Pharmacodiagnostic testing in breast cancer: focus on HER2 and trastuzumab therapy

Genomic testing and therapies for breast cancer in clinical practice

PURPOSE

Given the likely proliferation of targeted testing and treatment strategies for cancer, a better understanding of the utilization patterns of human epidermal growth factor receptor 2 (HER2) testing and trastuzumab and newer gene expression profiling (GEP) for risk stratification and chemotherapy decision making are important.

STUDY DESIGN

Cross-sectional.

METHODS

We performed a medical record review of women age 35 to 65 years diagnosed between 2006 and 2007 with invasive localized breast cancer, identified using claims from a large national health plan (N = 775).

RESULTS

Almost all women received HER2 testing (96.9%), and 24.9% of women with an accepted indication received GEP. Unexplained socioeconomic differences in GEP use were apparent after adjusting for age and clinical characteristics; specifically, GEP use increased with income. For example, those in the lowest income category (< $40,000) were less likely than those with an income of $125,000 or more to receive GEP (odds ratio, 0.34; 95% CI, 0.16 to 0.73). A majority of women (57.7%) with HER2-positive disease received trastuzumab; among these women, differences in age and clinical characteristics were not apparent, although surprisingly, those in the lowest income category were more likely than those in the high-income category to receive trastuzumab (P = .02). Among women who did not have a positive HER2 test, 3.9% still received trastuzumab. Receipt of adjuvant chemotherapy increased as GEP score indicated greater risk of recurrence.

CONCLUSION

Identifying and eliminating unnecessary variation in the use of these expensive tests and treatments should be part of quality improvement and efficiency programs.

A UK NEQAS ISH multicenter ring study using the Ventana HER2 dual-color ISH assay

We performed a multicenter assessment of a new HER2 dual-color chromogenic in situ hybridization (CISH) test and herein report on concordance of CISH data with fluorescence in situ hybridization (FISH) data and intraobserver and interlaboratory scoring consistency. HER2 results were evaluated using duplicate cores from 30 breast cancers in 5 laboratories using the Ventana HER2 dual-color ISH assay (Ventana Medical Systems, Cambridgeshire, England) and in 1 central laboratory using a standard FISH assay. Overall 93.3% of cases were successfully analyzed by CISH across the 5 participating laboratories. There was excellent concordance (98.0% overall) for diagnosis of HER2 amplification by CISH compared with FISH. Intraobserver variability (7.7%) and intersite variability (9.1%) of absolute HER2/chromosome enumeration probe 17 ratios were tightly controlled across all participating laboratories. The Ventana HER2 dual-color ISH assay is robust and reproducible, shows good concordance with a standard FISH assay, and complies with requirements in national and international guidelines for performance of ISH-based diagnostic tests.

Polysialic acid neural cell adhesion molecule (PSA-NCAM) is an adverse prognosis factor in glioblastoma, and regulates olig2 expression in glioma cell lines

BACKGROUND

Glioblastoma multiforme (GBM) is the most aggressive and frequent brain tumor, albeit without cure. Although patient survival is limited to one year on average, significant variability in outcome is observed. The assessment of biomarkers is needed to gain better knowledge of this type of tumor, help prognosis, design and evaluate therapies. The neurodevelopmental polysialic acid neural cell adhesion molecule (PSA-NCAM) protein is overexpressed in various cancers. Here, we studied its expression in GBM and evaluated its prognosis value for overall survival (OS) and disease free survival (DFS).

METHODS

We set up a specific and sensitive enzyme linked immunosorbent assay (ELISA) test for PSA-NCAM quantification, which correlated well with PSA-NCAM semi quantitative analysis by immunohistochemistry, and thus provides an accurate quantitative measurement of PSA-NCAM content for the 56 GBM biopsies analyzed. For statistics, the Spearman correlation coefficient was used to evaluate the consistency between the immunohistochemistry and ELISA data. Patients' survival was estimated by using the Kaplan-Meier method, and curves were compared using the log-rank test. On multivariate analysis, the effect of potential risk factors on the DFS and OS were evaluated using the cox regression proportional hazard models. The threshold for statistical significance was p = 0.05.

RESULTS

We showed that PSA-NCAM was expressed by approximately two thirds of the GBM at variable levels. On univariate analysis, PSA-NCAM content was an adverse prognosis factor for both OS (p = 0.04) and DFS (p = 0.0017). On multivariate analysis, PSA-NCAM expression was an independent negative predictor of OS (p = 0.046) and DFS (p = 0.007). Furthermore, in glioma cell lines, PSA-NCAM level expression was correlated to the one of olig2, a transcription factor required for gliomagenesis.

CONCLUSION

PSA-NCAM represents a valuable biomarker for the prognosis of GBM patients.

