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Kruhlak NL, Schmidt M, Froetschl R, Graber S, Haas B, Horne I, Horne S, King ST, Koval IA, Kumaran G, Langenkamp A, McGovern TJ, Peryea T, Sanh A, Siqueira Ferreira A, van Aerts L, Vespa A, Whomsley R. Determining recommended acceptable intake limits for N-nitrosamine impurities in pharmaceuticals: Development and application of the Carcinogenic Potency Categorization Approach (CPCA). Regul Toxicol Pharmacol 2024; 150:105640. [PMID: 38754805 DOI: 10.1016/j.yrtph.2024.105640] [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: 04/22/2024] [Accepted: 05/06/2024] [Indexed: 05/18/2024]
Abstract
N-Nitrosamine impurities, including nitrosamine drug substance-related impurities (NDSRIs), have challenged pharmaceutical industry and regulators alike and affected the global drug supply over the past 5 years. Nitrosamines are a class of known carcinogens, but NDSRIs have posed additional challenges as many lack empirical data to establish acceptable intake (AI) limits. Read-across analysis from surrogates has been used to identify AI limits in some cases; however, this approach is limited by the availability of robustly-tested surrogates matching the structural features of NDSRIs, which usually contain a diverse array of functional groups. Furthermore, the absence of a surrogate has resulted in conservative AI limits in some cases, posing practical challenges for impurity control. Therefore, a new framework for determining recommended AI limits was urgently needed. Here, the Carcinogenic Potency Categorization Approach (CPCA) and its supporting scientific rationale are presented. The CPCA is a rapidly-applied structure-activity relationship-based method that assigns a nitrosamine to 1 of 5 categories, each with a corresponding AI limit, reflecting predicted carcinogenic potency. The CPCA considers the number and distribution of α-hydrogens at the N-nitroso center and other activating and deactivating structural features of a nitrosamine that affect the α-hydroxylation metabolic activation pathway of carcinogenesis. The CPCA has been adopted internationally by several drug regulatory authorities as a simplified approach and a starting point to determine recommended AI limits for nitrosamines without the need for compound-specific empirical data.
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Affiliation(s)
- Naomi L Kruhlak
- US Food and Drug Administration (US FDA), Silver Spring, MD, USA.
| | | | - Roland Froetschl
- Federal Institute for Drugs and Medical Devices (BfArM), Bonn, Germany
| | - Stefan Graber
- Swiss Agency for Therapeutic Products (Swissmedic), Bern, Switzerland
| | - Bodo Haas
- Federal Institute for Drugs and Medical Devices (BfArM), Bonn, Germany
| | - Irene Horne
- Therapeutic Goods Administration (TGA), Canberra, Australia
| | - Stephen Horne
- Pharmaceutical Drugs Directorate, Health Canada, Ottawa, Ontario, Canada
| | - Sruthi T King
- US Food and Drug Administration (US FDA), Silver Spring, MD, USA
| | - Iryna A Koval
- Medicines Evaluation Board (MEB), Utrecht, Netherlands
| | | | - Anja Langenkamp
- Swiss Agency for Therapeutic Products (Swissmedic), Bern, Switzerland
| | | | - Tyler Peryea
- US Food and Drug Administration (US FDA), Silver Spring, MD, USA
| | - Alan Sanh
- French National Agency for Medicines and Health Products Safety (ANSM), Saint-Denis, France
| | | | | | - Alisa Vespa
- Pharmaceutical Drugs Directorate, Health Canada, Ottawa, Ontario, Canada
| | - Rhys Whomsley
- European Medicines Agency (EMA), Amsterdam, Netherlands
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Dieckhoff J, Bringezu F, Simon S. Metabolic activation of short-chain alkyl N-nitrosamines using Aroclor 1254 or phenobarbital/beta-naphthoflavone-induced rat or hamster S9 - A comparative analysis. Toxicol Rep 2024; 12:215-223. [PMID: 38322170 PMCID: PMC10844645 DOI: 10.1016/j.toxrep.2024.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/18/2024] [Accepted: 01/20/2024] [Indexed: 02/08/2024] Open
Abstract
N-nitrosamines, a very heterogeneous class of chemicals, may enter humans in small amounts through various sources and are produced endogenously, too. Some are known to be mutagenic carcinogens and have recently been detected as impurities in several marketed pharmaceuticals. Despite their known mutagenic properties, the suitability of the bacterial reverse mutation (Ames) assay and in particular the use of induced rat liver S9 to detect their mutagenic potential, is often discussed. Recently, it could be demonstrated that induced rat liver S9 is capable of metabolizing small alkyl nitrosamines to exert their mutagenic potential (Bringezu & Simon, 2022). In this project, the mutagenic potential of nitrosamines in vitro under different S9 conditions applying the preincubation protocol and OECD 471-compliant