New supporting data to guide the use of evident toxicity in acute oral toxicity studies (OECD TG 420).

Currently there are three test guidelines (TG) for acute oral toxicity studies of substances or mixtures from the Organisation for Economic Co-operation and Development (OECD). TG 423 and TG 425 use lethality as an endpoint, while TG 420 replaces death with 'evident toxicity', defined as clear signs that exposure to a higher dose would result in death. However, the perceived subjectivity of 'evident toxicity' may be preventing wider use of TG 420. To address this, the UK National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) and the European Partnership for Alternative Approaches to Animal Testing (EPAA) collaborated to provide recommendations on the recognition of 'evident toxicity'. Historical data from acute oral toxicity studies were analysed for clinical signs at the lower dose that could have predicted death at the higher dose. Several signs including ataxia, laboured respiration, and eyes partially closed, alone or in combination, are highly predictive. Others such as lethargy, decreased respiration, and loose faeces have lower but still appreciable positive predictive value (PPV). The data has been used to develop recommendations to promote use of TG 420 and thus reduce the suffering and numbers of animals used in acute oral toxicity studies.

The future of pyrogenicity testing: Phasing out the rabbit pyrogen test. A meeting report.

The rabbit pyrogen test (RPT) was the benchmark for pyrogenicity testing, but scientific advancements have provided innovative and humane methods, such as the in vitro monocyte-activation test (MAT). However, transitioning from the RPT to the MAT has been challenging. The European Directorate for the Quality of Medicines & HealthCare, the Council of Europe, and the European Partnership for Alternative Approaches to Animal Testing jointly hosted an international conference entitled "The future of pyrogenicity testing: phasing out the rabbit pyrogen test". The conference aimed to show how the European Pharmacopoeia intends to remove the RPT from its texts by 2026, facilitate the use of MAT, and identify gaps in the suppression of RPT. The events contributed to a better understanding of the barriers to RPT replacement and acceptance of in vitro alternatives. Participants comprised stakeholders from Asia, Europe, and North America, including vaccine developers, contract laboratories, and regulators. Participants shared their replacement strategies and experiences with MAT implementation. They emphasised the need for continued cooperation between stakeholders and stressed the importance of international harmonisation of regulatory requirements to help accelerate MAT acceptance outside Europe. Despite the challenges, the willingness to eliminate the unnecessary use of RPT was common across all participants.

Use of New Approach Methodologies (NAMs) in regulatory decisions for chemical safety: Report from an EPAA Deep Dive Workshop.

New Approach Methodologies (NAMs) are considered to include any in vitro, in silico or chemistry-based method, as well as the strategies to implement them, that may provide information that could inform chemical safety assessment. Current chemical legislation in the European Union is limited in its acceptance of the widespread use of NAMs. The European Partnership for Alternative Approaches to Animal Testing (EPAA) therefore convened a 'Deep Dive Workshop' to explore the use of NAMs in chemical safety assessment, the aim of which was to support regulatory decisions, whilst intending to protect human health. The workshop recognised that NAMs are currently used in many industrial sectors, with some considered as fit for regulatory purpose. Moreover, the workshop identified key discussion points that can be addressed to increase the use and regulatory acceptance of NAMs. These are based on the changes needed in frameworks for regulatory requirements and the essential needs in education, training and greater stakeholder engagement as well the gaps in the scientific basis of NAMs.

Towards a mechanism-based approach for the prediction of nongenotoxic carcinogenic potential of agrochemicals.

Chemical substances are subjected to assessment of genotoxic and carcinogenic effects before being marketed to protect man and the environment from health risks. For agrochemicals, the long-term rodent carcinogenicity study is currently required from a regulatory perspective. Although it is the current mainstay for the detection of nongenotoxic carcinogens, carcinogenicity studies are shown to have prominent weaknesses and are subject to ethical and scientific debate. A transition toward a mechanism-based weight-of-evidence approach is considered a requirement to enhance the prediction of carcinogenic potential for environmental (agro)chemicals. The resulting approach should make optimal use of innovative (computational) tools and be less animal demanding. To identify the various mode of actions (MOAs) underlying the nongenotoxic carcinogenic potential of agrochemicals, we conducted an extensive analysis of 411 unique agrochemicals that have been evaluated for carcinogenicity by the United States Environmental Protection Agency (US EPA) and the European Chemicals Agency (ECHA). About one-third of these substances could be categorized as nongenotoxic carcinogens with an average of approximately two tumor types per substance, observed in a variety of organs. For two-third of the tumor cases, an underlying MOA (network) could be identified. This analysis demonstrates that a limited set of MOA (networks) is underlying nongenotoxic carcinogenicity of agrochemicals, illustrating that the transition toward a MOA-driven approach appears manageable. Ultimately the approach should cover relevant MOAs and its associated key events; this will also facilitate the evaluation of the human relevance. This manuscript describes the results of the analysis while identifying knowledge gaps and necessities to achieve a mechanism-based weight-of-evidence approach.

