ABSTRACT Located at the level of brain capillaries, the blood–brain barrier (BBB) is a crucial co... more ABSTRACT Located at the level of brain capillaries, the blood–brain barrier (BBB) is a crucial component of the neurovascular unit, since its highly regulated properties are needed to maintain optimal conditions for proper neuronal and glial functions. By modelling the BBB it is possible to make predictions about whether a compound’s interaction with the BBB is likely to compromise its functionality. A dysfunctional BBB may either affect brain entry of an agent or indirectly generate unwanted effects on neurons and glial cells by disturbing the brain homeostasis. Since the BBB controls the exchanges between the blood and brain compartments modelling the BBB in vitro can also help to investigate the ability of compounds to cross the BBB. In this chapter, the plethora of in vitro BBB models that exist today is discussed and several methods needed to set up and use of these in vitro models in the framework of in vitro toxicity study is detailed.
The use of sandwich-cultured rat hepatocytes to determine the intrinsic clearance of compounds wi... more The use of sandwich-cultured rat hepatocytes to determine the intrinsic clearance of compounds with different extraction ratios; 7-ethoxycoumarin and warfarin
neurotoxicity Integration of in vitro neurotoxicity data with biokinetic modelling for the estima... more neurotoxicity Integration of in vitro neurotoxicity data with biokinetic modelling for the estimation of in vivo
Mardas Daneshian I, Mohammad A. Akbarsha2, Bas Blaauboer3, Francesca Caloni4, Pierre Cosson 5, Ro... more Mardas Daneshian I, Mohammad A. Akbarsha2, Bas Blaauboer3, Francesca Caloni4, Pierre Cosson 5, Rodger Curren 6, Alan Goldberg 7, Franz Gruber8, Frauke Oh19, Waiter Pfaller 10, Jan van der Valkll, Pilar VinardellI2, Joanne Zurlo7, Thomas Hartungl• 7,13, and Marcel Leist1•14 ' Center for Alternatives to Animal Testing Europe, University of Konstanz, Germany; 2 Mahatma Gandhi-Doerenkamp Center (MGDC) for Alternatives to Use of Animals in Life Science Education, Bharathidasan University, Tiruchirappalli , India; 3 Doerenkamp Zbinden Chair on Alternatives to Animal Testing in Toxicological Risk Assessment, Institute for Risk Assessment Sciences, Division of Toxicology, Utrecht University, The Netherlands; 4 Department of Veterinary Sciences Technologies for Food Safety, Universita degli Studi di Milano , Italy; 5 Doerenkamp-Naef-Zbinden Chair on In vitro alternatives to animal experiments, Geneva Faculty of Medicine, Switzerland; 6 Institute for In Vitro Sciences, Inc., USA; 7 Doere...
A mode-of-action ontology model for safety evaluation of chemicals: outcome of a series of worksh... more A mode-of-action ontology model for safety evaluation of chemicals: outcome of a series of workshops on repeated dose toxicity
ADME (absorption, distribution, metabolism, elimination) has rapidly evolved over the past two de... more ADME (absorption, distribution, metabolism, elimination) has rapidly evolved over the past two decades, creating a unique interdisciplinary interface between medicinal chemists, biologists, formulators, toxicologists, clinicians, and regulators across industries, but has advanced most rapidly in the pharmaceutical industry. The implementation of ADME profiling of drug candidates, in conjunction with biological efficacy and safety optimization, has dramatically reduced pharmacokinetic drug failures in clinical trials and has become a lingua franca between disciplines that are involved in drug development. This article briefly reviews the basics and current state-of-the-art of ADME and the major lessons from the pharmaceutical industry on its efficient use, points out the importance of defining ADME properties leading to toxicity across industries for safety and toxicity prediction of chemicals, and raises the issues of quality, reliability, and reproducibility of tests and inclusion ...
Toxicology in vitro : an international journal published in association with BIBRA, 2017
In this paper, an in vitro basal cytotoxicity testing strategy is described for new chemical enti... more In this paper, an in vitro basal cytotoxicity testing strategy is described for new chemical entities that lack any pre-existing information on potential toxicity. Special attention is paid to the selection of the cellular system, cytotoxicity assay and exposure conditions. This approach is based on a newly proposed generic adverse outcome pathway from chemical insult to cell death that consists of 3 steps, including initial cell injury, mitochondrial dysfunction and cell demise. The suggested strategy to consider in vitro basal cytotoxicity as a first step in evaluating the toxicity of new chemical entities can be placed in a tiered strategy that could be continued by evaluating more specific types of toxicity.
