Abstracts of the 25 th National Congress of Digestive Diseases / Digestive and Liver Disease 51/S2 (2019) e71–e243 e101 Conclusions: TH is an ambitious and powerful treatment goal associated, to a greater extent than MH, with improvement of all clinical outcomes. Additionally, TH is associated with better long-term clinical outcomes than MH also after discontinuation of biologics. OC.09.3 INFLIXIMAB DOSE-REDUCTION IN INFLAMMATORY BOWEL DISEASE (IBD) PATIENTS IN PROLONGED DEEP REMISSION: POTENTIAL IMPLICATIONS ON DE-ESCALATION STRATEGIES IN A REAL LIFE CLINICAL SETTING WITHOUT A THERAPEUTIC DRUG MONITORING (TDM) APPROACH A. Buda *,1 , S. Facchin 2 , G. Lorenzon 2 , B. Barberio 2 , F. Zingone 2 , E. Savarino 2 , R. D’Incà 2 1 Department of Gastrointestinal Oncological Surgery, S. Maria del Prato Hospital, Feltre (BL), Italy; 2 Department of Surgery, Oncology and Gastroenterology, Gastroenterology Section, University Hospital of Padova, Padua, Italy Background and aim: An increasing number of IBD patients are treated with Infliximab (IFX). Potential costs and safety concerns encourage de-escalation strategies particularly in patients with low risk of relapse. Few studies investigated the impact of increasing dose intervals on maintenance of remission in IBD patients whereas a dose reduction strategy has been reported only in conjunction with a TDM approach. The aim of this study was to evaluate the effect of Infliximab dose reduction on clinical remission in IBD patients Material and methods: In this retrospective single centre study, patients treated with IFX monotherapy every 8 weeks and in composite deep remission for at least 1 year had a dose reduction of their infusion from 5 mg/kg to 3 mg/kg. Patients were followed up every 3 months and relapse was defined by composite markers of clinical, biological and endoscopic recurrence. IFX was increased at 5 mg/kg in patients with relapse and infusion reaction or intolerance to IFX was recorded. Results: 57 patients (17F, 40M) were included (33 Crohn’s disease [CD] and 24 ulcerative colitis 8.5 months. Mean duration of IFX before [UC]) with a mean follow-up after dose reduction of 12.7 28.4 months. Overall, 14 (24.5%, 6 UC and 8 CD) patients had a fail- ure of dose reduction was 45.8 IFX de-escalation during follow-up. Cumulative probability of relapse free survival was 74.9±0.06% at 1 year and 69.2% ± 0.08% at 2 years (Fig. 1). Patients with relapse had an IFX reescalation with clinical response in 11/14 (78.5%). None of the patients showed signs of immunisation during maintenance with dose reduction whereas one patient (1/14, 7.1%) reported an Figure 1 infusion reaction after re-escalation to 5 mg/kg. No difference in the mean duration of IFX before dose reduction was observed in patients with relapse compared to patients maintaining remission (45.2±28.6% months vs. 44.8±28.2% months, p=0.1). In CD patients there was a trend of association between duration of IFX before dose reduction <36 months and the risk of relapse although not statistically significant (OR=2.07; 95% CI: 0.3–12.4, p=0.4). Conclusions: In a real-life clinical setting, IFX dose reduction is fea- sible and safe in IBD patients with composite deep remission with a relatively low risk of relapse at 2 years. More than three-quarter of patients who relapse regain remission after IFX re-escalation. In CD patients an IFX use >36 months seems to be associated with a lower risk of relapse. OC.09.4 FECAL CALPROTECTIN COULD PREDICT MUCOSAL HEALING IN PATIENTS WITH INFLAMMATORY BOWEL DISEASES TREATED WITH VEDOLIZUMAB: A PROSPECTIVE SINGLE-CENTER STUDY L. Bertani *,1 , L. Ceccarelli 2 , M.G. Mumolo 2 , E. Albano 1 , G. Tapete 1 , G. Baiano Svizzero 1 , R. Tedeschi 1 , N. De Bortoli 1 , A. Ricchiuti 2 , M. Bellini 1 , S. Marchi 1 , F. Costa 2 1 University of Pisa - Department of New Technologies and Translational Research in Medicine and Surgery, Pisa, Italy; 2 Azienda Ospedaliero-Universitaria Pisana - Department of Surgery and Gastroenterology, Pisa, Italy Background and aim: Vedolizumab (VDZ) is currently a good ther- apeutic option for Ulcerative Colitis (UC) and Crohn’s Disease (CD); nevertheless, according to real-life studies, despite a good effec- tiveness in terms of clinical response, only 40% of patients achieve Clinical Remission (CR), and even less Mucosal Healing (MH). There is little knowledge about early markers of therapeutic response, especially of MH. Material and methods: A prospective observational study was carried out among patients with moderate-to severe UC and CD who started VDZ between June 2016 and June 2017. Primary non responder were excluded. Partial Mayo Score (PMS) for UC and Harvey Bradshaw Index (HBI) for CD, C-Reactive Protein (CRP) and fecal calprotectin (FC) were assessed before treatment, at week 6 and every 8 weeks during the follow up. All the patients underwent colonoscopy at baseline and at week 54 or in case of discontinua- tion of therapy due to loss of response (LOR). We defined as MH a Mayo Endoscopic Score ≤1 for UC, and the absence of ulcerations for CD. All the colonoscopies were performed by a single blinded operator. Clinical remission (PMS<2 or HBI <5), a normal CRP value (<0.5mg/dL), and the values of FC were evaluated as potential predictors of MH and CR at week 54. Statistical analysis was carried out using ROC curves and Fisher’s test as appropriate. Results: We enrolled 45 patients (31 UC and 14 CD). 13 (29%) patients (10 UC and 3 CD) experienced LOR. MH was reached in 18 patients (40%) – 14 UC and 4 CD, whereas CR in 26 (58%) – 17 UC and 9 CD. FC at week 6 correlated with MH, and ROC curve analysis identified an AUC of 0.822 with a sensitivity of 82% and a specificity of 83% at the cut-off of 180.5μg/g (p<0.001). The same results were observed for CR, where ROC curve identified an AUC of 0.739 with a sensitivity of 84% and a specificity of 69% at the cut-off of 195.5μg/g (p<0.01). CR and CRP values at week 6 showed no correlation with MH or CR at week 54. Conclusions: Our results showed that an early drop of FC levels is a good predictor of MH and CR at one year in UC and CD patients treated with VDZ. FC assessment could represent a promising early marker of response to therapy, especially considering the slow onset of action of VDZ.