P069 Ontamalimab, a Fully Human Monoclonal Antibody Against Mucosal Addressin Cell Adhesion Molecule-1, Provides Sustained Exposure Following Long-Term Treatment in Patients With Ulcerative Colitis

Abstract

Introduction Ontamalimab is a fully human immunoglobulin G2 monoclonal antibody against mucosal addressin cell adhesion molecule-1 in development for the induction and maintenance of clinical remission in patients with ulcerative colitis (UC). This study aimed to assess the long-term pharmacokinetics (PK) of ontamalimab in patients with UC, and the effects of concomitant medications on PK parameters. Methods A 12-week induction study (TURANDOT; NCT01620255) was performed to assess the PK, efficacy and safety of ontamalimab (7.5, 22.5, 75 and 225 mg subcutaneous [s.c.] every four weeks [Q4W]) in patients with UC. Individuals who completed the induction study were eligible for enrollment in an open-label extension (OLE) study (TURANDOT II; NCT01771809) to assess the long-term PK, efficacy and safety of ontamalimab (75 or 225 mg s.c. Q4W up to week 72). Population PK analyses were performed using nonlinear mixed-effects modelling. Exposure-response analyses were performed to assess the relationships between minimum concentration (Cmin,ss) of ontamalimab and clinical response, clinical remission and mucosal healing. The effect of concomitant treatments (used for ≥20% of treatment duration) on PK parameters was also evaluated. Results The PK population included 130 (39.8%) women and 197 (60.2%) men, of median age of 40 years. A 1-compartment model with linear elimination adequately described the PK of ontamalimab. Population estimates of apparent clearance (CL/F) and volume of distribution (V/F) were 0.00917 L/h (0.22 L/day) and 7.44 L, respectively. Albumin had a significant effect on the variability of CL/F. Individuals with albumin levels of 30 g/L and 47 g/L are expected to have CL/F values 44% higher and 23% lower, respectively, than a typical patient with an albumin level of 39 g/L. Anti-inflammatory agents affected CL/F, such that CL/F is expected to be 14% higher in patients receiving than not receiving these agents. Other medications including immunosuppressants, steroids and treatments for peptic ulcers and gastroesophageal reflux disease had no effect on CL/F. Weight was the only covariate that significantly affected V/F. The half-life of ontamalimab was 23.4 days. Concentrations of ontamalimab over 72 weeks in the OLE study were consistent with those observed in the 12-week induction study. Ontamalimab Cmin,ss was related to efficacy, such that at week 16 (week 28 in total including induction), patients with higher Cmin,ss values were more likely to have clinical response, clinical remission and mucosal healing than those with lower Cmin,ss. Conclusion The exposure to ontamalimab was sustained following prolonged treatment in patients with UC for up to 72 weeks. Higher ontamalimab exposure was associated with a higher probability of clinical response.