Toxicology in vitro : an international journal published in association with BIBRA, Jan 6, 2017
Acute systemic toxicity testing provides the basis for hazard labeling and risk management of che... more Acute systemic toxicity testing provides the basis for hazard labeling and risk management of chemicals. A number of international efforts have been directed at identifying non-animal alternatives for in vivo acute systemic toxicity tests. A September 2015 workshop, Alternative Approaches for Identifying Acute Systemic Toxicity: Moving from Research to Regulatory Testing, reviewed the state-of-the-science of non-animal alternatives for this testing and explored ways to facilitate implementation of alternatives. Workshop attendees included representatives from international regulatory agencies, academia, nongovernmental organizations, and industry. Resources identified as necessary for meaningful progress in implementing alternatives included compiling and making available high-quality reference data, training on use and interpretation of in vitro and in silico approaches, and global harmonization of testing requirements. Attendees particularly noted the need to characterize variabil...
Toxicology in vitro : an international journal published in association with BIBRA, Jan 25, 2015
This special Issue of Toxicology in Vitro covers the most relevant findings of a large scale inte... more This special Issue of Toxicology in Vitro covers the most relevant findings of a large scale integrating Project on ''Profiling the toxicity of new drugs: a non-animal based approach integrating toxicodynamics and biokinetics", funded by the European Commission (Grant No. 202222, Predict-IV), which started in May 2008 and was finalised in October 2013. To prevent events like the Elixir Sulfanilamide scandal in 1937 in the USA or the Thalidomide disaster in the 1950s and early 1960s in Germany, almost all regulatory authorities have introduced safety testing for new or previously untested chemical entities (Limonciel, 2014). The consequence was the establishment of a battery of animal-based tests for specific toxicological endpoints. However, we now know that there are large species differences in xenobiotic handling and thus there is a drive to use human derived models. New developments in cell culture and molecular biology provide a unique opportunity to meet regulatory requirements while improving on the predictivity of pre-clinical test systems, as already suggested by Russell and Burch (1959). In addition to in vitro models the use of in silico predictions of toxicity as well as the use of physiologically-based biokinetics has matured over the last decades (Blaauboer, 2010; Blaauboer et al., 2012). The utilisation and integration of in vitro and in silico techniques promise to increase the speed of drug safety testing, decrease the costs incurred thereby having more drugs on the market. Also by using human-derived models we aim to improve on the predictivity of animal-based models (Jennings, 2015), thus these drugs will likely be safer than ever before. In the Predict-IV project we divided the problem into four main aspects: (1) cell culture models suitable for repeat dose exposures, (2) mechanistic toxicology based on ''omic" analysis, (3) biokinetics, and (4) quantitative in vitro to in vivo extrapolation. Here we provide a short overview of the project outcomes, the majority of which are published in this issue.
In April 2013 the mouse antibody serum neutralization test (SNT) was formally incorporated into E... more In April 2013 the mouse antibody serum neutralization test (SNT) was formally incorporated into European Pharmacopoeia monograph 0451 for potency testing of inactivated veterinary rabies vaccines. The SNT is designed to replace the highly variable and pain and distress causing NIH mouse rabies challenge assay. The adoption of the SNT meets the European ambition (i.e., EC and CoE) to replace, reduce and/or refine laboratory animal testing. However, regulatory acceptance and use of 3R models, such as the SNT, remains challenging. This paper aims at clarifying the process of acceptance and use of the SNT. For this purpose it reconstructsthe process and reveals barriers and drivers that have been observed by involved stakeholders to have played a role. In addition it extracts lessons to stimulate regulatory acceptance in similar future processes. The incorporation of the SNT into the monographs went relatively quick due to a thorough test development and pre-validation phase, commitment...
