Applying new approach methodologies to assess next-generation tobacco and nicotine products

Abstract

In vitro toxicology research has accelerated with the use of in silico, computational approaches and human in vitro tissue systems, facilitating major improvements evaluating the safety and health risks of novel consumer products. Innovation in molecular and cellular biology has shifted testing paradigms, with less reliance on low-throughput animal data and greater use of medium- and high-throughput in vitro cellular screening approaches. These new approach methodologies (NAMs) are being implemented in other industry sectors for chemical testing, screening candidate drugs and prototype consumer products, driven by the need for reliable, human-relevant approaches. Routine toxicological methods are largely unchanged since development over 50 years ago, using high-doses and often employing in vivo testing. Several disadvantages are encountered conducting or extrapolating data from animal studies due to differences in metabolism or exposure. The last decade saw considerable advancement in the development of in vitro tools and capabilities, and the challenges of the next decade will be integrating these platforms into applied product testing and acceptance by regulatory bodies. Governmental and validation agencies have launched and applied frameworks and "roadmaps" to support agile validation and acceptance of NAMs. Next-generation tobacco and nicotine products (NGPs) have the potential to offer reduced risks to smokers compared to cigarettes. These include heated tobacco products (HTPs) that heat but do not burn tobacco; vapor products also termed electronic nicotine delivery systems (ENDS), that heat an e-liquid to produce an inhalable aerosol; oral smokeless tobacco products (e.g., Swedish-style snus) and tobacco-free oral nicotine pouches. With the increased availability of NGPs and the requirement of scientific studies to support regulatory approval, NAMs approaches can supplement the assessment of NGPs. This review explores how NAMs can be applied to assess NGPs, highlighting key considerations, including the use of appropriate in vitro model systems, deploying screening approaches for hazard identification, and the importance of test article characterization. The importance and opportunity for fit-for-purpose testing and method standardization are discussed, highlighting the value of industry and cross-industry collaborations. Supporting the development of methods that are accepted by regulatory bodies could lead to the implementation of NAMs for tobacco and nicotine NGP testing.

Keywords: adverse outcome pathway (AOP); airway models; dosimetry; high-content analysis; human 3D tissues; new approach methodologies (NAM); next-generation products (NGP); organs on a chip (OoC).

FIGURE 1

Main considerations when selecting an in vitro model. Reproduced with permission from Lee et al. (2022), Sharma et al. (2023). Note: 1) Test chemical and its physicochemical properties, 2) In vitro exposure system and aerosol characterization, 3) In vitro 2D/3D systems including 2D/3D, 4) cellular types and relevant tissues, and 5) assay endpoints and clinical relevance.

FIGURE 2

Key considerations in developing and qualifying NAM tools. Reproduced with permission from van der Zalm et al. (2022). Note: the figures illustrates the five inter-connected elements that are essential in establishing scientific confidence in NAM applications.