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

Development and application of potency assays based on genetically modified cells for biological products

Potency assays are key to the development, registration, and quality control of biological products. Although previously preferred for clinical relevance, in vivo bioassays have greatly diminished with the advent of dependent cell lines as well as due to ethical concerns. However, for some products, the development of in vitro cell-based assay is challenging, or existing method has limitations such as tedious procedure or low sensitivity. The generation of genetically modified (GM) cell line with improved response to the analyte provides a scientific and promising solution. Potency assays based on GM cell lines are currently used for the quality control of biological products including cytokines, hormones, therapeutic antibodies, vaccines and gene therapy products. In this review, we have discussed the general principles of designing and developing GM cells-based potency assays, including identification of cellular signaling pathways and detectable biological effects, generation of responsive cell lines and constitution of test systems, based on the current research progress. In addition, the applications of some novel technologies and the common concerns regarding GM cells have also been discussed. The research presented in this review provides insights for the development and application of novel GM cells-based potency assays for biological products.

Replacement of animal testing by integrated approaches to testing and assessment (IATA): a call for in vivitrosi

Alternative methods to animal use in toxicology are evolving with new advanced tools and multilevel approaches, to answer from one side to 3Rs requirements, and on the other side offering relevant and valid tests for drugs and chemicals, considering also their combination in test strategies, for a proper risk assessment.

While stand-alone methods, have demonstrated to be applicable for some specific toxicological predictions with some limitations, the new strategy for the application of New Approach Methods (NAM), to solve complex toxicological endpoints is addressed by Integrated Approaches for Testing and Assessment (IATA), aka Integrated Testing Strategies (ITS) or Defined Approaches for Testing and Assessment (DA). The central challenge of evidence integration is shared with the needs of risk assessment and systematic reviews of an evidence-based Toxicology. Increasingly, machine learning (aka Artificial Intelligence, AI) lends itself to integrate diverse evidence streams.

In this article, we give an overview of the state of the art of alternative methods and IATA in toxicology for regulatory use for various hazards, outlining future orientation and perspectives. We call on leveraging the synergies of integrated approaches and evidence integration from in vivo, in vitro and in silico as true in vivitrosi.

The use of Bayesian methodology in the development and validation of a tiered assessment approach towards prediction of rat acute oral toxicity

There exists consensus that the traditional means by which safety of chemicals is assessed—namely through reliance upon apical outcomes obtained following in vivo testing—is increasingly unfit for purpose. Whilst efforts in development of suitable alternatives continue, few have achieved levels of robustness required for regulatory acceptance. An array of “new approach methodologies” (NAM) for determining toxic effect, spanning in vitro and in silico spheres, have by now emerged. It has been suggested, intuitively, that combining data obtained from across these sources might serve to enhance overall confidence in derived judgment. This concept may be formalised in the “tiered assessment” approach, whereby evidence gathered through a sequential NAM testing strategy is exploited so to infer the properties of a compound of interest. Our intention has been to provide an illustration of how such a scheme might be developed and applied within a practical setting—adopting for this purpose the endpoint of rat acute oral lethality. Bayesian statistical inference is drawn upon to enable quantification of degree of confidence that a substance might ultimately belong to one of five LD50-associated toxicity categories. Informing this is evidence acquired both from existing in silico and in vitro resources, alongside a purposely-constructed random forest model and structural alert set. Results indicate that the combination of in silico methodologies provides moderately conservative estimations of hazard, conducive for application in safety assessment, and for which levels of certainty are defined. Accordingly, scope for potential extension of approach to further toxicological endpoints is demonstrated.

Current EU regulatory requirements for the assessment of chemicals and cosmetic products: challenges and opportunities for introducing new approach methodologies

The EU Directive 2010/63/EU   on the protection of animals used for scientific purposes and other EU regulations, such as REACH and the Cosmetic Products Regulation advocate for a change in the way toxicity testing is conducted. Whilst the Cosmetic Products Regulation bans animal testing altogether, REACH aims for a progressive shift from in vivo testing towards quantitative in vitro and computational approaches. Several endpoints can already be addressed using non-animal approaches including skin corrosion and irritation, serious eye damage and irritation, skin sensitisation, and mutagenicity and genotoxicity. However, for systemic effects such as acute toxicity, repeated dose toxicity and reproductive and developmental toxicity, evaluation of chemicals under REACH still heavily relies on animal tests. Here we summarise current EU regulatory requirements for the human health assessment of chemicals under REACH and the Cosmetic Products Regulation, considering the more critical endpoints and identifying the main challenges in introducing alternative methods into regulatory testing practice. This supports a recent initiative taken by the International Cooperation on Alternative Test Methods (ICATM) to summarise current regulatory requirements specific for the assessment of chemicals and cosmetic products for several human health-related endpoints, with the aim of comparing different jurisdictions and coordinating the promotion and ultimately the implementation of non-animal approaches worldwide. Recent initiatives undertaken at European level to promote the 3Rs and the use of alternative methods in current regulatory practice are also discussed.

Qualitative and Quantitative Analysis of Certain Aspects of the Cytotoxic and Genotoxic Hazard of Hospital Wastewaters by Using a Range of In Vitro Assays

Health care facilities and hospitals generate significant amounts of wastewater which are released into the sewage system, either after a preliminary treatment or without any further treatment. Hospital wastewater may contain large amounts of hazardous chemicals and pharmaceuticals, some of which cannot be eliminated entirely by wastewater treatment plants. Moreover, hospital effluents may be loaded with a plethora of pathogenic microorganisms or other microbiota and microbiome residues. The need to monitor hospital effluents for their genotoxic hazard is of high importance, as detailed information is scarce. DNA-based information can be acquired directly from samples through the application of various molecular methods, while cell-based biomonitoring assays can provide important information about impaired cellular pathways or mechanisms of toxicity without prior knowledge of the identity of each toxicant. In our study, we evaluated samples of chlorinated hospital wastewater discharged into the sewage system after this disinfection process. The assessment of cytotoxicity, genotoxicity and mutagenicity of the hospital effluents was performed in vitro by using a broad battery of biomonitoring assays that are relevant for human health effects. All the tested hospital wastewater samples could be classified as potentially genotoxic, and it is concluded that the microbiota present in hospital wastewater might contribute to this genotoxic potential.

Molecular Image-Based Prediction Models of Nuclear Receptor Agonists and Antagonists Using the DeepSnap-Deep Learning Approach with the Tox21 10K Library

The interaction of nuclear receptors (NRs) with chemical compounds can cause dysregulation of endocrine signaling pathways, leading to adverse health outcomes due to the disruption of natural hormones. Thus, identifying possible ligands of NRs is a crucial task for understanding the adverse outcome pathway (AOP) for human toxicity as well as the development of novel drugs. However, the experimental assessment of novel ligands remains expensive and time-consuming. Therefore, an in silico approach with a wide range of applications instead of experimental examination is highly desirable. The recently developed novel molecular image-based deep learning (DL) method, DeepSnap-DL, can produce multiple snapshots from three-dimensional (3D) chemical structures and has achieved high performance in the prediction of chemicals for toxicological evaluation. In this study, we used DeepSnap-DL to construct prediction models of 35 agonist and antagonist allosteric modulators of NRs for chemicals derived from the Tox21 10K library. We demonstrate the high performance of DeepSnap-DL in constructing prediction models. These findings may aid in interpreting the key molecular events of toxicity and support the development of new fields of machine learning to identify environmental chemicals with the potential to interact with NR signaling pathways.