Whenever a vivisection activist is faced with the undeniable truth that animal models are not predictive for human response, or that basic research using animals has a success rate comparable to astrology, he will respond that the law requires animal testing. He is correct in this but what the law requires is not always consistent with what science says is effective.
In an article in The Observer, Robin McKie discusses the use and production of animals for research and testing at Harlan in the UK. Harlan both produces and tests on animals with approximately 6,000 rats and mice being shipped out of Harlan each week. Because of this activity, Harlan has been the target of animal rights activists. Andy Cunningham, a Harlan manager is quoted as justifying Harlan’s existence saying: “Yet EU legislation requires us to use more and more animals for toxicity testing today, while scientists are making more and more key discoveries that require animals for research. We have to have animals if we want to develop new drugs for Alzheimer's and heart disease and to test products used by the public.”
Professor Roger Morris, head of bioscience at King's is also quoted in the article as saying: “You cannot use tissue cultures for such work. You have to test chemicals on an entire living animal to uncover any unexpected side-effects on different organs. Mice and rats are surprisingly similar physiologically to humans and therefore very useful. If we didn't test drugs on rats and mice, there would be a lot more dead people. It is as simple as that.” Neuzi et al state: “Currently, however, the results obtained with new in vitro systems cannot replace animal testing because they do not take into account the complex interactions between different tissues and organs. Animal testing is not ideal either, as the predictive value of such tests is limited owing to metabolic differences between humans and animals . . .” 
Most of what Cunningham, Neuzi et al, and Morris say is correct in what it confirms but wrong in what it denies. In vitro and in silico cannot predict human response except for a few properties. But the fact that in vitro and in silico are not predictive modalities does not mean in vivo is. (This defense of animal testing is called the intact systems argument and I address it here.) Nor are animal models contributing to cures for Alzheimer's and heart disease. They are also wrong in stating that more deaths would result from abandoning animal testing. That is like saying more deaths would result if people stopped using homeopathy or stopped consulting Ouija boards when attempting to make a diagnosis. As homeopathy and Ouija boards are not effective, stopping the practice would have no negative effect at all. The fact is: Pharma has almost no predictive technologies hence the crisis in the drug industry.
I have criticized animal protection organizations (APOs) for focusing on alternatives to using animals in drug development and research in general, instead of pointing out that most uses of animal models are simply not medically productive or effective. The reasons for this criticism are as follows. 1. Most of the animal-based techniques APOs seek to replace through funding for alternatives are not viable in the first place. There is no reason to seek an alternative to an assay or technique that uses intact animals or animal tissues when nothing medically productive is coming from the technique. Most of these uses are in the area of basic research. 2. The use of animals to predict human response to drugs and disease is not viable either but society really does need predictive modalities and Pharma is actively looking for them. The amount of money being spent by Pharma and the government dwarfs anything the APOs can contribute and Pharma knows more about what is needed and how to find it than the nice people that work at APOs. 3. The uses of animals that are productive, such as for replacement parts for humans, do not seem to receive any attention from APOs suggesting once again that most of the people making the funding decisions are incompetent. The areas where APOs could contribute they don’t, and the areas that are outside their expertise, they focus on. (There are rare exceptions.)
Opar, writing in Nature Reviews Drug Discovery, supports my position regarding the lack of predictive modalities in drug development and what is being done about the situation:
The damage hit without warning. Of the 40 healthy volunteers who had enrolled in a Phase I trial for panadiplon, an experimental anxiety drug, 11 quickly showed liver injury, even though rat, dog and monkey studies hadn’t hinted at any toxicity issues. “That was really scary,” says Roger Ulrich, who worked on the study in the 1980s, “we had no idea what would happen to these people.” The individuals recovered, but the agent was killed. Fast forward to 2009, when liver toxicity popped up in a Phase I trial for Gilead’s cancer drug CAL-101. “It was the same boat — we didn’t know what was causing it, or whether these people were in dire straits or not,” says Ulrich, who has 30 years of drug development experience at big and small pharma companies. The elevated liver enzyme levels turned out to be asymptomatic, and the agent has since progressed into Phase III trials.
Drug-induced liver injury (DILI) is the primary reason why companies abandon compounds during development, and risks of idiopathic DILI even as low as 1 in 100,000 treated patients can lead companies to withdraw approved drugs. . . . “Animal models fall short, so a lot of people believe the solution is to humanize drug development,” says Paul Watkins, director of the Hamner-UNC Institute for Drug Safety Sciences and a member of the MIP-DILI external advisory committee.
Opar then describes actions being taken by government and Pharma in order to find predictive technologies. The government is funding research in the area and drug companies are actually coming together to work on the problem. This is a rare event both in the form of government funding a problem that essentially belongs to industry and industry sharing information in an effort to solve the problem.
Opar’s article is available here but probably for a fee.
People that say animal models are predictive for humans are simply wrong. Single predictions that come from hypotheses are not the same as claiming a modality is predictive. The only reasons I can think of that explain why people make this mistake are lack of education or malfeasance. Sadly, those reasons apply to people on both sides of the animals in research debate.
1. Mckie R (2012) Animal activists' terror tactics drive staff out of laboratories. The Observer, July 30 http://www.guardian.co.uk/science/2012/jul/29/animal-activists-terror-tactics-harlan-laboratories-staff?newsfeed=true
2. Neuzi P, Giselbrecht S, Lange K, Huang TJ, Manz A (2012) Revisiting lab-on-a-chip technology for drug discovery. Nature Reviews. Drug Discovery 11:620-632. 10.1038/nrd3799. http://www.ncbi.nlm.nih.gov/pubmed/22850786.
3. Opar A (2012) Overtaking the DILI Model-T. Nat Rev Drug Discov 11:585-586. http://dx.doi.org/10.1038/nrd3818.