Revolutionizing drug trials: Amendments and the shift away from animal testing

Emerging ethical concerns

Throughout the 20^th century, ethical concerns about animal welfare started to gain momentum. Activists and scholars raised questions about the ethics of using animals in research.⁷ Several animal welfare organizations were founded, advocating for the humane treatment of animals in experiments.⁸

Importance of drug trials in pharmaceutical research

By generating real-world evidence and driving innovation, drug trials play a pivotal role in improving patient care by developing safe, effective, and innovative medications.

Safety and efficacy assessment

Drug trials in animals and humans are pivotal in determining the safety and effectiveness of new pharmaceutical compounds.⁹ They provide valuable data on potential side effects, dosage regimens, and therapeutic outcomes.¹⁰

Regulatory approval

Regulatory agencies, such as the FDA, EMA, and others, require extensive preclinical and clinical testing before approving new drugs for market release. These trials are essential to ensure that drugs meet rigorous safety and efficacy standards.⁶

Innovation and progress

Drug trials drive innovation in pharmaceuticals. They allow researchers to test new treatment approaches, discover novel therapies, and advance medical knowledge.¹¹ Breakthroughs in drug development often result from successful trials, leading to the introduction of life-saving medications.

Patient welfare

Drug trials offer patients access to cutting-edge treatments, even before they are widely available. Participating in trials can be a lifeline for individuals with serious or rare diseases.¹²

Data generation and scientific understanding

Drug trials generate vast amounts of data, contributing to our understanding of disease mechanisms and treatment strategies.¹³ This data can lead to insights into personalized medicine, tailoring treatments to individual patient profiles.

Statement of the problem

The use of animals in drug testing and biomedical research has long been a subject of ethical debate and concern. Here are some of the key ethical concerns associated with animal testing in pharmaceutical research.

Animal welfare and suffering

Perhaps the most fundamental ethical concern revolves around the welfare and suffering of animals subjected to testing. Experiments can involve pain, distress, and even death for the animals involved.^7,14

Informed consent

Unlike human participants in clinical trials who can provide informed consent, animals cannot voice their consent or dissent. This raises questions about the moral implications of conducting experiments on sentient beings without their consent.¹⁵

Alternative methods

Ethical concerns extend to the availability of alternative methods that could replace or reduce the use of animals in experiments. Failing to explore and implement these alternatives is seen as ethically problematic.¹⁶

Translational validity

The ethical debate also encompasses the issue of translational validity, how well results from animal experiments can be extrapolated to humans. Concerns arise when the outcomes of animal tests do not reliably predict human responses, potentially leading to ineffective or unsafe treatments.^17-19

Humane endpoints

Ethical guidelines often emphasize the need to establish humane endpoints in animal testing, which define criteria for ending an experiment if an animal experiences severe suffering or distress. Adherence to these endpoints is vital but not always enforced.²⁰

Legislative changes

An amendment to the New Drugs and Clinical Trial Rules (2023), recently passed by the Government of India, aims to replace the use of animals in research, especially in drug testing. The amendment authorizes researchers to instead use non-animal and human-relevant methods, including technologies like 3D organoids, organs-on-chip, and advanced computational methods, to test the safety and efficacy of new drugs.²¹

International influence

International organizations and collaborations, such as the European Union’s ban on cosmetics tested on animals and global pressure for ethical research practices, influenced India’s decision. The US Congress has passed the FDA Modernization Act 2.0, which no longer requires new drugs to undergo animal testing before human trials.^22,23 Similarly, South Korea introduced a bill called the “Vitalization of Development, Dissemination, and Use of Alternatives to Animal Testing Methods”.²⁴ In June 2023, Canada amended its Environmental Protection Act to replace, reduce, or refine the use of vertebrate animals in toxicity testing.²⁵

Ethical considerations

India’s ban on animal testing underscores the nation’s commitment to promoting ethical research practices, acknowledging the concerns related to animal welfare and the validity of such experiments.

Shift towards alternatives

The ban has catalyzed a shift towards exploring and implementing alternative methods in drug trials. India’s research community has been increasingly embracing technologies like in vitro testing, computer modelling, and human clinical trials to replace animal testing [Figure 2].²⁶

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Figure 2:

Factors leading to the ban on animal testing in India.

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Global impact

India’s stance on animal testing in drug trials has not only influenced its domestic research landscape but also had a global impact, contributing to a broader shift in pharmaceutical research ethics.

