Exploring Alternatives to Animal Testing: Scientific, Legal and Ethical Challenges in Developing Novel Alternative Methods with a Focus on Organoids as Potential NAMs

Abstract

Keywords

Novel alternative methods, NAMs, 3R principle, organoids, Swiss law

Suggested Citation Style

Fausch Inesa, Zeyer-Iyengar, Daniel, Cajiga Morales, Rosa Maria, Elger, Bernice, Enzmann, Volker and Früh, Alfred (2025). Exploring Alternatives to Animal Testing: Scientific, Legal and Ethical Challenges in Developing Novel Alternative Methods with a Focus on Organoids as Potential NAMs. Journal of Animal Law, Ethics and One Health (LEOH), 81-99. DOI: 10.58590/leoh.2025.008

¹ Center for Life Sciences Law (ZLSR), University of Basel, Basel, Switzerland.

² Institute for Biomedical Ethics, University of Basel, Basel, Switzerland.

³ Center of Legal Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland.

⁴Department of Ophthalmology, Bern University Hospital, Inselspital, Bern, Switzerland.

⁵Department for BioMedical Research, University of Bern, Bern, Switzerland.

Inhaltsverzeichnis

• I. Introduction
• II. The 3R Principle
• III. Novel Alternative Methods
• 1. Harm-Benefit Analysis
• 2. Validation Criteria
• IV. Organoids as NAMs
• 1. Potential
• 2. Limitations
• a) Financial Commitment
• b) Personal Commitment
• c) Regulatory Commitment
• V. Conclusion and Outlook

I. Introduction

Society’s criticism of animal testing[1] is growing. This is evidenced by initiatives against the use of animals in Europe and Switzerland[2] as well as ethical[3] and scientific[4] restrictions of animal model use. A reduction of animal testing, however, calls for the use of non-animal models, novel alternative methods or new approach methodologies. All these terms are commonly abbreviated as NAMs.[5] NAMs could be developed using human or animal cells and tissues for in chemico, in vitro, and advanced computer-modeling techniques (in silico approaches),[6] for the use in basic research, chemical and toxicity testing or biomedical research application with a concrete context of use, i.e. screening, hazard identification etc. Although their goal is to show the similarities between the physiology or biology measured by the test system, the environment and human biology, developing NAMs face not only scientific and technical but, as our research shows, also legal barriers.[7]

II. The 3R Principle

The use of animals for research has remained ethically controversial throughout time.[8] In 1959, Russell and Burch attempted to make animal research more humane with the publication of the Principles of Humane Experimental Techniques, containing the concept of the 3R (Replacement, Reduction, Refinement). According to Russell and Burch replacement means “the substitution for conscious living higher animals of insentient material”, reduction means “reducing the number of animals used to obtain information of a given amount and precision” and refinement means “any decrease in the incidence or severity of inhumane procedures applied to those animals which still have to be used”.[9]

Despite some criticism,[10] other attempts to draw up principles (such as the 3V principle[11] proposed by Eggel and Würbel,[12] the 6P principle[13] developed by DeGrazia and Beauchamp,[14] or the 3S principle[15] developed by Smith and Hawkins[16]), and the suggestion to shift the focus to the use of systematic reviews to improve animal welfare,[17] the 3R principle is widely accepted by researchers today as a moral obligation to treat animals as humanely as possible and, if available, to use alternative methods in experiments.

