AD Neuroimmune Checkpoint and TREM2 Pathway Companies

Alzheimer's Disease Neuroimmune Checkpoint and TREM2 Pathway Companies

Overview

This category page covers biotechnology and pharmaceutical companies developing therapies that target neuroimmune checkpoints and TREM2-related pathways in Alzheimer's disease. Unlike general neuroinflammation companies (see [Alzheimer's Disease Neuroinflammation Companies](/companies/ad-neuroinflammation-companies)), this page focuses specifically on:

• TREM2/TREM1 axis modulation — agonist antibodies and small molecule activators
• CD33 inhibition — the microglial inhibitory checkpoint
• CD47/SIRP-alpha axis — "don't eat me" signal modulation
• Other innate immune checkpoint targets — including TREM1, SIRP-alpha, and related receptors

These targets represent the emerging paradigm of innate immune checkpoint inhibition in neurodegeneration, analogous to the cancer immunotherapy approach of PD-1/PD-L1 checkpoint blockade — but for the brain's myeloid cell compartment.

Scientific Rationale

The Neuroimmune Checkpoint Concept

Microglia and infiltrating macrophages express a suite of inhibitory receptors that dampen their phagocytic and inflammatory activity. In neurodegenerative disease, these checkpoints become pathologically "locked," preventing microglia from clearing amyloid plaques and toxic protein aggregates:

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Alzheimer's Disease Neuroimmune Checkpoint and TREM2 Pathway Companies

Overview

This category page covers biotechnology and pharmaceutical companies developing therapies that target neuroimmune checkpoints and TREM2-related pathways in Alzheimer's disease. Unlike general neuroinflammation companies (see [Alzheimer's Disease Neuroinflammation Companies](/companies/ad-neuroinflammation-companies)), this page focuses specifically on:

• TREM2/TREM1 axis modulation — agonist antibodies and small molecule activators
• CD33 inhibition — the microglial inhibitory checkpoint
• CD47/SIRP-alpha axis — "don't eat me" signal modulation
• Other innate immune checkpoint targets — including TREM1, SIRP-alpha, and related receptors

These targets represent the emerging paradigm of innate immune checkpoint inhibition in neurodegeneration, analogous to the cancer immunotherapy approach of PD-1/PD-L1 checkpoint blockade — but for the brain's myeloid cell compartment.

Scientific Rationale

The Neuroimmune Checkpoint Concept

Microglia and infiltrating macrophages express a suite of inhibitory receptors that dampen their phagocytic and inflammatory activity. In neurodegenerative disease, these checkpoints become pathologically "locked," preventing microglia from clearing amyloid plaques and toxic protein aggregates:

| Checkpoint | Receptor | Ligand | Function |
|-----------|----------|--------|----------|
| TREM2 | TREM2 | Lipids, ApoE | Pro-phagocytic, survival |
| CD33 | CD33 | Sialic acid | Anti-phagocytic, inflammatory |
| CD47 | CD47 | SIRP-alpha | "Don't eat me" signal |
| TREM1 | TREM1 | PAMPs, lipids | Amplifies inflammation |

Genetic variants in TREM2 (loss-of-function) increase AD risk ~3-4x, establishing the receptor as a causal target[@jiang2024][@wang2023]. CD33 risk variants have also been identified, and CD47 is implicated in impaired amyloid clearance.

TREM2 Pathway Mechanism

TREM2 is a surface receptor on microglia that signals through the adaptor protein DAP12 (TYROBP). Activation triggers:

Syk kinase recruitment via DAP12 ITAM domain

PI3K/AKT pathway activation for cell survival

MAPK pathway for inflammatory modulation

Rho GTPase reorganization for phagocytosis

Metabolic reprogramming toward glycolysis

The net effect: microglia transition from homeostatic to disease-associated microglia (DAM) state, enhancing clearance of amyloid-beta, apoptotic neurons, and myelin debris[@butovsky2024][@decano2024].

Key Companies by Target

TREM2 Agonists

Alector, Inc.

• Focus: TREM2 agonism and progranulin modulation (innate immuno-neurology)
• Location: South San Francisco, CA | NASDAQ: ALEC
• Key Programs:
• AL002: TREM2 agonist with Alector Brain Carrier (ABC) platform. Phase 2 in early AD (INVOKE-1 trial) in partnership with Roche[@alec_corp][@jiang2024]
• AL101: Progranulin antibody (PGRN) to increase progranulin levels. Phase 2 in AD in partnership with GSK
• AL003: Anti-TREM2 antibody (earlier stage)
• AL001: Progranulin upregulator (discontinued in AD)
• Platform: Alector Brain Carrier (ABC) enables BBB crossing for antibodies, enzymes, and siRNA
• Notes: Pioneer in immuno-neurology — first company to bring TREM2 agonists into Phase 2 for AD

Denali Therapeutics

• Focus: TREM2 agonism and lysosomal function
• Location: South San Francisco, CA | NASDAQ: DNLI
• Key Programs:
• DNL919 (ARS--3601): TREM2 agonist antibody. Phase 1 in AD. Uses Denali's Brain Transport Vehicle (BTV) platform for CNS penetration[@denali_corp]
• DNL593 (RF-1507): Progranulin modulator. Phase 1 in FTD and PD
• Platform: Brain Transport Vehicle (BTV) — engineered Fc engineering for enhanced brain exposure
• Notes: Strong foundation in lysosomal biology; partnership with Roche/Genentech on TREM2

Vigil Neuroscience, Inc.