A comprehensive view on mechanistic approaches for cancer risk assessment of non-genotoxic agrochemicals.

Currently the only methods for non-genotoxic carcinogenic hazard assessment accepted by most regulatory authorities are lifetime carcinogenicity studies. However, these involve the use of large numbers of animals and the relevance of their predictive power and results has been scientifically challenged. With increased availability of innovative test methods and enhanced understanding of carcinogenic processes, it is believed that tumour formation can now be better predicted using mechanistic information. A workshop organised by the European Partnership on Alternative Approaches to Animal Testing brought together experts to discuss an alternative, mechanism-based approach for cancer risk assessment of agrochemicals. Data from a toolbox of test methods for detecting modes of action (MOAs) underlying non-genotoxic carcinogenicity are combined with information from subchronic toxicity studies in a weight-of-evidence approach to identify carcinogenic potential of a test substance. The workshop included interactive sessions to discuss the approach using case studies. These showed that fine-tuning is needed, to build confidence in the proposed approach, to ensure scientific correctness, and to address different regulatory needs. This novel approach was considered realistic, and its regulatory acceptance and implementation can be facilitated in the coming years through continued dialogue between all stakeholders and building confidence in alternative approaches.

New ideas for non-animal approaches to predict repeated-dose systemic toxicity: Report from an EPAA Blue Sky Workshop.

The European Partnership for Alternative Approaches to Animal Testing (EPAA) convened a 'Blue Sky Workshop' on new ideas for non-animal approaches to predict repeated-dose systemic toxicity. The aim of the Workshop was to formulate strategic ideas to improve and increase the applicability, implementation and acceptance of modern non-animal methods to determine systemic toxicity. The Workshop concluded that good progress is being made to assess repeated dose toxicity without animals taking advantage of existing knowledge in toxicology, thresholds of toxicological concern, adverse outcome pathways and read-across workflows. These approaches can be supported by New Approach Methodologies (NAMs) utilising modern molecular technologies and computational methods. Recommendations from the Workshop were based around the needs for better chemical safety assessment: how to strengthen the evidence base for decision making; to develop, standardise and harmonise NAMs for human toxicity; and the improvement in the applicability and acceptance of novel techniques. "Disruptive thinking" is required to reconsider chemical legislation, validation of NAMs and the opportunities to move away from reliance on animal tests. Case study practices and data sharing, ensuring reproducibility of NAMs, were viewed as crucial to the improvement of non-animal test approaches for systemic toxicity.

Applying non-animal strategies for assessing skin sensitisation report from an EPAA/cefic-LRI/IFRA Europe cross sector workshop, ECHA helsinki, February 7th and 8th 2019.

Four years on since the last cross sector workshop, experience of the practical application and interpretation of several non-animal assays that contribute to the predictive identification of skin sensitisers has begun to accumulate. Non-animal methods used for hazard assessments increasingly are contributing to the potency sub-categorisation for regulatory purposes. However, workshop participants generally supported the view that there remained a pressing need to build confidence in how information from multiple methods can be combined for classification, sub-categorisation and potency assessment. Furthermore, the practical experience gained over the last few years, highlighted the overall high potential value of using the newly validated methods and testing strategies, but also that limitations for certain substance/product classes may become evident with further use as had been the case with other new regulatory methods. As the available information increases, review of the data and collated experience could further determine strengths and limitations leading to more confidence in their use. Finally, the need for a substantial and universally accepted dataset of non-sensitisers and substances of different sensitising potencies, based on combined human and in vivo animal data for validation of methods and test strategies was re-emphasised.

Finding synergies for the 3Rs - Repeated Dose Toxicity testing: Report from an EPAA Partners' Forum.