standard Ames test recommendations was investigated. These conditions included various amounts of S9 fraction from hamster and rat, uninduced or induced with Aroclor 1254 or Phenobarbital/beta-Naphthoflavone (PB/NF). The findings indicated that in addition to induced S9, uninduced hamster S9 also demonstrated effectiveness. Moreover, both rat and hamster S9 fractions exhibited suitable responses in terms of mutation frequencies. Increasing the S9 content did not increase the sensitivity of the Ames test. However, above 20% S9, reduced mutation frequency was observed in the higher concentration range suggesting cytotoxicity to the bacteria. Thus, limiting the S9 content to 10% provides reliable results and relates to a lower number of animals required for S9 production which is in concordance with the 3R principles (reduce, refine, replace) for animal testing. In addition, results obtained show that uninduced and induced hamster S9 are similarly effective, doubting the requirement of pretreating animals with enzyme inducers. Further investigations to compare mutagenicity data and rat and hamster S9 proteome analyses are ongoing.
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Affiliation(s)
- Jessica Dieckhoff
- Merck Healthcare KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Frank Bringezu
- Merck Healthcare KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | - Stephanie Simon
- Merck Healthcare KGaA, Frankfurter Straße 250, 64293 Darmstadt, Germany
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Guo X, Xu H, Seo JE. Application of HepaRG cells for genotoxicity assessment: a review. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, TOXICOLOGY AND CARCINOGENESIS 2024:1-24. [PMID: 38566478 DOI: 10.1080/26896583.2024.2331956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
There has been growing interest in the use of human-derived metabolically competent cells for genotoxicity testing. The HepaRG cell line is considered one of the most promising cell models because it is TP53-proficient and retains many characteristics of primary human hepatocytes. In recent years, HepaRG cells, cultured in both a traditional two-dimensional (2D) format and as more advanced in-vivo-like 3D spheroids, have been employed in assays that measure different types of genetic toxicity endpoints, including DNA damage, mutations, and chromosomal damage. This review summarizes published studies that have used HepaRG cells for genotoxicity assessment, including cell model evaluation studies and risk assessment for various compounds. Both 2D and 3D HepaRG models can be adapted to several high-throughput genotoxicity assays, generating a large number of data points that facilitate quantitative benchmark concentration modeling. With further validation, HepaRG cells could serve as a unique, human-based new alternative methodology for in vitro genotoxicity testing.
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Affiliation(s)
- Xiaoqing Guo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA
| | - Hannah Xu
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA
| | - Ji-Eun Seo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA
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Li X, Le Y, Li Y, Chen S, Guo L, Fu X, Manjanatha MG, Mei N. Evaluation of weak genotoxicity of hydroxychloroquine in human TK6 cells. Toxicol Lett 2024; 393:84-95. [PMID: 38311193 DOI: 10.1016/j.toxlet.2024.01.012] [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: 11/08/2023] [Revised: 01/25/2024] [Accepted: 01/29/2024] [Indexed: 02/10/2024]
Abstract
Hydroxychloroquine (HCQ), a derivative of chloroquine (CQ), is an antimalarial and antirheumatic drug. Since there is limited data available on the genotoxicity of HCQ, in the current study, we used a battery of in vitro assays to systematically examine the genotoxicity of HCQ in human lymphoblastoid TK6 cells. We first showed that HCQ is not mutagenic in TK6 cells up to 80 μM with or without exogenous metabolic activation. Subsequently, we found that short-term (3-4 h) HCQ treatment did not cause DNA strand breakage as measured by the comet assay and the phosphorylation of histone H2A.X (γH2A.X), and did not induce chromosomal damage as determined by the micronucleus (MN) assay. However, after 24-h treatment, both CQ and HCQ induced comparable and weak DNA damage and MN formation in TK6 cells; upregulated p53 and p53-mediated DNA damage responsive genes; and triggered apoptosis and mitochondrial damage that may partially contribute to the observed MN formation. Using a benchmark dose (BMD) modeling analysis, the lower 95% confidence limit of BMD50 values (BMDL50) for MN induction in TK6 cells were about 19.7 μM for CQ and 16.3 μM for HCQ. These results provide additional information for quantitative genotoxic risk assessment of these drugs.