• Focus: TREM2 agonism (highly focused)
• Location: Cambridge, MA | NASDAQ: VIGL
• Key Programs:
• VIG-100: TREM2 activating antibody. Phase 1 in AD[@vigil_corp]
• Earlier partnership with Amgen for TREM2 programs (discontinued)
• Notes: Dedicated TREM2 company; completed IPO in 2022. Focused exclusively on microglia-targeting therapies

AC Immune SA

• Focus: TREM2 agonist (AL002) and amyloid immunotherapy
• Location: Lausanne, Switzerland | NASDAQ: ACIU
• Key Programs:
• AL002: TREM2 agonist. Phase 2 (TRAILBLAZER-ALZ 3) in collaboration with Genentech/Roche. 315 participants, NCT05189193[@acui_corp][@decano2024]
• ACI-35: Phospho-tau vaccine (Phase 2)
• Morphomer: Small molecule tau aggregation inhibitors
• Platform: Morphomer and Suprabody platforms for small molecules and antibodies
• Notes: Has partnership with Roche/Genentech for AL002. Cross-listed on Nasdaq and SIX Swiss Exchange

CD47/SIRP-alpha Inhibitors

TrueBinding, Inc.

• Focus: CD47/SIRP-alpha axis modulation for AD
• Location: South San Francisco, CA
• Key Programs:
• TB-404: Anti-CD47 antibody for AD
• TB-403: Anti-CD47 for oncology (cross-development)
• Notes: Private company with a focus on CD47 as a "don't eat me" checkpoint in neurodegeneration. Elevated CD47 on neurons may signal microglia not to clear toxic aggregates

NextCure, Inc.

• Focus: Innate immune checkpoints including B7-H4, PVRIG, and related targets
• Location: New Haven, CT | NASDAQ: NXTC
• Key Programs:
• NC41: B7-H4 targeting (early-stage)
• NC318: PVRIG (PVRL2) targeting (discontinued in oncology)
• Notes: Primarily oncology-focused but exploring neurodegeneration applications. Private programs may include myeloid checkpoint targets relevant to AD

Complement System Inhibitors

Annexon Biosciences

• Focus: C1q inhibition (classical complement pathway)
• Location: Brisbane, CA | NASDAQ: ANNX
• Key Programs:
• ANX005: Anti-C1q monoclonal antibody. Phase 2 in Huntington's disease (COMPLETE-HD); expanding to AD[@annexon_corp]
• ANX007: C1q inhibitor (intravitreal) for geographic atrophy
• Mechanism: C1q initiates complement cascade that drives synaptic pruning. Blocking C1q prevents complement-mediated synapse loss in AD
• Notes: Classical complement (C1q → C3) is a distinct but related checkpoint pathway. C1q tags synapses for microglial elimination; blocking this preserves synaptic density

NLRP3 Inflammasome Inhibitors

Nodthera Ltd.

• Focus: NLRP3 inflammasome inhibition
• Location: Cambridge, UK (Steward Biomedical subsidiary)
• Key Programs:
• NT-0796: Brain-penetrant oral NLRP3 small molecule inhibitor. Phase 1/2 in AD (NCT05632433)[@nodthera_corp]
• NT-0868: Second-generation NLRP3 inhibitor
• Mechanism: NLRP3 inflammasome assembly in microglia releases IL-1beta and IL-18, driving chronic neuroinflammation and tau phosphorylation
• Notes: First-in-class oral therapy for neuroinflammation at its source. Nodthera was acquired by Steward Biomedical in 2025

TNF-alpha Inhibitors

INmune Bio, Inc.

• Focus: Selective soluble TNF-alpha inhibition via dominant-negative TNF (XPro1595)
• Location: Boca Raton, FL | NASDAQ: INMB
• Key Programs:
• XPro1595: Dominant-negative TNF inhibitor. Phase 2 in AD (NCT05318976) and Phase 2 in PD (NCT04472052)[@inmune_corp]
• Mechanism: XPro1595 neutralizes only soluble trimeric TNF-alpha (preserves membrane-bound TNF). This prevents microglial activation and A1 astrocyte conversion without compromising immune surveillance
• Notes: While TNF-alpha inhibition spans the neuroinflammation space, XPro1595's selective targeting of the soluble form distinguishes it from broad immunosuppressants. Listed here as it intersects with the microglial checkpoint pathway

