New research, published in The Lancet Neurology, highlights the development of a vaccine targeting one of the proteins responsible for damage to the brain observed in cases of Alzheimer's disease. Promising initial results should soon give rise to a new phase of clinical trials.
Researchers at Sweden's Karolinska Institutet, based in Stockholm, have developed a vaccine that, when administered in humans, stimulates the production of an antibody that specifically targets one of the proteins implicated in the formation of aggregates, plaques and fibrils that disrupt brain function, specific to Alzheimer's disease.
Two main types of protein are linked to Alzheimer's disease: beta-amyloid and tau proteins (tubule-associated unit).
The study, presented in The Lancet Neurology, highlights the vaccine's remarkable ability to trigger an immune response specifically targeting the tau protein. In fact, 29 of the 30 patients who were given the vaccine showed a favorable immune response.
The study focused on patients with light to moderate forms of the disease, aged from 50 to 85, in a period spanning June 2013 to March 2015.
The researchers succeeded in coupling the antibody to a carrier molecule that isn't present in humans, thus avoiding an immune reaction towards the body itself.
More clinical trials
Most of the antibodies previously studied in the treatment of Alzheimer's disease have targeted amyloid plaques.
A drug called Verubecestat, for example, was recently validated following a phase one clinical trial. Developed by the American pharmaceuticals firm Merck, the compound reduces the presence of toxic beta-amyloid proteins in the brain by blocking an enzyme called BACE1.
However, most other studies targeting amyloid have concluded with failed treatment or severe side effects, including the abnormal accumulation of CSF (cerebrospinal fluid) and brain inflammation. This was caused by a reaction toward "normal" amyloid protein present in blood vessels.
Two other compounds found to reduce amyloid plaques (solanezumab, from American pharmaceuticals firm Eli Lilly, and aducanumab, from Biogen Inc.) are also currently subject to phase three clinical trials, the final phase before marketing.
The vaccine, however, instead focuses on combatting pathological tau protein. Its only observed side effects were localized reactions at the injection site for 53 per cent of patients. These are likely to be linked to the additive aluminum hydroxide, used to improve the production of autoantibodies. No serious side effects were directly observed during the initial trail.
Given the promising nature of these first results, the scientists plan to continue clinical trials.
According to figures from the World Health Organization (WHO), more than 36 million people worldwide are living with dementia, a majority of which are Alzheimer's cases. This number is expected to double by 2030 and triple by 2050 if no effective treatment is found.
