A comprehensive study of all of the clinical trials for Alzheimer’s drugs in the US has highlighted a very high failure rate of the drugs being tested. The study found that 99.6% of trials of potential Alzheimer’s treatments aimed at preventing, curing or improving the symptoms of the disease failed or were discontinued. The study is published on 3 July in the journal Alzheimer’s Research and Therapy.
The study was conducted by scientists at the Cleveland Clinic Lou Ruvo Centre for Brain Health and the Touro University Nevada College of Osteopathic Medicine. The researchers used the public access site clinicaltrials.gov to compile a database of all Alzheimer’s drug trials which have occurred in the US over the past decade. They then used the database to determine the outcome of trials at the three clinical phases and for drugs targeting various different mechanisms thought to contribute towards the disease.
The trial was deemed to have failed if there was no difference in symptoms between people who were treated with the drug versus the placebo, or if the side-effects were too severe to continue with the drug. This study found that the vast majority of drugs in all three phases of clinical testing failed during the period of 2002-2012. This includes treatments aimed at reducing the levels of the hallmark proteins amyloid and tau which are present in abnormal formations in the brain in people with Alzheimer’s. Of 244 compounds that were assessed over the ten-year period, only 1 was approved for marketing – the drug memantine which can help with symptoms of the disease.
The study also took into account treatments which are still being tested, known as pipeline drugs. The authors note that there are very few drugs currently being tested, with only 23 compounds in the final phase of testing. There are 108 ongoing trials for Alzheimer’s drugs compared to 1438 trials for cancer drugs. The study concludes that there are too few trials for Alzheimer’s drugs given the huge social and economic impact of the disease.
Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, the UK’s leading dementia research charity, said:
“This study adds to other analyses showing high levels of failure of trials for Alzheimer’s drugs. Whilst the failure rate of clinical trials for cancer is also quite high, at 81%, the 99.6% failure rate in Alzheimer’s disease trials is especially troubling. Alzheimer’s disease is the most common form of dementia, which affects over 820,000 people in the UK and costs the economy £23 billion a year. There are multiple genetic and environmental risk factors for Alzheimer’s, making drug trials for the disease particularly challenging. People with Alzheimer’s are often diagnosed relatively late in the disease process which also means that the best window of opportunity for treatment may have passed. The rising numbers of people with dementia, along with the devastating effect that it has on those affected, mean that despite these setbacks we have to keep dementia at the forefront of clinical trials.
“The authors of the study highlight a worrying decline in the number of clinical trials for Alzheimer’s treatments in more recent years. There is a danger that the high failure rates of trials in the past will discourage pharmaceutical companies from investing in dementia research. We need to use this data to understand the reasons behind the discontinuation of these trials and address those issues. Pharmaceutical companies and other industries need to commit to continued investment in drug development and clinical trials in order to achieve a breakthrough in treating Alzheimer’s and other dementias.
“Alzheimer’s Research UK is continually working to reignite research and development in dementia, to put new treatments into the hands of those who so desperately need them. We are implementing a number of important initiatives, including funding a network of Drug Discovery Institutes and being a part of the Dementia Consortium in partnership with MRC Technology and the pharmaceutical companies Eisai and Lilly. The only way we will successfully defeat dementia is to continue with high-quality, innovative research, improve links with industry and increase investment in clinical trials”.