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When is a failed clinical trial not a failure?

Dr Laura PhippsKirsty MaraisClaire LucasRobin BrisbourneKaty StubbsEd PinchesGlyn Morris

Back in 2002, the news broke that Elan had halted its phase II clinical trial for the AN1792 vaccine, designed to combat Alzheimer’s. It was a severe disappointment for people with Alzheimer’s and their loved ones. Many hopes had been pinned on the vaccine, and its failure saw those hopes dashed for hundreds of thousands of people. That could have been the end of the story – had it not been for a team of dedicated researchers at the University of Southampton who saw potential for something positive in the outcome.

Originally, the researchers had feared the vaccine may have worsened the disease…but the latest findings show this was not the case.

These scientists, with part-funding from Alzheimer’s Research UK, were able to gain vital access to the data from the original phase I trial, and set about recruiting people who had taken part in the study to be followed up in the long term. With regular clinical assessments, and with many of the participants volunteering to donate their brains after their death, the research team has been steadily gaining more information about the long-term effects of the vaccine on this group of people.

Breathing new life into dementia trials

The latest results from the study have proved one of the more interesting dementia research stories of the summer. They showed not only that an inflammatory response in the brain plays an important role in the development of Alzheimer’s – but that the AN1792 vaccine suppressed this response in the long term, many years after the vaccine was administered.

AN1792 was designed to remove a protein called amyloid from the brain, similar to a number of new drugs that are now in clinical trials, but the phase II trial was halted after a small number of participants developed inflammation in the brain. Originally, the researchers had feared the vaccine may have worsened the disease by over-stimulating the immune response and causing long term brain inflammation – but the latest findings show this was not the case. By demonstrating that amyloid can be removed from the brain without causing lasting damage, this study offers new hope for the latest breed of anti-amyloid drugs.

As the follow-up to this trial continues to yield more results, researchers are not simply learning more about what’s happening in Alzheimer’s, although this in itself is vital for finding new ways to tackle the disease. The results from this ongoing study have also helped guide later clinical trials, turning what could have been perceived as a failure into a real positive.

The power of research volunteers

None of this would have been possible without the determination of the scientists who saw value in continuing to follow the participants of the trial – and of course, without the original trial data being made available to the team. Their work is a shining example of perseverance, where every effort has been made to understand as much as possible about the effects of this vaccine.

But most importantly, the research could never have taken place were it not for those people who volunteered to continue being a part of it. Having already suffered the disappointment of being enrolled in an unsuccessful trial, this group chose to take part in a follow-up study, despite knowing that the findings would not help them directly. By willingly signing up to take part in this research, they have helped achieve results that could make a real difference for the future.

You don’t have to have been registered on a clinical trial to get involved in research. To learn more about taking part in dementia studies or donating your brain to research, visit:

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