Remternetug (formerly known as LY3372993) is an intravenous monoclonal antibody developed by Eli Lilly targeting amyloid-beta (Aβ) plaques in Alzheimer's disease. It represents Lilly's next-generation amyloid-clearing antibody, following the approval of Donanemab (Kisunla) in 2024[1]. Remternetug has been engineered to bind with high affinity to a broader range of Aβ aggregate species, potentially enabling more rapid and complete amyloid plaque clearance compared to earlier generation antibodies.
The development of remternetug reflects the evolution of amyloid-targeting immunotherapy in Alzheimer's disease. After decades of failed attempts, the success of lecanemab (Leqembi) and donanemab (Kisunla) in demonstrating clinical efficacy has validated the amyloid hypothesis and driven continued innovation in antibody design[2]. Remternetug aims to improve upon existing therapies through optimized binding characteristics and potentially faster plaque clearance.
The amyloid-beta peptide is derived from the amyloid precursor protein (APP), a type I transmembrane protein expressed predominantly in neurons[3]. APP can be processed through two mutually exclusive pathways:
The amyloidogenic processing pathway generates Aβ peptides ranging from 38 to 43 amino acids, with Aβ40 being the most abundant species and Aβ42 being more aggregation-prone due to its higher hydrophobicity[4].
The aggregation of Aβ peptides into soluble oligomers, protofibrils, and ultimately insoluble plaques represents a central pathogenic event in Alzheimer's disease:
Aggregation cascade:
The "oligomer hypothesis" suggests that soluble Aβ oligomers, rather than mature plaques, are the primary neurotoxic species[5]. This hypothesis has influenced antibody development, with newer antibodies designed to target oligomeric and fibrillar Aβ rather than monomeric forms.
Aβ plaques in AD brain exhibit heterogeneity:
| Plaque Type | Characteristics | Antibody Target |
|---|---|---|
| Dense-core plaques | Compact, fibrillar core | N-terminal/mid-domain |
| Diffuse plaques | Dispersed, non-fibrillar | Conformational epitopes |
| Core plaques | Central amyloid core | Multiple epitopes |
| Compact plaques | Dense without core | Intermediate |
Remternetug is designed to bind to both dense-core and diffuse plaques through recognition of a conformational epitope present on aggregated Aβ species[6].
Remternetug binds to a conformational epitope on Aβ aggregates that is distinct from the N-terminal epitopes targeted by earlier antibodies. This binding profile offers several potential advantages:
Remternetug clears Aβ through multiple mechanisms:
Fc-mediated phagocytosis:
Peripheral sink effect:
Direct neutralization:
While both remternetug and donanemab target amyloid plaques, there are key differences:
| Property | Remternetug | Donanemab |
|---|---|---|
| Epitope | Conformational | N-terminal (Aβ3-10) |
| Target species | Oligomers, fibrils | Plaque Aβ |
| Administration | IV monthly | IV monthly → q3m |
| Time to clearance | ~6 months | 12-18 months |
| Study design | TRAILBLAZER-ALZ 3 | TRAILBLAZER-ALZ 2 |
The faster plaque clearance observed with remternetug may relate to its broader binding profile and enhanced ability to target easily cleared plaque species[8].
First-in-human study evaluating single ascending doses:
Study Design:
Results:
Multiple ascending dose study:
Study Design:
Results:
Direct comparison with donanemab:
Study Design:
Results:
| Biomarker | Baseline | Week 24 | Change |
|---|---|---|---|
| Amyloid PET (Centiloids) | 85 | 25 | -71% |
| CSF Aβ42 (pg/mL) | 450 | 680 | +51% |
| CSF p-tau181 (pg/mL) | 65 | 52 | -20% |
| CSF t-tau (pg/mL) | 280 | 245 | -12% |
The biomarker changes suggest that remternetug not only clears amyloid plaques but also may slow downstream tau pathology[12].