Alternatives to animal testing

New Approach Methods or NAM refers to innovative techniques, tools, and approaches that aim to replace, reduce, or refine the use of animals in scientific research.²⁹ These methods are part of the broader framework known as the “3Rs” principle: Replacement, Reduction, and Refinement.³⁰ NAMs include various strategies such as in vitro models, computational modelling, organ-on-a-chip (OOC) technology, and alternative testing methods.

3-D cell cultures

The integration of three-dimensional (3D) cell cultures into drug discovery processes marks a significant leap forward in preclinical study accuracy. Their ability to mimic in vivo physiology more accurately than 2D cultures results in a more reliable prediction of a drug’s efficacy or toxicity. This reliability is crucial in mitigating the risks associated with false negatives or positives that often arise from animal studies.³¹

Organ-on-a-chip

The OOC technology is a transformative force in pharmacology and drug development, offering a microfluidic platform that replicates human organ functions with high fidelity. The application of OOCs in drug discovery encompasses disease modelling, target identification, and validation, leading to more efficient lead selection and safety assessment. These chips can replicate disease states and genetic disorders, providing a platform for testing drug toxicity and identifying biomarkers crucial for drug discoveries.^32,33

Quantitative structure-activity relationship (QSAR) modelling

Quantitative Structure-Activity Relationship (QSAR) models are a cornerstone in modern drug discovery, utilizing mathematical algorithms to predict the biological activity of compounds based on their chemical structures. By correlating structural features with pharmacological effects, QSAR models facilitate the identification of promising drug candidates early in the discovery phase. This predictive capability is particularly valuable in lead optimization, where it aids in refining the chemical structure of compounds to enhance their efficacy and safety profiles. The application of QSAR models extends to various stages of drug development, including hit and lead discovery, virtual screening, and the prediction of drug-like properties. These models are instrumental in prioritizing vast libraries of compounds, focusing experimental efforts on those with the highest potential for success.^34,35

Artificial intelligence (AI)

Machine learning algorithms, a subset of artificial intelligence, are particularly adept at uncovering patterns and insights within large volumes of data. AI-driven platforms complement machine learning by providing a framework for integrating various data sources, including genomic, proteomic, and clinical data. This integration facilitates a more comprehensive understanding of disease mechanisms and drug interactions, crucial for the development of targeted therapies.^36-39

Organoids

Organoids, derived from human cells, are miniaturized and simplified models that replicate the functionality of organs. They enable researchers to study the effects of drugs on an individual’s unique cellular makeup, paving the way for tailored therapies that are more effective and have fewer side effects. In disease modelling, organoids serve as a powerful platform for understanding the progression and treatment of various conditions. They allow for the simulation of disease states in a controlled environment, facilitating the discovery of new therapeutic targets and the evaluation of drug responses.^40,41

Multi-organ Micro-physiological systems (MPS)

Multi-Organ Microphysiological Systems (MPS) represent a significant stride in the field of pharmacology, providing a comprehensive platform to simulate the systemic effects of drugs on the human body. The interconnected nature of MPS allows for the observation of drug responses across multiple organ systems, offering a more accurate prediction of systemic effects than could be achieved with isolated organ models. This is particularly crucial for understanding the pharmacokinetics and pharmacodynamics of drugs, as it accounts for the complex interplay between different organ systems.^42,43

Clinical trial alternatives

Biomarker Discovery: Advanced molecular techniques facilitate the identification of biomarkers that predict patient responses to drugs, enabling more personalized treatment strategies.⁴⁴ Human Challenge Trials: In controlled settings, volunteers are intentionally exposed to pathogens to study the effectiveness of vaccines and treatments. While ethically challenging, these trials can provide valuable data in a shorter timeframe.⁴⁵

Advantages of alternative methods for drug testing

The adoption of alternative methods in drug testing heralds a significant advancement in pharmacology research. These methods offer compelling advantages over traditional animal experimentation.

Ethical considerations

One of the most significant advantages is the ethical aspect. Alternative methods reduce or eliminate the need for animal testing, which raises ethical concerns related to animal welfare.

Human relevance

Many alternative methods, such as 3D cell cultures, organoids, and OOCs, provide a more physiologically relevant environment for drug testing. This improves the accuracy of predicting human responses to drugs.⁴⁶

Cost efficiency

In the long run, alternative methods can be more cost-effective than traditional animal testing. They reduce the expenses associated with the care and maintenance of laboratory animals.⁴⁷

Speed and efficiency

Computational models and artificial intelligence can significantly speed up the drug discovery process by rapidly analyzing vast datasets and predicting drug interactions and outcomes.⁴⁸

Personalized medicine

Alternative methods, such as organoids, enable personalized drug testing, where treatments can be tailored to an individual’s unique genetic and physiological characteristics.

