Antibody therapies represent one of the most advanced disease-modifying approaches in neurodegenerative disease treatment. These therapeutics use monoclonal antibodies designed to bind specifically to pathological proteins—including amyloid-beta, tau, and alpha-synuclein—marking them for immune clearance. The approval of lecanemab (Leqembi) in 2023 and donanemab (Kisunla) in 2024 marked historic milestones as the first disease-modifying therapies for Alzheimer's disease.
Antibody therapeutics work through several complementary mechanisms:
¶ Target Binding and Clearance
- Soluble oligomer neutralization: Antibodies bind to toxic oligomeric forms of proteins before they can form plaques or tangles
- Fc receptor-mediated phagocytosis: Antibody-coated targets are recognized by microglia and macrophages
- Peripheral sink effect: Antibodies in blood may bind circulating protein, shifting equilibrium from the brain
Different antibodies target different forms of the pathological proteins:
- N-terminal antibodies: Bind early, aggregate-prone regions
- Mid-domain antibodies: Target sequences involved in aggregation
- C-terminal antibodies: Bind late-aggregation species
- Conformational antibodies: Recognize specific aggregate conformations
Lecanemab (Leqembi)
- Target: Amyloid-beta protofibrils
- Manufacturer: Eisai/Biogen
- Approval: FDA accelerated approval January 2023, full approval July 2023
- Efficacy: 27% slowing of clinical decline in CLARITY-AD trial
- Limitations: ARIA (amyloid-related imaging abnormalities) in 12.6% of patients
Donanemab (Kisunla)
- Target: Amyloid-beta plaques
- Manufacturer: Eli Lilly
- Approval: FDA approval July 2024
- Efficacy: 35% slowing in TRAILBLAZER-ALZ 2 trial
- Limitations: ARIA in 24% of patients, requires regular imaging monitoring
| Drug |
Company |
Target |
Phase |
Status |
| Prasinezumab |
Roche/Genentech |
Alpha-synuclein |
Phase 2 |
Primary endpoint missed, post-hoc signal in motor progression |
| Semorinemab |
Roche/Genentech |
Tau |
Phase 2 |
Failed in LAURIET trial |
| Tilavonemab |
AbbVie |
Tau |
Phase 2 |
Failed in PSP trial |
| ABBV-916 |
AbbVie |
Tau |
Phase 1 |
Ongoing |
| JNJ-63742057 |
Janssen |
Amyloid-beta |
Phase 3 |
Ongoing |
| Remternetug |
Eli Lilly |
Amyloid-beta |
Phase 3 |
Subcutaneous formulation |
Antibodies offer exceptional target specificity:
- Designed to bind single protein epitopes
- Minimal off-target effects
- Well-characterized pharmacology
The approval of lecanemab and donanemab validates:
- Amyloid removal correlates with clinical benefit
- Disease modification is achievable
- The amyloid hypothesis has clinical relevance
- Scalable biopharmaceutical production
- Rigorous quality control standards
- Extensive regulatory precedent
- Annual treatment costs exceed $30,000
- Additional costs for monitoring and administration
- Long-term treatment may be required
- Only 1-2% of peripheral antibodies reach the CNS
- Requires high doses for effect
- Limits efficacy ceiling
- Brain edema (ARIA-E): 10-15% of patients
- Microhemorrhages (ARIA-H): 15-20% of patients
- Requires MRI monitoring
- More common in APOE4 carriers
- Clinical benefit limited to early disease stages
- Significant plaque burden may limit reversibility
- Biomarker screening required
- Brain shuttle antibodies: Engineering to enhance CNS delivery
- Vectorized antibodies: AAV-delivered antibody genes
- Dual-target antibodies: Simultaneous amyloid and tau targeting
- Conformational specificity: Antibodies targeting toxic oligomers specifically
- Antibody + small molecule (e.g., BACE inhibitor)
- Antibody + ASO
- Antibody + immunomodulator