The European Partnership for Alternative Approaches to Animal Testing (EPAA) convened a Partners' Forum on repeated dose toxicity (RDT) testing to identify synergies between industrial sectors and stakeholders along with opportunities to progress these in existing research frameworks. Although RTD testing is not performed across all industrial sectors, the OECD accepted tests can provide a rich source of information and play a pivotal role for safety decisions relating to the use of chemicals. Currently there are no validated alternatives to repeated dose testing and a direct one-to-one replacement is not appropriate. However, there are many projects and initiatives at the international level which aim to implement various aspects of replacement, reduction and refinement (the 3Rs) in RDT testing. Improved definition of use, through better problem formulation, aligned to harmonisation of regulations is a key area, as is the more rapid implementation of alternatives into the legislative framework. Existing test designs can be optimised to reduce animal use and increase information content. Greater use of exposure-led decisions and improvements in dose selection will be beneficial. In addition, EPAA facilitates sharing of case studies demonstrating the use of Next Generation Risk Assessment applying various New Approach Methodologies to assess RDT.

One science-driven approach for the regulatory implementation of alternative methods: A multi-sector perspective.

EU regulations call for the use of alternative methods to animal testing. During the last decade, an increasing number of alternative approaches have been formally adopted. In parallel, new 3Rs-relevant technologies and mechanistic approaches have increasingly contributed to hazard identification and risk assessment evolution. In this changing landscape, an EPAA meeting reviewed the challenges that different industry sectors face in the implementation of alternative methods following a science-driven approach. Although clear progress was acknowledged in animal testing reduction and refinement thanks to an integration of scientifically robust approaches, the following challenges were identified: i) further characterization of toxicity pathways; ii) development of assays covering current scientific gaps, iii) better characterization of links between in vitro readouts and outcome in the target species; iv) better definition of alternative method applicability domains, and v) appropriate implementation of the available approaches. For areas having regulatory adopted alternative methods (e.g., vaccine batch testing), harmonised acceptance across geographical regions was considered critical for broader application. Overall, the main constraints to the application of non-animal alternatives are the still existing gaps in scientific knowledge and technological limitations. The science-driven identification of most appropriate methods is key for furthering a multi-sectorial decrease in animal testing.

Finding synergies for 3Rs - Toxicokinetics and read-across: Report from an EPAA partners' Forum.

The European Partnership for Alternative Approaches to Animal Testing (EPAA) convened a Partners' Forum Toxicokinetics and Read-Across to provide an overview on research activities to develop in vitro toxicokinetics methods and physiologically-based kinetic (PBK) models and to find synergies to enhance use of toxicokinetic data to strengthen read-across. Currently, lacking toxicokinetic data often prevent the application of read-across. Preferably, toxicokinetic data should be generated using in vitro and in silico tools and anchored towards human relevance. In certain sectors, PBK modelling is being used for risk assessment, but less so in others. Specific activities were identified to facilitate the use of in vitro and in silico toxicokinetic data to support read-across: The collation of available tools indicating the parameters and applicability domains covered; endpoint-specific guidance on toxicokinetics parameters required for read-across; case studies exemplifying how toxicokinetic data help support read-across. Activities to enhance the scientific robustness of read-across include the further user-friendly combination of read-across tools and formal guidance by the authorities specifying the minimum information requirements to justify read-across for a given toxicity endpoint. The EPAA was invited to continue dissemination activities and to explore possibilities to collate a contemporaneous list of open toxicokinetics tools that assist risk assessment.

Alternatives for skin sensitisation: Hazard identification and potency categorisation: Report from an EPAA/CEFIC LRI/Cosmetics Europe cross sector workshop, ECHA Helsinki, April 23rd and 24th 2015.

In the two years since the last workshop report, the environment surrounding the prediction of skin sensitisation hazards has experienced major change. Validated non-animal tests are now OECD Test Guidelines. Accordingly, the recent cross sector workshop focused on how to use in vitro data for regulatory decision-making. After a review of general approaches and six case studies, there was broad consensus that a simple, transparent stepwise process involving non-animal methods was an opportunity waiting to be seized. There was also strong feeling the approach should not be so rigidly defined that assay variations/additional tests are locked out. Neither should it preclude more complex integrated approaches being used for other purposes, e.g. potency estimation. All agreed the ultimate goal is a high level of protection of human health. Thus, experience in the population will be the final arbiter of whether toxicological predictions are fit for purpose. Central to this is the reflection that none of the existing animal assays is perfect; the non-animal methods should not be expected to be so either, but by integrated use of methods and all other relevant information, including clinical feedback, we have the opportunity to continue to improve toxicology whilst avoiding animal use.

