Setting the stage for next-generation risk assessment with non-animal approaches: the EU-ToxRisk project experience

Abstract

In 2016, the European Commission launched the EU-ToxRisk research project to develop and promote animal-free approaches in toxicology. The 36 partners of this consortium used in vitro and in silico methods in the context of case studies (CSs). These CSs included both compounds with a highly defined target (e.g. mitochondrial respiratory chain inhibitors) as well as compounds with poorly defined molecular initiation events (e.g. short-chain branched carboxylic acids). The initial project focus was on developing a science-based strategy for read-across (RAx) as an animal-free approach in chemical risk assessment. Moreover, seamless incorporation of new approach method (NAM) data into this process (= NAM-enhanced RAx) was explored. Here, the EU-ToxRisk consortium has collated its scientific and regulatory learnings from this particular project objective. For all CSs, a mechanistic hypothesis (in the form of an adverse outcome pathway) guided the safety evaluation. ADME data were generated from NAMs and used for comprehensive physiological-based kinetic modelling. Quality assurance and data management were optimized in parallel. Scientific and Regulatory Advisory Boards played a vital role in assessing the practical applicability of the new approaches. In a next step, external stakeholders evaluated the usefulness of NAMs in the context of RAx CSs for regulatory acceptance. For instance, the CSs were included in the OECD CS portfolio for the Integrated Approach to Testing and Assessment project. Feedback from regulators and other stakeholders was collected at several stages. Future chemical safety science projects can draw from this experience to implement systems toxicology-guided, animal-free next-generation risk assessment.

Identifying, naming and documenting of test and tool compound stocks

“…General guidance on test descriptions, like OECD GD 211 or its more extensive version, the ToxTemp (Krebs et al, 2019), do not give detailed advice. However, the issue is very clearly addressed, e.g., in documents on important conditions for collaborative testing campaigns (Krebs et al, 2020;Moné et al, 2020;Delp et al, 2018Delp et al, , 2019Nyffeler et al, 2017a,b), for developmental neurotoxicity screening (Masjosthusmann et al, 2020 -Appendix A), and also in the establishment of toxicological in vitro testing databases such as ToxCast 2 . The following chapters will make it clear why the names "ciguatoxin", "MPTP" and "FeSO 4 " are not well-suited as chemical identifiers and why, therefore, the positive controls used for testing in our anchor story example may have varied in concentrations or even have contained different substances.…”

A framework for chemical safety assessment incorporating new approach methodologies within REACH

“…Technical progress has been made, but fitting new technology into the existing regulatory system is proving to be difficult for many reasons, scientific and otherwise. There have been many programmes heralding the need for reform fit for the 21st century including the US Federal Program Tox21 (Thomas et al 2018 ), HESI’s programme Risk21 (Pastoor et al 2014 ), and EU-ToxRisk21 (Moné et al 2020 ), but a quarter of the twenty-first century will have soon passed, and the old system is still in place.…”

“…The outcome of a hazard assessment process should be judged on whether an adequate hazard profile results in terms of type and category of hazard and setting of safe dose limits, not on whether all the endpoints from individual conventional toxicology studies could be predicted. It has been argued that the acceptability of a new approach to chemical safety assessment should be judged on whether it provides results which allow appropriate risk management actions to protect human health (Daston et al 2015 ; Herzler et al 2021 ; Lanzoni et al 2019 ; Moné et al 2020 ; Tralau et al 2015 ).…”

Profiling of Human Neural Crest Chemoattractant Activity as a Replacement of Fetal Bovine Serum for In Vitro Chemotaxis Assays

“…An NCC chemotaxis assay could be incorporated in a NAM test battery [45] and used in the context of next-generation risk assessment (NGRA) [46,47]. Based on this, animal-free risk assessment for the safety of compounds may be performed [48].…”