An experimental vaccine against Alzheimer’s disease has demonstrated efficacy in clearing brain tissue of an abnormal tau protein, but it is not yet clear whether it can preserve brain function. In the few patients with really high levels of tau protein, cognitive deterioration was markedly reduced. The results of phase II clinical trials of a new drug against an incurable and deadly form of dementia for which there is as yet no cure are reported in the article.
Experts from the Slovak pharmaceutical company AXON Neuroscience have tested a peptide vaccine AADvac1 on 196 patients with a mild form of dementia. Throughout the trial (24 months), one group of participants was given 11 doses of the drug (40 micrograms each) and another group was given a placebo. The main goal was to test the safety of the vaccine and its tolerability during long-term administration. Researchers also evaluated the immunogenicity and effectiveness of AADvac1 in reducing cognitive impairment caused by tau protein accumulation.
Tau protein, along with beta-amyloid, is considered a major factor in the pathological process in Alzheimer’s disease. These toxic proteins accumulate and form neurofibrillary tangles, which are thought to cause neuronal death and destruction of brain tissue.
Trial results showed no difference in the development of side effects from the vaccine and placebo. The drug induced an increase in immunoglobulin IgG levels, but had no significant effect on patients’ cognitive function. This can be explained by the fact that among all patients there were too few people with diagnosed Alzheimer’s disease and high levels of tau protein. Those who had it, however, showed some improvements in standardized tests of memory, reasoning, and thinking. In this group of patients, the decline in brain function slowed by 30 percent.
AXON is planning the next phase of the trial, which will include more patients with Alzheimer’s disease who have accumulation of both amyloid plaques and tau-proteins.