Alzheimer's disease treatment encompasses pharmacological and non-pharmacological approaches aimed at modifying disease progression, managing symptoms, and improving quality of life. Current treatments include disease-modifying therapies targeting amyloid and [tau](/proteins/tau), symptomatic treatments for cognitive and behavioral symptoms, and lifestyle interventions[@masters2015][@cummings2024].
Disease-Modifying Therapies
Amyloid-Targeting Therapies
Monoclonal antibodies that remove [amyloid-beta](/proteins/amyloid-beta) plaques:
Tau-Targeting Therapies
Drugs targeting tau pathology:
LMTM (Methylene Blue derivative): Tau aggregation inhibitor
Anti-tau antibodies: Various in clinical development
Tau kinase inhibitors: Target phosphorylation pathways
TREM2 (Triggering Receptor Expressed on Myeloid Cells 2) is a cell surface receptor primarily expressed on microglia in the brain. It plays a critical role in modulating microglial function, including phagocytosis, metabolic reprogramming, survival signaling, and clustering around pathological protein deposits. Loss-of-function variants in TREM2 (such as R47H, R62H) significantly increase Alzheimer's disease risk, making TREM2 activation a promising therapeutic strategy[@jonsson][@wang].
Mechanism of Action
TREM2 agonists work by:
Enhancing phagocytosis: Activating microglia to clear amyloid-beta plaques and cellular debris more efficiently
Supporting disease-associated microglia (DAM): Promoting the inflammatory metabolic state of protective microglial phenotypes
Providing survival signals: Preventing microglial apoptosis and maintaining cell viability
Promoting plaque clustering: Facilitating microglial clustering around amyloid plaques to form protective barriers
Clinical Trials
AL002 (Alector/AbbVie)
AL002 is a monoclonal antibody designed to activate TREM2 by binding to a distinct epitope that promotes receptor clustering and signaling. It represents the first TREM2-targeting antibody to enter clinical trials for Alzheimer's disease.
Phase 1 (completed): Demonstrated dose-dependent engagement of TREM2 and acceptable safety profile in healthy volunteers and AD patients
Phase 2 (INVOKE-2, ongoing): Evaluating clinical efficacy in patients with early Alzheimer's disease
Enrollment: Approximately 265 participants with early AD
Primary endpoints: Change in amyloid PET, cognitive measures (ADAS-Cog13, ADCS-ADL), and multiple fluid and imaging biomarkers
Mechanism: Intended to optimize TREM2 signaling to improve microglia activity and counteract decreased TREM2 functionality
AL003 (Alector)
AL003 uses a different mechanism, potentially acting as a TREM2-activating antibody with enhanced brain penetration.
Status: Phase 1 completed, clinical development continued with strategic partner
Pipeline Summary
Eligibility Criteria
Patients being considered for TREM2 agonist trials typically meet the following criteria:
Age: Typically 50-85 years
Diagnosis: Mild cognitive impairment (MCI) due to AD or mild Alzheimer's disease
Amyloid status: Confirmed amyloid-positive via PET scan or CSF biomarkers
MMSE score: Usually 20-26 (mild disease)
Exclusion: No significant vascular disease, psychiatric conditions, or other neurodegenerative diseases
Safety and Adverse Effects
Similar to other antibody therapies targeting immune pathways:
ARIA-E: Amyloid-related imaging abnormalities - edema; monitoring required via MRI
ARIA-H: Microhemorrhages; particular attention in anti-amyloid combination trials
Infusion reactions: Potential for cytokine release with first doses
Infections: Monitor for respiratory and urinary tract infections
Long-term immune modulation: Effects on microglial function require extended monitoring
Biomarkers for Patient Selection
CSF sTREM2: Soluble TREM2 in cerebrospinal fluid reflects microglial activation and may predict treatment response
Genetic stratification: Patients with TREM2 risk variants (R47H, R62H) may particularly benefit from TREM2 agonism
Amyloid status: Required for patient selection as amyloid plaques are the primary ligand for microglial phagocytosis
[Masters et al., Alzheimer's disease (2015) (2015)](https://doi.org/10.1038/nrdp.2015.56)
[Cummings et al., Alzheimer's disease drug development pipeline: 2024 (2024)](https://doi.org/10.1002/trc2.12465)
[van Dyck et al., Lecanemab (2023) (2023)](https://doi.org/10.1056/NEJMoa2212948)
[Jonsson T, Stefansson H, Steinberg S, et al., Variant of TREM2 associated with the risk of Alzheimer's disease. N Engl J Med (n.d.)](https://pubmed.ncbi.nlm.nih.gov/23344310/)
[Wang Y, Cella M, Mallinson K, et al., TREM2 lipid sensing sustains the microglial response in an Alzheimer's disease model. Cell (n.d.)](https://pubmed.ncbi.nlm.nih.gov/25795636/)
Related Hypotheses
From the [SciDEX Exchange](/exchange) — scored by multi-agent debate
[Cell-Type Specific TREM2 Upregulation in DAM Microglia](/hypothesis/h-seaad-51323624) — <span style="color:#81c784;font-weight:600">0.70</span> · Target: TREM2