Abstract 5426: Assessing factors predictive of response to ADCs for companion diagnostic strategies

One premise of antibody-drug conjugates (ADC) is that the bound mAb-antigen complex on the cell surface will internalize and be metabolized by lysosomal proteases to release the free drug. Thus, the efficacy of an ADC is dependent not only on the presence of cell surface antigens, but also in-tact delivery of the conjugated drug, and an active pathway of receptor-mediated endocytosis. On a cellular level, the biological mechanisms behind receptor internalization and turnover have not been elucidated for novel therapeutic targets. On a tissue level, vascularization and hypoxic profile will affect delivery of the antibody into the tissue. Varying expression of the antibody target within the tissue (antigen density) will also affect the uptake of the ADC. Furthermore, the extracellular stability of the ADC may be affected by the activity of the various proteases in the tumor microenvironment (TME), outside of the lysozome. These concepts are critical for efficacy, and thus are especially important for companion diagnostic approaches (CDx) meant to predict response to ADCs. Thus, a predictive assay which would account not only for the degree of cell surface expression of the target, but also receptor internalization and potential effects of tumor microenvironment is required. To answer this need, Flagship Biosciences has invented several proprietary approaches for measuring critical properties of the therapeutic target on the cell surface or inside the cell, as well as properties of the TME which could be used to understand and predict efficacy to an ADC using FFPE biopsies. These quantitative pathology approaches are based on image analysis approaches which been designed specifically for ADC CDx programs to answer these critical questions: 1) Defining cell surface target expression independent of cytoplasmic expression; 2) Estimating receptor flux (turnover, internalization) based on staining profile; 3) Assessing critical factors in the TME which may affect delivery of the in-tact drug to the intracellular target; 4) Assaying vascular properties which may affect delivery of the drug; and 5) Heterogeneity of the target within a tumor. We are able to provide these as discrete evaluations or multiplex these evaluations for an integrative answer which can be derived from a typical clinical biopsy. Incorporation of these novel tools will enable ADC developers to create efficacy and patient stratification paradigms which incorporate the critical biological endpoints unique to ADCs.

Citation Format: Joseph S. Krueger, Holger Lange, Steve Potts, David Young. Assessing factors predictive of response to ADCs for companion diagnostic strategies. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5426. doi:10.1158/1538-7445.AM2014-5426

Abstract 2842: Evaluation of immunohistochemistry assays against c-Met and HGF to guide companion diagnostic decisions

Establishing reagent specificity during immunohistochemistry (IHC) based biomarker or companion diagnostic (CDx) assays is challenging. Antibody specificity is dictated in part by recognition of 3D confirmation of the target binding, target activity, and and/or epitope's post-translation modifications. Fixation effects pose additional challenges to epitope recognition during IHC assay. For these reasons, different antibodies against the same target biomarker may demonstrate diversity in prevalence, range, and staining patterns over identical specimens. Thus, determining reagent specificity is a critical part of IHC and CDx assay development. Interpretation is further complicated by the pattern of biomarker expression in specific cell types (e.g. tumor v. stroma) or cell compartments (e.g. membrane v. cytosol). These factors may be critical to associate the drug's mechanism of action with efficacy. In the companion diagnostic (CDx) setting, the mechanism of the drug, epitope recognition, and staining features used to interpret and quantify the biomarker to predict patient response requires an evidence-based approach, where all features of an IHC assay are considered and tied empirically to patient response to the drug. In this study, we demonstrate these complexities in gastric cancer specimens, by comparing IHC assays using two antibodies that recognize either intracellular or extracellular domains of c-Met receptor (SP44/ C-term and EP154Y/ N-term) in the context of the ligand for c-Met, Hepatocyte Growth Factor (HGF). Therapeutic antibodies targeting c-Met [such as MetMab® (OA-5D5/ Roche)]; or HGF directly [such as Rilotumumab (AMG 102/ Amgen)], have directly linked c-Met protein expression as revealed by IHC to patient response. Thus, we hypothesized that a link between c-Met protein expression and HGF should be discernible. To test this hypothesis, we used image analysis approaches to determine the staining features of each IHC assay in comparison to each other. Surprisingly, we found little concordance between the two c-Met antibodies in evaluating c-Met and HGF expression. We found distinct populations of c-Met expressing vs HGF expressing specimens, whose HGF-c-Met association differed with the c-Met assay used. We examined the tissue and cell compartmentalization, and identified staining features of each reagent which would aid or impede in interpretation strategies for understanding the relationship between c-Met and HGF. These results suggest that the epitope-specific features of each c-Met antibody determines the relationship with HGF expression, and how quantitative image analysis endpoints can be used to make critical decisions during the development of an IHC companion diagnostic.

