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Louekari K, Jacobs MN. A modular strategy for the testing and assessment of non-genotoxic carcinogens. Arch Toxicol 2024; 98:2463-2485. [PMID: 38811392 PMCID: PMC11272678 DOI: 10.1007/s00204-024-03753-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 03/26/2024] [Indexed: 05/31/2024]
Abstract
A modular strategy is described for the testing and assessment (MoSt) of non-genotoxic carcinogenicity (NGTxC) that is suitable for regulatory applications. It utilizes and builds upon work conducted by the OECD expert group on NGTxC. The approach integrates relevant test methods from the molecular- to cellular- and further to tissue level, many of which have been recently reviewed. Six progressive modules are included in the strategy. Advice is provided for the iterative selection of the next appropriate test method within each step of the strategy. Assessment is completed by a weight of evidence conclusion, which integrates the different streams of modular information. The assessment method gives higher weight to findings that are mechanistically linked with biological relevance to carcinogenesis. With a focus on EU-REACH, and pending upon successful test method validation and acceptance, this will also enable the MoSt for NGTxC to be applied for regulatory purposes across different regulatory jurisdictions.
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Affiliation(s)
| | - Miriam N Jacobs
- UK Health Security Agency, Radiation, Chemical and Environmental Hazards, Harwell Science and Innovation Campus, Chilton, Oxfordshire, OX11 0RQ, UK.
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Wilhelmi P, Giri V, Zickgraf FM, Haake V, Henkes S, Driemert P, Michaelis P, Busch W, Scholz S, Flick B, Barenys M, Birk B, Kamp H, Landsiedel R, Funk-Weyer D. A metabolomics approach to reveal the mechanism of developmental toxicity in zebrafish embryos exposed to 6-propyl-2-thiouracil. Chem Biol Interact 2023; 382:110565. [PMID: 37236578 DOI: 10.1016/j.cbi.2023.110565] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 05/12/2023] [Accepted: 05/23/2023] [Indexed: 05/28/2023]
Abstract
A crucial component of a substance registration and regulation is the evaluation of human prenatal developmental toxicity. Current toxicological tests are based on mammalian models, but these are costly, time consuming and may pose ethical concerns. The zebrafish embryo has evolved as a promising alternative model to study developmental toxicity. However, the implementation of the zebrafish embryotoxicity test is challenged by lacking information on the relevance of observed morphological alterations in fish for human developmental toxicity. Elucidating the mechanism of toxicity could help to overcome this limitation. Through LC-MS/MS and GC-MS metabolomics, we investigated whether changes to the endogenous metabolites can indicate pathways associated with developmental toxicity. To this aim, zebrafish embryos were exposed to different concentrations of 6-propyl-2-thiouracil (PTU), a compound known to induce developmental toxicity. The reproducibility and the concentration-dependence of the metabolome response and its association with morphological alterations were studied. Major morphological findings were reduced eye size, and other craniofacial anomalies; major metabolic changes included increased tyrosine, pipecolic acid and lysophosphatidylcholine levels, decreased methionine levels, and disturbance of the 'Phenylalanine, tyrosine and tryptophan biosynthesis' pathway. This pathway, and the changes in tyrosine and pipecolic acid levels could be linked to the mode of action of PTU, i.e., inhibition of thyroid peroxidase (TPO). The other findings suggested neurodevelopmental impairments. This proof-of-concept study demonstrated that metabolite changes in zebrafish embryos are robust and provide mechanistic information associated with the mode of action of PTU.
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Affiliation(s)
- Pia Wilhelmi
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany; University of Barcelona, Research Group in Toxicology-GRET, 08028, Barcelona, Spain.
| | - Varun Giri
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany.
| | | | - Volker Haake
- BASF Metabolome Solutions, 10589, Berlin, Germany
| | | | | | - Paul Michaelis
- Helmholtz Centre for Environmental Research-UFZ, Department of Bioanalytical Ecotoxicology, 04318, Leipzig, Germany
| | - Wibke Busch
- Helmholtz Centre for Environmental Research-UFZ, Department of Bioanalytical Ecotoxicology, 04318, Leipzig, Germany
| | - Stefan Scholz
- Helmholtz Centre for Environmental Research-UFZ, Department of Bioanalytical Ecotoxicology, 04318, Leipzig, Germany
| | - Burkhard Flick
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany
| | - Marta Barenys
- University of Barcelona, Research Group in Toxicology-GRET, 08028, Barcelona, Spain; German Centre for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), 10589, Berlin, Germany
| | - Barbara Birk
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany
| | | | - Robert Landsiedel
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany; Free University of Berlin, Institute of Pharmacy, Pharmacology and Toxicology, 14195, Berlin, Germany
| | - Dorothee Funk-Weyer
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany
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Berggren E, Worth AP. Towards a future regulatory framework for chemicals in the European Union - Chemicals 2.0. Regul Toxicol Pharmacol 2023:105431. [PMID: 37315707 PMCID: PMC10390824 DOI: 10.1016/j.yrtph.2023.105431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 06/03/2023] [Accepted: 06/08/2023] [Indexed: 06/16/2023]
Abstract
The body of EU chemicals legislation has evolved since the 1960s, producing the largest knowledge base on chemicals worldwide. Like any evolving system, however, it has become increasingly diverse and complex, resulting in inefficiencies and potential inconsistencies. In the light of the EU Chemicals Strategy for Sustainability, it is therefore timely and reasonable to consider how aspects of the system could be simplified and streamlined, without losing the hard-earned benefits to human health and the environment. In this commentary, we propose a conceptual framework that could be the basis of Chemicals 2.0 - a future safety assessment and management approach that is based on the application of New Approach Methodologies (NAMs), mechanistic reasoning and cost-benefit considerations. Chemicals 2.0 is designed to be a more efficient and more effective approach for assessing chemicals, and to comply with the EU goal to completely replace animal testing, in line with Directive 2010/63/EU. We propose five design criteria for Chemicals 2.0 to define what the future system should achieve. The approach is centered on a classification matrix in which NAMs for toxicodynamics and toxicokinetics are used to classify chemicals according to their level of concern. An important principle is the need to ensure an equivalent, or higher, protection level.