The importance placed on risk avoidance in our society has resulted in a broad range of regulatio... more The importance placed on risk avoidance in our society has resulted in a broad range of regulations intended to guarantee safety of products such as pharmaceuticals and chemicals. Many of these regulations rely on animal tests. As a result, about 25% of the animal experiments in Europe are done for regulatory purposes. There are many initiatives that aim to replace, reduce, or refine laboratory animal use, but the regulatory acceptance and use of 3R models lags behind. The central question of this study is: "Which variables influence the regulatory acceptance and use of 3R models and in what way?" Regulatory acceptance is seen as one of the biggest hurdles 3R models face, but the rationale behind this is still underexplored. This study is an approach to filling that gap by combining opinions from experts in the field with literature on technology acceptance and risk regulation, resulting in a model of the variables that determine the process of the regulatory acceptance an...
Toxicological sciences : an official journal of the Society of Toxicology, Jan 30, 2015
The present debate on chemicals with Hormonal activity, often termed 'endocrine disruptors... more The present debate on chemicals with Hormonal activity, often termed 'endocrine disruptors', is highly controversial and includes challenges of the present paradigms used in toxicology and in hazard identification and risk characterization. In our opinion, chemicals with hormonal activity can be subjected to the well-evaluated health risk characterization approach used for many years including adverse outcome pathways. Many of the points arguing for a specific approach for risk characterization of chemicals with hormonal activity are based on highly speculative conclusions. These conclusions are not well supported when evaluating the available information.
Systemic toxicity testing forms the cornerstone for the safety evaluation of substances. Pressure... more Systemic toxicity testing forms the cornerstone for the safety evaluation of substances. Pressures to move from traditional animal models to novel technologies arise from various concerns, including: the need to evaluate large numbers of previously untested chemicals and new products (such as nanoparticles or cell therapies), the limited predictivity of traditional tests for human health effects, duration and costs of current approaches, and animal welfare considerations. The latter holds especially true in the context of the scheduled 2013 marketing ban on cosmetic ingredients tested for systemic toxicity. Based on a major analysis of the status of alternative methods (Adler et al., 2011) and its independent review (Hartung et al., 2011), the present report proposes a roadmap for how to overcome the acknowledged scientific gaps for the full replacement of systemic toxicity testing using animals. Five whitepapers were commissioned addressing toxicokinetics, skin sensitization, repea...
Industrial sectors perform toxicological assessments of their potential products to ensure human ... more Industrial sectors perform toxicological assessments of their potential products to ensure human safety and to fulfill regulatory requirements. These assessments often involve animal testing, but ethical, cost, and time concerns, together with a ban on it in specific sectors, make appropriate in vitro systems indispensable in toxicology. In this study, we summarize the outcome of an EPAA (European Partnership of Alternatives to Animal Testing)-organized workshop on the use of stem cell-derived (SCD) systems in toxicology, with a focus on industrial applications. SCD systems, in particular, induced pluripotent stem cell-derived, provide physiological cell culture systems of easy access and amenable to a variety of assays. They also present the opportunity to apply the vast repository of existing nonclinical data for the understanding of in vitro to in vivo translation. SCD systems from several toxicologically relevant tissues exist; they generally recapitulate many aspects of physiology and respond to toxicological and pharmacological interventions. However, focused research is necessary to accelerate implementation of SCD systems in an industrial setting and subsequent use of such systems by regulatory authorities. Research is required into the phenotypic characterization of the systems, since methods and protocols for generating terminally differentiated SCD cells are still lacking. Organotypical 3D culture systems in bioreactors and microscale tissue engineering technologies should be fostered, as they promote and maintain differentiation and support coculture systems. They need further development and validation for their successful implementation in toxicity testing in industry. Analytical measures also need to be implemented to enable compound exposure and metabolism measurements for in vitro to in vivo extrapolation. The future of SCD toxicological tests will combine advanced cell culture technologies and biokinetic measurements to support regulatory and research applications. However, scientific and technical hurdles must be overcome before SCD in vitro methods undergo appropriate validation and become accepted in the regulatory arena.
