NCT05164068 is a Phase 2 randomized, double-blind, placebo-controlled clinical trial evaluating PLX5622 (poblitinib), a selective colony-stimulating factor 1 receptor (CSF1R) inhibitor, in patients with early Alzheimer's disease. The trial investigates whether pharmacological microglial depletion via CSF1R inhibition can modulate neuroinflammation and slow disease progression.
| Attribute | Value |
|---|---|
| NCT Number | NCT05164068 |
| Drug Name | PLX5622 (Poblitinib) |
| Phase | Phase 2 |
| Status | Completed |
| Sponsor | Eli Lilly and Company |
| Intervention | PLX5622 oral tablets vs. placebo |
| Enrollment | ~120 patients |
| Duration | 52 weeks (1 year) |
| Study Design | Randomized, double-blind, placebo-controlled |
CSF1R (Colony Stimulating Factor 1 Receptor) is a receptor tyrosine kinase expressed primarily on microglia in the brain, where it serves as the master regulator of microglial survival, proliferation, and function[1]. CSF1R is activated by two ligands:
Upon ligand binding, CSF1R triggers downstream signaling through PI3K/AKT, MAPK/ERK, and STAT3 pathways, promoting microglial survival and the disease-associated microglia (DAM) phenotype.
PLX5622 is a highly selective small molecule inhibitor of CSF1R kinase activity[2]. By blocking CSF1R signaling, PLX5622 induces:
The rationale for targeting microglia in Alzheimer's disease rests on the observation that chronic neuroinflammation driven by disease-associated microglia (DAM) contributes to neuronal loss and cognitive decline[3]. Key mechanisms include:
By depleting the existing DAM population and allowing for repopulation with more quiescent microglia, PLX5622 aims to reset the neuroimmune environment.
The trial was conducted at multiple academic medical centers specializing in Alzheimer's disease research in the United States and potentially Europe. Sites included major memory disorder centers at:
PLX5622 has demonstrated significant therapeutic potential in multiple preclinical studies:
The Phase 2 trial represents a critical test of the microglial depletion hypothesis in humans. Key considerations include:
Potential Benefits:
Potential Concerns:
Based on prior clinical studies with PLX5622 and related CSF1R inhibitors:
Positive results from NCT05164068 would support:
Negative results would prompt reconsideration of the microglial depletion hypothesis and potentially shift focus to microglial modulation approaches rather than depletion.
Ginhoux F, Greter M, Leboeuf M, et al. Fate mapping analysis reveals that adult microglia derive from primitive macrophages. 2010. ↩︎
Olmos-Alonso A, O'Hara K, Pearce LA, et al. Pharmacological inhibition of CSF1R by PLX3397 reduces microglial activation and disease progression in ALS mouse models. 2021. ↩︎
Wang Y, Cella M, Wang L, et al. TREM2 maintains microglial metabolic fitness in Alzheimer's disease. 2017. ↩︎
Sosna J, Philipp S, Regnier L, et al. PLX5622 reduces amyloid plaques in APP/PS1 mice. 2018. ↩︎