Enrupatinib (EI-1071): A Comprehensive Analysis of a Selective CSF-1R Inhibitor in Clinical Development

Executive Summary

Enrupatinib (EI-1071) is an investigational, orally bioavailable, and brain-penetrant small molecule engineered as a potent and highly selective inhibitor of the Colony Stimulating Factor-1 Receptor (CSF-1R).[1] Its primary clinical development program is focused on Alzheimer's disease (AD), where it aims to offer a novel disease-modifying therapeutic approach by modulating microglia-mediated neuroinflammation.[3] The rationale for this approach is supported by a growing body of evidence implicating neuroinflammation as a central pillar in the pathophysiology of AD.

The compound has successfully completed a Phase 1 first-in-human study in healthy volunteers, which established a favorable safety and tolerability profile, with all treatment-emergent adverse events in the multiple-dose cohort being mild and unrelated to the drug.[6] Building on these results, Elixiron Immunotherapeutics has initiated a Phase 2 proof-of-concept clinical trial in patients with AD (NCT06745583). This study is strategically designed to use biomarker endpoints, including advanced neuroimaging, to validate target engagement in the central nervous system before proceeding to larger, more resource-intensive efficacy trials.[8]