Phase II trials of Alzheimer's vaccine show safety

Embargoed until: Publicly released: 2021-06-15 01:00

International

International researchers have trialed an Alzheimer's vaccine and found it to be safe and capable of creating an immune response, but it did not impact the rate of cognitive decline in patients. The vaccine was made to target tau proteins that form tangles in the brain, a hallmark of Alzheimer’s. In the trial, several doses of the vaccine or a placebo were administered to 196 patients with mild Alzheimer’s Disease and researchers monitored the vaccine's safety, immune response, and effectiveness over two years. Those who received the vaccine had a bigger immune response, but there was no positive or negative change in cognition compared to the placebo group. Exploratory analyses found the vaccine slowed accumulation of a protein that indicates neurodegeneration, but the authors say further studies with more people will be needed to figure out whether this vaccine will be clinically effective.

Media release

From: Springer Nature

Safety and immune response of vaccine against Alzheimer’s disease demonstrated

The vaccine AADvac1 was found to be both safe and capable of eliciting an immune response in patients with mild Alzheimer’s disease (AD), according to a phase 2 clinical trial published in Nature Aging. However, AADvac1 did not detectably impact cognitive decline in patients.

The accumulation and spread of toxic forms of a protein called tau in the brain of patients with AD is a pathological hallmark of the disease. It is thought to be responsible for the widespread death of neurons that ultimately leads to dementia. Immunotherapy is currently under consideration as a strategy to decrease the levels of toxic tau proteins and help slow cognitive decline in patients.

Petr Novak and colleagues conducted a phase 2, randomized placebo-controlled trial in which they administered several doses of a peptide vaccine called AADvac1, or placebo, to 196 patients (mean age 71.4 years; 45.1% male; 100% white) with mild AD and monitored the vaccine’s safety, immunogenicity — its ability to stimulate an immune response — and clinical efficacy over two years. The authors found that the vaccine was safe and that it led to high levels of antibodies against the vaccine’s peptide in the treated group. However, the vaccine did not lead to statistically significant positive or negative effects on congnition in the whole study sample. Exploratory analyses suggested that AADvac1 slowed the accumulation of plasma neurofilament light-chain protein (NfL) — a marker of neurodegeneration.

The authors conclude that although AADvac1 was well tolerated and led to an immune response against tau, it did not result in statistically significant cognitive benefits, potentially because a number of patients did not have AD tau pathology or of the study’s small sample size. Larger trials stratified according to the presence of disease biomarkers with patients who are therefore needed to replicate these results and adequately test the possible clinical efficacy of AADvac1.

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Journal/
conference: Nature Aging

Research:Paper

Organisation/s: AXON Neuroscience CRM Services SE, Slovakia

Funder: The study was funded by AXON Neuroscience SE. The authors thank the patients and their caregivers and the ADAMANT investigators (Supplementary Section 13).

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