Note: This abstract was not presented at the meeting.

Citation Format: Joseph S. Krueger, Brian Laffin, Holger Lange, Eric Neeley, Mirza Peljto, Mohamed Salama, Mahipal Suraneni, David Young. Evaluation of immunohistochemistry assays against c-Met and HGF to guide companion diagnostic decisions. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2842. doi:10.1158/1538-7445.AM2014-2842

Abstract 4981: Evaluating the contribution of heterogeneity and the tumor microenvironment in companion diagnostic approaches

As our understanding of the factors which affect efficacy of a targeted therapy increases, the reliance on histopathological analysis of a biomarker has also increased. This is often due to the necessity to weigh the critical factors of a target or biomarker protein in tissue and cellular context. Currently, histopathologic assessment of tumors which aims to project patient clinical outcome utilize drug target response factors, such as relative expression of the drug target of the drug target or a resistance mechanism in the target (tumor) cells or the tumor microenvironment (TME ). Multiple studies have also shown that TME factors such as inflammatory cell content can be prognostic and predictive. For example, adding the Immunoscore assessment to the TNM classification systems improves the accuracy of disease prognosis. This correlation has led to the concept of predictive “immunoprofiling”, which uses an individual's immune system profile to predict that patient's response to immunomodulating antibody therapy. For these reasons, it is critical to evaluate the drug target or biomarker in conjunction with TME features when defining a patient selection strategy.

Critical factors such as tissue and/or cellular compartmentalization and tumor heterogeneity direct the interpretation of these measures and their predictive value. To address the need for careful, contextual interpretation of histopathological evaluations, Flagship has built CellMap™ image analysis algorithms to directly measure heterogeneity and the TME components in a whole tissue section. These approaches allow biomarker interpretation in the complex context of spatial, architectural, and morphological information to aid histological definition and quantification. In this study, we utilized a cohort of specimens from 20 colorectal cancer (CRC) patients and immunologically stained them in order to visualize c-Met, as a characteristic and biologically relevant therapy target; and CD3+ and CD8+ to visualize the inflammatory cell environment. Using these immunohistochemical markers as a prototype for a simultaneous evaluation of a molecular target and the TME, we characterized the biomarker and inflammatory content in both the tumor and stroma using our CellMap™ image analysis algorithms. This provided detailed accounting of the molecular target profile (tumor vs stroma; membrane vs cytoplasm vs nucleus), and the “immunoprofile”, which allowed us to quantitatively describe and associate these features relative to each other in the context of heterogeneity. This data demonstrated discrete patterns of association between c-met and the TME, serving as a potentially critical measure which reflects a biological process relevant to disease outcome. These studies demonstrate novel tools which can assess both the prognostic and predictive value of key measurements which reflect complex tumor biology.

