Drug Development.

Area of Science:

• Neurology
• Immunology
• Pharmacology

Background:

• Alzheimer's disease (AD) involves Aβ40, implicated in amyloid deposition in blood vessels.
• ABvac40 is an investigational vaccine targeting Aβ40 for AD treatment.
• Phase 2 trials indicated ABvac40 has a good safety profile and immunogenicity.

Purpose of the Study:

• To assess the clinical relevance of ABvac40 by evaluating meaningful within-patient changes (MWPC) in AD patients.
• To analyze the impact of ABvac40 on cognitive decline and disease progression.

Main Methods:

• A randomized, double-blind, placebo-controlled phase 2 study (AB1601) included patients with mild cognitive impairment or very mild AD.
• Meaningful within-patient change (MWPC) was defined as a ≥3-point decline in MMSE at two consecutive visits over 24 months.
• Cox proportional hazard models were used to assess the risk of MWPC, with stratification by CSF antibody levels.

Main Results:

• ABvac40 significantly reduced the risk of MWPC by 53% compared to placebo (HR=0.47; P=0.012) in the overall population.
• In amyloid-PET positive patients, ABvac40 showed a more pronounced effect, reducing MWPC risk by 62% (HR=0.38; P=0.005).
• Patients with higher CSF antibody levels post-vaccination experienced an 81% reduction in MWPC risk (HR=0.19; P=0.029).

Conclusions:

• ABvac40 significantly reduces clinically meaningful cognitive decline in early-stage AD, particularly in amyloid-PET positive individuals.
• The strongest effects were observed in patients with the highest antibody levels, suggesting a dose-response relationship.
• Further research is warranted to explore ABvac40's impact on cerebral vasculature and its role in cognitive benefits.