Clinical Research - Testing times

Testing times

Last year the UK experienced a 14% jump in animal experiments. Katrina Megget looks at this sensitive issue

Over the past few years, animal experiments for research and product safety have increased dramatically in the UK. Last year’s figures show a 14% jump in animal testing procedures, which is the biggest rise in more than five years and is more than double the 2007 increase. Animal welfare groups have condemned the figures, calling them “shocking”, “an outrage”, and “extremely concerning”. But there is more to the increase than just a percentage.

The 2008 figures, published by the Home Office, show the number of procedures started in 2008 reached 3,656,080, up from around 3.2 million in 2007. There was also an increase in the use of turkeys by 135%, pigs 114%, fish 85%, amphibians 81%, non-human primates 16%, and mice 9%. However, there were also decreases, such as ‘new-world’ primates, where use dropped by 53%, beagles were down 17%, rabbits 13%, and rats 8%.

But these fluctuations are not the only important ones. The use of genetically modified animals increased by 16%, and made up 38% of all animal procedures. And while toxicological procedures increased by 16% from 2007, they only accounted for 13% of the total procedures in 2008. In 1995, by comparison, toxicological procedures accounted for 25% of the total.

So what does this mean?

According to the Association of the British Pharmaceutical Industry (ABPI), the jump in procedures in the past year reflects increased investment in R&D and the development of more complex targeted therapies – “in large part down to the success of the scientific community working in the UK”. Indeed, Understanding Animal Research (UAR), the pro-animal research organisation formed at the end of last year from the Research Defence Society and the Coalition for Medical Progress, points out that biomedical research increased by more than 50% in the decade to 2006.

However, it is too quick to jump to the conclusion that like-for-like increase in animal experiments follows an increase in R&D, and both the ABPI and UAR say animal testing has not followed the same rate of increase as R&D because of the pressure to reduce animal research. For instance, the 50% figure mentioned by UAR was only matched by a 12.5% increase in animal procedures over the same 10-year period, it says.

‘Roadmap to replacement’

Yet, animal welfare groups are calling for more to be done. In response to the announcement of the 2008 figures, the Dr Hadwen Trust for Humane Research, a non-animal medical research charity, wrote to the UK’s political parties asking for them to commit to a ‘roadmap to replacement’ that would see increased funding, research and technology development leading to reducing and replacing animal experiments.

But the idea of replacing animal experiments is not a new one. Indeed, 2009 marks the 50-year anniversary of the concept of the ‘Three Rs’ – ‘Replace’ animals with non-animal alternatives, ‘Refine’ testing procedures to minimise pain and suffering and improve welfare, and ‘Reduce’ the number of animals used in experiments. In May 2004, the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) was established by the UK Government to do just that and provide funding to put the 3Rs into practice. Since its establishment, the Centre’s total investment in refinement and reduction, as well as replacement of live animals in the laboratory has reached nearly £13 million. The pharmaceutical industry has also played its role, spending an estimated £300 million a year on developing alternatives to replace animals over the past 10-15 years.

So has this funding failed to hit its target, considering the UK has seen its seventh year of consecutive rises in animal procedures? Dr Sebastien Farnaud, Science Director at the Dr Hadwen Trust, says while the efforts are not failing, “it has to be considered that funding to the NC3Rs still amounts to a very small proportion of all funding awarded for research in the UK”. There is also the issue that statistics focus on animal use and not on the numbers of procedures where there has been replacement or reduction.

Meanwhile, it has been suggested the pace at which alternatives are developed is outstripped by the demand for animal research. Indeed, the Dr Hadwen Trust has held the opinion in the past that funding and research efforts have been too narrowly focused and so have not impacted on the majority of research where animals are used. Dr Farnaud adds: “The increase in animal use suggests a lack of replacement innovation and a lack of will to move forward from traditional animal methods.”

However, it is important to consider the latest figures. As Barbara Davies, Communications Director at UAR, says, the fact that the increase in R&D is not followed by a like-for-like rise in animal testing “suggests that ‘alternatives’ are playing a greater part in research”. Furthermore, she says this year’s increase in mice and fish reflects the fact that they are being used to breed better models for serious illnesses such as cancer or Alzheimer’s disease, or to replace higher animals such as monkeys or dogs.

A lack of alternatives

Despite this, there is a lack of non-animal alternatives, particularly for more complex medicines and for advanced stages of screening. While computer simulations and in vitro systems, such as cell cultures, are being used in early medicines discovery, in many cases animal models still provide the best procedures to view how medicines operate in a whole body system.

“The advance of science has led to new classes of medicines which target disease with much greater accuracy. Most research is still done traditionally in test tubes, but this accuracy means new medicines have to be tested in final stages on animals that are much closer to humans to show they work and they are safe,” says the ABPI. “This is the reason why the number of non-human primates has risen this year and is likely to rise next year.” The same can be said for the increase in the use of genetically modified animals, which help characterise human genes and create better animal models of diseases.

The other factor is that by law animal tests are required in many cases before medicines can be trialled in humans – and this is a sentiment that has been echoed by the European Commission, which has said it is currently not feasible either to ban the use of animals or to establish a timeline to phase out some animal tests, such as the use of non-human primates. The law also says that if an alternative method exists it must be used. But, says Davies, “the law does not provide a mechanism to reduce use of animals overall – animal use will depend on unmet clinical need and advances in science and technology”. The ABPI is candid in its opinion of the use of animals in research. “The choice is a stark one,” it says. “If animals can’t be used in research, there will be far fewer new medicines and safety cannot be assured.”

