A Multi-center, Randomized, Double-blind, Placebo-controlled, 24 Months Study in Patients With Amnestic Mild Cognitive Impairment or Very Mild Alzheimer's Disease to Investigate the Safety, Tolerability and Immune Response of Repeated Subcutaneous Injections of ABvac40

Detailed Summary

Alzheimer's disease (AD) is the most common type of dementia, accounting for 50-75% of the estimated 47 million people with dementia worldwide. The amyloid cascade hypothesis of AD proposes that amyloid-β (Aβ) peptide accumulation in the brain, caused by an imbalance between Aβ production and clearance, is the initiating factor of a cascade ultimately leading to dementia. Aβ peptides are generated from sequential cleavage of the amyloid precursor protein (APP), including Aβ40 and Aβ42. Aβ40 is the predominant variant (90%) among the secreted Aβ forms and although Aβ42 is more hydrophobic and prone to aggregate, and Aβ42 oligomers are regarded to be the most neurotoxic species, Aβ40 can also produce highly toxic diffusible aggregates, which can be prevented in vitro by specific anti-Aβ40 antibodies. Several studies have proposed that a high concentration of Aβ40 in the brain distinguishes patients with AD from those who have senile plaques but are cognitively normal, pointing to the importance of Aβ40 in the onset of dementia. In keeping with this, previous studies have demonstrated that specific anti-Aβ40 antibodies label NFTs in the entorhinal cortex and the hippocampus of AD brains, and that these do not co-localize with tau NFTs, suggesting the presence of degenerating neuronal populations filled with C-terminal fragments of Aβx-40. In addition, Aβ40 is the main component of amyloid deposition around cerebral arteries causing cerebral amyloid angiopathy (CAA), which has a prevalence of about 80-90% in patients with AD (for more information see Lacosta et al. Alzheimer's Research \& Therapy (2018) 10:12 DOI 10.1186/s13195-018-0340-8). Considering those previous results suggesting that strategies targeting Aβ40 could represent novel disease-modifying therapies, we have developed ABvac40, the first active vaccine targeting the C-terminal end of the Aβ40 peptide. The purpose of this Phase II study is to confirm in patients with a-MCI or vm-AD the level of safety and tolerability obtained in the ABvac40 Phase I clinical trial in patients with mm-AD. In addition, the study is aimed to better characterize the immune response elicited by ABvac40 and to explore its effects on AD biomarkers.

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