Citation Format: Joseph S. Krueger, Brian Laffin, Holger Lange, Anthony Milici, Mirza Peljto, Eric Neeley, Mahipal Suraneni, David Young. Evaluating the contribution of heterogeneity and the tumor microenvironment in companion diagnostic approaches. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4981. doi:10.1158/1538-7445.AM2014-4981

Zur Wirkung von N-Methyl-N-β-chloräthylhydrazin und seinem Benzaldehydhydrazon auf die RNA -und Proteinsynthese sowie Stoffwechsel von synchronisierten Hefezellen / Effect of N-Methyl-N-β-chloroethylhydrazine and Its Benzaldehydhydrazone on RNA- and Protein Synthesis as Soon as Metabolism of Synchronously Growing Yeast Cells ( Saccharomyces cerevisiae)

N-methyl-N-β-chloroethylhydrazine and its benzaldehydhydrazone inhibit the influx of [6-3H]- uracil and ʟ- [U-14C] leucin in yeast cells as well as the incorporation in RNA and protein. Experi­ments with synchronously and asynchronously growing cells showed the N-methyl-N-β-chloroethyl- hydrazine essentially influences the dividing phase while the benzaldehydhydrazone is more ef­fective in the growthphase. The effect of these two substances on respiration, glycolysis and the concentration of fructose-1,6-diphosphate, triose phosphate, and adenosine triphosphate is small.

Über den biologischen Einfluß von N-Methyl-N-β-chloräthylhydrazin und seinem Benzaldehydhydrazon auf Hefezellen ( Saccharomyces cerevisiae) / Effect of N-Methyl-N-β-chloroethyl-hydrazine-HCl on the Growth and Multiplication of Yeast Cells (Saccharomyces cerevisiae)

N-Methyl-N-β-chloroethyl-hydrazine-HCl and its benzaldehydhydrazone inhibit growth and multi­plication of yeast cells. The DNA-synthesis is partially blocked. After removal of the substances the rate of this synthesis is much more increased than that of RNA and protein. The both sub­ stances we tested are more effective than simple alkylhydrazines.

Regulation glykolytischen Umsatzes durch Synthese und Abbau von Enzymen Regulation of Glycolysis by the Synthesis and Degradation of Enzymes

Differential derepression of the genome of potato tuber cells causes the onset of a vigorous metabolic activity, which is initiated by rapid synthesis of different RNA species, various proteins and phospholipids. Consequently enhanced respiration and the build up of cell compartments such as ribosomes and mitochondria as well as the performance of cell divisions and suberization of new-formed cell walls occur. Although there is an activation of metabolism in general with a concomitant rise in concentration of most glycolytic metabolites — as was proved for fructose-1.6-diphosphate, dihydroxyacetone, glyceraldehade-3-phosphate, phosphoenolepyruvate and pyruvate — the activities of the corresponding enzymes do not reflect these uniform metabolic changes. Aldolase and in a pronounced manner enolase and glutamate — pyruvate — transaminase lower their activities suddenly after derepression. The activity of triosephosphateisomerase remains constant. In contrast phosphoglyceromutase, pyruvate kinase and to a lower extent malic enzyme enhance their action during the same time.

Without doubt, differential lowering and enhancing the activity of glycolytic chain constituents at the same time is an important regulatory mechanism of the cell. The activation represents de novo synthesis of the protein concerned whereas the inactivation depends largely on protein synthesis. This is clearly shown by experiments with inhibitors of protein synthesis.

It is proposed that this differential synthesis and degradation represent a “long-time-regulation” of enzymatic activity of the cell in contrast to the known “short-time-regulation” by feedback or competition.

Ongoing hepatitis A outbreak in Europe 2013 to 2014: imported berry mix cake suspected to be the source of infection in Norway

On 7 March 2014, an increase in hepatitis A virus (HAV) infections was identified in Norway. As of 12 April, 19 cases of HAV infection with a virus strain identical to an ongoing European outbreak have been identified. Six probable cases are currently under investigation. On 11 April, a frozen berry mix cake imported from another European country was found as the likely source of the outbreak; the importer has withdrawn the product in Norway.

