Examples of drugs which have failed after being considered successful in animaltests
1. In 2006, six men took a drug (known as TGN1412) in a clinical trial at Northwick Park Hospital inLondon, which caused life threatening and disastrous side effects in less than 2 hours ,includingorgan failure and brain swelling . The same drug had previously been given to monkeys at a 500
fold higher dose. The monkeys showed no ill effects and the drug was therefore considered safe toproceed to human trials 1 Since the Northwick park disaster, an alternative, human based toxicity
test has been developed and when TGN1412 was tested, the method was shown to predict andtherefore avoid the side effects seen in the volunteers 2
2. In 2004, a new anti inflammatory drug called rofecoxib (also known under the brand name Vioxx)
was withdrawn from the market over safety concerns, after a reported 88,000-140,000 people
suffered heart attacks from taking the drug3. Vioxx and similar drugs had previously been
considered not only safe, but protective in animal tests 4
3. 150 potential treatments for stroke, considered successful following animal tests have gone onto
fail in human clinical trials 54. Decades of HIV testing in animals have yet to result in a successful vaccine and global prevention
programmes have proved far more effective. In 2013, human trials of an experimental HIV vaccine– that were expanded based on experiments in monkeys – were halted when it was discovered thatthe vaccine did not prevent HIV infection or reduce viral load in those already infected. 6 This is oneof over 80 preventive HIV and therapeutic AIDS vaccines that have progressed through animaltests, only to fail in more than 100 human clinical trials 7
5. In 2007, a new drug to treat Parkinson's disease known as CEP-1347 8 failed clinical trial in humans
after being considered successful in animal tests and further recent examples include Cogane, atrial drug which appeared to be effective against Parkinson's disease in animals, but failed to show
clinical effect in human trials and was announced a failure in 2013. 9
6. Many potential treatments for Alzheimer's diease have failed in recent years, with the rate ofattrition recently being announced as an 'astounding 99.6%' 10. A recent study looked at how 244compounds in 413 clinical trials fared for Alzheimer's disease between 2002 and 2012. Of those 244
compounds, only one was approved. 11 One recent example is the drug Dimebon, which failed toprove effective in human trials which were halted 12 13, despite being considered successful in earlier
animal tests 14
7. A recent US study concluded that of every eight drugs which enter clinical trials, only one will beapproved, with 80% of new drugs being abandoned by drugs companies 15. These findings aresupported by other studies on the failure of animal models to translate into success in clinical trials
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1References

1.

Attarwala, H. (2010) TGN1412: From discovery to disaster J Young Pharm. 2(3):332-6.
http://www.ncbi.nlm.nih.gov/pubmed/21042496
2. Ahmed, S. et al (2014) The use of human (non-3D equivalent) skin assays (Skimune TM) for detectionof adverse reactions, sensitization, potency and efficacy
http://www.animalreplacementscience.com/poster-abstracts/
3. Up to 140,000 heart attacks linked to Vioxx . New Scientist, 2005
http://www.newscientist.com/article/dn6918-up-to-140000-heart-attacks-linked-tovioxx.html#.VTDOWZN9zfY
4. Pippin, J. (2005) The failure of COX-2 inhibitors
https://pcrm.org/pdfs/research/testing/exp/COX2Report.pdf
5. Macleod M. (2005) What can systematic review and meta-analysis tell us about the experimental
data supporting stroke drug development? Int J Neuroprot Neuroregener ; 1: 201
6. http://www.huffingtonpost.com/2013/04/25/experimental-hiv-vaccine-fails-study-haltedhvtn-505_n_3156064.html
7. http://www.niaid.nih.gov/topics/hivaids/understanding/prevention/Pages/clinicalStudies.asp
x
8. Parkinson's Study Group (2007) Mixed lineage kinase inhibitor CEP-1347 fails to delay disability inearly Parkinson disease Neurology. 9;69(15):1480-90.
9. Parkinson's Disease Foundation. Statement on Results of Recent Cogane Clinical Trial
http://www.pdf.org/en/science_news/release/pr_1361290946
10. http://www.fiercebiotech.com/story/alzheimers-rd-suffers-trial-failure-rate-hits-astounding996/2014-07-03
11. Cummings, J. et al (2014) Alzheimer’s disease drug-development pipeline: few candidates, frequent
failures. Alzheimer's Research & Therapy 6:37 http://alzres.com/content/6/4/37#B13
12. Medivation And Pfizer Axe their new Alzheimer's drug Dimebon
http://www.medicalnewstoday.com/articles/240404.php
13. Bezprozvanny, I. (2010) The rise and fall of Dimebon. Drug News Perspect2010 October ; 23(8): 518–523.
[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3922928/pdf/nihms417273.pdf]
14. Lermontova, N. et al. (2000) Dimebon improves learning in animals with experimental Alzheimer's
disease Bull Exp Biol Med. 129(6):544-6. [http://www.ncbi.nlm.nih.gov/pubmed/11022244]

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15. Tufts study: it takes eight drugs in clinical trials to get one approval
http://www.bizjournals.com/boston/blog/bioflash/2014/11/tufts-study-it-takes-eight-drugs-inclinical.html?page=all
16. Mak, I. et al. (2013) Lost in translation: animal models and clinical trials in cancer treatment.
Am J Transl Res 6(2):114-118
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3902221/pdf/ajtr0006-0114.pdf

Research compiled by Rebecca Ram (Clinical Data Scientist and Research Consultant- AnimalWelfare) for the Lush Prize in April 2015.

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