P614 The utility as a biomarker of faecal calprotectin for predicting the clinical outcome of granulocyte and monocyte adsorptive apheresis treatment in patients with ulcerative colitis

The diagnosis and assessment of ulcerative colitis (UC) has been based on the clinical symptoms, blood parameters, and the findings of endoscopy and radiological examinations. Recently, faecal calprotectin (Fcal) was developed as a non-invasive and easy marker that could be used to detect and monitor intestinal inflammation in clinical practice. However, its value as a biomarker for predicting the clinical outcome of remission induction therapy in patients with UC is still unclear. Granulocyte and monocyte adsorptive apheresis (GMA) treatment is widely used as a remission induction therapy for UC in Japan. The aim of this study was to evaluate the utility of Fcal as a biomarker for predicting the efficacy of GMA treatment. This multi-centre prospective observational study was conducted to assess the usefulness of Fcal as a biomarker for the prediction of remission induction in UC patients treated with GMA from October 2015 to November 2018. Fcal was measured at weeks 0, 1, 2 and the end of GMA treatment. Colonoscopy was performed at week 0 and within 24 weeks after the end of GMA treatment. Clinical activity was assessed using the partial Mayo score at the same time as Fcal was monitored. Clinical remission was defined a partial Mayo score (pMayo) of ≤2 and a score of ≤1 on all subscores. Mucosal healing was defined as a Mayo endoscopic subscore (MES) of ≤1. Twenty of the 30 patients who enrolled in this study completed GMA treatment. Nine patients achieved clinical remission, three showed a clinical response, and eight showed no response to GMA treatment. Three patients achieved mucosal healing. pMayo was more strongly associated with Fcal than the CRP level, the WBC count and the MES. The Fcal level decreased before the partial Mayo score and the rate of Fcal reduction (ΔFC) at Week 1 was approximately 50% that of the baseline value in the clinical remission group. A ROC analysis demonstrated that the ΔFC at Week 1 was the most accurate predictor of clinical remission at the end of GMA treatment (AUC=0.83, p = 0.01) among the patient data, including pMayo and the CRP level at Week 1. When the cut-off value was defined as a >60% reduction in ΔFC at Week 1, the sensitivity and the specificity for the prediction of clinical remission were 77.8% and 81.8%, respectively. Fcal is considered to be a useful and objective predictor of the efficacy of GMA treatment in UC patients and superior to symptomatic scores and blood parameters.