AC Immune’s Anti-Abeta Vaccine Results from Phase 1b Study in Down Syndrome Published in JAMA Neurology
First study of an anti-Abeta vaccine in people living with Down syndrome (DS)
Immune response and Alzheimer's disease (AD) biomarkers showed positive impact of ACI-24 first generation vaccine
Optimized formulation of the ACI-24 vaccine to enter Phase 1b/2 testing this year
The landmark study was led by principal investigator
Dr. Marie Kosco-Vilbois, Ph.D., Chief Scientific Officer of AC Immune and one of the co-authors of the article, concluded: "The ACI-24 vaccine is derived from our SupraAntigen® platform and designed to generate a polyclonal antibody response targeting pathological forms of Abeta, which following the optimization of its formulation now also includes oligomeric and pyroGlutamate-Abeta. The ensemble of clinical results obtained with ACI-24, encourage us to push the program forward taking the optimized ACI-24 formulation into the next stage of clinical development in both AD and AD in DS in 2022."
As presented in the JAMA Neurology article, the ACI-24 vaccine demonstrated immunogenicity along with pharmacodynamic and target engagement evidence as measured by a greater increase in plasma Abeta40 and Abeta42 in treated groups compared to placebo. Importantly, anti-Abeta antibody titers were not associated with any adverse findings.
An optimized formulation of ACI-24 has demonstrated strong immunogenicity, inducing a polyclonal response in non-human primates against Abeta and, importantly, high titers of antibodies targeting pyroGlutamate-Abeta (as published in
- Rafii MS et al, Safety, Tolerability, and Immunogenicity of the ACI-24 Vaccine in Adults With Down Syndrome, A Phase 1b Randomized Clinical Trial, JAMA Neurology, 2022 May 9:79(5).
- Jawhar S et al, Pyroglutamate Amyloid-β (Aβ): A Hatchet Man in Alzheimer Disease, J Biol Chem. 2011 Nov 11; 286(45).
About the Phase 1b anti-Abeta Vaccine Trial in people living with DS
This randomized, double-blind, placebo-controlled, dose-escalation, phase 1b multi-center study reported in JAMA Neurology included 16 adults, aged 25-41 years. Participants were treated for 48 weeks receiving seven subcutaneous injections of ACI-24 (300μg or 1000μg) or placebo (active/placebo ratio was 3:1) and monitored for an additional 48 weeks of post-treatment follow-up. Primary outcomes included assessment of safety, tolerability and antibody titers. Exploratory outcomes evaluated included levels of plasma and CSF amyloid-β42, amyloid-β40, total tau and phospho-tau (pTau) as well as hippocampal volume and cognitive functioning. In the trial, most adverse events were of mild intensity and unrelated or unlikely related to ACI-24. Treatment compliance was 100%. No cases of meningoencephalitis, death or other serious adverse events occurred as well as no withdrawals due to adverse events.
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