Maximizing insights from nonclinical safety studies in the context of rising costs and changing regulations.

The traditional paradigm of non-rodent safety assessment studies, primarily reliant on non-human primates (NHPs) and dogs, is undergoing a transformation. During the 2023 Safety Pharmacology Society Annual Meeting, scientists from leading nonclinical contract organizations discussed how traditional IND-enabling studies can benefit from employing underutilized alternative non-rodent models, such as the swine. Swine offer a cost-effective approach to drug development and share many anatomical and physiological similarities with humans. The inclusion of non-traditional species in safety assessments, coupled with advanced measurement techniques, aids in de-risking compounds early on and adapting projects to the evolving cost landscape.

The benefits of validation of methods for toxicity testing outweigh its costs

The 4th Annual Forum on Endocrine Disrupters organized by the European Commission brought together the authors of this article around the topic: "From bench to validated test guidelines: (pre)val­idation of test methods". Validation activities are meant to demonstrate the relevance and reliability of methods and approaches used in regulatory safety testing. These activities are essential to facil­itate regulatory use, still they are largely underfunded and unattractive to the scientific community. In the last decade, large amounts of funding have been invested in European research towards the development of approaches that can be used in regulatory decision-making, including for the identification of endocrine disrupters. There is a vast pool of candidate test methods for potential reg­ulatory applications, but most of them will not be used due to the absence of consideration of their relevance and reliability outside the method developer's laboratory. This article explains the reasons why such a gap exists between the outputs of research projects and the uptake in a regulatory context. In parallel, there are also increasing expectations from the regulatory science community that validation becomes more efficient with respect to time and resources. This article shares some of the lessons learned and proposes paths forward for validation of new methods that are not intended as one-to-one replacements of animal studies. This includes submitting only mature methods for validation that were developed following good practices and good documentation, proposing a greater emphasis on well-documented transferability studies, and adopting a cost-sharing model among those who benefit from validated methods.

Validation activities for methods intended to be used to assess chemical safety have a cost but also bring substantial benefits when the validated methods are established as OECD Test Guidelines, which results in mutual acceptance of data generated by the methods across OECD member and adhering countries. The article discusses some of the challenges faced when method validation is underfunded and unattractive for researchers. Proposals are made to improve the current situation, gain efficiency, and make validation a shared responsibility.

Animal testing and its alternatives - the most important omics is economics.

For a long time, the discussion about animal testing vs its alternatives centered on animal welfare. This was a static warfare, or at least a gridlock, where life scientists had to take a position and make their value choices and hardly anyone changed sides. Technical advances have changed the frontline somewhat, with in vitro and in silico methods gaining more ground. Only more recently has the economic view begun to have an impact: Many animal tests are simply too costly, take too long, and give misleading results. As an extension and update to previous articles in this series written a decade ago, we reanalyze the economic landscape of especially regulatory use of animal testing and this time also consider respective alternative tests. Despite some ambiguity and data gaps, which we have filled with crude estimates, a picture emerges of globally regulated industries that are subject to stark geographic and sectorial differences in regulation, which determine their corresponding animal use. Both animal testing and its alternatives are industries in their own right, offering remarkable business opportunities for biotech and IT companies as well as contract research organizations. In light of recent revelations as to the reproducibility and relevance issues of many animal tests, the economic consequences of incorrect results and the reasons for still maintaining often outdated animal test approaches are discussed.

A tutorial for analysing the cost-effectiveness of alternative methods for assessing chemical toxicity: the case of acute oral toxicity prediction.

Compared with traditional animal methods for toxicity testing, in vitro and in silico methods are widely considered to permit a more cost-effective assessment of chemicals. However, how to assess the cost-effectiveness of alternative methods has remained unclear. This paper offers a user-oriented tutorial for applying cost-effectiveness analysis (CEA) to alternative (non-animal) methods. The purpose is to illustrate how CEA facilitates the identification of the alternative method, or the combination of methods, that offers the highest information gain per unit of cost. We illustrate how information gains and costs of single methods and method combinations can be assessed. By using acute oral toxicity as an example, we apply CEA to a set of four in silico methods (ToxSuite, TOPKAT, TEST, ADMET Predictor), one in vitro method (the 3T3 Neutral Red Uptake cytotoxicity assay), and various combinations of these methods. Our results underline that in silico tools are more cost-effective than the in vitro test. Battery combinations of alternative methods, however, do not necessarily outperform single methods, because additional information gains from the battery are easily outweighed by additional costs.

