Background: Multiple studies have described the effectiveness of ustekinumab (UST) and vedolizumab (VDZ) in patients with Crohn’s disease (CD) failing anti- Tumor necrosis factors (TNFs); however, the effectiveness of VDZ or UST as a third-class biologic has not yet been described. Aims and Methods: In this retrospective multicenter cohort study, we aimed to investigate the effectiveness of VDZ and UST as a third-class biologic in patients with CD. Results: Two-hundred and four patients were included; 156/204 (76%) patients received VDZ as a second- and UST as a third-class therapy (group A); the remaining 48/204 (24%) patients received UST as a second- and VDZ as a third-class therapy (group B). At week 16–22, 87/156 (55.5%) patients and 27/48 (56.2%) in groups A and B, respectively, responded to treatment (p = 0.9); 41/156 (26.2%) and 15/48 (31.2%) were in clinical remission (p = 0.5). At week 52; 89/103 (86%) patients and 25/29 (86.2%) of the patients with available data had responded to third-class treatment in groups A and B, respectively (p = 0.9); 31/103 (30%) and 47/29 (24.1%) were in clinical remission (p = 0.5). Conclusion: Third-class biological therapy was effective in more than half of the patients with CD. No differences in effectiveness were detected between the use of VDZ and UST as a third-class agent.

Background: Monitoring inflammatory bowel disease (IBD) during pregnancy is challenging due tolimited use of invasive tools. While fecal calprotectin is considered reliable, its use is limited by patient adherence and availability. Blood-based markers, such as serum chitinase-3-like-1 (CHI3L1), offer a promising alternative. Aim: To evaluate whether serum CHI3L1 reflects disease activity in pregnant IBD patients, compared to standard markers and clinical questionnaires. Methods: Pregnant IBD patients were recruited from a multidisciplinary clinic. Blood samples were collected to assess inflammatory markers. Stool samples were used to measure calprotectin levels. Each visit was classified as a distinct sample for analysis. Correlations between CHI3L1 and disease activity markers were examined. Results: A total of 124 samples from 80 pregnant IBD patients were analyzed: 90 from Crohn’s disease (CD) patients and 34 from ulcerative colitis (UC) patients. CHI3L1 levels showed a significant positive correlation with fecal calprotectin (r_p = 0.366, p = 0.008), ESR (r_p = 0.358, p = 0.001), CRP (r_p = 0.478, p < 0.001) and standardized clinical scoring questionnaires. Elevated CHI3L1 (>56.6 ng/mL) is a risk factor for active disease (OR 8.78, 95% CI 1.54–49.83, p = 0.014). Conclusions: Serum CHI3L1 is positively associated with established markers of inflammation and may serve as a useful non-invasive biomarker for monitoring IBD activity during pregnancy, a medical condition in which invasive procedures are not recommended. Based on CHI3L1 levels, personalized treatment for pregnant IBD patients can be tailored. However, further validation is recommended.