Abstract B44: Assessing factors predictive of response to ADCs for companion diagnostic strategies

One premise of antibody-drug conjugates (ADC) is that the bound mAb-antigen complex on the cell surface will internalize and be metabolized by lysosomal proteases to release the free drug. Thus, the efficacy of an ADC is dependent not only on the presence of cell surface antigens, but also in-tact delivery of the conjugated drug, and an active pathway of receptor-mediated endocytosis. On a cellular level, the biological mechanisms behind receptor internalization and turnover have not been elucidated for novel therapeutic targets. On a tissue level, vascularization and hypoxic profile will affect delivery of the antibody into the tissue. Varying expression of the antibody target within the tissue (antigen density) will also affect the uptake of the ADC. Furthermore, the extracellular stability of the ADC may be affected by the activity of the various proteases in the tumor microenvironment (TME), outside of the lysozome. These concepts are critical for efficacy, and thus are especially important for companion diagnostic approaches (CDx) meant to predict response to ADCs. Thus, a predictive assay which would account not only for the degree of cell surface expression of the target, but also receptor internalization and potential effects of tumor microenvironment is required. To answer this need, Flagship Biosciences has invented several proprietary approaches for measuring critical properties of the therapeutic target on the cell surface or inside the cell, as well as properties of the TME which could be used to understand and predict efficacy to an ADC using FFPE biopsies. These quantitative pathology approaches are based on image analysis approaches which been designed specifically for ADC CDx programs to answer these critical questions: 1) Defining cell surface target expression independent of cytoplasmic expression; 2)Estimating receptor flux (turnover, internalization) based on staining profile; 3) Assessing critical factors in the TME which may affect delivery of the in-tact drug to the intracellular target; 4) Assaying vascular properties which may affect delivery of the drug; and 5)Heterogeneity of the target within a tumor. We are able to provide these as discrete evaluations or multiplex these evaluations for an integrative answer which can be derived from a typical clinical biopsy. Incorporation of these novel tools will enable ADC developers to create efficacy and patient stratification paradigms which incorporate the critical biological endpoints unique to ADCs.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B44.

Citation Format: Joseph S. Krueger, Holger Lange, Steve Potts, David Young. Assessing factors predictive of response to ADCs for companion diagnostic strategies. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B44.

Abstract C34: Using quantitative image analysis of a putative immunohistochemistry assay against C-met to guide companion diagnostic decisions

When developing an immunohistochemistry (IHC) based biomarker or companion diagnostic assay, establishing reagent specificity is very challenging. Because antibodies recognize three dimensional epitopes, epitope recognition may be based on a specific confirmation (activated, receptor occupied, etc) or biological state (glycosylation, cell surface vs cytoplasmic) of the target protein. Furthermore, recognition of the epitope in Formalin-Fixed, Paraffin Embedded (FFPE) specimens imposes additional challenges due to the fixation effects. For these reasons, different antibodies against the same target biomarker may demonstrate different prevalence, range, and staining patterns in the same specimens. Determining reagent specificity is a critical part of IHC assay development; but the typical approaches utilized (such as Western Blotting, etc) do not directly prove specificity in the FFPE setting. Additionally, the presence or absence of the protein in a particular tissue (tumor vs stroma) or cell (membrane/ cytosol/ nuclear) compartment may be critical to associate the drugs mechanism of action with efficacy.

In the companion diagnostic (CDx) setting, the mechanism of the drug, epitope recognition, and staining features used to interpret and quantify the biomarker to predict patient response requires an evidence-based approach, where all features of an IHC assay are considered and tied empirically to patient response to the drug.

In this study, we demonstrate these complexities in gastric cancer specimens, by comparing IHC assays using two antibodies against the intracellular vs extracellular domains of c-met (SP44/ C-term and EP154Y/ N-term) in the context of the ligand for c-met, Hepatocyte Growth Factor (HGF). Therapeutic antibodies targeting c-met [such as MetMab® (OA-5D5/ Roche)]; or HGF directly [such as Rilotumumab (AMG 102/ Amgen)], have linked c-met protein expression by IHC directly to patient response. Thus, we hypothesized that a link between c-met protein expression and HGF should be discernible. To test this hypothesis, we used image analysis approaches to determine the staining features of each IHC assay in relation to each other. Surprisingly, we found little concordance between the two c-met antibodies in evaluating c-met and HGF expression. We found distinct populations of c-met expressing vs HGF expressing specimens, whose HGF-c-met association differed with the c-met assay used. We examined the tissue and cell compartmentalization, and identified staining features of each reagent which would aid or impede in interpretation strategies for understanding the relationship between c-met and HGF. These results suggest that the epitope-specific features of each c-met antibody determines the relationship with HGF expression, and how quantitative image analysis endpoints can be used to make critical decisions during the development of an IHC companion diagnostic.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C34.

