XPro1595 (also known as XPro) is a selective inhibitor of soluble TNF-alpha (TNF-alpha) developed by INmune Bio Inc. as a novel approach to treating Alzheimer's disease by targeting chronic neuroinflammation. Unlike first-generation TNF inhibitors that block both soluble and transmembrane TNF, XPro1595 selectively targets the soluble form, allowing for more precise immunomodulation while preserving normal immune function. This selective approach addresses a critical limitation of earlier anti-TNF strategies, which were associated with increased infection risk and other adverse effects due to broad immunosuppression. [@chin2023]
XPro1595 (also known as XPro) is a selective inhibitor of soluble TNF-alpha (TNF-alpha) developed by INmune Bio Inc. as a novel approach to treating Alzheimer's disease by targeting chronic neuroinflammation. Unlike first-generation TNF inhibitors that block both soluble and transmembrane TNF, XPro1595 selectively targets the soluble form, allowing for more precise immunomodulation while preserving normal immune function. This selective approach addresses a critical limitation of earlier anti-TNF strategies, which were associated with increased infection risk and other adverse effects due to broad immunosuppression. [@chin2023]
The development of XPro1595 represents a significant advancement in neuroinflammation-targeted therapy for Alzheimer's disease. While amyloid and tau-focused approaches have dominated the field for decades, growing evidence indicates that neuroinflammation plays a central role in disease progression and may represent a complementary or even upstream therapeutic target. XPro1595 is being evaluated in the XANADU Phase 2 clinical trial (NCT05318982) for patients with early to moderate Alzheimer's disease, representing one of the most advanced neuroinflammation-modulating therapeutic candidates currently in development. [@colacicchi2022]
TNF-alpha is a pleiotropic cytokine produced by multiple cell types including microglia, astrocytes, macrophages, and neurons. It exists in two distinct forms with different biological activities:
Soluble TNF-alpha (sTNF-α): The homotrimeric secreted form that acts through TNF receptor 1 (TNFR1) and TNF receptor 2 (TNFR2). Soluble TNF-alpha is the primary driver of inflammatory signaling and is elevated in the brains and cerebrospinal fluid of patients with Alzheimer's disease. [@touzani2023]
Transmembrane TNF-alpha (tmTNF-α): The cell surface-bound form that primarily signals through TNFR2 and is involved in immune homeostasis, tissue repair, and normal immune surveillance. This form is essential for maintaining protective immune function.
XPro1595 specifically neutralizes soluble TNF-alpha while sparing transmembrane TNF-alpha, preserving the beneficial TNFR2-mediated signaling that is important for immune regulation and neuroprotection. This selectivity is crucial because complete TNF inhibition has been associated with increased infection risk, reactivation of latent infections, and other safety concerns that have limited the use of earlier TNF inhibitors in neurodegenerative diseases. [@cherry2020]
Chronic microglial activation is a hallmark of Alzheimer's disease pathology. In the healthy brain, microglia play essential roles in synaptic pruning, immune surveillance, and debris clearance. However, in Alzheimer's disease, chronic activation leads to a detrimental pro-inflammatory state characterized by:
XPro1595 reduces microglial activation by neutralizing the soluble TNF-alpha that drives pro-inflammatory microglial phenotype switching. This reduction in microglial activation may preserve synaptic integrity and prevent the excessive synaptic pruning that contributes to cognitive decline. [@meda2023]
TNF-alpha has direct effects on synaptic plasticity and function. Elevated TNF-alpha levels:
Beyond modulating microglial function, TNF-alpha inhibition provides neuroprotection through multiple pathways:
Mitochondrial protection: TNF-alpha signaling promotes mitochondrial dysfunction and apoptosis. XPro1595 may protect neurons from TNF-alpha-induced mitochondrial损伤. [@li2019]
Axonal preservation: Chronic inflammation contributes to axonal degeneration. TNF-alpha neutralization may help maintain axonal integrity.
Blood-brain barrier modulation: TNF-alpha increases blood-brain barrier permeability. XPro1595 may help restore barrier integrity, reducing leukocyte infiltration into the CNS.
Preclinical research with XPro1595 in Alzheimer's disease models demonstrated:
The Phase 1 study (NCT03931954) evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of XPro1595 in patients with mild-to-moderate Alzheimer's disease.
Study Design:
The XANADU trial (NCT05318982) is a Phase 2 randomized, double-blind, placebo-controlled study evaluating XPro1595 in patients with early to moderate Alzheimer's disease.