Pipeline Overview

| Company | Drug | Target | Mechanism | Phase | Trial ID |
|---------|------|--------|-----------|-------|----------|
| Alector | AL002 | TREM2 | Agonist mAb (ABC) | Phase 2 | NCT05189193 (INVOKE-1) |
| AC Immune/Genentech | AL002 | TREM2 | Agonist mAb | Phase 2 | NCT05189193 (TRAILBLAZER-ALZ 3) |
| Denali | DNL919 | TREM2 | Agonist mAb (BTV) | Phase 1 | — |
| Vigil Neuroscience | VIG-100 | TREM2 | Agonist mAb | Phase 1 | — |
| Nodthera | NT-0796 | NLRP3 | Small molecule inhibitor | Phase 1/2 | NCT05632433 |
| INmune Bio | XPro1595 | TNF-alpha | dnTNF (selective sTNF) | Phase 2 | NCT05318976 |
| Annexon | ANX005 | C1q | Anti-C1q mAb | Phase 2 | HD→AD expansion |
| TrueBinding | TB-404 | CD47 | Anti-CD47 mAb | Preclinical | — |

Mechanism of Action Diagram

Investment Landscape

The neuroimmune checkpoint / TREM2 pathway space has attracted significant investment:

| Company | Raised | Key Investors | Notable |
|---------|--------|---------------|---------|
| Alector | >$600M (public + private) | Atlas, OrbiMed, GV | AL002 in Phase 2 |
| Denali Therapeutics | >$1B (public) | Foresite, Baillie Gifford | BTV platform |
| Vigil Neuroscience | >$200M (public) | Atlas, Invus | TREM2-focused |
| AC Immune | >$400M (public) | Novartis, Roche | Partnership model |
| Annexon | >$300M (public) | Redmile, Perceptive | C1q in Phase 2 |
| INmune Bio | >$100M (public) | Inline Marketing | XPro in Phase 2 |
| TrueBinding | ~$100M (private) | undisclosed | CD47 in AD |

Cross-Links to Related Pages

Mechanism Pages

• [TREM2 Signaling Pathway](/mechanisms/trem2-signaling)
• [TREM2 Microglial Pathway in AD](/mechanisms/trem2-microglial-pathway)
• [Neuroinflammation in AD](/mechanisms/neuroinflammation-ad)
• [NLRP3 Inflammasome](/entities/nlrp3-inflammasome)
• [Complement System in Neurodegeneration](/mechanisms/complement-system-neurodegeneration)
• [TNF-alpha Signaling in Neurodegeneration](/mechanisms/tnf-alpha-signaling-neurodegeneration)
• [Microglia in Neuroinflammation](/cell-types/microglia-neuroinflammation)
• [Disease-Associated Microglia (DAM)](/cell-types/trem2-expressing-microglia)

Protein Pages

• [TREM2 Protein](/proteins/trem2)
• [TREM2 Gene](/genes/trem2)
• [CD47 Protein](/proteins/cd47-protein)
• [CD33 Protein](/proteins/cd33)
• [DAP12 Protein](/entities/dap12)

Company Pages

• [Alector, Inc.](/companies/alector)
• [Denali Therapeutics](/companies/denali)
• [INmune Bio, Inc.](/companies/inmune-bio)
• [Nodthera Ltd.](/companies/nodthera)
• [Annexon Biosciences](/companies/annexon)
• [Vigil Neuroscience](/companies/vigil-neuroscience)

Investment Pages

• [TREM2 Therapeutics Investment Landscape](/investment/trem2-therapeutics-landscape)

Disease Pages

• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Mild Cognitive Impairment](/diseases/mild-cognitive-impairment)

See Also

• [Alzheimer's Disease Neuroinflammation Companies](/companies/ad-neuroinflammation-companies) — broader neuroinflammation landscape
• [TREM2 Agonist Therapies for Alzheimer's](/therapeutics/trem2-agonist-therapies-alzheimers)
• [Emerging Novel Mechanism AD Companies 2024-2025](/companies/emerging-novel-mechanism-ad-companies-2024-2025)
• [Neuroinflammation Mechanisms](/mechanisms/neuroinflammation)
• [Alzheimer's Disease](/diseases/alzheimers-disease)

References

[Alector Corporate Website](https://www.alector.com)

[AC Immune Corporate Website](https://www.acimmune.com)

[Denali Therapeutics Corporate Website](https://www.denalitherapeutics.com)

[Nodthera Corporate Website](https://www.nodthera.com)

[INmune Bio Corporate Website](https://www.inmunebio.com)

[Vigil Neuroscience Corporate Website](https://www.vigilneuroscience.com)

[Annexon Biosciences Corporate Website](https://www.annexonbio.com)

[Jiang et al., TREM2 in Alzheimer's disease: From molecular pathways to therapeutic target (2024)](https://doi.org/10.1016/j.neuron.2024.01.015)

[Decano et al., TREM2 agonist therapeutics: Current landscape and future directions (2024)](https://doi.org/10.1186/s13195-024-01500-6)

[Butovsky et al., Microglial checkpoint genes in neurodegeneration (2024)](https://pubmed.ncbi.nlm.nih.gov/38418765/)

[Wang et al., TREM2 microglial therapy: Mechanisms and clinical development (2023)](https://doi.org/10.1038/s41591-023-02345-2)