This moral obligation is also implemented in Swiss law, as animals are constitutionally protected; this protection involves two main aspects. On the one hand, the Swiss Federal Constitution protects the dignity of living beings including all animals’ inherent worth, which not only mandates protection against the misuse of gene technology on animals but is also considered to be a general constitutional principle in Swiss law.[18] On the other hand, animal welfare is a constitutionally protected interest and the constitution empowers the Swiss government to regulate animal welfare. The Swiss Animal Welfare Act (AniWA), which was enacted in 1981 as a law based on the constitution (and has been revised several times since it came into force), protects the welfare of animals by addressing specific areas including their keeping, care, and use in experiments.[19] The AniWA states in its Art. 3 that the animal’s dignity is disregarded “if any strain imposed on the animal cannot be justified by overriding interests”. The same article also includes definitions of animal welfare and animal experiments.[20] Art. 17 AniWA, which relates to the “indispensable extent” of animal testing, explicitly aims to limit the pain, suffering or harm inflicted on animals to the “indispensable minimum”, and these can be inflicted only if it is unavoidable for the purpose of the experiment according to Art. 20 AniWA. Moreover, animal experiments are subject to an authorization procedure which requires a review of each animal experiment to approve those that meet the requirements (Art. 18 AniWA). The Animal Protection Ordinance (AniPO) particularly addresses the performance of animal experiments. Its Art. 137 para. 2 stipulates that applicants show that the objective of the experiment cannot be achieved without animal experiments.[21]

In this vein, the 3R are – at least to some extent – represented at all levels of the legal system in Switzerland: the constitutional provisions embody elements of refinement, the relevant AniPO provisions aim at both refinement and reduction and Art. 137 para. 2 AniPO even puts forward a notion of replacement.

III. Novel Alternative Methods

The genesis of NAMs can be traced to the advent of the 3R principle[22] in various jurisdictions including Switzerland.[23] The promotion of NAMs started with several international initiatives. In 1991 the European Centre for Validation of Alternative Methods (ECVAM) and in 2000 the Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) were constituted with the objective of coordinating the collective endeavors towards the advancement and validation of alternative test methods. The legislative measures introduced by the European Union in 2013, which prohibited the use of animals for the testing of cosmetic products, placed an emphasis on the development of NAMs. A resolution was recently issued by the European Parliament to the European Council and Commission, emphasizing the necessity to prioritize the development and implementation of NAMs strategies with the objective of phasing out animal-based tests.[24] Nevertheless, there is currently no legislation at the EU level that defines or regulates NAMs specifically. Similarly, in Switzerland, compared to the 3R principle, NAMs are more difficult to trace in the legal provisions. The explanatory memorandum to the Swiss Animal Welfare Act (AniWA) makes reference to NAMs in the context of the 3R and the necessity for alternative methods,[25] as well as “a need for special requirements for persons who carry out animal experiments to have specialist training in alternative methods to animal testing”.[26] The use of NAMs, even if NAMs are not defined, is mentioned in the AniWA as well as the AniPO. Namely, Art. 20 para. 2 AniWA states that: “Experiments on animals higher on the evolutionary scale may only be carried out if the purpose of the experiment cannot be achieved in animal species that are lower on the evolutionary scale and no suitable alternative methods are available.” And in conducting any experiment, which could involve the use of animals, the applicant “must also show that the objective of the experiment cannot be achieved using procedures without animal experiments that are suitable according to the state of the art” (Art. 137 para. 2 AniPO). This means that available alternatives shall generally be used instead of animals. Additionally, their development, accreditation and application shall be promoted (Art. 22 para. 2 of AniWA). Similar provisions also exist in the EU.[27] An even greater acceptance of NAMs was seen in the US, where since 2022 the FDA Modernization Act 2.0[28] addresses the utilization of specific NAMs to animal testing such as cell-based assays, including organoids or computer models.[29] Additionally, the FDA Modernization Act 2.0 authorizes the use of certain alternatives to obtain an exemption from the Food and Drug Administration to investigate the safety and effectiveness of a drug. It also removes a requirement to use animal studies as part of the process to obtain a license for a biological product that is biosimilar or interchangeable with another biological product.[30] Although Swiss law also mentions the necessity to use NAMs, it does not provide a definition or any specific requirements for NAMs. To prove that a NAM is indeed a suitable alternative, it has to be compared to existing methods – in most cases established animal experiments – to determine if it yields the same or better results.[31] If animals are used for the development of alternatives, we presume that researchers have to apply for an animal experimentation license from Swiss cantonal authorities and comply with the validation requirements. Both prerequisites have to be addressed in detail.