Characterizing the HER2/neu status and metastatic potential of breast cancer stem/progenitor cells

INTRODUCTION

Treatment resistance, long latency, and high recurrence rates suggest that breast cancers arise from defective breast stem cells.

HYPOTHESIS

Within cancers, subpopulations of cells will demonstrate differences in stem/progenitor potential, HER2/neu amplification, and gene expression. Related cells will be found in normal breast tissue.

METHODS

ER-/PR-/HER2/neu + breast cancer cells were flow-sorted into subpopulations: (A) CD49f(+) CD24(-), (B) CD49f(+)CD24(+), (C) CD49f CD24(-), and (D) CD49f(-)CD24(+). Gel matrix cell invasion, fluorescence in situ hybridization (FISH) HER2/neu amplification, and qRT-PCR gene expression were measured in all groups. Cells from sorted groups were implanted into rat brains. Resultant tumors were analyzed by immunohistochemistry (IHC) and FISH. Normal breast tissue was examined by IHC.

RESULTS

Tumor development varied among sorted groups (25-75%), but was highest in group A. Tumor cells were mostly CD49f(-)CD24(-), with variable fractions of other stem/progenitor cells. Tumors showed HER2/neu amplification, but fewer chromosome 17 per cell than inoculates. Group A tumors exhibited cells with normal chromosome 17 copy number and near normal HER2/neu amplification. Cell invasion was 61% higher in unsorted cells and 34-42% in sorted groups compared with controls. Sorted groups showed significantly different expression of development, proliferation, and invasion associated genes. In normal breast tissue, CD49f(+) cells were identified in CD14(+) CK19(-) basal epithelial layers of mammary glands; these were 95% CD24(+) and 60% CD44(+).

CONCLUSIONS

Breast cancer stem/progenitor cell populations differ in tumor-initiating potential but are not solely responsible for metastasis. Cancer stem/progenitor cells are less polyploid than cancer cells in general and may not be HER2/neu amplified. In normal breast tissue, breast stem/progenitor cell-like populations are present.

Chromogenic in situ hybridization: a multicenter study comparing silver in situ hybridization with FISH

Our purposes were to perform a robust assessment of a new HER2 chromogenic in situ hybridization test and report on concordance of silver in situ hybridization (SISH) data with fluorescence in situ hybridization (FISH) data and on intraobserver and interlaboratory scoring consistency. HER2 results were scored from 45 breast cancers in 7 laboratories using the Ventana (Tucson, AZ) INFORM HER-2 SISH assay and in 1 central laboratory using a standard FISH assay. Overall, 94.8% of cases were successfully analyzed by SISH across the 6 participating laboratories that reported data. Concordance for diagnosis of HER2 amplification by SISH compared with FISH was high (96.0% overall). Intraobserver variability (8.0%) and intersite variability (12.66%) of absolute HER2/chromosome 17 ratios appear to be tightly controlled across all 6 participating laboratories. The Ventana INFORM HER-2 SISH assay is robust and reproducible, shows good concordance with a standard FISH assay, and complies with requirements in national guidelines for performance of diagnostic tests.

Standardization of HER2 immunohistochemistry in breast cancer by automated quantitative analysis

CONTEXT

There is critical need for standardization of HER2 immunohistochemistry testing in the clinical laboratory setting. Recently, the American Society of Clinical Oncology and the College of American Pathologists have submitted guidelines recommending that laboratories achieve 95% concordance between assays and observers for HER2 testing.

OBJECTIVE

As a potential aid to pathologists for achieving these new guidelines, we have conducted an examination using automated quantitative analysis (AQUA analysis) to provide a standardized HER2 immunohistochemistry expression score across instruments (sites), operators, and staining runs.

DESIGN

We analyzed HER2 expression by immunohistochemistry in a cohort (n = 669) of invasive breast cancers in tissue microarray format across different instruments (n = 3), operators (n = 3), and staining runs (n = 3). Using light source, instrument calibration techniques, and a new generation of image analysis software, we produced normalized AQUA scores for each parameter and examined their reproducibility.

RESULTS

The average percent coefficients of variation across instruments, operators, and staining runs were 1.8%, 2.0%, and 5.1%, respectively. For positive/negative classification between parameters, concordance rates ranged from 94.5% to 99.3% for all cases. Differentially classified cases only occurred around the determined cut point, not over the entire distribution.

CONCLUSIONS

These data demonstrate that AQUA analysis can provide a standardized HER2 immunohistochemistry test that can meet current guidelines by the American Society of Clinical Oncology/College of American Pathologists. The use of AQUA analysis could allow for standardized and objective HER2 testing in clinical laboratories.

