How ABvac40 works
One of the main causes of Alzheimer’s disease is the aggregation of protein fragments called beta-amyloid (Aβ), which are produced by the specific enzymatic cleavage of a large protein called amyloid precursor protein (APP). Several types of Aβ peptides are produced in Alzheimer’s disease, but the most abundant is the Aβ40. Large aggregates of the Aβ peptides are called amyloid plaques. These can cause brain cells to die or not function properly. As regions of the brain that control memory, language, reasoning, and social behavior become affected, patients eventually lose the ability to live and function independently.
ABvac40 is the first active vaccine that targets the Aβ40 peptide. It consists of several repeats of a short version of the Aβ40 peptide. When injected into patients, it is designed to trigger an immune response, which includes the production of specific antibodies against the Aβ40 peptide. Once bound by these Aβ40-specific antibodies, the Aβ40 peptide will be ingested by immune cells that are found in the brain. It is hoped this will help clear the amyloid plaques, as well as prevent the formation of new Aβ aggregates. It is hoped that brain cells will be protected and brain function will be preserved, or perhaps improved, following treatment.
ABvac40 in clinical trials
A single-center, randomized, double-blind, placebo-controlled, Phase 1 clinical trial (NCT03113812) was conducted at the Memory Clinic and Research Center of Fundació ACE in Barcelona, Spain, to analyze the safety and tolerability of ABvac40 in 24 patients, ages 50–85, with mild-to-moderate Alzheimer’s disease. Participants were randomly assigned to one of three groups to receive ABvac40 or placebo as an injection under the skin. The first group received two half-doses of ABvac40 or placebo, whereas the second and third group received two and three doses of ABvac40 or placebo, respectively. The doses were all administered at four-week intervals. The primary outcome measure was the number of patients who reported adverse side effects during treatment, and until 16 weeks after treatment ended. The secondary outcome measure was the ability of the antibodies raised in the body against ABvac40 to generate an immune response.
The results of that study were published in the Alzheimer’s Research and Therapy journal. A total of 18 patients reported 71 adverse side effects, of whom 11 of 16 (69%) were treated with ABvac40 and seven of eight (88%) were treated with the placebo. None of the adverse side effects were severe and related to Alzheimer’s. Eleven of 12 (92%) Alzheimer’s patients who received three doses of ABvac40 developed specific antibodies against Aβ40.
A Phase 2, multi-center, randomized, double-blind, placebo-controlled study (NCT03461276) is currently recruiting an estimated 120 patients with mild Alzheimer’s disease to determine the safety, tolerability, and immune response to repeated under-the-skin injections of ABvac40. The patients will receive five injections of ABvac40 or placebo once every four weeks, and a sixth injection at week 42. The primary outcome measures include the incidences of treatment-linked adverse side effects and the levels of antibodies against Aβ40 in the blood for 24 months. That study is expected to be completed in February 2022.
Last updated: Aug. 31, 2019
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