1. Harm-Benefit Analysis

Once living animals from one of the species protected by law[32] are used in NAM development, the development process shall comply with the Harm-Benefit Analysis or HBA. The HBA is a test related to the proportionality principle,[33] meaning that a research study involving animals shall be planned and executed with minimal harm caused to the animals while maximizing the potential benefits from the used animals.[34] In general, animal use in research, including NAMs development, shall be beneficial to society by, e.g. improving human health, veterinary medicine, the environment, safety testing and to advance scientific knowledge,[35] however, animal use cannot be solely justified by economic benefit.[36] The HBA is recognized by legislators in Switzerland,[37] the EU[38] as well as numerous international organizations.[39] However, its implementation varies nationally.[40] In Switzerland, the HBA must be carried out both by the applicant (i.e. the researcher) and by the committees on animal experiments or the cantonal animal welfare authorities.[41]

2. Validation Criteria

The use of NAMs is context specific, meaning the method is applied within a defined set of circumstances. What a NAM needs to accomplish may differ if the NAM is to be applied within toxicology screenings or drug development compared to a NAM used in basic research of a disease. Yet, regardless of the specific context of the NAM’s application, it must first be thoroughly validated before it can be safely used. A reference to NAMs and their validation criteria is found in Art. 4 para. 1 of the Therapeutic Products Licensing Requirements Ordinance (TPLRO), which stipulates that the documentation of the evidence for the pharmacological and toxicological tests is also accepted if the tests were carried out using qualified or validated NAMs. However, the question arises as to which NAMs are considered qualified or validated.

In Switzerland, the exact validation process is not explicitly regulated in a law or ordinance, neither by the Federal Council nor by the national authorization and supervisory authority for drugs and medical products (Swissmedic). This inevitably leads to an unclear regulatory situation and does not foster NAMs use, as there is neither a specific law one can turn to for clarity nor are the government bodies giving structured assistance by providing the required information. Additionally, anyone willing to use NAMs faces the risk that Swissmedic will reject the results of pharmacological and toxicological studies, unless they have been carried out on animals.

Although there are no Swiss laws or ordinances in this area, there are both national and international guidelines addressing the validation process of NAMs. However, these guidelines are as context specific as the NAMs themselves. For example, the guidelines by the Organization for Economic Co-operation and Development (OECD) provide information on the validation requirements for the use of NAMs to determine the toxicity of chemicals,[42] whereas the guidelines of the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH)[43] provide a detailed list of validation criteria in the field of pharmaceuticals.[44] In the context of NAMs as a whole, we are of the opinion that the validation criteria set out by the ICH provide a more effective framework for defining the expectations of NAMs, by providing a clear list of criteria that are needed for the validation of any procedure. In contrast to the OECD, the ICH has issued a considerable number of documents in this field, including a wide range of multidisciplinary guidelines as well as guidelines in the areas of quality, safety and efficacy, which allows the ICH and the pharmaceutical industry to serve as an example on how to set forth rules for validation procedures.[45] Furthermore, since the reform of the ICH in 2015, Swissmedic has also been a Standing Regulatory Member of the Management Committee and a member of the Assembly. Thus, Swissmedic experts are involved in various ICH working groups, allowing them to exert a certain influence on the guidelines issued.[46] Based on the connection between Swissmedic and the ICH, Swissmedic also applies these guidelines. This means that manufacturers and researchers in Switzerland can use them as a guidance. Accordingly, the ICH guidelines are the primary source for our analysis of validation requirements.

For the general validation of NAMs, Guidance Q2(R1) “Validation of Analytical Procedures: Text and Methodology” applies. This guideline is intended to provide a formal and general overview of the criteria necessary for regulatory authorities to validate an analytical method.[47] The data generated by the new method should show that the specific NAM is “fit for purpose”.[48] There are various validation criteria that can be used to enable an authority to check whether the results are fit for their intended purpose. It is possible that a method does not need to meet all the criteria if some of them cannot be applied to the method. Q2(R1) defines, among others, the following criteria:

Table 1: Validation criteria and definitions according to ICH Guideline Q2(R1)[49]

The criteria listed in ICH Guideline Q2(R1) are intended to help both manufacturers and regulatory authorities determine whether NAMs used can be considered validated. Furthermore, the Swiss Accreditation Service (SAS) has issued guidelines based on the ICH guidelines that accredited laboratories are obliged to adhere to when performing validation.[50] The guidelines on validation of chemical-physical test methods and estimation of measurement uncertainty are particularly important for laboratories involved in method validation.[51] The content of the guideline is similar to the ICH Q2(R1) guideline and also mentions the criteria listed above. The guideline also states that the objective of test method validation is to provide reproducible evidence that a test method can fulfil the specific test task.