Knowledge sharing to facilitate regulatory decision-making in regard to alternatives to animal testing: Report of an EPAA workshop.

The European Partnership for Alternative Approaches to Animal Testing (EPAA) convened a workshop Knowledge sharing to facilitate regulatory decision-making. Fifty invited participants from the European Commission, national and European agencies and bodies, different industry sectors (chemicals, cosmetics, fragrances, pharmaceuticals, vaccines), and animal protection organizations attended the workshop. Four case studies exemplarily revealed which procedures are in place to obtain regulatory acceptance of new test methods in different sectors. Breakout groups discussed the status quo identifying the following facilitators for regulatory acceptance of alternatives to animal testing: Networking and communication (including cross-sector collaboration, international cooperation and harmonization); involvement of regulatory agencies from the initial stages of test method development on; certainty on prerequisites for test method acceptance including the establishment of specific criteria for regulatory acceptance. Data sharing and intellectual property issues affect many aspects of test method development, validation and regulatory acceptance. In principle, all activities should address replacement, reduction and refinement methods (albeit animal testing is generally prohibited in the cosmetics sector). Provision of financial resources and education support all activities aiming at facilitating the acceptance and use of alternatives to animal testing. Overall, workshop participants recommended building confidence in new methodologies by applying and gaining experience with them.

Skin sensitisation--moving forward with non-animal testing strategies for regulatory purposes in the EU.

In a previous EPAA-Cefic LRI workshop in 2011, issues surrounding the use and interpretation of results from the local lymph node assay were addressed. At the beginning of 2013 a second joint workshop focused greater attention on the opportunities to make use of non-animal test data, not least since a number of in vitro assays have progressed to an advanced position in terms of their formal validation. It is already recognised that information produced from non-animal assays can be used in regulatory decision-making, notably in terms of classifying a substance as a skin sensitiser. The evolution into a full replacement for hazard identification, where the decision is not to classify, requires the generation of confidence in the in vitro alternative, e.g. via formal validation, the existence of peer reviewed publications and the knowledge that the assay(s) are founded on key elements of the Adverse Outcome Pathway for skin sensitisation. It is foreseen that the validated in vitro assays and relevant QSAR models can be organised into formal testing strategies to be applied for regulatory purposes by the industry. To facilitate progress, the European Partnership for Alternative Approaches to animal testing (EPAA) provided the platform for cross-industry and regulatory dialogue, enabling an essential and open debate on the acceptability of an in vitro based integrated strategy. Based on these considerations, a follow up activity was agreed upon to explore an example of an Integrated Testing Strategy for skin sensitisation hazard identification purposes in the context of REACH submissions.

Optimised testing strategies for skin sensitization--the LLNA and beyond.

As toxicology in the 21st century progresses towards a future which aims at avoiding the use of in vivo testing, the endpoint of skin sensitisation can now be found in the front line. Accordingly, it was appropriate for several industry sectors to meet and review what has been learned from the currently most widely used in vivo method, the local lymph node assay (LLNA), and to consider the status of progress as we attempt to move beyond that test. No toxicology test is perfect, an experience brought into focus by issues of false positives and, to a lesser extent, false negatives in the LLNA. Use of weight of evidence arguments for classification and labelling, as well as for risk assessment was emphasised and it was also noted that a sufficient body of evidence now exists for conduct of methods other than the LLNA for carefully defined chemical classes. In terms of in vitro alternatives, progress towards methods which will deliver mainly hazard identification is being made, with some entering the final stages of validation, whereby (Q)SAR tools still need improvement to be used on a large scale in practise. As various other challenges also remain, e.g. testing lipophilic substances, as well as the development of non-animal methods which deliver reliable information on potency for risk assessment, these will remain a topic for continuing research and development.

Computational chemistry, systems biology and toxicology. Harnessing the chemistry of life: revolutionizing toxicology. a commentary.