The cost of self-imposed regulatory burden in animal research.

U.S. federal regulations and standards governing the care and use of research animals enacted in the mid- to late 1980s, while having positive effects on the welfare and quality of the animals, have resulted in dramatic increases in overall research costs. In addition to the expenses of housing and caring for animals according to the standards, establishing the requisite internal compliance bureaucracies has markedly driven up costs, in both institutional monetary expenditures and lost research effort. However, many institutions are increasing these costs even further through additional self-imposed regulatory burden, typically characterized by overly complex compliance organizations and unnecessary policies and procedures. We discuss the sources of this self-imposed burden and recommend strategies for avoiding it while preserving an appropriate focus on animal well-being and research success.

Developmental neurotoxicity - challenges in the 21st century and in vitro opportunities.

In recent years neurodevelopmental problems in children have increased at a rate that suggests lifestyle factors and chemical exposures as likely contributors. When environmental chemicals contribute to neurodevelopmental disorders developmental neurotoxicity (DNT) becomes an enormous concern. But how can it be tackled? Current animal test- based guidelines are prohibitively expensive, at $ 1.4 million per substance, while their predictivity for human health effects may be limited, and mechanistic data that would help species extrapolation are not available. A broader screening for substances of concern requires a reliable testing strategy, applicable to larger numbers of substances, and sufficiently predictive to warrant further testing. This review discusses the evidence for possible contributions of environmental chemicals to DNT, limitations of the current test paradigm, emerging concepts and technologies pertinent to in vitro DNT testing and assay evaluation, as well as the prospect of a paradigm shift based on 21st century technologies.

Reducing the number of animals used for microsurgery training programs by using a task-trainer simulator.

To master the skills needed for microsurgery techniques, residents must enrol in a long and complex training program that includes manipulations on simulators, on ex vivo tissues and finally in vivo training. This final step consists of performing vascular anastomoses on murine models. We propose here a simulation program designed to decrease the number of rats used during the final in vivo training. Our study presents the materials used, the various exercises proposed and their evaluations. Two identical student groups were compared in the framework of the University Diploma of Microsurgery. Group A (seven students) followed a classic training program, all of whom achieved permeable vascular anastomoses. A total of 149 rats were needed for this group. Group B (seven students) first validated their manipulations on the task-trainer simulation program. A mean of 6 h was necessary to obtain this validation. All these students achieved the required permeable vascular anastomoses but only 77 rats were used for this group. This simulation program spared 72 rats, abiding by the Russell and Burch concept of a humane experimental technique, namely the 3R principles. This home-made, cost-efficient and easy-to-use task trainer included various exercises with increasing difficulty levels and a progressive scoring system. We believe that microsurgery training needs to include both simple and sophisticated tools in order to reduce the number of animals used to master these surgical skills.

Economic benefits of using adaptive predictive models of reproductive toxicity in the context of a tiered testing program.

A predictive model of reproductive toxicity, as observed in rat multigeneration reproductive (MGR) studies, was previously developed using high throughput screening (HTS) data from 36 in vitro assays mapped to 8 genes or gene-sets from Phase I of USEPA ToxCast research program, the proof-of-concept phase in which 309 toxicologically well characterized chemicals were testing in over 500 HTS assays. The model predicted the effects on male and female reproductive function with a balanced accuracy of 80%. In a theoretical examination of the potential impact of the model, two case studies were derived representing different tiered testing scenarios to: 1) screen-out chemicals with low predicted probability of effect; and 2) screen-in chemicals with a high probability of causing adverse reproductive effects. We define 'testing cost efficiency' as the total cost divided by the number of positive chemicals expected in the definitive guideline toxicity study. This would approach $2.11 M under the current practice. Under case study 1, 22% of the chemicals were screened-out due to low predicted probability of adverse reproductive effect and a misclassification rate of 12%, yielding a test cost efficiency of $1.87 M. Under case study 2, 13% of chemicals were screened-in yielding a testing cost efficiency of $1.13 M per test-positive chemical. Applying the model would also double the total number of positives identified. It should be noted that the intention of the case studies is not to provide a definitive mechanism for screening-in or screening-out chemicals or account for the indirect costs of misclassification. The case studies demonstrate the customizability of the model as a tool in chemical testing decision-making. The predictive model of reproductive toxicity will continue to evolve as new assays become available to fill recognized biological gaps and will be combined with other predictive models, particularly models of developmental toxicity, to form an initial tier to an overarching integrated testing strategy.

