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Practical experience of the EOGRTS protocol in use
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Abstracts / Toxicology Letters 221S (2013) S4–S30
analysis to identify additional genes and pathways that may also be associated with inter-individual differences in toxicity. We conclude that genomic-anchored in vitro screening model offers unique advantages for identifying variations in toxicity responses at the DNA sequence level and for defining experimentally based confidence intervals for population variability. http://dx.doi.org/10.1016/j.toxlet.2013.06.061
S10-4 Genetic susceptibly: relevance to adverse drug reactions Ruth A. Roberts AstraZeneca, Macclesfield, UK Adverse drug reactions pose a significant challenge in drug discovery and development, halting or delaying the progress of many potential new medicines in clinical development through from Phase 1 to post marketing surveillance. One of the most interesting aspects is in understanding how genetic variability can impact on an individual patient’s response to drug treatment both in terms of the dose required for efficacy and any individual susceptibility to toxicity. As toxicologists, one key question is whether this variability in toxicity could be predicted from pre-clinical models. Before a potential new drug can progress into humans, its safety and tolerability must be assessed in pivotal GLP toxicology studies usually of one month’s duration in two species, most frequently rat and dog. An analysis of the study data from several drug projects shows that outliers are common. The challenge comes in interpreting these types of study data for human risk assessment; could these outliers potentially predict human response? A key step in answering this question would be to be able to relate the variability in endpoints such as ALT to variations in exposure. One block to this at present is that in rodents exposure is measured in different animals to the toxicity work, preventing this type of analysis. However, the introduction of micro sampling should overcome this issue for future studies. In summary, inter animal variability in toxicity in pre-clinical species offers an opportunity to better understand human variability. Any information on the mechanisms of the inter animal variability will assist in this translation. http://dx.doi.org/10.1016/j.toxlet.2013.06.062 Symposium 11: The Extended One Generation Reproductive Toxicity (EOGRT) assay - scientific challenges and regulatory implementation
S11-1 Practical experience of the EOGRTS protocol in use Steffen Schneider Experimental Toxicology and Ecology, BASF SE, Ludwigshafen, Germany The extended one-generation reproductive toxicity study (EOGRTS) was established to evaluate relevant reproductive and developmental toxicity parameters across all life stages in a higher tier study, while simultaneously reducing the number of animals required for regulatory assessment. A series of EOGRTSs were performed to validate the draft OECD technical guidance (OECD 443). These studies attest to the effectiveness of the EOGRTS for
detecting critical reproductive, neuro-, endocrine, and immunotoxic effects. Furthermore, the design offers integrated assessment of toxicokinetics with multiple endpoints, increased utilization of the F1 generation, and enhanced evaluation throughout a variety of life stages. The latter includes assessment of effects on the embryonic, fetal and juvenile development of the nervous and immune systems as well as alterations in endocrine function (including thyroid pertubations). The inclusion of these endpoints makes the overall sensitivity of the extended one-generation protocol comparable to or even greater than the current two-generation study. Despite the advantage of obtaining enhanced information for risk assessment, the study design is still being discussed among the regulatory community, particularly the duration of the premating treatment and the inclusion of a F2 generation. The study design is a challenge, requiring coordinated effort from diverse personnel, experience with similar higher-tier studies and detailed planning and coordination. Each post-weaning cohort represents a full study, distribution of 3 cohorts to rooms and cages needs comprehensive preparation and logistics. Data management needs to be capable of handling and integrating data from different sub-studies and investigations. Bottlenecks occur, but are manageable. http://dx.doi.org/10.1016/j.toxlet.2013.06.064
S11-2 Analysis of immune toxicity in the extended one-generation reproduction toxicity study Aldert H. Piersma ∗ , Elisa C.M. Tonk, Henk van Loveren Center for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands The Extended One generation Reproduction Toxicity Study (EOGRTS) was accepted as an OECD test guideline (TG 443) in July 2011. It varies from existing generation study guidelines (OECD TG 415 and 416) by a different exposure duration with different coverage of the reproductive cycle and a more in-depth analysis of reproductive parameters, both by testing more offspring for each parameter and by adding additional parameters. In addition, two cohorts of offspring are dedicated to the assessment of developmental neurotoxicity and developmental immunotoxicity parameters, respectively. As to the immune parameters, both structural parameters such as organ weights and cellularities of thymus and spleen, and functional parameters, in this case the T-cell antibody response to KLH challenge, are included in the study. We have tested dioctyl-tin-chloride and ethanol using this exposure protocol. We observed that especially the KLH challenge response was the most sensitive parameter both as compared to structural immune parameters and as compared to reproductive parameters. This study provides further support for the mandatory inclusion of testing functional immunity in the EOGRTS. The developing immune system could be more sensitive to toxic exposures than the mature immune system, and in addition, developmental exposure may compromise the immune system irreversibly resulting in untoward consequences throughout life, enhancing risk for a host of immune-related diseases. Relatively little is known about causes of immune-related diseases in man, including allergies, asthma and a host of auto-immune diseases. Regular testing for developmental toxicity parameters could establish whether chemical exposures affect these prevalences. http://dx.doi.org/10.1016/j.toxlet.2013.06.065
