A potential vaccine against Alzheimer's has been found safe and capable of producing an immune response, new research has shown. The vaccine AADvac1 is a revolutionary approach in treating and preventing Alzheimer’s disease and has currently completed its phase II clinical trial, with some encouraging albeit limited results.
As reported in Nature Aging, the vaccine appears to be safe and stimulates an immune response against specific bits of the tau protein whose accumulation appears to be one of the causes of Alzheimer’s. While that is good news, the trial, in general, didn’t show a major impact on the cognitive decline of the patients, although a subset of them benefited from the vaccine.
Phase II randomized clinical trials are used to assess appropriate dosing levels as well as the efficacy of the drug. The team reports that the vaccine slowed down the accumulation of plasma neurofilament light-chain protein (NfL), which is a marker of neurodegeneration. However, more research will be necessary to assess if the vaccine stops and reverses the disease in a meaningful fraction of the population.
The trial had 196 participants from eight European countries, with 117 of them receiving the vaccine and the remaining 79 being given a placebo. They received 11 doses of the vaccine (or placebo) over the course of 24 months. Among them, the participants who had already been diagnosed with Alzheimer’s appeared to have the most beneficial effect from this trial, which is comforting to hear, although more investigation is needed.
“The recent approval of an amyloid-based therapy was encouraging for the whole Alzheimer’s industry. Unlike amyloid, which influences speed of Alzheimer’s progression, there is strong evidence that tau pathology relates to the underlying cause of the disease,” Norbert Zilka, the CSO of Axon Neuroscience, the company that developed the drug, said in a statement seen by IFLScience. “Our vaccine aims to halt the formation and spread of tau pathology, which has ultimately the potential to show a higher benefit for Alzheimer’s disease patients.”
Not all tau proteins are bad and the vaccine is designed to teach the immune system to recognize between good ones and harmful ones. The objective of AADvac1 is to slow down the formation of these damaging tau proteins and halt the spread of those already formed.
“The results confirm the disease-modifying effect of AADvac1, and support Axon’s progress toward a pivotal stage of clinical development. In view of the recent approval of amyloid-based therapy, our strong NfL endpoint results could serve as a surrogate in our forthcoming clinical development to achieve accelerated approval,” Michal Fresser, CEO of Axon Neuroscience, added.
According to the World Health Organization, around 50 million people have dementia with 10 million new cases diagnosed every year. Alzheimer's disease is the most common form of dementia with estimates placing it at about 60 to 70 percent of all cases.