A placebo-controlled Phase 2 trial of E6011, anti-human fractalkine monoclonal antibody, in primary biliary cholangitis.

Background: While ursodeoxycholic acid (UDCA) remains the first-line therapy for primary biliary cholangitis (PBC), the autoimmune nature of PBC underscores the need for treatments targeting immunological pathways that may achieve a cure. E6011, a novel humanized anti-fractalkine monoclonal antibody, has emerged as a potential therapeutic option for PBC. We conducted a randomized, placebo-controlled, double-blind study to evaluate the efficacy and safety of E6011 in patients with PBC with an incomplete response to UDCA. Methods: The study was composed of 12-week Double-Blind Phase (placebo, E6011 10 mg/kg/month, 15 mg/kg/month, or 10 mg/kg/every other week [eow]) followed by a 52-week Open-Label Phase. The primary endpoint was the percent change in alkaline phosphatase (ALP) at Week 12. Results: A total of 29 patients were enrolled. Histological evaluation at screening revealed that 83 % of the enrolled patients were classified as Stage 4 according to the Nakanuma Classification. The mean percent changes in ALP at Week 12 were +0.45 % in the placebo, +0.65 % in the 10 mg/kg/month, +1.23 % in the 15 mg/kg/month and +1.19 % in the 10 mg/kg/eow, with no observed trends toward ALP reduction in the E6011 treatment. Based on the interim analysis, the study was discontinued due to a lack of the efficacy. E6011 was generally safe and well tolerated. Conclusion: This study of E6011 failed to meet the primary endpoint in patients with PBC with an incomplete response to UDCA. The advanced histological severity present in more than 80 % of patients at baseline may have contributed to these findings.