Passive immunotherapy for Alzheimer's disease: challenges & future directions

Area of Science:

• Neuroscience
• Immunology
• Pharmacology

Background:

• Passive immunotherapy using antibodies targeting amyloid-beta (Aβ) or tau protein is a key strategy for Alzheimer's disease (AD).
• Previous clinical trials of several anti-Aβ and anti-tau antibodies have yielded disappointing results, failing to demonstrate significant clinical benefits.

Purpose of the Study:

• To analyze the divergent outcomes of passive immunotherapy in Alzheimer's disease clinical trials.
• To explore the potential reasons for differing efficacy among antibodies targeting Aβ.

Main Methods:

• Review of Phase II and III clinical trial data for passive immunotherapy agents in Alzheimer's disease.
• Analysis of antibody targets, including different forms of Aβ (soluble protofibrils, aggregated, N-terminal truncated) and tau protein.

Main Results:

• Solanezumab, bapineuzumab, crenezumab, and gantenerumab (anti-Aβ) failed to slow cognitive decline in AD patients.
• Several anti-tau antibodies also failed in Phase II trials.
• Lecanemab, donanemab, and aducanumab (anti-Aβ) have shown efficacy in slowing cognitive decline in early-stage AD.

Conclusions:

• The specific Aβ target (e.g., soluble protofibrils vs. aggregated forms) is critical for the efficacy of passive immunotherapy in AD.
• Further long-term studies are needed to assess the efficacy, safety, and cost-effectiveness of anti-Aβ antibodies across different AD stages.
• Combination therapies involving anti-Aβ antibodies and other agents warrant exploration.