Sorrentino, DarioGray, James M.2022-10-112022-10-112021-080021-8812http://hdl.handle.net/10919/112130Background: Fecal lactoferrin (FL) levels may mirror drug-induced changes in inflammation in ulcerative colitis and Crohn disease in a timely way and could be used to assess loss of response (LOR) to biologics. Methods: This study is a retrospective outcome review in 61 patients on adalimumab, infliximab, or vedolizumab managed in our center and followed for 6 to 24 months. Patients were 1) in clinical remission or 2) were experiencing possible LOR. Results: For group 1, in 71% of 31 patients, FL slowly increased during the therapeutic interval (R-2=0.769; P<0.001), thus reflecting increasing inflammation as drug concentrations decreased. In the remaining patients, FL was undetectable throughout the therapeutic interval because of a stronger suppression of inflammation. For group 2, in 30 patients negative for infections, FL levels measured 1 to 3 days after infusion/injection compared to preadministration values either increased (nonresponders)-in these patients the medication was switched to another class; partially decreased (partial responders)-the therapeutic interval was shortened; or were normal throughout (responders)-causes for symptoms unrelated to disease activity were found for all. After FL-based management, 3-month standardized clinical scores were normalized in both partial responders (0.580.21 vs 0.13<plus/minus>0.09; P<0.001) and nonresponders (0.81<plus/minus>0.17 vs 0.12 +/- 0.08; P<0.001), and FL levels dropped by up to 99%. Conclusions: Levels of FL reflect drug-induced changes in mucosal inflammation in a timely way, thus enabling rapid assessment of therapeutic response in patients with ulcerative colitis and with Crohn disease. In patients with suspected LOR, FL levels before and after infusion/injection accurately separated responders, partial responders, and nonresponders. The strategy proposed here is simple, accurate, and easily applicable to clinical practice.application/pdfenCreative Commons Attribution-NonCommercial 4.0 Internationalinflammatory bowel diseasestherapeutic responsefecal lactoferrinArticle - Refereedhttps://doi.org/10.1093/ibd/izaa34810091525-3163