The role that in vitro systems can play in toxicological risk assessment is determined by the app... more The role that in vitro systems can play in toxicological risk assessment is determined by the appropriateness of the chosen methods, with respect to the way in which in vitro data can be extrapolated to the in vivo situation. This report presents the results of a workshop aimed at better defining the use of in vitro-derived biomarkers of toxicity (BoT) and determining the place these data can have in human risk assessment. As a result, a conceptual framework is presented for the incorporation of in vitro-derived toxicity data into the risk assessment process. The selection of BoT takes into account that they need to distinguish adverse and adaptive changes in cells. The framework defines the place of in vitro systems in the context of data on exposure, structural and physico-chemical properties, and toxicodynamic and biokinetic modeling. It outlines the determination of a proper point-of-departure (PoD) for in vitro-in vivo extrapolation, allowing implementation in risk assessment procedures. A BoT will need to take into account both the dynamics and the kinetics of the compound in the in vitro systems. For the implementation of the proposed framework it will be necessary to collect and collate data from existing literature and new in vitro test systems, as well as to categorize biomarkers of toxicity and their relation to pathways-of-toxicity. Moreover, data selection and integration need to be driven by their usefulness in a quantitative in vitro-in vivo extrapolation (QIVIVE). Keywords: biomarker of toxicity, integrated testing strategies, quantitative in vitro-in vivo extrapolations * a report of t 4-the transatlantic think tank for toxicology, a collaboration of the toxicologically oriented chairs in Baltimore, Konstanz, and Utrecht, sponsored by the Doerenkamp-Zbinden Foundation. The opinions expressed in this report are those of the participants as individuals and do not necessarily reflect the opinions of the organizations they are affiliated with. § Competing Interests Declaration: K. Boekelheide is an occasional expert consultant for chemical and pharmaceutical companies.
This paper describes the evolution of chemical risk assessment from its early dependence on gener... more This paper describes the evolution of chemical risk assessment from its early dependence on generic default approaches to the current situation in which mechanistic and biokinetic data are routinely incorporated to support a more chemical-specific approach. Two methodologies that have played an important role in this evolution are described: mode-of-action evaluation and physiologically based biokinetic (PBBK) modelling. When used together, these techniques greatly increase the opportunity for the incorporation of biokinetic and mechanistic data in risk assessment. The resulting risk assessment approaches are more appropriately tailored to the specific chemical and are more likely to provide an accurate assessment of the potential hazards associated with human exposures. The appropriate application of PBBK models in risk assessment demands well-formulated statements about the chemical mode of action. It is this requirement for an explicit, mechanistic hypothesis that gives biologically motivated models their power, but at the same time serves as the greatest impediment to the acceptance of a chemical-specific risk assessment approach by regulators. The chief impediment to the regulatory acceptance and application of PBBK models in risk assessment is concern about uncertainties associated with their use. To some extent such concerns can be addressed by the development of generally accepted approaches for model evaluation and quantitative uncertainty analysis. In order to assure the protection of public health while limiting the economic and social consequences of over-regulation, greater dialogue between researchers and regulators is crucially needed to foster an increased use of emerging scientific information and innovative methods in chemical risk assessments.
There are now numerous in vitro and in silico ADME alternatives to in vivo assays but how do diff... more There are now numerous in vitro and in silico ADME alternatives to in vivo assays but how do different industries incorporate them into their decision tree approaches for risk assessment, bearing in mind that the chemicals tested are intended for widely varying purposes? The extent of the use of animal tests is mainly driven by regulations or by the lack of a suitable in vitro model. Therefore, what considerations are needed for alternative models and how can they be improved so that they can be used as part of the risk assessment process? To address these issues, the European Partnership for Alternative Approaches to Animal Testing (EPAA) working group on prioritisation, promotion and implementation of the 3Rs research held a workshop in November, 2008 in Duesseldorf, Germany. Participants included different industry sectors such as pharmaceuticals, cosmetics, industrial-and agro-chemicals. This report describes the outcome of the discussions and recommendations (a) to reduce the number of animals used for determining the ADME properties of chemicals and (b) for considerations and actions regarding in vitro and in silico assays. These included: standardisation and promotion of in vitro assays so that they may become accepted by regulators; increased availability of industry in vivo kinetic data for a central database to increase the power of in silico predictions; expansion of the applicability domains of in vitro and in silico tools (which are not necessarily more applicable or even exclusive to one particular sector) and continued collaborations between regulators, academia and industry. A recommended immediate course of action was to establish an expert panel of users, developers and regulators to define the testing scope of models for different chemical classes. It was agreed by all participants that improvement and harmonization of alternative approaches is needed for all sectors and this will most effectively be achieved by stakeholders from different sectors sharing data.