Trial Design:
The XANADU trial incorporates an extensive biomarker program:
CSF Biomarkers:
Multiple lines of evidence support TNF-alpha as a therapeutic target in Alzheimer's disease:
Post-mortem studies: Elevated TNF-alpha protein and mRNA in AD brain tissue, particularly around amyloid plaques and in regions vulnerable to neurodegeneration. [@smith2021]
CSF studies: Increased TNF-alpha concentration in cerebrospinal fluid of AD patients compared to age-matched controls, with levels correlating with disease severity. [@touzani2023]
Genetic associations: Polymorphisms in TNF gene associated with increased AD risk in some populations.
Animal models: TNF-alpha overexpression in mouse models accelerates amyloid pathology and cognitive deficits.
The failure of amyloid-targeting therapies to consistently demonstrate clinical benefit has renewed interest in neuroinflammation as an independent or complementary therapeutic approach:
Complementary mechanism: Neuroinflammation may amplify amyloid and tau pathology while also causing independent neuronal damage. Targeting inflammation may address multiple pathogenic pathways simultaneously. [@calsolaro2021]
Upstream role: Some evidence suggests neuroinflammation may precede or drive amyloid and tau pathology, making anti-inflammatory therapy potentially disease-modifying.
Synaptic protection: Unlike amyloid or tau-targeted approaches, TNF-alpha inhibition may directly protect synapses from inflammation-mediated damage.
XPro1595 represents a more targeted approach than earlier anti-inflammatory strategies:
| Approach | Target | Status | Key Considerations |
|----------|-------|--------|-------------------|
| XPro1595 | Soluble TNF-α | Phase 2 | Selective, preserves immune function |
| Etanercept | All TNF | Phase 2 (AD) | Mixed results, infection risk |
| Sargramostim | GM-CSF | Phase 2 | Immune enhancement |
| AL002 | TREM2 | Phase 2 | Microglial modulation |
| Minocycline | Microglia | Phase 3 | Broad anti-inflammatory |
The selective targeting of soluble TNF-alpha by XPro1595 addresses concerns about broad immunosuppression that limited earlier anti-TNF approaches in neurological diseases. [@hennessy2022]
Based on Phase 1 data and experience with other TNF inhibitors:
Common adverse events:
The selective targeting of soluble TNF-alpha provides potential safety advantages:
Preserved immune surveillance: Transmembrane TNF-alpha signaling through TNFR2 maintains normal immune function
Reduced infection risk: Sparing TNFR2-mediated immune responses may reduce serious infection rates compared to non-selective TNF inhibitors
Preserved tissue repair: TNFR2 signaling is involved in tissue regeneration and neuroprotection
The XANADU trial includes comprehensive safety monitoring:
The understanding of neuroinflammation in Alzheimer's disease has evolved significantly:
Original hypothesis: Chronic NSAID use would prevent or delay AD onset. This was based on the observation that arthritic patients taking NSAIDs had lower AD rates.
Refinement: Early trials of non-selective NSAIDs failed, leading to the recognition that timing and target selection are critical. Neuroinflammation may be both a cause and consequence of pathology, making treatment timing essential.
Current model: A dual-target approach that reduces harmful neuroinflammation while preserving protective immune function may be more effective than broad immunosuppression. [@cunningham2020]
TNF-alpha is being investigated as a predictive and response biomarker:
Diagnostic: Elevated CSF TNF-alpha may help distinguish AD from other dementias
Prognostic: Higher baseline TNF-alpha correlates with more rapid cognitive decline
Pharmacodynamic: Changes in TNF-alpha or downstream markers may indicate target engagement
XPro1595 may be suitable for combination with disease-modifying therapies:
Anti-amyloid antibodies: Lecanemab, donanemab could be combined with anti-inflammatory therapy
Anti-tau approaches: Tau-targeting therapies may benefit from reduced neuroinflammation
Symptomatic treatments: Cholinesterase inhibitors, NMDA receptor antagonists
This combination approach acknowledges the multifactorial nature of Alzheimer's disease pathogenesis.