Reduced variability

Alternative methods often yield more consistent and reproducible results compared to animal studies, where factors like genetics and housing conditions can introduce variability.⁴⁹

Disadvantages of alternative methods for drug testing

Despite their potential advantages, alternative methods for drug testing also come with inherent disadvantages that must be carefully considered.

Complexity and limitations

Some alternative methods, especially complex ones like multi-organ MPS, can be technically challenging to develop and maintain. They may not fully replicate the complexity of the human body.⁵⁰

Validation and acceptance

Regulatory acceptance and validation of alternative methods can be a lengthy and challenging process. There’s a need for standardized protocols and validation studies to demonstrate their reliability.⁵¹

Human variability

Even with advances in in vitro models, there may still be limitations in capturing the full spectrum of human variability in drug responses, which can be more diverse than animal models.⁵²

Computational limitations

Computational models and artificial intelligence systems are only as good as the data they are trained on. Biased or incomplete datasets can lead to inaccurate predictions.⁵³

Human challenge trials: ethical concerns

Human challenge trials, although faster, raise ethical concerns about intentionally exposing volunteers to potentially harmful pathogens, even with informed consent.⁵⁴

ZMapp (Ebola Treatment)

Background: ZMapp is a therapeutic antibody cocktail developed to combat the Ebola virus.⁵⁵

Approach: The development of ZMapp involved the use of tobacco plants to produce monoclonal antibodies rather than traditional animal models.

Outcome: ZMapp showed promising results in preclinical studies and gained attention during the Ebola outbreak in West Africa. While it faced challenges in large-scale production, it demonstrated the potential of plant-based systems as alternatives to animal testing in drug development.

Organs-on-chips (Various applications)

Background: OOCs are microfluidic cell culture devices that mimic the structure and function of human organs, offering a platform for drug testing and disease modelling.

Approach: Developed by researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University, OOCs enable the study of human physiology and drug responses in vitro.⁵⁶

Outcome: These innovative platforms have been utilized in various drug development efforts, including testing of cancer therapeutics, assessing drug toxicity, and modelling diseases such as asthma and Parkinson’s.⁴⁶ They provide more accurate and relevant data compared to traditional animal models, accelerating the drug discovery process while reducing reliance on animal testing.

Tox21 (Toxicity testing)

Background: Tox21 is a collaborative initiative involving the National Institutes of Health (NIH), National Toxicology Program (NTP), National Centre for Advancing Translational Sciences (NCATS), U.S. FDA, National Centre for Computational Toxicology, aimed at revolutionizing toxicity testing.⁵⁷

Approach: Tox21 employs high-throughput screening assays and computational models to evaluate the toxicity of chemicals and potential environmental hazards, replacing traditional animal testing methods.

Outcome: This initiative has led to the development of predictive models for assessing chemical toxicity, enabling more efficient and cost-effective safety evaluations for regulatory purposes. By reducing the reliance on animal testing, Tox21 promotes the use of alternative methods to prioritize human health and environmental safety.⁵⁸

SkinEthic (Cosmetics testing)

Background: SkinEthic is a reconstructed human epidermis model developed by the French company Episkin for cosmetic testing purposes.⁵⁹

Approach: SkinEthic consists of human-derived skin cells cultured into a three-dimensional model that closely mimics the structure and function of human skin. It is used to assess the safety and efficacy of cosmetic products without the need for animal testing.

Outcome: SkinEthic has been widely adopted by cosmetic companies worldwide as a reliable alternative to animal testing for evaluating skin irritation, corrosion, and other endpoints.⁶⁰

Tissue-engineered skin substitutes (TESS) for burn wound healing

Background: Tissue-engineered skin substitutes (TESS) are developed using cultured human cells and biomaterial scaffolds to promote wound healing in burn patients.

Approach: TESS is produced through in vitro cultivation of keratinocytes and fibroblasts on biocompatible matrices, avoiding the need for animal-derived materials.

Outcome: TESS has been successfully used in clinical practice to treat burn wounds, providing a functional and cosmetically acceptable alternative to traditional skin grafts. Studies have demonstrated the efficacy and safety of TESS in promoting wound closure and improving patient outcomes.⁶¹

Personalized cancer immunotherapy

Background: Personalized cancer immunotherapy utilizes a patient’s own immune cells, such as T-cells, genetically engineered to target and destroy cancer cells.