ABSTRACT Located at the level of brain capillaries, the blood–brain barrier (BBB) is a crucial co... more ABSTRACT Located at the level of brain capillaries, the blood–brain barrier (BBB) is a crucial component of the neurovascular unit, since its highly regulated properties are needed to maintain optimal conditions for proper neuronal and glial functions. By modelling the BBB it is possible to make predictions about whether a compound’s interaction with the BBB is likely to compromise its functionality. A dysfunctional BBB may either affect brain entry of an agent or indirectly generate unwanted effects on neurons and glial cells by disturbing the brain homeostasis. Since the BBB controls the exchanges between the blood and brain compartments modelling the BBB in vitro can also help to investigate the ability of compounds to cross the BBB. In this chapter, the plethora of in vitro BBB models that exist today is discussed and several methods needed to set up and use of these in vitro models in the framework of in vitro toxicity study is detailed.
The use of sandwich-cultured rat hepatocytes to determine the intrinsic clearance of compounds wi... more The use of sandwich-cultured rat hepatocytes to determine the intrinsic clearance of compounds with different extraction ratios; 7-ethoxycoumarin and warfarin
neurotoxicity Integration of in vitro neurotoxicity data with biokinetic modelling for the estima... more neurotoxicity Integration of in vitro neurotoxicity data with biokinetic modelling for the estimation of in vivo
Mardas Daneshian I, Mohammad A. Akbarsha2, Bas Blaauboer3, Francesca Caloni4, Pierre Cosson 5, Ro... more Mardas Daneshian I, Mohammad A. Akbarsha2, Bas Blaauboer3, Francesca Caloni4, Pierre Cosson 5, Rodger Curren 6, Alan Goldberg 7, Franz Gruber8, Frauke Oh19, Waiter Pfaller 10, Jan van der Valkll, Pilar VinardellI2, Joanne Zurlo7, Thomas Hartungl• 7,13, and Marcel Leist1•14 ' Center for Alternatives to Animal Testing Europe, University of Konstanz, Germany; 2 Mahatma Gandhi-Doerenkamp Center (MGDC) for Alternatives to Use of Animals in Life Science Education, Bharathidasan University, Tiruchirappalli , India; 3 Doerenkamp Zbinden Chair on Alternatives to Animal Testing in Toxicological Risk Assessment, Institute for Risk Assessment Sciences, Division of Toxicology, Utrecht University, The Netherlands; 4 Department of Veterinary Sciences Technologies for Food Safety, Universita degli Studi di Milano , Italy; 5 Doerenkamp-Naef-Zbinden Chair on In vitro alternatives to animal experiments, Geneva Faculty of Medicine, Switzerland; 6 Institute for In Vitro Sciences, Inc., USA; 7 Doere...
A mode-of-action ontology model for safety evaluation of chemicals: outcome of a series of worksh... more A mode-of-action ontology model for safety evaluation of chemicals: outcome of a series of workshops on repeated dose toxicity
ADME (absorption, distribution, metabolism, elimination) has rapidly evolved over the past two de... more ADME (absorption, distribution, metabolism, elimination) has rapidly evolved over the past two decades, creating a unique interdisciplinary interface between medicinal chemists, biologists, formulators, toxicologists, clinicians, and regulators across industries, but has advanced most rapidly in the pharmaceutical industry. The implementation of ADME profiling of drug candidates, in conjunction with biological efficacy and safety optimization, has dramatically reduced pharmacokinetic drug failures in clinical trials and has become a lingua franca between disciplines that are involved in drug development. This article briefly reviews the basics and current state-of-the-art of ADME and the major lessons from the pharmaceutical industry on its efficient use, points out the importance of defining ADME properties leading to toxicity across industries for safety and toxicity prediction of chemicals, and raises the issues of quality, reliability, and reproducibility of tests and inclusion ...
Toxicology in vitro : an international journal published in association with BIBRA, 2017
In this paper, an in vitro basal cytotoxicity testing strategy is described for new chemical enti... more In this paper, an in vitro basal cytotoxicity testing strategy is described for new chemical entities that lack any pre-existing information on potential toxicity. Special attention is paid to the selection of the cellular system, cytotoxicity assay and exposure conditions. This approach is based on a newly proposed generic adverse outcome pathway from chemical insult to cell death that consists of 3 steps, including initial cell injury, mitochondrial dysfunction and cell demise. The suggested strategy to consider in vitro basal cytotoxicity as a first step in evaluating the toxicity of new chemical entities can be placed in a tiered strategy that could be continued by evaluating more specific types of toxicity.
