PTH-074 Baseline calprotectin does not predict response to biological therapy in ulcerative colitis

Introduction Response to biological drugs in ulcerative colitis (UC) is variable with induction response rates of 64.5% (vs 29.3% for placebo), 50.4% (vs 34.6% for placebo), 51.0% (vs 30.3% for placebo), 47.1% (vs 25.5% for placebo) for infliximab, adalimumab, golimumab and vedolizumab, respectively. Apart from prior exposure to anti-tumour necrosis factor (anti-TNF) agents and concurrent immunomodulatory therapy, predictors of clinical response and remission to biological drugs have not been identified. We sought to investigate the utility of baseline faecal calprotectin (FC) and early change in FC in predicting clinical response and remission to biological therapy in UC. Method Patients who were commenced on any biological therapy for UC and had a baseline FC at the time of commencement were included in this retrospective study. Disease activity was monitored serially by calculation of Simple Clinical Colitis Activity Index (SCCAI) or by Physician global assessment (PGA) or by treatment persistence. Clinical response was defined as decrease in SCCAI≥3 or a decrease in PGA score from baseline to follow up. The ability of FC and fold change in FC to predict response and remission at 6 months was estimated using Mann-Whitney test. Results A total of 94 patients were commenced on biological therapy of who 70 commenced anti-TNF therapy and 24 commenced vedolizumab with a mean age of 41.8 (SD:+18.2). Fifty-one (72%) and 39 (55%) patients commencing anti-TNF therapy were on concurrent immunomodulators (IM) and steroids respectively compared to 9 (38%) and 16 (67%) patients respectively for vedolizumab. Sixteen (67%) patients treated with vedolizumab had prior exposure to anti-TNF agents compared to 4 (6%) in the anti-TNF treated group. The 6 month response among patients treated with vedolizumab and anti-TNF agents was 77.2% and 73.5% respectively. The calprotectin values were similar for responders (428.5 (72, 2100) [n=16]) and non-responders (600 (107, 2100) [n=5]) to vedolizumab (p=0.56). Similarly, responders (909 (13, 2100) [n=28]) and non-responders (850 (240, 2100) [n=13]) to anti-TNF agents had comparable calprotectin values at baseline, p=0.93 Conclusion In a single centre series of biologic treated UC patients, baseline FC did not predict clinical response at 6 months. Disclosure of Interest None Declared