However, non-animal research groups argue this is not necessarily the case and they call into question the relevance of animal models when translating data for human trials. According to the Dr Hadwen Trust, more than 90% of drugs that pass animal tests ultimately fail to be suitable for humans. Meanwhile, the European Coalition to End Animal Experiments (ECEAE) says more than 80 AIDS vaccines successfully tested in primates have not worked in humans, while some 150 neuroprotective stroke treatments that have progressed to human trials have met the same fate. Several published reviews have also suggested animal studies may be poor predictors of drug side effects once moved into human clinical trials.

One of the more notorious examples is the 2006 Northwick Park incident where human trials of the monoclonal antibody TGN1412, manufactured by TeGenero, saw the hospitalisation of six men after the drug seemingly over-stimulated the immune system and led to organ damage. The drug had been tested on rodents, dogs and monkeys, but these tests did not predict the side effects in the human trials. The Medicine and Healthcare products Regulatory Agency concluded in its final report on the incident that preclinical studies in monkeys “did not predict a safe dose for use in humans, even though current regulatory requirements were met”. Indeed, some experts have since said the researchers were lulled into a false sense of security by the animal tests.

In a submission to the expert group reviewing the incident, the Dr Hadwen Trust “denounced an over-reliance on pre-clinical information from animal studies to assess the safety of new medicines”. Dr Farnaud says: “Although the incident did prompt some people to call for more extensive pre-clinical animal tests, we believe this would be a serious mistake since tests in other species have limited predictive power for humans. In the long-term, the consequences could include further risks to volunteers and a fall in the number of people willing to participate in essential clinical trials.”

But, says Davies, there are around 300 clinical trials every year in the UK, yet incidents like Northwick Park are rare partly because of the use of animal tests. “To suggest that we should abandon some tests because they are not 100% perfect is like saying we should stop wearing seatbelts because they do not prevent all injuries… Animal disease models are just that – models – but they are the best way of modelling human diseases apart from using patients themselves, which in most circumstances is not ethical or possible.” Indeed, Davies goes as far as to say that if animal testing were to become too restrictive it is likely more incidents like Northwick Park would occur.

The European Directive 86/609 on animal experimentation is currently being revised to strengthen the protection of animals and to explicitly address the 3Rs. The Council of Ministers is still to discuss the proposed revisions, which many animal welfare lobby groups have argued have been weakened to appease the animal research industry. But industry is concerned that some aspects of the revisions will adversely affect research in Europe. Says Davies: “The bioscience sector has made its concerns known, as have antivivisection groups. No-one wants a ‘watered down’ Directive, but any new provisions must aim to better harmonise member state laws, be proportionate, maintain our ability to carry out good scientific and medical research and maintain scientific and commercial competitiveness.” Indeed, the European Commission hopes “the revision will greatly improve the quality of scientific research, boost innovation and promote the development of alternative methods”.

But in the meantime, it is expected the current trends in animal experiments may continue for some years to come.

Replacement successes

TESTING CHEMICALS

In 2007, R&D into non-animal tests to check the safety of chemicals and cosmetics on the skin showed that small discs of artificial human skin can effectively replace the regulatory Draize skin irritation test. The new test-tube method will save the lives of an estimated 20,000 rabbits due to be used for testing the skin irritancy of chemicals and cosmetics throughout Europe, and will also improve chemical safety, as it’s considered more accurate than rabbit tests. ECVAM (the European Centre for the Validation of Alternative Methods) has validated and endorsed the new tests.

SAFE INJECTABLE MEDICINES

New tests using human blood cells are quicker, cheaper, more adaptable and more sensitive than rabbit experiments for ensuring that injectable medicines are free from bacterial contamination. The European Commission estimates that 200,000 rabbit tests will be replaced in Europe as a result. The standard animal test, introduced in the 1940s, measures fever response in rabbits restrained in stocks. Some rabbits suffer fever, respiratory problems, organ failure or fatal shock. Additionally, the rabbit test is relatively insensitive, time-consuming and costly, and unsuitable for many new medicines. Better understanding of the human fever reaction, together with advances in cell biology, led to the development of the new test-tube techniques, which use human blood cells. Until recently, few people believed that a complex whole-body reaction such as fever would ever be transferred to the test tube.

BOTULINUM TOXIN TESTING

In Lethal Dose 50% (LD50) tests, groups of animals are dosed with different amounts of a test substance to identify the dose at which 50% die. LD50 tests are conducted routinely on tens of thousands of mice each year to standardise the potency of batches of Botulinum toxin. This toxin is used medically to treat neuromuscular conditions (and cosmetically as an anti-wrinkle treatment). Some mice used in these tests develop paralysis, first in the legs but then in the breathing muscles, causing them to die from suffocation. The SNAP-25 test – part funded by the Dr Hadwen Trust – is a non-animal replacement that is faster, cheaper and more sensitive than the mouse assay. The replacement test, which has already saved thousands of mice, uses a synthetic protein in the test tube and has been approved for final potency testing of botulinum toxin batches.

VACCINE BATCH TESTING

The potency of batches of yellow fever vaccine used to be tested by a lethal method requiring injection into the brains of mice. The cell culture replacement is more sensitive, practical and reproducible, and continues to save about 1,500 mice each year from severe tests.

Katrina Megget is an independent healthcare writer