Courage for simplification and imperfection in the 21st century assessment of "Endocrine disruption".

"Endocrine disruption" is a public and political buzzword that has and is still receiving high media attention. Based on the latter, numerous tiered testing strategies have evolved that should ensure that humans will not run a health risk due to the voluntary or involuntary exposure to endocrine active compounds (EAS). An analysis of the currently available knowledge on EAS mediated endocrine disruption in humans demonstrates that there are very few EAS that causally induce endocrine disruptive effects. Conversely, the association EAS exposure with increased risk or incidences of endocrine disruptive effects in humans are difficult to reconcile with the results from animal studies. Consequently, the analysis of the traditional and historically grown tiered approach in EAS testing, often at very high doses or concentrations, demonstrates that the likelihood of detecting EAS with true potential for endocrine disruption in humans is very low, primarily due to inherent differences between the surrogate species and the human, and will provide for a high number of false-positives commensurate with low efficiency, high cost, and often violently disputed interpretations of what the data would mean for human risk assessment. It is thus proposed that EAS testing for putative endocrine disruption in humans and qualitative and quantitative evaluation for risk assessment purposes should be entirely focused on human data, and derived from a combination of in silico and in vitro systems, PBPK modeling, metabonomic or genomic profiling of human tissue, realistic human EAS exposure, dose-effect principles and adverse effect scenarios, human patient or exposure cohort datasets, etc. Animals models should be used only where specific pathways in endocrine physiology and thus development and reproduction is nearly identical to the situation in the human, thereby guaranteeing that causal exposure and effect relationships in the animals can be extrapolated to the human.

Re-evaluation of animal numbers and costs for in vivo tests to accomplish REACH legislation requirements for chemicals - a report by the transatlantic think tank for toxicology (t(4)).

The EU REACH legislation for chemicals of 2006 represents the largest investment into consumer product safety ever. A reanalysis of cost and animal use estimates was carried out based on the final legislation, test guidance for industry published by the European Chemical Agency, and the preregistration completed in December 2008. The new estimates for the number of substances falling under REACH range from 68 to 101,000 chemicals, substantially exceeding the earlier estimates of 29,000 substances. The latter estimates were, however, based on data before 1994 and both expansion of the EU and growth of the chemical industry since have contributed to higher numbers today. The lower estimate of 68,000 chemicals was carried through current testing requirements with due regard to emerging alternative approaches, using in all cases the most optimistic assumptions (minimal animal numbers per test and neglecting most triggering of additional tests and confirmatory (re-)tests as well as tests requested but not yet defined for endocrine disruption, respiratory irritation, respiratory sensitization and developmental neurotoxicity). The most demanding studies are in the area of reproductive toxicity testing with about 90% of all animal use and 70% of the required costs for registration. The overall result suggests a demand of 54 million vertebrate animals and testing costs of 9.5 billion euro. This clearly challenges the feasibility of the program without a major investment into high-throughput methodologies.

Reflections on improved health status of rodents bred for research: contributions to the reduction and refinement of animal use.

Reductions and refinements in the use of animals have steadily occurred over the last century. The need for improved health status has been a catalyst for much of this effort. This has also driven improvements in the housing and husbandry techniques required to maintain the health status of animals produced or used for biomedical research. This has decreased the number of animals used in biomedical research studies, contributed to refinements in animal care and use, and has resulted in better science as well as better animal welfare.