Association Between Plasma Concentrations of Certolizumab Pegol and Endoscopic Outcomes of Patients With Crohn's Disease.

BACKGROUND & AIMS: Monitoring plasma concentrations of anti-tumor necrosis factor agents could optimize treatment of patients with Crohn's Disease (CD). In a post hoc analysis of data from a clinical trial, we compared the relationship between plasma concentrations of certolizumab pegol (CZP) and endoscopic and clinical responses and remission with CZP therapy in patients with moderate to severe ileocolonic CD. METHODS: We analyzed data from the Endoscopic Mucosal Improvement in Patients with Active CD Treated with CZP trial, from 89 adult patients with active endoscopic CD (ulceration in ≥ 2 intestinal segments and CD Endoscopic Index of Severity [CDEIS] scores of ≥ 8 points). Patients received subcutaneous CZP (400 mg) at weeks 0, 2, and 4 and then every 4 weeks until week 52. Endoscopic evaluations were performed at weeks 0, 10, and 54. Blood samples were collected to measure CZP plasma concentrations at weeks 8 and 54. CZP quartiles at weeks 8 (n = 80) and 54 (n = 45) were correlated with endoscopic response (>5-point decrease in CDEIS from baseline) and remission (CDEIS,