Citation Format: Joseph S. Krueger, Brian Laffin, Mirza Peljto, Mahipal Suraneni, Holger Lange, David Young. Using quantitative image analysis of a putative immunohistochemistry assay against C-met to guide companion diagnostic decisions. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C34.

Assessing factors for predictive response to ADC targets in clinical tissue for companion diagnostic development

e22187

Background: One premise of antibody-drug conjugates (ADC) is that the bound mAb-antigen complex on the cell surface will internalize and be metabolized by lysosomal proteases to release the free drug. Thus, the efficacy of an ADC is dependent not only on the presence of cell surface antigens, but also intact delivery of the conjugated drug. In most cases, the biological mechanisms behind these processes have not been elucidated. Furthermore, the extracellular stability of the ADC may be affected by the activity of the target proteases in the tumor microenvironment outside of the lysozome. These concepts are especially important for CDx approaches, which would ideally account not only for the degree of cell surface expression of the target, but also receptor internalization and potential effects of tumor microenvironment. Although in vitro approaches exist to measure these attributes, there are no clinically amenable approaches to measure these critical parameters. Methods: Flagship Biosciences has invented several proprietary approaches for measuring critical properties of the therapeutic target on the cell surface or inside the cell, as well as properties of the TME which could be used to predict efficacy to an ADC using FFPE biopsies. These image analysis approaches have been designed specifically in context of ADC CDx programs to: 1) Accurately define cell surface target expression independent of cytoplasmic expression; 2) Assess critical factors in the TME which may affect delivery of the drug to the intracellular target; and 3) Multiplex these evaluations for an integrative answer to be derived from a typical clinical biopsy. Results: The measurement of cytoplasm/membrane localization was evaluated on several hundred tissue sections, and the methodology was found to be highly reproducible, with coefficients of variation lower than that observed by manual pathologist accessment. Conclusions: Our approach discretely measures endpoints of cell surface biomarker prevalence, biomarker membrane/cytoplasmic ratio, heterogeneity, stromal contribution, inflammatory environment, and other important cell-by-cell outputs from a single FFPE slide in the context of typical drug discovery.

A modified ingrowth core method for measuring fine root production, mortality and decomposition in forests

The ingrowth core method is widely used to assess fine root (diameter < 2 mm) production but has many inherent deficiencies. In this study, we modified this method by adopting mini ingrowth cores (diameter 1.2 cm), extending sample intervals to a growing season, and developing new models to quantify the concurrent production, mortality and decomposition, and applied them to a secondary Mongolian oak (Quercus mongolica Fischer ex Ledebour) forest. Annual fine root production, mortality and decomposition estimated by our method were 2.10 ± 0.23, 1.78 ± 0.20 and 0.85 ± 0.13 t ha(-1), respectively, and 33.3% of the production was decomposed in the growing season. The production estimate using our method was significantly higher than those using two long-term ingrowth core (sample interval >2 months) methods. However, it was significantly lower than that using the short-term ingrowth core (sample interval <2 months) method, presumably due to the lower root competition and less decomposition occurring in the short-term cores. The fine root estimates using our method in the growing season were generally higher than those using the forward and continuous inflow methods but lower than those using the backward method. Our method reduces the disturbances in roots and soil, minimizes the sampling frequency and improves the quantification of fine root decomposition during the sample intervals. These modifications overcome the limitations associated with the previous ingrowth core methods. Our method provides an improved alternative for estimating fine root production, mortality and decomposition.