By following the international ICH guidelines and the SAS guideline, any NAMs can be used, for instance, to perform the necessary pharmaceutical and toxicological studies to demonstrate that an active pharmaceutical ingredient can be used safely in humans.

IV. Organoids as NAMs

At present, there is no legal definition of organoid technology. Indeed, even scientists have yet to reach a consensus on how this technology should be defined. Based on the available literature [and expert interviews][52], we identified several key elements of organoids.[53] Accordingly, organoids are “multicellular, stem cell derived three-dimensional structures, which need an extracellular matrix and are able to recapitulate cell types, organ structure and organ function”.

There are numerous fields for the application of organoids. These organoids are — at least to some extent — already used in fundamental research,[54] disease modelling,[55] drug screening[56] or personalized medicine.[57] Organoids are also a solution for therapy development for rare diseases.[58] A lot of work is carried out on organoids in Switzerland.[59] As these mini organ prototypes are a potential alternative to animal testing,[60] they can promote the 3R principle.[61] Swiss universities in their recent report on NAMs[62] draw attention to the development of organoids and their role to promote 3R in many research projects, highlighting their potential as a NAM.

1. Potential

A good example to illustrate the usefulness of organoid use in connection to the 3R principle and especially NAMs is the field of cancer research: Current state-of-the-art animal models such as genetically modified models (GEM)[63] or patient-derived xenografts (PDX)[64] offer the advantage of recapitulating tumor behavior in vivo and demonstrating the efficacy of a drug or intended treatment due to the provided microenvironment.[65] However, there are numerous technical disadvantages associated with their use, even besides the obvious ethical issue of animal use:[66] It is questionable if the results obtained through animal models are truly transferable, as it was established that animal studies cannot accurately predict the potential effects in human studies.[67] Moreover, animal models have shown difficulties in accurately recapitulating the human immune system or even made the evaluation impossible, if immunodeficient mice were used.[68] And lastly, models such as PDX are very costly and take a lot of time to establish, what makes them less suitable for certain purposes like high-throughput drug screenings (HTS).[69]

When focusing on the particular potential of organoids (rather than the shortcomings of animal models) as a means to assess the efficacy of treatment options and guide clinical decisions, several advantages stand out: First of all, human organoids – as a human-derived model – have an inherent advantage by effectively recapitulating parts of the human organism.[70] Patient derived tumor organoids (PDTO) used in cancer research can, for example, faithfully reproduce the histological and molecular characteristics of the original tumor. Second, they can be rapidly expanded from a small sample size and the treatment responses of PDTO correlates to the clinical responses.[71] Third, a comparative analysis conducted by Thorel, Morice et al. showed that among several cancer models, only the PDX and the PDTO models were able to recapitulate the patient tumor heterogeneity.[72] The study also showed that cell lines were more sensitive to certain treatments than the PDX and the PDTO, which suggests that cell lines are not suitable methods when it comes to predictive purposes. The description of the differences between the models showcases the potential of organoids as a NAM and is a good foundation for validation studies and more widespread implementation in clinical trials.[73]

2. Limitations

Despite the organoid technology’s potential as a NAM, there are still numerous limitations in their application that prevent them from effectively replacing animal models. This is particularly true, if NAMs are not purely used for research purposes.[74]