There is a continuing interest in, and increasing imperatives for, the development of alternative methods for toxicological evaluations that do not require the use of animals. Although a significant investment has resulted in some achievements, progress has been patchy and there remain many challenges. Among the most significant hurdles is developing non-animal methods that would permit assessment of the potential for a chemical or drug to cause adverse health effects following repeated systemic exposure. Developing approaches to address this challenge has been one of the objectives of the European Partnership for Alternative Approaches to Animal Testing (EPAA). The EPAA is a unique partnership between the European Commission and industry that has interests in all aspects of reducing, refining and replacing the use of animals (the '3Rs'). One possible strategy that emerged from a broad scientific debate sponsored by the EPAA was the opportunity for developing entirely new paradigms for toxicity testing based upon harnessing the increasing power of computational chemistry in combination with advanced systems biology. This brief commentary summarizes a workshop organized by the EPAA in 2010, that had the ambitious title of 'Harnessing the Chemistry of Life: Revolutionizing Toxicology'. At that workshop international experts in chemistry, systems biology and toxicology sought to map out how best developments in these sciences could be exploited to design new strategies for toxicity testing using adverse effects in the liver as an initial focus of attention. Here we describe the workshop design and outputs, the primary purpose being to stimulate debate about the need to align different areas of science with toxicology if new and truly innovative approaches to toxicity testing are to be developed.

Management of an integrated project (Sens-it-iv) to develop in vitro tests to assess sensitisation.

Sens-it-iv is an integrated project, funded by European Commission Framework Programme 6, the overall objective of which is to develop in vitro tests and test strategies to be used by the chemical, cosmetic and pharmaceutical industries to assess the risk for potential contact and respiratory sensitisers. Such tests, once formally validated and accepted, will permit the evaluation of the sensitising potential of existing and new chemical entities and the products of the European industries for classification and labelling, as required by the new EU REACH legislation on chemicals, or for the purpose of risk assessment as required by the 7th Amendment to the EU Cosmetics Directive. Sens-it-iv involves 28 partners, representing industries, universities and regulatory bodies, including various institutes in the EU Member States and different competencies, all with the common aim of achieving a final deliverable - increasing the safety of consumer products, whilst reducing animal experimentation. This paper provides an overview of the structure of the project and a detailed description of the organisation of its management.

The European Partnership for Alternative Approaches to Animal Testing (EPAA): promoting alternative methods in Europe and beyond.

Here in we introduce the European Partnership for Alternative Approaches to Animal Testing (EPAA) and its activities, which are focused on international cooperation toward alternative methods. The EPAA is one of the leading organizations in Europe for the promotion of alternative approaches to animal testing. Its innovative public-private partnership structure enables a consensus-driven dialogue across 7 industry sectors to facilitate interaction between regulators and regulated stakeholders. Through a brief description of EPAA's activities and organizational structure, we first articulate the value of this collaboration; we then focus on 2 key projects driven by EPAA. The first project aims to address research gaps on stem cells for safety testing, whereas the second project strives for an approach toward demonstration of consistency in vaccine batch release testing. We highlight the growing need for harmonization of international acceptance and implementation of alternative approaches and for increased international collaboration to foster progress on nonanimal alternatives.

Stem cell-derived systems in toxicology assessment.

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.

Reprint of: Characterising hepatic mitochondrial function as a model for systemic toxicity: a commentary.

A major challenge in toxicology is the development of non-animal methods for the assessment of human health risks that might result from repeated systemic exposure. We present here a perspective that considers the opportunities that computational modelling methods may offer in addressing this challenge. Our approach takes the form of a commentary designed to inform responses to future calls for research in predictive toxicology. It is considered essential that computational model-building activities be at the centre of the initiative, driving an iterative process of development, testing and refinement. It is critical that the models provide mechanistic understanding and quantitative predictions. The aim would be to predict effects in humans; in order to help define a challenging but yet feasible initial goal the focus would be on liver mitochondrial toxicity. This will inevitably present many challenges that naturally lead to a modular approach, in which the overall problem is broken down into smaller, more self-contained sub-problems that will subsequently need to be connected and aligned to develop an overall understanding. The project would investigate multiple modelling approaches in order to encourage links between the various disciplines that hitherto have often operated in isolation. The project should build upon current activities in the wider scientific community, to avoid duplication of effort and to ensure that investment is maximised. Strong leadership will be required to ensure alignment around a set of common goals that would be derived using a problem-statement driven approach. Finally, although the focus here is on toxicology, there is a clear link to the wider challenges in systems medicine and improving human health.