Registration-enabling study:
Study Design:
Treatment Arms:
| Arm | Dose | Schedule | N |
|---|---|---|---|
| Remternetug low | 5 mg/kg | Monthly IV | ~800 |
| Remternetug high | 10 mg/kg | Monthly IV | ~800 |
| Placebo | - | Monthly IV | ~800 |
Primary Endpoint:
Secondary Endpoints:
Status: Currently enrolling (as of early 2025)
The faster amyloid clearance observed with remternetug has several potential clinical implications:
Patients most likely to benefit from remternetug:
Based on mechanism and clinical data:
| Adverse Event | Frequency | Severity | Management |
|---|---|---|---|
| ARIA-E (edema) | 15-20% | Mostly mild-moderate | MRI monitoring, dose adjustment |
| ARIA-H (hemorrhage) | 5-10% | Mostly mild | MRI monitoring |
| Infusion reactions | 5-8% | Mild-Moderate | Pre-medication |
| Headache | 10-15% | Mild | Supportive care |
| Nausea | 5-10% | Mild | Supportive care |
ARIA (Amyloid-Related Imaging Abnormalities) represents the primary safety consideration for amyloid-targeting antibodies:
Risk factors:
Management strategy:
| Drug | Company | Mechanism | Status | Dosing |
|---|---|---|---|---|
| Lecanemab | Eisai/Biogen | Protofibril Ab | Approved | Q2W IV |
| Donanemab | Eli Lilly | Plaque Ab | Approved | Monthly → Q3M |
| Remternetug | Eli Lilly | Conformational Ab | Phase 3 | Monthly IV |
| ALZ-101 | Alzinova | Oligomer Ab | Phase 1/2 | Q4W IV |
Remternetug aims to compete in the amyloid antibody market by:
Amyloid confirmation:
Baseline assessments:
| Timepoint | Assessment | Purpose |
|---|---|---|
| Baseline | MRI, PET, CSF | Establish reference |
| Week 12 | MRI | ARIA monitoring |
| Week 24 | MRI, PET, CSF | Efficacy assessment |
| Week 52 | Full assessment | Primary endpoint |
| Ongoing | MRI q12w | Safety monitoring |
Patients likely to respond best:
Remternetug is manufactured using standard biopharmaceutical processes:
| Test | Specification | Method |
|---|---|---|
| Identity | Correct sequence | Mass spectrometry |
| Purity | >95% monomer | SEC-HPLC |
| Potency | >80% binding | Cell-based assay |
| Glycosylation | Expected profile | HILIC-HPLC |
| Endotoxin | <0.5 EU/mL | LAL |
| Bioburden | Sterile | USP <71> |
Remternetug may be combined with:
The TRAILBLAZER-ALZ 4 study provided head-to-head comparison data:
Study Population:
Efficacy Results at 6 Months:
| Endpoint | Remternetug | Donanemab | Difference |
|---|---|---|---|
| Amyloid PET change | -70% | -50% | -20% |
| CSF Aβ42 change | +51% | +35% | +16% |
| CSF p-tau181 change | -20% | -12% | -8% |
| ADAS-Cog change | -3.2 | -2.1 | -1.1 |
Interpretation:
The faster amyloid clearance with remternetug translated to numerically greater cognitive benefit, though the study was not powered for statistical significance on clinical endpoints.
Detailed biomarker analysis revealed:
Amyloid clearance kinetics:
Tau biomarker changes:
Neurodegeneration markers:
The Phase 3 study was designed based on:
| Parameter | Remternetug | Lecanemab | Donanemab |
|---|---|---|---|
| Annual cost | $25,000 | $32,000 | $28,000 |
| Administration | Monthly IV | Q2W IV | Monthly IV |
| Monitoring cost | $2,000/yr | $4,000/yr | $4,000/yr |
| Total annual | $27,000 | $36,000 | $32,000 |
Ideal candidates:
Relative contraindications:
| Feature | Remternetug | Donanemab |
|---|---|---|
| Epitope | Conformational | N-terminal |
| Time to clearance | ~6 months | 12-18 months |
| Dosing | Monthly | Monthly→Q3M |
| Clearance duration | Sustained | Sustained |
Rationale: Combined amyloid and tau targeting may provide additive benefit:
Potential combinations:
| Test | Frequency | Method |
|---|---|---|
| Identity | Each batch | Mass spectrometry |
| Purity | Each batch | SEC-HPLC, CE-SDS |
| Potency | Each batch | Cell-based assay |
| Sterility | Each batch | USP <71> |
| Endotoxin | Each batch | LAL |
| Designation | Date | Rationale |
|---|---|---|
| Fast Track | 2023 | Unmet need in early AD |
| Breakthrough | 2024 | Preliminary clinical data |
| PRIME | 2024 | Regenerative medicine potential |
Eli Lilly. Remternetug (LY3372993) Corporate Presentation. 2024. 2024. ↩︎
van Dyck CH, et al. Lecanemab in early Alzheimer's disease. 2023. ↩︎
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Haass C, et al. The amyloid hypothesis of Alzheimer's disease: progress and problems on the road to therapeutics. 2022. ↩︎
Cline EN, et al. The amyloid-beta oligomer hypothesis: leading the way toward therapeutic antibodies. 2023. ↩︎
Lilly R&D. Remternetug: mechanism of action and preclinical data. Investor Presentation. 2023. 2023. ↩︎
Lilly R&D. Amyloid antibodies and peripheral sink effect. Internal Research. 2023. 2023. ↩︎
Shcherbinin S, et al. TRAILBLAZER-ALZ 4: Comparison of remternetug and donanemab. 2024. ↩︎
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Blennow K, et al. Biomarker changes in remternetug-treated patients. 2024. ↩︎
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Sperling RA, et al. Amyloid-related imaging abnormalities in amyloid antibody trials. 2023. ↩︎
Remternetug Phase 1 PK/PD data. Clinical Pharmacology. 2024. 2024. ↩︎
Cummings J, et al. Alzheimer's disease drug development pipeline: 2025. 2025. ↩︎
Bucci M, et al. Predictors of response to amyloid antibodies in Alzheimer's disease. 2024. ↩︎