Toxicology in vitro : an international journal published in association with BIBRA, Jan 6, 2017
Acute systemic toxicity testing provides the basis for hazard labeling and risk management of che... more Acute systemic toxicity testing provides the basis for hazard labeling and risk management of chemicals. A number of international efforts have been directed at identifying non-animal alternatives for in vivo acute systemic toxicity tests. A September 2015 workshop, Alternative Approaches for Identifying Acute Systemic Toxicity: Moving from Research to Regulatory Testing, reviewed the state-of-the-science of non-animal alternatives for this testing and explored ways to facilitate implementation of alternatives. Workshop attendees included representatives from international regulatory agencies, academia, nongovernmental organizations, and industry. Resources identified as necessary for meaningful progress in implementing alternatives included compiling and making available high-quality reference data, training on use and interpretation of in vitro and in silico approaches, and global harmonization of testing requirements. Attendees particularly noted the need to characterize variabil...
Toxicology in vitro : an international journal published in association with BIBRA, Jan 25, 2015
This special Issue of Toxicology in Vitro covers the most relevant findings of a large scale inte... more This special Issue of Toxicology in Vitro covers the most relevant findings of a large scale integrating Project on ''Profiling the toxicity of new drugs: a non-animal based approach integrating toxicodynamics and biokinetics", funded by the European Commission (Grant No. 202222, Predict-IV), which started in May 2008 and was finalised in October 2013. To prevent events like the Elixir Sulfanilamide scandal in 1937 in the USA or the Thalidomide disaster in the 1950s and early 1960s in Germany, almost all regulatory authorities have introduced safety testing for new or previously untested chemical entities (Limonciel, 2014). The consequence was the establishment of a battery of animal-based tests for specific toxicological endpoints. However, we now know that there are large species differences in xenobiotic handling and thus there is a drive to use human derived models. New developments in cell culture and molecular biology provide a unique opportunity to meet regulatory requirements while improving on the predictivity of pre-clinical test systems, as already suggested by Russell and Burch (1959). In addition to in vitro models the use of in silico predictions of toxicity as well as the use of physiologically-based biokinetics has matured over the last decades (Blaauboer, 2010; Blaauboer et al., 2012). The utilisation and integration of in vitro and in silico techniques promise to increase the speed of drug safety testing, decrease the costs incurred thereby having more drugs on the market. Also by using human-derived models we aim to improve on the predictivity of animal-based models (Jennings, 2015), thus these drugs will likely be safer than ever before. In the Predict-IV project we divided the problem into four main aspects: (1) cell culture models suitable for repeat dose exposures, (2) mechanistic toxicology based on ''omic" analysis, (3) biokinetics, and (4) quantitative in vitro to in vivo extrapolation. Here we provide a short overview of the project outcomes, the majority of which are published in this issue.
In April 2013 the mouse antibody serum neutralization test (SNT) was formally incorporated into E... more In April 2013 the mouse antibody serum neutralization test (SNT) was formally incorporated into European Pharmacopoeia monograph 0451 for potency testing of inactivated veterinary rabies vaccines. The SNT is designed to replace the highly variable and pain and distress causing NIH mouse rabies challenge assay. The adoption of the SNT meets the European ambition (i.e., EC and CoE) to replace, reduce and/or refine laboratory animal testing. However, regulatory acceptance and use of 3R models, such as the SNT, remains challenging. This paper aims at clarifying the process of acceptance and use of the SNT. For this purpose it reconstructsthe process and reveals barriers and drivers that have been observed by involved stakeholders to have played a role. In addition it extracts lessons to stimulate regulatory acceptance in similar future processes. The incorporation of the SNT into the monographs went relatively quick due to a thorough test development and pre-validation phase, commitment...