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Affiliation(s)
| | - Andrew P Worth
- European Commission, Joint Research Centre (JRC), Ispra, Italy.
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Dimitrijevic D, Fabian E, Funk-Weyer D, Landsiedel R. Rapid equilibrium dialysis, ultrafiltration or ultracentrifugation? Evaluation of methods to quantify the unbound fraction of substances in plasma. Biochem Biophys Res Commun 2023; 651:114-120. [PMID: 36812744 DOI: 10.1016/j.bbrc.2023.02.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 02/09/2023] [Indexed: 02/12/2023]
Abstract
In pharmacokinetics plasma protein binding (PPB) is a well-established parameter impacting drug disposition. The unbound fraction (fu) is arguably regarded the effective concentration at the target site. Pharmacology and toxicology, increasingly use in vitro models. The translation of in vitro concentrations to in vivo doses can be supported by toxicokinetic modelling, e.g. physiologically based toxicokinetic models (PBTK). PPB of a test substance is an input parameter for PBTK. We compared three methods to quantify fu: rapid equilibrium dialysis (RED), ultrafiltration (UF) and ultracentrifugation (UC) using twelve substances covering a wide range of Log Pow (-0.1 to 6.8) and molecular weights (151 and 531 g/mol): Acetaminophen, Bisphenol A, Caffeine, Colchicine, Fenarimol, Flutamide, Genistein, Ketoconazole, α-Methyltestosterone, Tamoxifen, Trenbolone and Warfarin. After RED and UF separation, three polar substances (Log Pow < 2) were largely unbound (fu > 70%), while more lipophilic substances were largely bound (fu < 33%). Compared to RED or UF, UC resulted in a generally higher fu of lipophilic substances. fu obtained after RED and UF were more consistent with published data. For half of the substances, UC resulted in fu higher than the reference data. UF, RED and both UF and UC, resulted in lower fu of Flutamide, Ketoconazole and Colchicine, respectively. For fu quantifications, the separation method should be selected according to the test substance's properties. Based on our data, RED is suitable for a broader range of substances while UC and UF are suitable for polar substances.
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Affiliation(s)
- Dunja Dimitrijevic
- Free University of Berlin, Institute of Pharmacy, Pharmacology and Toxicology, Königin-Luise-Straße 2-4, 14195, Berlin, Germany.
| | - Eric Fabian
- BASF SE, Experimental Toxicology and Ecology, Carl-Bosch-Straße 38, 67063, Ludwigshafen am Rhein, Germany.
| | - Dorothee Funk-Weyer
- BASF SE, Experimental Toxicology and Ecology, Carl-Bosch-Straße 38, 67063, Ludwigshafen am Rhein, Germany.
| | - Robert Landsiedel
- Free University of Berlin, Institute of Pharmacy, Pharmacology and Toxicology, Königin-Luise-Straße 2-4, 14195, Berlin, Germany; BASF SE, Experimental Toxicology and Ecology, Carl-Bosch-Straße 38, 67063, Ludwigshafen am Rhein, Germany.
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Fowkes A, Foster R, Kane S, Thresher A, Werner AL, de Oliveira AAF. Enhancing global and local decision making for chemical safety assessments through increasing the availability of data. Toxicol Mech Methods 2023:1-12. [PMID: 36600456 DOI: 10.1080/15376516.2022.2156007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Toxicity safety assessments are a fundamental part of the lifecycle of products and aim to protect human health and the environment from harmful exposures to chemical substances. To make decisions regarding the suitability of testing strategies, the applicability of individual tests or concluding an assessment for an individual chemical requires data. This review outlines how different forms of data sharing, from enhancing publicly-available data to extracting knowledge from commercially-sensitive data, leads to increased quantity and quality of evidence being available for safety assessors to review. This can result in more confident decisions for different use cases in the context of chemical safety assessments. Although a number of challenges remain with progressing the evolution of toxicity safety assessments, data sharing should be considered as a key approach to accelerating the development and uptake of new best practices.
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