GLIMMER assessed dose-response, efficacy, and safety of linerixibat, an ileal bile acid transporter inhibitor in development for cholestatic pruritus associated with primary biliary cholangitis (PBC). GLIMMER was a Phase 2b, multicenter, randomized, parallel-group study in adults with PBC and moderate-to-severe pruritus (≥4 on 0-10 numerical rating scale [NRS]). After 4 weeks of single-blind placebo, patients with NRS ≥3 were randomized (3:1) to double-blind linerixibat/placebo for 12 weeks (to week 16), followed by single-blind placebo (to week 20). The primary objective was to investigate dose-related changes in mean worst daily itch (MWDI) score. One hundred forty-seven patients received placebo (n= 36) or linerixibat (once daily: 20 mg, n= 16; 90 mg, n= 23; 180 mg, n= 27; twice daily: 40 mg, n= 23; 90 mg, n= 22). Linerixibat groups exhibited ≥2-point mean reductions in MWDI from baseline at week 16; however, differences from placebo were not significant. Post hoc analysis of change from baseline in monthly itch score over the treatment period (Phase 3 endpoint) showed significant differences between placebo and linerixibat 180 mg once daily (P= .0424), 40 mg twice daily (P= .0105), and 90 mg twice daily (P= .0370). A significant relationship between total daily dose and response was observed post hoc in the per protocol population (P= .0542). Consistent with mechanism of action, diarrhea was the most frequent adverse event, and incidence increased with dose. Linerixibat effect on itch was not significantly different versus placebo in the primary intent-to-treat analysis but was associated with a significant dose-dependent reduction in itch in the per protocol population. A well-tolerated dose was identified for Phase 3 investigation for cholestatic pruritus in PBC. gov ID: NCT02966834.