The importance placed on risk avoidance in our society has resulted in a broad range of regulatio... more The importance placed on risk avoidance in our society has resulted in a broad range of regulations intended to guarantee safety of products such as pharmaceuticals and chemicals. Many of these regulations rely on animal tests. As a result, about 25% of the animal experiments in Europe are done for regulatory purposes. There are many initiatives that aim to replace, reduce, or refine laboratory animal use, but the regulatory acceptance and use of 3R models lags behind. The central question of this study is: "Which variables influence the regulatory acceptance and use of 3R models and in what way?" Regulatory acceptance is seen as one of the biggest hurdles 3R models face, but the rationale behind this is still underexplored. This study is an approach to filling that gap by combining opinions from experts in the field with literature on technology acceptance and risk regulation, resulting in a model of the variables that determine the process of the regulatory acceptance an...
Toxicological sciences : an official journal of the Society of Toxicology, Jan 30, 2015
The present debate on chemicals with Hormonal activity, often termed 'endocrine disruptors... more The present debate on chemicals with Hormonal activity, often termed 'endocrine disruptors', is highly controversial and includes challenges of the present paradigms used in toxicology and in hazard identification and risk characterization. In our opinion, chemicals with hormonal activity can be subjected to the well-evaluated health risk characterization approach used for many years including adverse outcome pathways. Many of the points arguing for a specific approach for risk characterization of chemicals with hormonal activity are based on highly speculative conclusions. These conclusions are not well supported when evaluating the available information.
Systemic toxicity testing forms the cornerstone for the safety evaluation of substances. Pressure... more Systemic toxicity testing forms the cornerstone for the safety evaluation of substances. Pressures to move from traditional animal models to novel technologies arise from various concerns, including: the need to evaluate large numbers of previously untested chemicals and new products (such as nanoparticles or cell therapies), the limited predictivity of traditional tests for human health effects, duration and costs of current approaches, and animal welfare considerations. The latter holds especially true in the context of the scheduled 2013 marketing ban on cosmetic ingredients tested for systemic toxicity. Based on a major analysis of the status of alternative methods (Adler et al., 2011) and its independent review (Hartung et al., 2011), the present report proposes a roadmap for how to overcome the acknowledged scientific gaps for the full replacement of systemic toxicity testing using animals. Five whitepapers were commissioned addressing toxicokinetics, skin sensitization, repea...
Industrial sectors perform toxicological assessments of their potential products to ensure human ... more Industrial sectors perform toxicological assessments of their potential products to ensure human safety and to fulfill regulatory requirements. These assessments often involve animal testing, but ethical, cost, and time concerns, together with a ban on it in specific sectors, make appropriate in vitro systems indispensable in toxicology. In this study, we summarize the outcome of an EPAA (European Partnership of Alternatives to Animal Testing)-organized workshop on the use of stem cell-derived (SCD) systems in toxicology, with a focus on industrial applications. SCD systems, in particular, induced pluripotent stem cell-derived, provide physiological cell culture systems of easy access and amenable to a variety of assays. They also present the opportunity to apply the vast repository of existing nonclinical data for the understanding of in vitro to in vivo translation. SCD systems from several toxicologically relevant tissues exist; they generally recapitulate many aspects of physiology and respond to toxicological and pharmacological interventions. However, focused research is necessary to accelerate implementation of SCD systems in an industrial setting and subsequent use of such systems by regulatory authorities. Research is required into the phenotypic characterization of the systems, since methods and protocols for generating terminally differentiated SCD cells are still lacking. Organotypical 3D culture systems in bioreactors and microscale tissue engineering technologies should be fostered, as they promote and maintain differentiation and support coculture systems. They need further development and validation for their successful implementation in toxicity testing in industry. Analytical measures also need to be implemented to enable compound exposure and metabolism measurements for in vitro to in vivo extrapolation. The future of SCD toxicological tests will combine advanced cell culture technologies and biokinetic measurements to support regulatory and research applications. However, scientific and technical hurdles must be overcome before SCD in vitro methods undergo appropriate validation and become accepted in the regulatory arena.