XPro1595 is one of several neuroinflammation-targeting therapies in development:
| Drug | Target | Company | Phase | Mechanism |
|------|--------|---------|-------|-----------|
| XPro1595 | Soluble TNF-α | INmune Bio | Phase 2 | Selective inhibition |
| AL002 | TREM2 | Alector | Phase 2 | Agonist antibody |
| AL003 | TREM2 | Alector | Phase 1 | Blocking antibody |
| Bryostatin | PKC | Neurotrope | Phase 2 | Synaptic repair |
| Sargramostim | GM-CSF | University of Colorado | Phase 2 | Immune enhancement |
XPro1595's selective mechanism and advancement to Phase 2 make it a leading candidate in this emerging therapeutic class.
As of 2026, XPro1595 is advancing through the XANADU Phase 2 clinical trial. The trial is actively recruiting at multiple sites, with topline results expected in 2027-2028.
If successful, XPro1595 could represent:
XPro1595 is a selective TNF-alpha inhibitor with distinct pharmacological properties:
Structure: A dominant-negative inhibitor of soluble TNF-alpha, consisting of mutated human TNF-α sequences that form inactive homotrimers with wild-type TNF-alpha, preventing signaling through TNF receptors.
Mechanism: Unlike etanercept (which is a fusion protein decoy receptor), XPro1595 works by forming non-functional complexes with soluble TNF-alpha, effectively sequestering the cytokine without triggering receptor-mediated effects.
Selectivity: The compound shows >100-fold selectivity for soluble TNF-alpha versus transmembrane TNF-alpha, allowing preservation of TNFR2-mediated immune regulation.
Based on Phase 1 data:
Administration: Subcutaneous injection, allowing self-administration
Absorption: Moderate absorption rate with peak plasma concentrations achieved within 24-48 hours
Distribution: Limited distribution beyond vascular space; designed to act primarily on circulating soluble TNF-alpha
Metabolism: Expected to be degraded through normal protein catabolic pathways
Half-life: Approximately 2-3 weeks, supporting less frequent dosing
The XANADU trial uses multiple primary endpoints to assess efficacy:
Cognitive Measures:
Biomarker Endpoints:
The clinical trial includes robust safety monitoring:
Injection Site Reactions: Most common adverse event; typically mild and self-limiting
Infection Monitoring: Vigilance for signs of infection due to immunomodulatory effects
Laboratory Abnormalities: Regular monitoring of hematological and chemical parameters
Several strategies are implemented to minimize risks:
Screening: Thorough baseline evaluation including TB testing
Monitoring: Frequent safety assessments throughout treatment period
Stopping Rules: Predefined criteria for study discontinuation due to safety concerns
The Alzheimer's disease therapeutic market is evolving rapidly:
Approved Disease-Modifying Therapies:
XPro1595 occupies a unique position:
Mechanistic Distinction: Targeting neuroinflammation rather than amyloid or tau
Selective Action: More targeted than broad anti-inflammatory approaches
Combination Potential: May work synergistically with disease-modifying therapies
Future patient selection may be refined based on biomarkers:
Inflammatory Biomarkers: Patients with elevated baseline inflammatory markers may respond best
Genetic Factors: Certain genetic polymorphisms may predict response
Disease Stage: Early intervention may provide greatest benefit
Ideal candidates for XPro1595 therapy:
Successful implementation requires:
Physician Education: Training on patient selection and monitoring
Caregiver Training: Proper administration techniques and side effect recognition
Monitoring Systems: Infrastructure for safety surveillance
Considerations for broad access:
Pricing: Cost will impact patient accessibility
Coverage: Insurance and Medicare coverage decisions
Global Access: Availability in different healthcare systems
The path to FDA approval involves:
Phase 2 Validation: Demonstrating efficacy and safety in Phase 2
Accelerated Approval: Possible pathway based on biomarker endpoints
Full Approval: Requires demonstration of clinical benefit
Several questions remain to be addressed:
Several related studies are ongoing:
XPro1595 represents an innovative approach to Alzheimer's disease treatment that targets the neuroinflammatory component of the disease. By selectively inhibiting soluble TNF-alpha while preserving protective immune function, this therapy addresses a key gap in current treatment approaches.
The ongoing XANADU Phase 2 trial will provide critical data on efficacy and safety, potentially establishing proof-of-concept for neuroinflammation-targeted therapy in Alzheimer's disease. Given the complex multifactorial pathogenesis of AD, combination approaches that address amyloid, tau, and neuroinflammation may ultimately provide the greatest clinical benefit.
The development of XPro1595 highlights the evolving understanding of Alzheimer's disease as a condition requiring multiple therapeutic targets, and represents an important step toward more comprehensive disease-modifying treatments. Page updated: 2026-03-28