First, there are what could be called “technical limitations”: Organoids are only capable of recapitulating specific parts of an organism. Unlike animals, they are not a closed system. Consequently, they lack critical features such as a full immune system and a vascular system: The immune system is comprised of complex interactions between immune organs, immune cells and proteins that protect the body from diseases.[75] Organoids struggle to recapitulate this complexity and thus may not be fully representing the immune system’s responses, particularly in drug testing scenarios or studies assessing treatment options. The lack of a vascular system, which is generally responsible for cell survival by transporting nutrition, oxygen and waste products to and from the cell, is also a limitation.[76] Without such a system, an organoid may not be a suitable NAM, as the organoid may lack viability and long-term function. To address this limitation, researchers have developed methods of in vitro or in vivo vascularization.[77] In vitro vascularization is either achieved by co-culturing vascular cells or tissue engineering. In vivo vascularization is achieved by implanting the organoid into a host.[78] Whereas the in vitro methods could still be considered potential NAMs, the in vivo approach reverts back to animal experimentation according to Art. 3 of AniWA, as it requires a procedure in which a live animal is used with the aim of obtaining or testing cells and observing the effect of a particular procedure in the animal. Although both methods can provide a degree of vascularization, with the in vivo approach demonstrating better angiogenesis,[79] the limitation of not being a full system can – as of now – not be fully overcome.[80]

Another technical limitation is the fact that most processes of generating organoids currently relies on animal-derived materials, particularly a substrate for culturing organoids called Matrigel.[81] This substance is the secretion of Engelbreth–Holm–Swarm mouse sarcoma cells.[82] Its production thus requires mice carrying a malignant tumor. Matrigel is widely used and has, to date, unmatched properties. Nevertheless, the scientific community is aware alternatives need to be developed and there are efforts to create and make alternatives available.[83] As long as there are no alternatives to Matrigel or other non-animal extracellular matrices for a given experiment or research topic, the use of organoids is not a truly animal-free NAM.

Besides these technical limitations, there are similarly important “practical limitations”, most importantly a perceived lack of incentives to use organoids as NAM. Generally, the research community bears the burden and therefore also the financial risk of developing, validating as well as implementing NAMs. This can lead to a risk/reward imbalance, which may ultimately have the effect that researchers shy away from using NAMs, or organoids in particular, and turn to long-established animal models. The practical limitations are twofold: they require both additional financial and personal commitments. Yet, these limitations also identify points where impactful change could be achieved through appropriate changes to the current systems in place.

a) Financial Commitment

The costs associated with organoid research are largely based on the time and labor required to generate them, and the cost of the necessary materials and infrastructure required.[84] Even if some claim that animal experimentation is just as expensive or even more costly compared to organoids,[85] it may often be easier (and cheaper) to rely on existing infrastructure that is tailored to carrying out animal experiments.

Nevertheless, social and political demand may compel researchers to move towards the use of NAMs. But even if researchers or research institutions are willing to lead the change and invest in NAMs, they face significant challenges.

As indicated above, NAMs need to be validated. They must be considered “fit for purpose” to be supported within regulatory decision-making and must be brought forward within a specific context.[86] In the Swiss context, decisions outside of basic research usually lie within the competence of Swissmedic and the cantonal ethics committees, when it comes to approving clinical trials or a medicinal product. Moreover, the validation of a NAM could only be demonstrated in combination with a specific product or process. This means that NAM developers have to look for industrial partners who are willing to implement and use the NAM in connection with the product in question. For example, NAMs submitted as part of a Swissmedic dossier must already indicate their context of use, e.g. if they are intended for screening of a specific compound in a specific application. This means that a NAMs developer has to find a market for his application in practice before it has a chance of being approved.

These circumstances have two particular effects. First, they mean that researchers have recurring investments for validation every time they intend to use organoids as NAM for a specific product or process. This contrasts with the use of established animal models that – although being used for different products or processes – require fewer recurring investments. Second, and maybe more importantly, an applicant submitting a dossier to Swissmedic involving a NAM, must demonstrate the performance of the NAM in comparison to existing test methods in use. This is often achieved by testing reference compounds for biological endpoints, whose biological activities are well characterized and understood. The NAM must demonstrate that its use will provide information that is as good as or better than the existing method.[87] This means that even if NAMs are potentially applicable to a study, they may need to be combined with animal research in order to prove a potential superiority of the non-animal NAM.[88] Accordingly, applicants face double costs if a NAM is not yet validated; those for the existing method and those for the NAM that they aim to validate.

