This essay summarises the author’s thoughts on the current paradigm change in toxicology. The driving factors and mechanisms of this change, and obstacles to it, are discussed. Current developments are discussed on the basis of some key assumptions in Thomas Kuhn’s famous book, The Structure of Scientific Revolutions. The author’s personal view is that there is clear evidence that revolutionary changes in regulatory toxicology are emerging.
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During the 1990s and early 2000s, a number of manufacturing companies in the cosmetic, personal care and household product industries were able to substantially reduce their use of animals for testing (or to not use animals in the first place). These reductions were almost always the result of significant financial contributions to either direct, in-house alternatives research, or to support personnel whose duties were to understand and apply the current state-of-the-art for in vitro testing. They occurred almost exclusively in non-regulatory areas, and primarily involved acute topical toxicities. Over the last few years, the reduction in animal use has been much less dramatic, because some companies are still reluctant to change from the traditional animal studies, because systemic, repeat-dose toxicity is more difficult to model in vitro, and because many products still require animal testing for regulatory approval. Encouragingly, we are now observing an increased acceptance of non-animal methods by regulatory agencies. This is due to mounting scientific evidence from larger databases, agreement by companies to share data and testing strategies with regulatory agencies, and a focus on smaller domains of applicability. These changes, along with new emphasis and financial support for addressing systemic toxicities, promise to provide additional possibilities for industry to replace animals with in vitro methods, alone or in combination with in silico methods. However, the largest advance will not occur until more companies commit to using the non-animal test strategies that are currently available.
Quin Wills and Cathrine Mitchell
As a branch of pharmacogenomics aimed at predicting drug safety concerns, toxicogenomics drew much excitement with the emergence of technologies such as gene expression microarrays. A few years down the line, the evidence is scant that current approaches to toxicogenomics are really making an impact in areas such as preclinical toxicology. It has been argued that there needs to be a re-focus of application toward high-throughput approaches which combine the best of tissue and genomic modelling. This commentary gives a brief introduction to in vitro toxicogenomics, drawn from the perspectives of the specialist toxicogenomics company, SimuGen.
Katya Tsaioun and Mary Jacewicz
The advent of early Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) screening has increased the elimination rate of weak drug candidates early in the drug-discovery process, and decreased the proportion of compounds failing in clinical trials for ADMET reasons. This paper reviews the history of ADMET screening and why it has become so important in drug discovery and development. Assays that have been developed in response to specific needs, and improvements in technology that result in higher throughput and greater accuracy of prediction of human mechanisms of toxicity, are discussed. The paper concludes with the authors’ forecast of new models that will better predict human efficacy and toxicity.
Jarrod Bailey, Michelle Thew and Michael Balls
Dogs remain the main non-rodent species in preclinical drug development. Despite the current dearth of new drug approvals and meagre pipelines, this continues, with little supportive evidence of its value or necessity. To estimate the evidential weight provided by canine data to the probability that a new drug may be toxic to humans, we have calculated Likelihood Ratios (LRs) for an extensive dataset of 2,366 drugs with both animal and human data, including tissue-level effects and Medical Dictionary for Regulatory Activities (MedDRA) Level 1–4 biomedical observations. The resulting LRs show that the absence of toxicity in dogs provides virtually no evidence that adverse drug reactions (ADRs) will also be absent in humans. While the LRs suggest that the presence of toxic effects in dogs can provide considerable evidential weight for a risk of potential ADRs in humans, this is highly inconsistent, varying by over two orders of magnitude for different classes of compounds and their effects. Our results therefore have important implications for the value of the dog in predicting human toxicity, and suggest that alternative methods are urgently required.
Michelle Hudson and Michael Balls
The latest report on experimental animal use in the EU indicates a slight decrease. However, the figures, which are for 2008, show that around 12-million animals are still used in laboratories throughout Europe. To date, only a summary of the data has been published, and so this report is limited to giving a comparison of trends and significant changes. The impact on the figures of the revision of Directive 86/609 and the 7th Amendment to the Cosmetics Directive 76/768/EEC is discussed. In addition, consideration is given to which areas of research and regulation will need to be closely monitored, and the importance of continuing to push for the implementation of Three Rs initiatives is highlighted.
Filter-well Technology for Advanced Three-dimensional Cell Culture: Perspectives for Respiratory Research
Kelly BéruBé, Aldo Pitt, Patrick Hayden, Zoë Prytherch and Claire Job
Cell culture has long been a valuable tool for studying cell behaviour. Classical plastic substrates are two-dimensional, and usually promote cellular proliferation and inhibit differentiation. Understanding cell behaviour within complex multicellular tissues requires the systematic study of cells within the context of specific model microenvironments. A model system must mimic, to a certain degree, the in vivo situation, but, at the same time, can significantly reduce its complexity. There is increasing agreement that moving up to the third dimension provides a more physiologically-relevant and predictive model system. Moreover, many cellular processes (morphogenesis, organogenesis and pathogenesis) have been confirmed to occur exclusively when cells are ordered in a three-dimensional (3- D) manner. In order to achieve the desired in vivo phenotype, researchers can use microporous membranes for improved in vitro cell culture experiments. In the present review, we discuss the applications of filter-well technology for the advanced 3-D cell culture of human pulmonary cells.
The Latest Statistics of Scientific Procedures on Living Animals Reveal Little Three Rs Progress in Great Britain in 2010
The 2010 Statistics of Scientific Procedures on Living Animals showed that the level of animal experimentation in Great Britain continues to rise, with just over 3.7 million procedures being conducted. This is almost exclusively due to the sustained increase in the breeding and utilisation of genetically-altered animals. Here, the general trends in the species used and the numbers and types of procedures are reviewed. In addition, the impact of the recent Government announcement to ban testing of household products on animals is discussed, along with the implications of the fish becoming the second mostfrequently used animal in scientific research. Finally, concerns about primate use, the REACH System, cosmetics testing and the new EU Directive on the protection of laboratory animals are explained.
The Rational Use of Animals in Drug Development: Contribution of the Innovative Medicines Initiative
Magda Gunn, Elisabetta Vaudano and Michel Goldman
Animal models are still widely used to assess the efficacy or safety of new pharmaceutical products. Since their limitations in predicting actions of drugs in humans are becoming more and more apparent, there is an urgent need to revisit the use of animals in pharmaceutical research. Herein, we review how the Innovative Medicines Initiative (IMI), the largest public–private partnership in the life sciences, is reducing, refining and replacing the use of animals in the context of its global mission, namely, to boost research and the development of new medicines across the European Union.
Statistics of Scientific Procedures on Living Animals 2012:Another Increase in Experimentation — Genetically-altered Animals Dominate Again
The Annual Statistics of Scientific Procedures on Living Animals Great Britain 2012 reveal that the level of animal experimentation in Great Britain continues to rise, with just over 4.1 million procedures being started in that year. Despite the previous year’s indication that the dominance of the production and use of genetically-altered (GA, i.e. genetically-modified animals plus animals with harmful genetic defects) animal might be abating, it returned with a vengeance in 2012. Breeding increased from 43% to 48% of all procedures, and GA animals were involved in 59% of all the procedures. Indeed, if the breeding of these animals were removed from the statistics, the total number of procedures would actually decline by 2%. In order to honour their pledge to reduce animal use in science, the Coalition Government will have to address this issue. The general trends in the species used, and the numbers and types of procedures, are also reviewed. Finally, forthcoming changes to the statistics are discussed.