Evaluating tumor heterogeneity in immunohistochemistry-stained breast cancer tissue

Quantitative clinical measurement of heterogeneity in immunohistochemistry staining would be useful in evaluating patient therapeutic response and in identifying underlying issues in histopathology laboratory quality control. A heterogeneity scoring approach (HetMap) was designed to visualize a individual patient's immunohistochemistry heterogeneity in the context of a patient population. HER2 semiquantitative analysis was combined with ecology diversity statistics to evaluate cell-level heterogeneity (consistency of protein expression within neighboring cells in a tumor nest) and tumor-level heterogeneity (differences of protein expression across a tumor as represented by a tissue section). This approach was evaluated on HER2 immunohistochemistry-stained breast cancer samples using 200 specimens across two different laboratories with three pathologists per laboratory, each outlining regions of tumor for scoring by automatic cell-based image analysis. HetMap was evaluated using three different scoring schemes: HER2 scoring according to American Society of Clinical Oncology and College of American Pathologists (ASCO/CAP) guidelines, H-score, and a new continuous HER2 score (HER2(cont)). Two definitions of heterogeneity, cell-level and tumor-level, provided useful independent measures of heterogeneity. Cases where pathologists had disagreement over reads in the area of clinical importance (+1 and +2) had statistically significantly higher levels of tumor-level heterogeneity. Cell-level heterogeneity, reported either as an average or the maximum area of heterogeneity across a slide, had low levels of dependency on the pathologist choice of region, while tumor-level heterogeneity measurements had more dependence on the pathologist choice of regions. HetMap is a measure of heterogeneity, by which pathologists, oncologists, and drug development organizations can view cell-level and tumor-level heterogeneity for a patient for a given marker in the context of an entire patient cohort. Heterogeneity analysis can be used to identify tumors with differing degrees of heterogeneity, or to highlight slides that should be rechecked for QC issues. Tumor heterogeneity plays a significant role in disconcordant reads between pathologists.

Tunable plasmon coupling in distance-controlled gold nanoparticles

Plasmons are resonant excitations in metallic films and nanoparticles. For small enough static distances of metal nanoparticles, additional plasmon-coupled modes appear as a collective excitation between the nanoparticles. Here we show, by combining poly(N-isopropylacrylamide) micro- and nanospheres and Au nanoparticles, how to design a system that allows controllably and reversibly switching on and off, and tuning the plasmon-coupled mode.

Abstract 2683: Cellmap: Tumor cell subpopulation analysis in immunohistochemistry stained tumor tissue

All potential factors within individual patients which contribute to a lack of response to a given therapy are not known, but cancer biologists have long hypothesized that distinct and disparate populations within the tumor can be selected for by therapy to outgrow and emerge as a resistant tumor. As more targeted therapies are being developed, the understanding of these subpopulations of cells within a tumor has become very important to clinical strategy. Thus, there is a need to effectively distinguish and evaluate different populations of cells in a tumor within formalin fixed tissue. These contextual evaluations are important for understanding the biology of a target, evaluating pharmacodynamic or surrogate efficacy markers, or evaluating biomarkers for a companion diagnostic approach. Immunohistochemistry (IHC) remains the most direct approach to evaluating biomarkers within tissue context, but requires a pathologist to subjectively separate the complex components of tumor tissue and the compartments of the tumor cells themselves to deliver a numerical score that is based on the staining intensity of a cell and the percentage of cells which stain. This output is considered qualitative, due to pathologist subjectivity in scoring sample regions, the inability to effectively discriminate minor differences in staining intensities for a biomarker, and the inability to deliver a dataset with sufficient sample size to overcome bias deficiencies. Furthermore, a significant amount of information content is lost in this score, eliminating the potential to identify and analyze discrete cell populations within a tumor that may be leading to refractory to therapy. In contrast, modern image analysis (IA) approaches can deliver a far more quantitative IHC score by objectively distinguishing tumor components and cellular compartments, detecting minor differences in staining intensity, and by performing this function across the whole tumor section. However, current IA approaches are designed only to report an average or thresholded intensity across the analyzed region, without reporting the cell-by-cell statistics required to identify discrete cell populations within a tumor. To answer this, we have designed Cellmap, which can analyze an IHC stained tumor tissue section which has been digitally imaged, and make multiparametric measurements about cell morphology and biomarker staining in every cell individually. This information can be reported tumor-wide, or within a specific component of the tumor, and/or within a compartment of the cell simultaneously. Cellmap can be used to make quantitative measurements which identify specific cells with specific signaling processes, and determine their location within a tumor section. This information can be used to identify and quantify discrete cell populations relevant to a disease hypothesis which are associated with a specific tumor microenvironment.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2683. doi:1538-7445.AM2012-2683

