Elixiron Immunotherapeutics (TPEx: 7871), a clinical-stage biopharmaceutical company pioneering precision immunotherapy for neurodegenerative and autoimmune diseases,  announced positive interim results from its ongoing Phase 2 proof-of-concept study of enrupatinib (EI-1071), a brain-penetrant colony-stimulating factor 1 receptor (CSF-1R) inhibitor designed to modulate neuroinflammation in Alzheimer's disease (AD). The study is supported by the Alzheimer's Association through its Part the Cloud program.

The interim analysis demonstrated a favorable safety and tolerability profile, clear evidence of target engagement and neuroinflammation modulation as measured by translocator protein (TSPO)-PET imaging, and preliminary signals of clinical benefit in a biomarker-selected patient subgroup. The findings support the therapeutic rationale of targeting neuroinflammation in Alzheimer's disease and provide early in vivo evidence that enrupatinib modulates disease-associated neuroinflammatory processes.

Key Interim Data Highlights

• Favorable Safety and Tolerability Profile: No drug-related serious adverse events have been observed to date across all evaluable participants (n=7). Importantly, no clinically significant hepatotoxicity has been reported, potentially differentiating enrupatinib from earlier compounds within the same therapeutic class and supporting its suitability for chronic administration.
• Proof of Target Engagement: Within a biomarker-defined subgroup, 80% (4 out of 5) of participants showed TSPO-PET signal reductions exceeding 30% on average from baseline across multiple prespecified brain regions, with a significant reduction (p < 0.05) in Posterior Cingulate/Precuneus—a magnitude consistent with meaningful target engagement and providing direct in vivo evidence of pharmacodynamic activity. In the broader PET-evaluable population (n=7), 57% of participants also demonstrated reductions in TSPO-PET neuroinflammation signal from baseline following 28 days of oral enrupatinib.
• Early Signals of Cognitive Benefit: One TSPO-PET responder demonstrated marked improvements across all exploratory cognitive and functional assessments, most notably an 8-point increase in MMSE score from baseline. While the study was not designed or powered to evaluate cognitive efficacy at this interim stage, this observation raises the possibility that reducing neuroinflammation may translate into meaningful clinical benefit and merits formal evaluation in larger, controlled trials.
• Biomarker-Guided Precision Medicine Opportunity: A candidate predictive biomarker was identified in preliminary analyses. If validated prospectively, this biomarker may enable patient stratification strategies that improve clinical trial efficiency, enrich for responders, and support a targeted precision medicine approach to AD treatment.

These are exactly the signals we were looking for — clean safety, meaningful target engagement in biomarker-selected patients, and a first glimpse that dampening neuroinflammation can translate to cognitive benefit. Neuroinflammation amplifies amyloid and tau pathology yet has remained largely beyond therapeutic reach — enrupatinib is changing that. We're advancing to a larger, placebo-controlled study with clear momentum.

— Dr. Hung-Kai Kevin Chen, Chief Executive Officer and Chief Medical Officer, Elixiron Immunotherapeutics

Elixiron plans to initiate a placebo-controlled study enriched for likely responders using the predictive biomarker identified in this interim analysis, with the goal of confirming enrupatinib's efficacy in a precision-selected patient population.