AB-4166

**AB-4166** is an oral, gut-restricted small molecule developed by Axial Therapeutics (formerly Axial Biotherapeutics) as a first-in-class microbiome modulator for Parkinson's disease (PD). It is a patented targeted release formulation of epigallocatechin gallate (EGCG), a polyphenolic natural product with poor systemic bioavailability, enabling selective action in the gastrointestinal tract. AB-4166 blocks aggregation of bacterial amyloids like CsgA from gut microbes (e.g., *Escherichia coli*), reducing their propagation via the gut-brain axis, which ameliorates GI symptoms such as constipation and colonic dyskinesia, improves colonic transit time, and shows preclinical benefits in motor function and α-synuclein pathology in PD models.[1][3][9][10]