Abstract 5543: Hetmap: Evaluating tumor heterogeneity in immunohistochemistry-stained breast cancer tissue

Immunohistochemisty assays examining the HER2 receptor in breast cancer is the most widely adopted example of a companion diagnostic approach, which seeks to dictate therapeutic strategy based on a molecular description of a patient's disease. There are well-established guidelines for selecting patients for anti HER2 adjuvant therapies in breast cancer treatment, yet the current HER2 companion diagnostic approach is qualitative, does not sufficiently account for intratumor heterogeneity, and does not utilize any additional information about tumor cells that score beyond a specific threshold level. A major contributing factor for the failure of both treatment and diagnostic paradigm is thought to be intratumor heterogeneity. This lack of information in the scoring paradigm may contribute to inappropriate patient selection and explain why the disease in many trastuzumab treated patients progresses or becomes recurrent. Thus, a quantitative clinical measurement of heterogeneity in immunohistochemistry staining would be useful in better predicting patient therapeutic response. To answer this, we created a heterogeneity scoring approach (HetMap) that allows the visualization of an individual patient's IHC heterogeneity in the context of a cell population. We combined HER2 semi-quantitative analysis with the use of ecology diversity statistics to evaluate cell-level heterogeneity (consistency of protein expression within neighboring cells in a tumor nest) and tumor-level heterogeneity (differences of protein expression across a tumor as represented by a tissue section). We evaluated the approach on HER2 immunohistochemistry stained breast cancer samples, using 200 specimens across two different CLIA laboratories, with three pathologists at each laboratory each outlining regions of tumor for scoring by automatic cell-based image analysis. HetMap was evaluated using three different scoring schemes: HER2 scoring according to ASCO/CAP guidelines, H-Score and a new continuous HER2 score (HER2cont). Cell-level heterogeneity, reported either as an average or the maximum area of heterogeneity across a slide, had low levels of dependency on the pathologist choice of region. Tumor-level heterogeneity measurements had more dependence on the pathologist choice of regions. Significantly, discordant pathologist assessments of IHC scores in the +2, or equivocal score, range occurred most in tumors with high heterogeneity, leading to potentially major clinical impact. Thus, HetMap is a measure of heterogeneity, by which pathologists, oncologists, and drug development organizations can view cell-level and tumor-level heterogeneity for a patient for a given marker in the context of an entire patient cohort. Including such measures of heterogeneity in diagnostic approaches can help establish better thresholds for patient selection, thereby improving patient response.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5543. doi:1538-7445.AM2012-5543

P5-11-17: Evaluating Tumor Heterogeneity in Immunohistochemistry Stained Breast Cancer Tissue

Context: Quantitative clinical measurement of heterogeneity in immunohistochemistry staining would be useful in both evaluating patient therapeutic response and identifying underlying issues in histopathology laboratory quality control.

Objective: To create a heterogeneity scoring approach (HetMap) that allows the visualization of an individual patient's IHC heterogeneity in the context of a population.