Approach: In vitro methods are employed to expand and modify patient-derived immune cells ex vivo, enabling precise targeting of tumor antigens without relying on animal models.

Outcome: Personalized cancer immunotherapy, including chimeric antigen receptor (CAR) T-cell therapy, has revolutionized cancer treatment. Clinical trials and real-world applications have demonstrated remarkable efficacy in patients with hematologic malignancies and solid tumors, leading to FDA approvals for several CAR T-cell therapies.⁶²

Organoids for drug screening and disease modelling

Background: Organoids are 3D cell culture models derived from patient tissues or stem cells, mimicking the structure and function of human organs.

Approach: Organoids are generated through in vitro differentiation and self-organization of pluripotent or tissue-specific stem cells, providing a physiologically relevant platform for drug testing and disease modelling.

Outcome: Organoids have been instrumental in advancing precision medicine and drug discovery. They have been used to screen potential therapeutics, study disease mechanisms, and predict patient responses to treatment. Clinical studies have validated the utility of organoids in guiding treatment decisions for patients with gastrointestinal, pancreatic, and other cancers.⁶³

Future directions and recommendations

The transition away from animal-based drug testing in India requires a coordinated, multi-stakeholder approach grounded in clearly defined roles, actionable strategies, and strong implementation mechanisms. To ensure lasting and ethical transformation, it is imperative that academia, industry, and regulatory bodies work in synergy to establish a sustainable framework for the adoption of non-animal testing methodologies.

Academia responsibility

Academic institutions must lead in shaping the ethical mindset and scientific skillset required for the next generation of researchers. This includes integrating New Approach Methodologies (NAMs) and bioethics into pharmacology, life sciences, and biomedical curricula.

Recommended actions

Introduce specialized modules on alternative testing methods (e.g., organoids, computational models) in postgraduate and doctoral programs.

Establish interdisciplinary research centers focused on NAMs, involving pharmacologists, toxicologists, biotechnologists, and AI experts.

Promote student and faculty-led research in human-relevant testing platforms with seed funding and mentorship support.

Pharmaceutical industry responsibilities

The industry must ensure the implementation of validated alternatives to animal testing through investment, innovation, and ethical leadership.

Recommended actions

Partner with academic institutions, startups, and global leaders in organ-on-chip, 3D-tissue models, and AI-driven toxicity platforms.

Adopt transparency by publicly reporting preclinical models used and efforts to reduce animal use.

Government and regulatory Bodies’ responsibilities (CDSCO, ICMR, DBT, NITI Aayog)

Regulatory agencies must create enabling frameworks that facilitate the adoption, validation, and mainstreaming of non-animal testing strategies.

Recommended actions

Launch targeted funding calls under DBT/BIRAC to support the development and scale-up of organoids, AI toxicology tools, and in vitro platforms.

Integrate validated NAMs into regulatory approval pathways (e.g., CDSCO Schedule Y revisions).

Mandate ethical justification and humane endpoint documentation for any remaining animal use in research.

Actionable strategies for implementation

To drive progress, India should adopt well-defined strategies informed by both global practices and local research capacity:

Policy and regulation

India should accelerate the regulatory review process for drugs evaluated using validated non-animal methods, establish a national database of approved alternative models as a reference for researchers and reviewers, and require mandatory disclosure and ethical justification for any proposed animal use in Investigational New Drug (IND) applications.

Research and collaboration

India should promote collaborative initiatives between academia and industry in cutting-edge fields such as organ-on-chip technology and microphysiological systems and establish national validation centers to evaluate and approve emerging alternative methods, drawing inspiration from international models like EURL ECVAM.

Global inspiration

Alignment with international frameworks.

Funding support

Launch a unified funding platform (via DBT, BIRAC, and NITI Aayog) dedicated to research in organoid systems, AI-based drug testing, and 3D culture technologies. Offer financial incentives and tax benefits to firms investing in validated alternatives.

Regulatory benefits

Provide priority processing and reduced fees for applications using recognized non-animal methods. Develop comprehensive guidance to support researchers in using NAMs.

Monitoring and oversight

Establish a CDSCO-led advisory committee of experts to oversee adoption and progress. Implement periodic reviews of IAECs to ensure compliance with the 3Rs (Replace, Reduce, Refine) and promote accountability.