As the financial risks lie with the researchers, a potential target to affect change would be to create financial incentives. These incentives could be provided by government institutions or private organizations with a focus on implementing the 3R. Current examples of financial government support for projects to investigate and implement NAMs include the National Research Program “Advancing 3R – Animal, research and society” (NRP 79) by the Swiss National Science Foundation[89] and the ValNAM call,[90] which is an initiative by the German Federal Ministry of Education and research and the Dutch organization for knowledge and innovation, healthcare and well-being that was launched in January 2025. Most of the research projects within the NRP 79 focus on the bioscientific development of NAMs whereas the ValNAM call aims to financially support the validation of NAMs. Additionally, the ValNAM call is not only directed at researchers of educational institutions but also commercial organizations, which may serve as a bridge between academia and industry.[91] Regardless of the details of these projects, their support aids to alleviate the financial burdens of researchers, which in turn may help implement and validate NAMs.

b) Personal Commitment

In order to establish a NAM, developers have to generate not only evidence on its robustness, and reliability, but also its applicability in an industrial research and development (R&D) context.[92] This requires additional efforts to bring together different stakeholders like regulatory bodies and industry and convince them about the upsides of a successful NAMs validation. Even if such efforts are successful, they take a lot of time. A good example is the fish cell line acute toxicity test, which uses fish cells instead of living fish itself.[93] The idea to use fish cell lines instead of fish in toxicity studies came about in 1990 and the concept was proven in 2013, showing “that the new fish cell line assay arrives at the same toxicity values for over 30 chemicals as the conventional fish test”.[94] The NAM obtained ISO certification in 2019[95] and OECD recognition in 2021,[96] more than two decades after the initial creation of the idea. This shows that NAM validation is a long process that requires an extraordinary personal investment from the involved researchers or applicants. This personal commitment, however, is not part of their job profile and does not get rewarded, be it financially or through praise and recognition within their peer group or academia. Additionally, Swiss regulatory authorities are not entitled to mandate the use of recognized NAMs by applicants. Furthermore, academia, regulatory bodies and the broader public still perceive animal models as the gold standard for scientific research. It is essential that there is a change in mindset at an individual level if we are to see a commitment from the academic and regulatory communities to the invention, acceptance and implementation of NAMs where it is scientifically possible. This is a time-consuming process that requires the support of both individuals and the public.

One potential avenue for advancing the promotion and wider acceptance of NAMs is through the publication of findings regarding NAMs and animal models, including both positive and especially negative results of their functionality. The publication of negative results should be regarded as a contribution to the scientific community rather than a failure which could influence the personal career of researchers and the ability of the researchers or institutions to obtain future research funding. Encouraging the publication of negative results regarding animal experiments may even be considered a moral and ethical obligation.[97] Publishing negative results and allowing researchers to communicate successful NAM-based experiments or failed animal experiments could greatly improve the recognition as well as the implementation of NAMs. In the case of clinical trials, the preregistration of the studies incentivizes the publications of negative results. Nevertheless, the publication of negative results with animal studies seems to be lagging behind.[98]

c) Regulatory Commitment

Interestingly, even a NAM’s standardization, validation and international acceptance, i.e. from OECD, does not guarantee its acceptance by the authorities. This also applies to Switzerland, where the authority is not per se committed to require the use of validated NAMs. The wording of the relevant provisions (Art. 20 para. 2 AniWA and Art. 137 para. 2 AniPO), which both require “suitable alternative methods” do not extend to the degree that allow authorities to mandate the use of recognized NAMs. Accordingly, the validation, acceptance and standardization of NAMs does not guarantee their widespread use and implementation.[99] Even if validated and accepted NAMs are available, applicants are free to choose between NAMs or animal testing.[100] Although applicants are required to show how their research may not be conducted without using animals, this freedom of choice may be at odds with the constitutionally protected inherent worth of animals. We therefore make a few proposals to encourage the use of NAMs.

