Project description:The application of toxicogenomics as a predictive tool for chemical risk assessment has been under evaluation by the toxicology community for more than a decade. However, toxicogenomics predominately remains a tool for investigative research rather than for regulatory risk assessment. In this study, we aimed to determine whether the current generation of microarray technology in combination with an in vitro experimental design was capable of generating robust, reproducible data of sufficient quality to show promise as a tool for regulatory risk assessment. To this end, we designed a prospective collaborative study to determine the level of inter- and intra-laboratory reproducibility between three independent laboratories. All test sites adopted the same protocols for all aspects of the toxicogenomic experiment including cell culture, chemical exposure, RNA extraction, microarray data generation and analysis. As a case study, the genotoxic carcinogen B[a]P and the human hepatocyte cell line HepG2 were used to generate three comparable toxicogenomic data sets. High levels of technical reproducibility were demonstrated using a widely employed gene expression microarray platform. While differences at the global transcriptome level were still observed between the test sites, a common subset of B[a]P responsive genes was identified across all test sites which included both genes previously reported in the literature as B[a]P responsive in addition to the same most highly up and down regulated genes. Pending further analysis, these preliminary data show promise that the current generation of microarray technology in combination with a standard in vitro experimental design can produce robust data that can be reproducibly generated in independent laboratories. Future work will need to determine whether in vitro model(s) can be not only reproducible but also predictive for a range of toxic chemicals with different mechanisms of action. Such an approach may potentially be part of future in vitro testing regimes for regulatory risk assessment.

Project description:BackgroundIn breast cancer, immunohistochemical assessment of proliferation using the marker Ki67 has potential use in both research and clinical management. However, lack of consistency across laboratories has limited Ki67's value. A working group was assembled to devise a strategy to harmonize Ki67 analysis and increase scoring concordance. Toward that goal, we conducted a Ki67 reproducibility study.MethodsEight laboratories received 100 breast cancer cases arranged into 1-mm core tissue microarrays-one set stained by the participating laboratory and one set stained by the central laboratory, both using antibody MIB-1. Each laboratory scored Ki67 as percentage of positively stained invasive tumor cells using its own method. Six laboratories repeated scoring of 50 locally stained cases on 3 different days. Sources of variation were analyzed using random effects models with log2-transformed measurements. Reproducibility was quantified by intraclass correlation coefficient (ICC), and the approximate two-sided 95% confidence intervals (CIs) for the true intraclass correlation coefficients in these experiments were provided.ResultsIntralaboratory reproducibility was high (ICC = 0.94; 95% CI = 0.93 to 0.97). Interlaboratory reproducibility was only moderate (central staining: ICC = 0.71, 95% CI = 0.47 to 0.78; local staining: ICC = 0.59, 95% CI = 0.37 to 0.68). Geometric mean of Ki67 values for each laboratory across the 100 cases ranged 7.1% to 23.9% with central staining and 6.1% to 30.1% with local staining. Factors contributing to interlaboratory discordance included tumor region selection, counting method, and subjective assessment of staining positivity. Formal counting methods gave more consistent results than visual estimation.ConclusionsSubstantial variability in Ki67 scoring was observed among some of the world's most experienced laboratories. Ki67 values and cutoffs for clinical decision-making cannot be transferred between laboratories without standardizing scoring methodology because analytical validity is limited.

Project description:The application of toxicogenomics as a predictive tool for chemical risk assessment has been under evaluation by the toxicology community for more than a decade. However, toxicogenomics predominately remains a tool for investigative research rather than for regulatory risk assessment. In this study, we aimed to determine whether the current generation of microarray technology in combination with an in vitro experimental design was capable of generating robust, reproducible data of sufficient quality to show promise as a tool for regulatory risk assessment. To this end, we designed a prospective collaborative study to determine the level of inter- and intra-laboratory reproducibility between three independent laboratories. All test sites adopted the same protocols for all aspects of the toxicogenomic experiment including cell culture, chemical exposure, RNA extraction, microarray data generation and analysis. As a case study, the genotoxic carcinogen B[a]P and the human hepatocyte cell line HepG2 were used to generate three comparable toxicogenomic data sets. High levels of technical reproducibility were demonstrated using a widely employed gene expression microarray platform. While differences at the global transcriptome level were still observed between the test sites, a common subset of B[a]P responsive genes was identified across all test sites which included both genes previously reported in the literature as B[a]P responsive in addition to the same most highly up and down regulated genes. Pending further analysis, these preliminary data show promise that the current generation of microarray technology in combination with a standard in vitro experimental design can produce robust data that can be reproducibly generated in independent laboratories. Future work will need to determine whether in vitro model(s) can be not only reproducible but also predictive for a range of toxic chemicals with different mechanisms of action. Such an approach may potentially be part of future in vitro testing regimes for regulatory risk assessment. The aim of this study was to evaluate the inter- and intra-laboratory reproducibility of toxicogenomics data for toxicity testing in a regulatory setting. 3 Test Centres performed the same experimental protocol treating HepG2 cells with 3 mM Benzo[a]pyrene (B[a]P) (in 0.5% DMSO) for 24 hours prior to RNA extraction and microarray analysis. Three biological replicates of B[a]P and DMSO treatments were analysed by microarray analysis in each Test Centre. Two Test Centres analysed one sample in triplicate to determine technical reproducibility of the chosen array platform. One Centre analysed two samples in duplicate. 24 samples in total were used in this study

Dataset Information

Standardisation of EGFR FISH in colorectal cancer: results of an international interlaboratory reproducibility ring study.

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Standardisation of EGFR FISH in colorectal cancer: results of an international interlaboratory reproducibility ring study.

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