distant metastatic sites

BACKGROUND

The humanized anti-HER-2 monoclonal antibody trastuzumab (Herceptin) is a new treatment modality for metastatic breast cancer, the efficacy of which is directly correlated with the HER-2 status of the tumour, evaluated either by immunohistochemistry (IHC) and/or by fluorescence in situ hybridisation (FISH). This analysis is generally performed on the primary tumour. There are few data regarding the HER-2 status in the corresponding distant metastases.

METHODS

HER-2 status in 107 patients with a primary breast tumour and at least one distant metastatic lesion was analysed by IHC and FISH.

RESULTS

We found similar levels of amplification (25% and 24%) and overexpression (13% and 19%) of HER-2 in primary and metastatic samples, respectively. Among paired primary/metastatic tumours, six (6%) showed discordance by HercepTest(TM) (n = 100): all six cases showed greater Her-2 overexpression in the metastatic tissue. By FISH (n = 68), five (7%) cases were discordant: two cases were amplified in the primary tumour but not in the metastasis, and three samples showed amplification in the metastasis but not in the primary. Finally, we analysed HER-2 status in different metastatic lesions from 17 patients that had at least two distant metastatic sites. Discordance between different sites from the same patient was 18% by IHC and 19% by FISH.

CONCLUSIONS

Between the paired primary tumour and distant metastatic lesions, 94% and 93% of samples had concordant HER-2 status when analysed by IHC or FISH, respectively. These results do not support routine determination of HER-2 on metastatic sites, particularly when FISH results from the primary tumour are available.

c-erbB-2 in breast cancer: development of a clinically useful marker

c-erbB-2 amplification and/or overexpression occurs in 20% to 30% of breast cancers and appear to be associated with a more aggressive phenotype. Detecting abnormalities in c-erbB-2 might provide important clinical information for breast cancer patients. However, several of the potential clinical uses of c-erbB-2 remain unproven. Many variables influence c-erbB-2 results, including selection and characteristics of test populations and methods of analysis. Current literature suggests two roles for c-erbB-2, either as a pure prognostic factor with no association with therapy or as a factor predictive of benefit from specific types of systemic treatments. c-erbB-2 appears to be only a weak prognostic factor, although some individual studies suggest greater prognostic importance. c-erbB-2 abnormalities appear to predict for relative, but not absolute, resistance to endocrine therapy in estrogen receptor (ER)-positive women. When adjuvant chemotherapy is indicated, some studies have indicated that patients with c-erbB-2-positive cancers (by immunohistochemistry [IHC] or fluoresence in situ hybridization [FISH]) receive more benefit from anthracycline-containing regimens as compared to alkylating agents. c-erbB-2 testing appears critical for selecting patients with metastatic disease who should receive the anti-c-erbB-2 antibody, trastuzumab. Prospective randomized clinical trials of trastuzumab as adjuvant therapy are underway. Well-designed, prospective, randomized clinical trials (designed to test the value of c-erbB-2) or formal meta-analyses will help to better establish the predictive role of c-erbB-2 in breast cancer.

The significance of immunohistochemistry in the diagnosis and therapy of neoplasms

This review article details the diagnostical significance of immunohistochemistry, which has developed during the last quarter of the century. Certainly, the advancement of monoclonal antibody technology has been of great significance in assuring the place of immunohistochemistry in the modern accurate microscopic diagnosis of human neoplasms, as a method of choice in histopathology. The fact still remains that in order to properly assess any immunohistochemical reactivity used for differential diagnostic purposes, the target cells have to be identified as neoplastically transformed cells by routine histopathological techniques. Selected groups of target molecules of great significance in cancer biology are discussed. The discovery of neoplasm-associated antigens has not only made the more accurate diagnosis of human cancer feasible but has also shed light on the extensive immunophenotypical heterogeneity of even the most closely linked human malignancies. The identification of disseminated neoplastically transformed cells by immunohistochemistry has allowed for a clearer picture of cancer invasion and metastasis, as well as the evolution of the tumour cell associated immunophenotype towards increased malignancy. Some possibilities of neoplasm-associated antigen targeted, receptor-directed immunotherapy are discussed and reviewed in this manuscript. Future antineoplastic therapeutical approaches should see the inclusion of a variety of immunotherapies, in the form of an individualised 'cocktail' specific for the particular immunophenotypical pattern associated with each individual patient's neoplastic disease.