Firstly, regulatory authorities could consider offering specific incentives in the event that NAMs are used. One potential approach would be to give priority to the review of applications for medicinal products that are developed using an approved NAM.[101] Secondly, there is currently no unified approach to the acceptance of non-animal data. While there is a strong desire to accept NAMs based on non-animal data, the authorities must eliminate any requests for additional proof of animal research where evidence-based data provides otherwise, effectively making the use of NAMs compulsory. It is important to note that in some fields, such as lung research or specific cancers,[102] animal models do not provide a reliable basis for comparison with human subjects.[103] Lastly, systematic reviews of animal, human and NAM experiments are a promising approach to obtain the required evidence-based data.[104] On the one hand, they allow the regulatory bodies and authorities to effectively back their decisions to accept results of experiments conducted with NAMs. On the other hand, the regulatory bodies would be justified in refusing to approve or accept proposals for new animal experiments. If the existing and future findings of NAM-studies are effectively compiled[105] and made accessible, the regulatory authorities might be compelled to shift their commitment and adopt a more supporting stance towards NAMs.

V. Conclusion and Outlook

The use of organoids as NAMs is encouraged by the 3R principle, which is reflected in Swiss law. Nevertheless, their use still raises many difficult questions. Much like other NAMs, organoids are struggling to achieve widespread implementation. It is currently unknown how widely NAMs are used in practice. Data on available NAMs can be found in many different Swiss[106] and EU[107] competence centers, however, there is an observable lack of statistics specifically on their use.[108]

This paper has shown that irrespective of clear evidence regarding the use of NAMs, there are considerable limitations that stand in the way of their widespread use and implementation. NAM adoption, particularly with regards to organoid models, is not where it could – and maybe should – be. This is particularly disappointing because organoid models have a lot of potential and can contribute to the 3R principle.[109] In view of all the technical and practical obstacles,[110] we come to the sobering conclusion that the reference to NAMs in current law (i.e. Art. 20 para. 2 AniWA and Art. 137 para. 2 AniPO) is no more than a mere declaration of intent. Fortunately, this analysis also provides options for action. Besides the technical aspects that are subject to scientific research,[111] we identify three levers:

Regarding the financial commitment, currently there are little or no incentives for researchers and research institutions to switch to NAMs, irrespective of what the law says.[112] For a NAM to be used, it must be recognized as a validated method that is as good as or better than the existing animal method with regards to a specific product or process. This means that applicants not only bear the costs of validating the NAM but also the costs of using an established reference method. The applicant’s incentives could be improved by setting up specific funding for NAM validation.[113] Art. 22 para. 2 AniWA could be the legal basis of such a scheme.

Researchers and applicants that try to validate NAMs also have a very high personal commitment, which, to date, does not seem to be rewarded by the peer group or the scientific community as a whole. Accordingly, researchers who devote a significant part of their work to convincing stakeholders of their NAMs rather than using it for research, are, quite understandably, still the exception. The creation of a prestigious prize or similar – even non-financial – instruments could encourage more researchers to commit to NAMs and to shoulder this work.

Finally, there is also a lack of regulatory commitment, caused by two main factors: On the one hand, authorities are only starting to familiarize themselves with existing and new NAMs.[114] On the other hand, Swiss law currently has no legal criteria to prescribe the use and implementation of NAMs such as organoids. Art. 20 para. 2 AniWA and Art. 137 para. 2 AniPO are not specific enough[115] and the above-mentioned Art. 22 of the AniWA (calling on the federal government to conduct research on animal welfare and promote the development, accreditation and application of methods that replace animal experiments) is only a programmatic provision with little traction. Against this background even validated, accepted, and standardized NAMs are not widely used and implemented. This would change if either lawmakers or the authorities made clear, that validated or accepted NAMs are deemed “suitable” under the relevant provisions and would mandate their use.[116]

However, there is hope that organoids as NAMs could reduce or someday completely replace animal testing. While there is a long way to go, the proposed measures could serve as steppingstones to turn this hope into reality.

Copyright (c) 2025 Inesa Fausch, Daniel Zeyer-Iyengar, Rosa Maria Cajiga Morales , Bernice Elger, Volker Enzmann, Alfred Früh

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