Design: We combined HER2 semi-quantitative analysis with the use of ecology diversity statistics to evaluate cell-level heterogeneity (consistency of protein expression within neighboring cells in a tumor nest) and tumor-level heterogeneity (differences of protein expression across a tumor as represented by a tissue section). We evaluated the approach on HER2 immunohistochemistry stained breast cancer samples, using 200 specimens across two different CLIA laboratories, with three pathologists at each laboratory each outlining regions of tumor for scoring by automatic cell-based image analysis. HetMap was evaluated using three different scoring schemes: HER2 scoring according to ASCO/CAP guidelines, H-Score and a new continuous HER2 score (HER2cont).

Results: Two definitions of heterogeneity, cell-level and tumor-level, provided useful independent measures of heterogeneity. Cell-level heterogeneity, reported either as an average or the maximum area of heterogeneity across a slide, had low levels of dependency on the pathologist choice of region (coefficient of variation of 15%). Tumor-level heterogeneity measurements had more dependence on the pathologist choice of regions (coefficient of variation of 25%). Results were highly similar between the two laboratories, which is encouraging for HER2 standardization, as the labs involved different pathologists, different specimens, and different standardization procedures, although both complied with CLIA/CAP guidelines for HER2 testing.

Conclusions: HetMap is a measure of heterogeneity, by which pathologists, oncologists, and drug development organizations can view cell-level and tumor-level heterogeneity for a patient for a given marker in the context of an entire patient cohort. Heterogeneity analysis can be a useful means to identify tumors with higher degrees of heterogeneity, or to highlight slides that should be rechecked for QC issues.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-11-17.

Trainable immunohistochemical HER2/neu image analysis: a multisite performance study using 260 breast tissue specimens

CONTEXT

Aperio Technologies, Inc (Vista, California) provides a new immunohistochemistry (IHC) HER2 Image Analysis (IA) system that allows tuning of the intensity thresholds of the HER2/ neu scoring scheme to adapt to the staining characteristics of different reagents.

OBJECTIVE

To compare the trainable IHC HER2 IA system for different reagents to conventional manual microscopy (MM) in a multisite study.

DESIGN

Two hundred sixty formalin-fixed, paraffin-embedded breast cancer specimens from 3 clinical sites were assayed: 180 specimens stained with Dako's HercepTest (Carpinteria, California), and 80 specimens stained with Ventana's PATHWAY HER-2/neu (Tucson, California). At each site, 3 pathologists performed a blinded reading of the glass slides with the use of a light microscope. The glass slides were then scanned and after a wash-out period and randomization, the same pathologists outlined a representative set of tumor regions to be analyzed by IHC HER2 IA. Each of the methods, MM and IA, was evaluated separately and comparatively by using κ statistics of negative HER2/neu scores (0, 1+) versus equivocal HER2/neu scores (2+) versus positive HER2/neu scores (3+) among the different pathologists.

RESULTS

κ Values for IA and MM were obtained across all sites. MM: 0.565-0.864; IA: 0.895-0.947; MM versus IA: 0.683-0.892 for site 1; MM: 0.771-0.837; IA: 0.726-0.917; MM versus IA: 0.687-0.877 for site 2; MM: 0.463-0.674; IA: 0.864-0.918; MM versus IA: 0.497-0.626 for site 3.

CONCLUSION

Aperio's trainable IHC HER2 IA system shows substantial equivalence to MM for Dako's HercepTest and Ventana's PATHWAY HER-2/neu at 3 clinical sites. Image analysis improved interpathologist agreement in the different clinical sites.

Adsorption behavior of 4-methoxypyridine on gold nanoparticles

We demonstrate a phase transfer method to create stable colloidal solutions of Au nanoparticles with 4-methoxypyridine ligands. We then investigate the adsorption behavior of 4-methoxypyridine onto gold surfaces by Raman spectroscopy, DFT calculations, and (1)H NMR. In contrast to unsubstituted pyridine and the frequently used (N,N-dimethylamino)pyridine (DMAP), a flat adsorption of 4-methoxypyridine on gold was found.