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Affiliation(s)
- Xilin Li
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA.
| | - Yuan Le
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA
| | - Yuxi Li
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA
| | - Si Chen
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA
| | - Lei Guo
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA
| | - Xin Fu
- Division of Pharmacology Toxicology Review, Office of Safety and Clinical Evaluation, Center for Drug Evaluation and Research, Silver Spring, MD 20993, USA
| | - Mugimane G Manjanatha
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA
| | - Nan Mei
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA.
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Burns MJ, Ponting DJ, Foster RS, Thornton BP, Romero NE, Smith GF, Ashworth IW, Teasdale A, Simon S, Schlingemann J. Revisiting the Landscape of Potential Small and Drug Substance Related Nitrosamines in Pharmaceuticals. J Pharm Sci 2023; 112:3005-3011. [PMID: 37805074 DOI: 10.1016/j.xphs.2023.10.001] [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: 07/31/2023] [Revised: 10/01/2023] [Accepted: 10/01/2023] [Indexed: 10/09/2023]
Abstract
N-Nitrosamines are a class of indirect acting mutagens, as their metabolic degradation leads to the formation of the DNA-alkylating diazonium ion. Following up on the in-silico identification of thousands of nitrosamines that can potentially be derived from small molecule drugs and their known impurities described in a previous publication, we have now re-analyzed this dataset to apply EMA's Carcinogenic Potency Categorization Approach (CPCA) introduced with the 16th revision of their Q&A document for Marketing Authorization Holders. We find that the majority of potential nitrosamines from secondary amine precursors belongs to potency categories 4 and 5, corresponding to an acceptable daily intake of 1500 ng, whereas nitrosamines from tertiary amine precursors distribute more evenly among all categories, resulting in a substantial number of structures that are assigned the more challenging acceptable intakes of 18 ng/day and 100 ng/day for potency categories 1 and 2, respectively. However, the nitrosative dealkylation pathway for tertiary amine is generally far slower than the direct nitrosation on secondary amines, with a direct nitrosation mechanism suspected only for structures featuring electron-rich (hetero)aromatic substituents. This allows for greater focus towards those structures that require further review, and we demonstrate that their number is not substantial. In addition, we reflect on the nitrosamine risk posed by secondary amine API impurities and demonstrate that based on the ICH Q3A/B identification threshold unknown impurities may exist that could be transformed to relevant amounts of NA. We also demonstrate that the analytical sensitivity required for the quantification of high potency nitrosamines can be problematic especially for high dose APIs. In summary, the regulatory framework rolled out with the latest Q&A document represents a substantial improvement compared with the previous situation, but further refinement through interaction between manufacturers, regulators, not-for-profit and academic institutions will be required to ensure patient access to vital medicines without compromising safety.
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Affiliation(s)
- Michael J Burns
- Lhasa Limited, Granary Wharf House, 2 Canal Wharf, Leeds, United Kingdom
| | - David J Ponting
- Lhasa Limited, Granary Wharf House, 2 Canal Wharf, Leeds, United Kingdom
| | - Robert S Foster
- Lhasa Limited, Granary Wharf House, 2 Canal Wharf, Leeds, United Kingdom
| | | | - Naiffer E Romero
- U.S. Pharmacopeia, 12601 Twinbrook Parkway, Rockville, Maryland, USA
| | - Graham F Smith
- AstraZeneca, Data Science and AI, Clinical Pharmacology and Safety Sciences, R&D, Cambridge, United Kingdom
| | - Ian W Ashworth
- Chemical Development, Pharmaceutical Technology & Development, Operations, AstraZeneca, Macclesfield, United Kingdom
| | - Andrew Teasdale
- Chemical Development, Pharmaceutical Technology & Development, Operations, AstraZeneca, Macclesfield, United Kingdom
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