Abstracts / Toxicology Letters 221S (2013) S4–S30
analysis to identify additional genes and pathways that may also be associated with inter-individual differences in toxicity. We conclude that genomic-anchored in vitro screening model offers unique advantages for identifying variations in toxicity responses at the DNA sequence level and for defining experimentally based confidence intervals for population variability. http://dx.doi.org/10.1016/j.toxlet.2013.06.061
S10-4 Genetic susceptibly: relevance to adverse drug reactions Ruth A. Roberts AstraZeneca, Macclesfield, UK Adverse drug reactions pose a significant challenge in drug discovery and development, halting or delaying the progress of many potential new medicines in clinical development through from Phase 1 to post marketing surveillance. One of the most interesting aspects is in understanding how genetic variability can impact on an individual patient’s response to drug treatment both in terms of the dose required for efficacy and any individual susceptibility to toxicity. As toxicologists, one key question is whether this variability in toxicity could be predicted from pre-clinical models. Before a potential new drug can progress into humans, its safety and tolerability must be assessed in pivotal GLP toxicology studies usually of one month’s duration in two species, most frequently rat and dog. An analysis of the study data from several drug projects shows that outliers are common. The challenge comes in interpreting these types of study data for human risk assessment; could these outliers potentially predict human response? A key step in answering this question would be to be able to relate the variability in endpoints such as ALT to variations in exposure. One block to this at present is that in rodents exposure is measured in different animals to the toxicity work, preventing this type of analysis. However, the introduction of micro sampling should overcome this issue for future studies. In summary, inter animal variability in toxicity in pre-clinical species offers an opportunity to better understand human variability. Any information on the mechanisms of the inter animal variability will assist in this translation. http://dx.doi.org/10.1016/j.toxlet.2013.06.062 Symposium 11: The Extended One Generation Reproductive Toxicity (EOGRT) assay - scientific challenges and regulatory implementation
S11-1 Practical experience of the EOGRTS protocol in use Steffen Schneider Experimental Toxicology and Ecology, BASF SE, Ludwigshafen, Germany The extended one-generation reproductive toxicity study (EOGRTS) was established to evaluate relevant reproductive and developmental toxicity parameters across all life stages in a higher tier study, while simultaneously reducing the number of animals required for regulatory assessment. A series of EOGRTSs were performed to validate the draft OECD technical guidance (OECD 443). These studies attest to the effectiveness of the EOGRTS for
detecting critical reproductive, neuro-, endocrine, and immunotoxic effects. Furthermore, the design offers integrated assessment of toxicokinetics with multiple endpoints, increased utilization of the F1 generation, and enhanced evaluation throughout a variety of life stages. The latter includes assessment of effects on the embryonic, fetal and juvenile development of the nervous and immune systems as well as alterations in endocrine function (including thyroid pertubations). The inclusion of these endpoints makes the overall sensitivity of the extended one-generation protocol comparable to or even greater than the current two-generation study. Despite the advantage of obtaining enhanced information for risk assessment, the study design is still being discussed among the regulatory community, particularly the duration of the premating treatment and the inclusion of a F2 generation. The study design is a challenge, requiring coordinated effort from diverse personnel, experience with similar higher-tier studies and detailed planning and coordination. Each post-weaning cohort represents a full study, distribution of 3 cohorts to rooms and cages needs comprehensive preparation and logistics. Data management needs to be capable of handling and integrating data from different sub-studies and investigations. Bottlenecks occur, but are manageable. http://dx.doi.org/10.1016/j.toxlet.2013.06.064
S11-2 Analysis of immune toxicity in the extended one-generation reproduction toxicity study Aldert H. Piersma ∗ , Elisa C.M. Tonk, Henk van Loveren Center for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands The Extended One generation Reproduction Toxicity Study (EOGRTS) was accepted as an OECD test guideline (TG 443) in July 2011. It varies from existing generation study guidelines (OECD TG 415 and 416) by a different exposure duration with different coverage of the reproductive cycle and a more in-depth analysis of reproductive parameters, both by testing more offspring for each parameter and by adding additional parameters. In addition, two cohorts of offspring are dedicated to the assessment of developmental neurotoxicity and developmental immunotoxicity parameters, respectively. As to the immune parameters, both structural parameters such as organ weights and cellularities of thymus and spleen, and functional parameters, in this case the T-cell antibody response to KLH challenge, are included in the study. We have tested dioctyl-tin-chloride and ethanol using this exposure protocol. We observed that especially the KLH challenge response was the most sensitive parameter both as compared to structural immune parameters and as compared to reproductive parameters. This study provides further support for the mandatory inclusion of testing functional immunity in the EOGRTS. The developing immune system could be more sensitive to toxic exposures than the mature immune system, and in addition, developmental exposure may compromise the immune system irreversibly resulting in untoward consequences throughout life, enhancing risk for a host of immune-related diseases. Relatively little is known about causes of immune-related diseases in man, including allergies, asthma and a host of auto-immune diseases. Regular testing for developmental toxicity parameters could establish whether chemical exposures affect these prevalences. http://dx.doi.org/10.1016/j.toxlet.2013.06.065