Objective:

To elucidate the mechanism of action of lecanemab, an antibody therapy for Alzheimer's disease, particularly how it activates brain immune cells to clear amyloid plaques.

Key Findings:

• Lecanemab activates microglia through its Fc fragment, which is essential for clearing amyloid plaques.
• The treatment induces a specific microglial gene expression program linked to phagocytosis and lysosomal degradation.
• Microglial activation by lecanemab does not lead to excessive synapse loss, preserving surrounding neural structures.

Interpretation:

The findings suggest that lecanemab's mechanism involves a targeted immune response that effectively reduces amyloid burden while minimizing potential side effects, offering insights for future Alzheimer's therapies.

Limitations:

• Fc-mediated immune engagement may still pose risks of inflammation or vascular complications.
• Current models may not fully capture all adverse effects associated with lecanemab treatment.

Conclusion:

Understanding the mechanism of lecanemab provides a clearer direction for developing next-generation Alzheimer's drugs, emphasizing the importance of modulating the brain's immune response rather than solely targeting amyloid.