The role that in vitro systems can play in toxicological risk assessment is determined by the app... more The role that in vitro systems can play in toxicological risk assessment is determined by the appropriateness of the chosen methods, with respect to the way in which in vitro data can be extrapolated to the in vivo situation. This report presents the results of a workshop aimed at better defining the use of in vitro-derived biomarkers of toxicity (BoT) and determining the place these data can have in human risk assessment. As a result, a conceptual framework is presented for the incorporation of in vitro-derived toxicity data into the risk assessment process. The selection of BoT takes into account that they need to distinguish adverse and adaptive changes in cells. The framework defines the place of in vitro systems in the context of data on exposure, structural and physico-chemical properties, and toxicodynamic and biokinetic modeling. It outlines the determination of a proper point-of-departure (PoD) for in vitro-in vivo extrapolation, allowing implementation in risk assessment procedures. A BoT will need to take into account both the dynamics and the kinetics of the compound in the in vitro systems. For the implementation of the proposed framework it will be necessary to collect and collate data from existing literature and new in vitro test systems, as well as to categorize biomarkers of toxicity and their relation to pathways-of-toxicity. Moreover, data selection and integration need to be driven by their usefulness in a quantitative in vitro-in vivo extrapolation (QIVIVE). Keywords: biomarker of toxicity, integrated testing strategies, quantitative in vitro-in vivo extrapolations * a report of t 4-the transatlantic think tank for toxicology, a collaboration of the toxicologically oriented chairs in Baltimore, Konstanz, and Utrecht, sponsored by the Doerenkamp-Zbinden Foundation. The opinions expressed in this report are those of the participants as individuals and do not necessarily reflect the opinions of the organizations they are affiliated with. § Competing Interests Declaration: K. Boekelheide is an occasional expert consultant for chemical and pharmaceutical companies.
This paper describes the evolution of chemical risk assessment from its early dependence on gener... more This paper describes the evolution of chemical risk assessment from its early dependence on generic default approaches to the current situation in which mechanistic and biokinetic data are routinely incorporated to support a more chemical-specific approach. Two methodologies that have played an important role in this evolution are described: mode-of-action evaluation and physiologically based biokinetic (PBBK) modelling. When used together, these techniques greatly increase the opportunity for the incorporation of biokinetic and mechanistic data in risk assessment. The resulting risk assessment approaches are more appropriately tailored to the specific chemical and are more likely to provide an accurate assessment of the potential hazards associated with human exposures. The appropriate application of PBBK models in risk assessment demands well-formulated statements about the chemical mode of action. It is this requirement for an explicit, mechanistic hypothesis that gives biologically motivated models their power, but at the same time serves as the greatest impediment to the acceptance of a chemical-specific risk assessment approach by regulators. The chief impediment to the regulatory acceptance and application of PBBK models in risk assessment is concern about uncertainties associated with their use. To some extent such concerns can be addressed by the development of generally accepted approaches for model evaluation and quantitative uncertainty analysis. In order to assure the protection of public health while limiting the economic and social consequences of over-regulation, greater dialogue between researchers and regulators is crucially needed to foster an increased use of emerging scientific information and innovative methods in chemical risk assessments.
There are now numerous in vitro and in silico ADME alternatives to in vivo assays but how do diff... more There are now numerous in vitro and in silico ADME alternatives to in vivo assays but how do different industries incorporate them into their decision tree approaches for risk assessment, bearing in mind that the chemicals tested are intended for widely varying purposes? The extent of the use of animal tests is mainly driven by regulations or by the lack of a suitable in vitro model. Therefore, what considerations are needed for alternative models and how can they be improved so that they can be used as part of the risk assessment process? To address these issues, the European Partnership for Alternative Approaches to Animal Testing (EPAA) working group on prioritisation, promotion and implementation of the 3Rs research held a workshop in November, 2008 in Duesseldorf, Germany. Participants included different industry sectors such as pharmaceuticals, cosmetics, industrial-and agro-chemicals. This report describes the outcome of the discussions and recommendations (a) to reduce the number of animals used for determining the ADME properties of chemicals and (b) for considerations and actions regarding in vitro and in silico assays. These included: standardisation and promotion of in vitro assays so that they may become accepted by regulators; increased availability of industry in vivo kinetic data for a central database to increase the power of in silico predictions; expansion of the applicability domains of in vitro and in silico tools (which are not necessarily more applicable or even exclusive to one particular sector) and continued collaborations between regulators, academia and industry. A recommended immediate course of action was to establish an expert panel of users, developers and regulators to define the testing scope of models for different chemical classes. It was agreed by all participants that improvement and harmonization of alternative approaches is needed for all sectors and this will most effectively be achieved by stakeholders from different sectors sharing data.
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