title: Optimizing biologic treatment in IBD: objective measures, but when, how and how often?
abstract: BACKGROUND
  The advent of biologic agents for the treatment of inflammatory bowel disease (IBD) was accompanied in parallel with emerging understanding of persisting underlying inflammation and ensuing bowel damage that can occur even in patients with seeming clinical remission. This lead to the concepts of mucosal healing and deep remission gaining acceptance as the more desired goals for therapy within an ambitious disease-control therapeutic approach, namely, treat-to-target strategy. However, how to practically monitor IBD patients, which objective measures to follow, at what time-points and whether to act upon results in asymptomatic patients are all questions that remain disputed.
  
  
  RESULTS
  In this concise review we aim to provide an overview of objective measures for monitoring of IBD patients, focusing on the challenging group of patients treated by infliximab, adalimumab, vedolizumab and other biologics. These objective measures are discussed in the context of the different common clinical scenarios wherein the clinician may contemplate their use. Specifically, we will delineate the role of objective parameters to be monitored during induction phase of treatment, during maintenance therapy, at loss of response and after elective cessation of therapy in patients in remission.
  
  
  CONCLUSIONS
  Coupled with the non-negligible costs of therapy, and the over-all worse prognosis of moderate-severe patients who are the usual recipients of biologic therapies, this challenging patients seem to be the first candidates for this more proactive strategy combining inflammatory and pharmacokinetic monitoring of objective inflammatory and pharmacokinetic measures. More data is still desirable to better define the exact parameters to be followed and their optimal thresholds, and to delineate the optimal cost-effective interventions for these patients.
authors.affiliation: IBD service, Department of Gastroenterology, Sheba Medical Center & Sackler School of Medicine, Tel-Aviv University, Tel Hashomer, 52621, Israel. shomron.benhorin@hotmail.com.|Department of Gastroenterology, First Affilated Hospital, Sun-Yatsen University, 58 Zhongshan II Road, Guangzhou, 510080, P.R. China. shomron.benhorin@hotmail.com.
authors.forename: Shomron
authors.initials: S
authors.lastname: Ben-Horin
authors.affiliation: Department of Gastroenterology, First Affilated Hospital, Sun-Yatsen University, 58 Zhongshan II Road, Guangzhou, 510080, P.R. China. maoren2023@163.com.
authors.forename: Ren
authors.initials: R
authors.lastname: Mao
authors.affiliation: Department of Gastroenterology, First Affilated Hospital, Sun-Yatsen University, 58 Zhongshan II Road, Guangzhou, 510080, P.R. China. chenminhu@vip.163.com.
authors.forename: Minhu
authors.initials: M
authors.lastname: Chen
mesh_terms: D000068879:Adalimumab / Q000627:therapeutic use; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use; D001688:Biological Products / Q000627:therapeutic use*; D005765:Gastrointestinal Agents / Q000627:therapeutic use*; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000188:drug therapy*; D000069285:Infliximab / Q000627:therapeutic use
chemical_list: D000893:Anti-Inflammatory Agents; D061067:Antibodies, Monoclonal, Humanized; D001688:Biological Products; D005765:Gastrointestinal Agents; C543529:vedolizumab; D000069285:Infliximab; D000068879:Adalimumab