External quality assurance of HER2 FISH and ISH testing: three years of the UK national external quality assurance scheme

The American Society of Clinical Oncology/College of American Pathologists guidelines highlighted the critical importance of quality assurance in diagnostic testing for HER2. Unstained formalin-fixed, paraffin-embedded human breast carcinoma cell line sections were circulated to scheme participants on 9 occasions. "Reference laboratories" reported results for the HER2/chromosome 17 ratio and HER2 copy number for 3 years for each cell line, including 418 sets of results (1,671 results total). The number of participants was 62 laboratories in the final analysis. The mean and SD of results from reference laboratories demonstrated consistency during the 3-year period. The percentage of laboratories achieving "appropriate" results ranged from 45% to 88%, and the percentage achieving "inappropriate" results ranged from 5% to 29%. No consistent effect of the HER2 in situ hybridization testing method was demonstrated. Participation in external quality assurance schemes is a valuable mechanism for demonstrating and acquiring consistency for HER2 testing by in situ hybridization. Poor performance can be corrected via assistance and advice.

Comparison of quantitative immunofluorescence with conventional methods for HER2/neu testing with respect to response to trastuzumab therapy in metastatic breast cancer

CONTEXT

Selection for trastuzumab therapy depends on a companion diagnostic assessment of HER2 by either immunohistochemistry (IHC) for protein overexpression or fluorescence in situ hybridization (FISH) to detect gene amplification. Although many studies have compared IHC to FISH, few have compared the tests to the true gold standard, tumor response.

OBJECTIVE

To compare HER2 testing by FISH and IHC along with a third immunofluorescence-based assay (automated quantitative analysis-tissue microarray [AQUA-TMA]) and to assess the value of each test for prediction of response to trastuzumab.

DESIGN

Immunohistochemistry and FISH assays were done on both whole slides (IHC-WS and FISH-WS) and on TMAs (IHC-TMA and FISH-TMA). AQUA was only done on TMAs (AQUA-TMA). Response was assessed according to modified Response Evaluation Criteria in Solid Tumors.

RESULTS

AQUA-TMA scores showed a significant linear relationship to both the FISH signal ratio and IHC scores on whole sections and TMAs. Assay assessment by outcome showed no association between response and FISH-WS ratio (P = .96), FISH-TMA (P = .55), IHC-WS (P = .75), or IHC-TMA (P = .06), but a significant relationship between AQUA score and categoric response was observed (P = .01). Assessed as a function of outcome using models of logistic regression, both AQUA-TMA and IHC-TMA were equally significant (P = .01). FISH-WS was the most sensitive assay, with a significantly higher true-positive fraction than all other tests except AQUA-TMA, although it was the least specific. IHC-TMA was the most specific assay. The lowest misclassification rate was achieved using AQUA-TMA (0.30).

CONCLUSIONS

Both AQUA-TMA and IHC-TMA were substantially more predictive than the FISH or IHC-WS tests. Although these results are derived from a small retrospective series, they suggest that accurate measurement of protein expression and unbiased selection of tissue for measurement may be key factors in prediction of response.

A pharmacogenomics primer

The human genome project and related research initiatives have enabled the identification of a significant number of genetic variants that are predictive of drug response and outcome (pharmacogenomic biomarkers). As yet, incorporation of routine pharmacogenomic testing into clinical practice has been relatively modest. Potential barriers to adoption include a relative lack of prospective controlled trials establishing the benefits of such testing, economic constraints, and ethical concerns, among others. Clinicians considering the use of pharmacogenomic testing in their practice also may be unfamiliar with the concepts and principles underlying this rapidly evolving discipline. Consequently, the purpose of this review is to provide the clinical pharmacologist with a primer on the principles and molecular mechanisms underlying pharmacogenomics. In addition, the methods currently being used to discover novel pharmacogenomic biomarkers and then apply these to clinical practice will be described.

Compressing drug development timelines in oncology using phase '0' trials

The optimal evaluation of molecularly targeted anticancer agents requires the integration of pharmacodynamic assays into early clinical investigations. Phase '0' trials conducted under the new Exploratory Investigational New Drug Guidance from the US Food and Drug Administration can provide a platform to establish the feasibility of assays for target modulation in human samples, evaluate biomarkers for drug effects and provide pharmacokinetic data. Phase 0 trials could facilitate rational drug selection, identify therapeutic failures early, and might compress timelines for anticancer drug development. We expect that such trials will become a routine part of early-phase oncological drug development in the future.

