Recent efforts to elucidate the scientific validity of animal-based drug tests by the pharmaceutical industry, pro-testing lobby groups, and animal welfare organisations.

BACKGROUND: Even after several decades of human drug development, there remains an absence of published, substantial, comprehensive data to validate the use of animals in preclinical drug testing, and to point to their predictive nature with regard to human safety/toxicity and efficacy. Two recent papers, authored by pharmaceutical industry scientists, added to the few substantive publications that exist. In this brief article, we discuss both these papers, as well as our own series of three papers on the subject, and also various views and criticisms of lobby groups that advocate the animal testing of new drugs. MAIN TEXT: We argue that there still remains no published evidence to support the current regulatory paradigm of animal testing in supporting safe entry to clinical trials. In fact, the data in these recent studies, as well as in our own studies, support the contention that tests on rodents, dogs and monkeys provide next to no evidential weight to the probability of there being a lack of human toxicity, when there is no apparent toxicity in the animals. CONCLUSION: Based on these data, and in particular on this finding, it must be concluded that animal drug tests are therefore not fit for their stated purpose. At the very least, it is now incumbent on-and we very much encourage-the pharmaceutical industry and its regulators to commission, conduct and/or facilitate further independent studies involving the use of substantial proprietary data.

Predicting human drug toxicity and safety via animal tests: can any one species predict drug toxicity in any other, and do monkeys help?

Animals are still widely used in drug development and safety tests, despite evidence for their lack of predictive value. In this regard, we recently showed, by producing Likelihood Ratios (LRs) for an extensive data set of over 3,000 drugs with both animal and human data, that the absence of toxicity in animals provides little or virtually no evidential weight that adverse drug reactions will also be absent in humans. While our analyses suggest that the presence of toxicity in one species may sometimes add evidential weight for risk of toxicity in another, the LRs are extremely inconsistent, varying substantially for different classes of drugs. Here, we present further data from analyses of other species pairs, including non-human primates (NHPs), which support our previous conclusions, and also show in particular that test results inferring an absence of toxicity in one species provide no evidential weight with regard to toxicity in any other species, even when data from NHPs and humans are compared. Our results for species including humans, NHPs, dogs, mice, rabbits, and rats, have major implications for the value of animal tests in predicting human toxicity, and demand that human-focused alternative methods are adopted in their place as a matter of urgency.

An analysis of the use of animal models in predicting human toxicology and drug safety.

Animal use continues to be central to preclinical drug development, in spite of a lack of its demonstrable validity. The current nadir of new drug approvals and the drying-up of pipelines may be a direct consequence of this. To estimate the evidential weight given by animal data to the probability that a new drug may be toxic to humans, we have calculated Likelihood Ratios (LRs) for an extensive data set of 2,366 drugs, for which both animal and human data are available, including tissue-level effects and MedDRA Level 1-4 biomedical observations. This was done for three preclinical species (rat, mouse and rabbit), to augment our previously-published analysis of canine data. In common with our dog analysis, the resulting LRs show: a) that the absence of toxicity in the animal provides little or virtually no evidential weight that adverse drug reactions (ADRs) will also be absent in humans; and b) that, while the presence of toxicity in these species can add considerable evidential weight for human risk, the LRs are extremely inconsistent, varying by over two orders of magnitude for different classes of compounds and their effects. Therefore, our results for these additional preclinical species have important implications for their use in predicting human toxicity, and suggest that alternative methods are urgently required.

An analysis of the use of dogs in predicting human toxicology and drug safety.

Dogs remain the main non-rodent species in preclinical drug development. Despite the current dearth of new drug approvals and meagre pipelines, this continues, with little supportive evidence of its value or necessity. To estimate the evidential weight provided by canine data to the probability that a new drug may be toxic to humans, we have calculated Likelihood Ratios (LRs) for an extensive dataset of 2,366 drugs with both animal and human data, including tissue-level effects and Medical Dictionary for Regulatory Activities (MedDRA) Level 1-4 biomedical observations. The resulting LRs show that the absence of toxicity in dogs provides virtually no evidence that adverse drug reactions (ADRs) will also be absent in humans. While the LRs suggest that the presence of toxic effects in dogs can provide considerable evidential weight for a risk of potential ADRs in humans, this is highly inconsistent, varying by over two orders of magnitude for different classes of compounds and their effects. Our results therefore have important implications for the value of the dog in predicting human toxicity, and suggest that alternative methods are urgently required.

Translation of new technologies: from basic research to drug discovery and development.

Despite increasing investment in drug discovery and development, only around one in every ten new medicinal products that progresses to clinical testing ever reach from the registration stage. Approximately half of all drug failures are attributed to problems with efficacy and toxicity not anticipated from preclinical studies. As a consequence, the pharmaceutical industry is adopting a much more flexible and multi-disciplinary approach to drug discovery and development. Indeed, the line between basic and applied science is constantly being eroded, not least because of the increasing sophistication of therapeutic procedures and the complexity of the diseases that they aim to treat. Here, we look at the new technologies that are being explored as a way of reducing drug attrition rates and the development of chemical drugs and biotherapeutics. Specifically, we will consider the ways in which genomics and related disciplines, engineered cell-based and microfluidics systems, and nanotechnologies are being developed and used alongside in silico platforms during early drug pharmacokinetics and toxicity studies. The way in which information from such systems biology-oriented approaches can be integrated with information from animal based preclinical safety, toxicological and pharmacological studies on investigative medicinal products is considered, in view of its current and possible impact on clinical trial design.

The use of non-human primates in regulatory toxicology: comments submitted by FRAME to the Home Office.

The Home Office have circulated a document that summarises the discussions of a Primate Stakeholders Forum. The Forum took place in January 2004, and was convened to address the issues raised and the recommendations made in the Animal Procedures Committee 2002 report on the use of primates under the Animals (Scientific Procedures) Act 1986. The report emphasises the need for more resources focused on alternatives to toxicological testing in primates, including harmonising worldwide regulatory requirements, investigating the relevance of primate models, and improving the retrospective analysis of procedures involving primates. The document called for reasoned comments about the report to be submitted to the Home Office. In response, FRAME submitted a comprehensive paper, which evaluated each of the Animal Procedures Committees recommendations, along with the Home Office Forums comments. FRAME believes that, in coming to a decision as to whether primates should be used for regulatory testing, there must be full consideration of all the information available, including whether the ethological needs of any given species can be met prior to, during and following experimental use. Where these needs cannot be met, there must be a concerted effort to develop alternative models for research and testing. However, this should not detract from the ultimate goal of phasing out primate research altogether.

The establishment of ECVAM and its progress since 1993.

The background to the establishment of ECVAM in 1991 is summarised, and progress made since 1993 is briefly reviewed in relation to 12 recommendations made at the ECVAM Opening Symposium in 1994 and to statements on tests for chemicals and biologicals endorsed by the ECVAM Scientific Advisory Committee since 1997.