The failure rate for the translation of drugs from animal testing to human treatments remains at over 92%, where it has been for the past few decades. The majority of these failures are due to unexpected toxicity — that is, safety issues revealed in human trials that were not apparent in animal tests — or lack of efficacy. However, the use of more innovative tools, such as organs-on-chips, in the preclinical pipeline for drug testing, has revealed that these tools are more able to predict unexpected safety events prior to clinical trials and so can be used for this, as well as for efficacy testing. Here, we review several disease areas, and consider how the use of animal models has failed to offer effective new treatments. We also make some suggestions as to how the more human-relevant new approach methodologies might be applied to address this.

Decades of costly failures in translating drug candidates from preclinical disease models to human therapeutic use warrant reconsideration of the priority placed on animal models in biomedical research. Following an international workshop attended by experts from academia, government institutions, research funding bodies, and the corporate and non-governmental organisation (NGO) sectors, in this consensus report, we analyse, as case studies, five disease areas with major unmet needs for new treatments. In view of the scientifically driven transition towards a human pathways-based paradigm in toxicology, a similar paradigm shift appears to be justified in biomedical research. There is a pressing need for an approach that strategically implements advanced, human biology-based models and tools to understand disease pathways at multiple biological scales. We present recommendations to help achieve this.

This year marks the 60th anniversary of Russell and Burch’s pioneering book, The Principles of Humane Experimental Technique. Their 3Rs framework has helped to inspire humane and scientific progress in experimental technique. However, it is time to update its strategic application. The 21st century has already seen the development of promising, high-tech non-animal models, such as organs-on-a-chip and computational approaches that, in our view, will replace animals as the default option in biomedical experimentation. How fast this transition will take place will depend on the pace at which these new models are optimized to reflect the biology of humans, rather than that of non-human animals. While the new methods are likely to reshape all areas in which animals are currently used in science, we particularly encourage their application in biomedical research, which accounts for the bulk of animals used. We call for the pursuit of a three-prong strategy that focuses on (1) advancing non-animal methods as replacements of animal experiments, (2) applying them to biomedical research, and (3) improving their relevance to human biology. As academics and scientists, we feel that educational efforts targeted at young scientists in training will be an effective and sustainable way to advance this vision. Our strategy may not promise an imminent end to the use of animals in science, but it will bring us closer to an era in which the 3Rs are increasingly perceived as a solution to a receding problem. Russell and Burch themselves surely would have welcomed these positive changes.

The brain is arguably the most powerful computation system known. It is extremely efficient in processing large amounts of information and can discern signals from noise, adapt, and filter faulty information all while running on only 20 watts of power. The human brain's processing efficiency, progressive learning, and plasticity are unmatched by any computer system. Recent advances in stem cell technology have elevated the field of cell culture to higher levels of complexity, such as the development of three-dimensional (3D) brain organoids that recapitulate human brain functionality better than traditional monolayer cell systems. Organoid Intelligence (OI) aims to harness the innate biological capabilities of brain organoids for biocomputing and synthetic intelligence by interfacing them with computer technology. With the latest strides in stem cell technology, bioengineering, and machine learning, we can explore the ability of brain organoids to compute, and store given information (input), execute a task (output), and study how this affects the structural and functional connections in the organoids themselves. Furthermore, understanding how learning generates and changes patterns of connectivity in organoids can shed light on the early stages of cognition in the human brain. Investigating and understanding these concepts is an enormous, multidisciplinary endeavor that necessitates the engagement of both the scientific community and the public. Thus, on Feb 22–24 of 2022, the Johns Hopkins University held the first Organoid Intelligence Workshop to form an OI Community and to lay out the groundwork for the establishment of OI as a new scientific discipline. The potential of OI to revolutionize computing, neurological research, and drug development was discussed, along with a vision and roadmap for its development over the coming decade.

Pain has a profound effect on an animal’s wellbeing. In Germany, researchers using animals have been legally required since 1972 to reduce any possible pain, suffering, distress or lasting harm to an absolute minimum. To evaluate how these provisions have been implemented in practice, an assessment of refinements to experimental techniques was conducted by retrospectively reviewing 684 surgical interventions described in 506 animal research applications that were sent to the German competent authorities for approval in 2010. This paper focuses on the efficacy of proposed anesthesia and peri- and postoperative analgesia. Postoperative analgesia was not proposed for 30 % of surgeries. Following 10 % of procedures, animals were to be given pain relieving medication if the investigators decided this was necessary; however, structured assessments to detect pain were absent. Consequences of unalleviated pain and omission of pain assessment techniques are discussed, and some recommendations to improve anesthesia and analgesia are given. The findings of this review highlight the need for improvement, both to fulfil legal requirements and to improve animal welfare. To monitor compliance with animal welfare regulations, and ensure good veterinary and scientific practices, education and training needs to be intensified. Adherence to the items listed in the PREPARE and ARRIVE guidelines and the Gold Standard Publication checklist (GSPC) should become legally binding.

Refinement refers to the use of methods that help to minimise animal suffering in the laboratory. Research in this area has increased significantly over the past two decades. However, the extent to which refinements are applied in practice is uncertain. To provide an indication of the implementation and awareness of refinements, we reviewed the experimental techniques for 684 surgical interventions described in 506 animal research applications sent to the German competent authorities for approval in 2010. In this paper, we describe and discuss the appropriateness of the proposed humane endpoints and killing methods. We found that, when the investigators included humane endpoints in their application, these were often lacking in detail and/or were to be implemented at a late stage of suffering. In addition, the choice of method to kill the animals could be improved in the majority of the applications. We provide recommendations for future improvements, based on the recent literature. To ensure scientific rigour, avoid needless animal suffering and enable an accurate harm–benefit analysis, animal researchers have to be knowledgeable about refinement methods and apply them effectively. To assess compliance and ensure that only those studies in which potential benefits outweigh the harms are carried out, reviews such as ours — as well as retrospective assessments of actual harms and benefits — should be conducted widely and regularly, and the findings should be published.