A Reagent Resource to Identify Proteins and Peptides of Interest for the Cancer Community

On the basis of discussions with representatives from all sectors of the cancer research community, the National Cancer Institute (NCI) recognizes the immense opportunities to apply proteomics technologies to further cancer research. Validated and well characterized affinity capture reagents (e.g. antibodies, aptamers, and affibodies) will play a key role in proteomics research platforms for the prevention, early detection, treatment, and monitoring of cancer. To discuss ways to develop new resources and optimize current opportunities in this area, the NCI convened the "Proteomic Technologies Reagents Resource Workshop" in Chicago, IL on December 12-13, 2005. The workshop brought together leading scientists in proteomics research to discuss model systems for evaluating and delivering resources for reagents to support MS and affinity capture platforms. Speakers discussed issues and identified action items related to an overall vision for and proposed models for a shared proteomics reagents resource, applications of affinity capture methods in cancer research, quality control and validation of affinity capture reagents, considerations for target selection, and construction of a reagents database. The meeting also featured presentations and discussion from leading private sector investigators on state-of-the-art technologies and capabilities to meet the user community's needs. This workshop was developed as a component of the NCI's Clinical Proteomics Technologies Initiative for Cancer, a coordinated initiative that includes the establishment of reagent resources for the scientific community. This workshop report explores various approaches to develop a framework that will most effectively fulfill the needs of the NCI and the cancer research community.

Current and future issues in the manufacturing and development of monoclonal antibodies

Despite a slow beginning, monoclonal antibodies have had many successes over the past decade. It is important that these successes continue, bringing more products for more indications to market. Although manufacturing is not the most common cause of product failure, product quality issues can delay antibody development. Manufacturing has depended on the triad of process validation, process control and product testing. Applying product knowledge proactively to manufacturing (quality by design) may allow greater flexibility and maintain or improve product quality. An integrated approach to biological characterization is an important aspect of product knowledge. Greater product knowledge also facilitates development in other disciplines. Independent of manufacturing strategy, there are a number of regulatory hurdles in initial and ongoing antibody development. These are described to help prevent unnecessary delays.

Past, present and future of gene expression-tailored therapy for lung cancer

“Variability is the law of life, and as no two faces are the same, so no two bodies are alike, and no two individuals react alike and behave alike under the abnormal conditions which we know as disease.” Sir William Osler (1849–1919). All human beings are different and some of these differences are the variations in response to xenobiotics. Personalized medicine means: the right patient population, the right drug, the right dose, the right indication, and administration at the right time. This review provides an update on concepts of personalized therapy for lung cancer.

Personalized medicine: new perspectives - new ethics?

Are new concepts in biomedical ethics required to keep pace with the developments in post-Human Genome Project (HGP) genomics? This paper traces the place of ethics in the post-HGP landscape. The need for a revision of the approach taken by biomedical ethics toward questions in genomics has been appreciated for years. Traditional biomedical ethics, led by the protection paradigm, was devised to serve a very different context. Today, compelling ethical questions arise from the tension between individual and collective interests in the context of population-based data collection and research. The collection of phenotype data, and the development of new sequencing technologies, raises burning questions that call for innovative tools and models in ethics. Future developments that will likely include the routine availability of personal genome information, and the advent of systems biology as a framework for interpretation, will require ongoing flexibility and a creative approach.

Cancer diagnostics: decision criteria for marker utilization in the clinic

A new diagnostic tool must pass three major tests before it is adopted for routine clinical use. First, the tool must be robust and reproducible; second, the clinical value of the tool must be proven, i.e. the tool should reliably trigger a clinical decision that results in patient benefit; and, third, the clinical community has to be convinced of the need for this tool and the benefits it affords. Another factor that can influence the adoption of new tools relates to the cost and the vagaries of insurance reimbursement. The Cancer Diagnosis Program (CDP) of the US National Cancer Institute (NCI) launched the Program for the Assessment of Clinical Cancer Tests (PACCT) in 2000 to develop a process for moving the results of new technologies and new understanding of cancer biology more efficiently and effectively into clinical practice. PACCT has developed an algorithm that incorporates the iterative nature of assay development into an evaluation process that includes developers and end users. The effective introduction of new tests into clinical practice has been hampered by a series of common problems that are best described using examples of successes and failures. The successful application of the PACCT algorithm is described in the discussion of the recent development of the OncotypeDX assay and plan for a prospective trial of this assay by the NCI-supported Clinical Trials Cooperative Groups. The assay uses reverse transcription (RT)-PCR evaluation of a set of 16 genes that were shown to strongly associate with the risk of recurrence of breast cancer in women who presented with early stage disease (hormone responsive, and no involvement of the auxiliary lymph nodes). The test is highly reproducible. It provides information to aid the physician and patient in making important clinical decisions, including the aggressiveness of the therapy that should be recommended. A trial is planned to test whether OncotypeDX can be used as a standalone trigger for specific treatment decisions. The problems that have been encountered and have delayed the development of other diagnostic tools are exemplified in the development of tests for human epidermal growth factor receptor (HER2) overexpression, for predictors of response to epidermal growth factor receptor inhibitors, and for the detection of residual disease following chemotherapy.