Introduction

The optimal management strategy for patients with Crohn’s disease (CD) and ulcerative colitis (UC) who exhibit a partial response following induction therapy with intravenous (IV) vedolizumab (VDZ) remains undefined.

Aims & Methods

The Partial Response Following Induction of Remission with Intravenous Vedolizumab (PRIVEDO) study is a prospective, multicenter investigation conducted within the Sicilian Network for Inflammatory Bowel Disease (SN-IBD). The study aims to evaluate the efficacy of subcutaneous (SC) vedolizumab compared to early optimization of the IV formulation in patients with CD or UC who experienced a partial response after IV induction therapy. Eligible adult patients with active CD or UC who demonstrated a partial response at week 14 following IV VDZ induction were subsequently treated in a 1:1 ratio to receive either SC VDZ (108 mg every two weeks) or IV VDZ (300 mg every four weeks).
Partial response was defined as either: (i) achievement of clinical remission with persistent faecal calprotectin >250 µg/g and/or continued use of systemic corticosteroids; or (ii) a reduction in the Harvey-Bradshaw Index by ≥3 points (for CD) or in the Partial Mayo Score by ≥2 points (for UC) from baseline, without fulfilling clinical remission criteria, regardless of oral steroid use. The primary endpoint was the proportion of patients achieving steroid-free clinical remission and faecal calprotectin <250 µg/g at weeks 26 and 52. The secondary endpoint was the rate of clinical benefit—defined as steroid-free clinical remission or partial response—regardless of faecal calprotectin levels at the same time points. Here, we report interim data on 88 patients at week 26 and 69 patients at week 52.

Results

A total of 106 patients were enrolled [CD: n=57 (53.8%); UC: n=49 (46.2%)], with 52 patients (49.1%) allocated to the IV group and 54 (50.9%) to the SC group. Baseline characteristics were comparable between the two treatment arms. At week 26, the primary endpoint was achieved more frequently in the SC group compared to the IV group (42.9% vs. 10.9%; p=0.006). The proportion of patients achieving clinical benefit (secondary endpoint) was also higher in the SC group (73.8% vs. 58.7%), although this difference was not statistically significant (p=0.13). At week 52, the proportion of patients meeting the primary endpoint was 35.5% in the SC group and 18.4% in the IV group (p=0.29). Clinical benefit rates at this time point were 41.9% and 36.8%, respectively (p=0.67).

Conclusion

These preliminary findings suggest that in patients with an incomplete response to VDZ induction, switching to SC administration may offer a more profound remission at mid-term follow-up (26 weeks) compared to continued intensified IV therapy. Further analysis of the complete 52-week data set is required to confirm these observations.

Disclosure

FSM served as an advisory board member and/or received lecture grants from AbbVie, Ferring, Galapagos, Giuliani, Janssen, Lilly, Liohealth s.r.l., Pfizer, Sandoz, Takeda Pharmaceuticals. WF served as an advisory board member and/or received lecture grants from Abbvie, MSD, Takeda, Pfizer, Biogen, Sandoz, Zambon, Ferring, Sofar. AV received lecture grants from Pfizer. MC served as an advisory board member for AbbVie, MSD, Takeda Pharmaceuticals, and received lecture grants from AbbVie, MSD, Chiesi, and Takeda Pharmaceuticals. MC served as an advisory board member for AbbVie, MSD, Takeda Pharmaceuticals, and received lecture grants from AbbVie, MSD, Chiesi, and Takeda Pharmaceuticals. FM served as an advisory board member for Janssen and Galapagos, and received lecture grants from Takeda Pharmaceuticals. SR served as an advisory board member for AbbVie, Janssen, and MSD Pharmaceuticals, and received lecture grants from AbbVie, Galapagos, Janssen, MSD, Pfizer, and Takeda Pharmaceuticals. AO served as an advisory board member for AbbVie, Ferring, Galapagos, Lilly, MSD, Janssen, Pfizer, Samsung Bioepis, and Takeda Pharmaceuticals, and received lecture grants from AbbVie, Fresenius Kabi, Galapagos, Lionheath s.r.l., MSD, Sofar, Chiesi, Janssen, Pfizer, and Takeda Pharmaceuticals. All other authors: nothing to disclose.

Introduction

Microscopic colitis is a chronic inflammatory condition defined by a clinical triad: chronic diarrhea, endoscopy without significant abnormalities, and distinct histopathological features characterized by a largely normal appearance of the mucosa but increased numbers of lymphocytes in the epithelium and lamina propria on microscopy.

Aims & Methods

This study aims to explore the relationship between clinical presentation and histopathological features in microscopic colitis, with a focus on identifying prognostic factors linked to therapeutic response and symptom resolution.
This is a retrospective, descriptive study conducted over a 10-year period (September 2015 to May 2025), involving 54 patients diagnosed with microscopic colitis based on histological examination of colonic biopsies. Among them, 19 cases were identified as collagenous colitis and 35 as lymphocytic colitis. Data collected included epidemiological, clinical, endoscopic, histopathological, therapeutic, and follow-up information.
The histological parameters assessed were: characteristics of the lamina propria, intraepithelial lymphocytosis, presence and thickness of the subepithelial collagen band, and surface epithelial damage.

Results

A total of 54 cases of microscopic colitis were included in the study, among which 51 patients (94.4%) presented with chronic diarrhea, with a median of 7 diarrheic stools [IQR: 4.5–10.5]. One patient with lymphocytic colitis had concomitant celiac disease. Concerning medication use, 2 patients (3.7%) were taking proton pump inhibitors, and 3 (5.6%) were on venotonic agents.
Our analysis revealed several statistically significant correlations:

• A very strong positive correlation between the number of intraepithelial lymphocytes (IELs) and the frequency of diarrheal stools (r = 0.873; p < 0.001).

• A strong positive correlation between the number of diarrheal stools and the rate of clinical improvement (r = 0.633; p < 0.001).

• A strong association between subepithelial collagen band thickness and clinical improvement (r = 0.509; p < 0.001).

In addition, patients with an IEL count <30% experienced a significantly faster clinical response compared to those with ≥30%, with a median time to symptom resolution of 2 weeks versus 4 weeks, respectively (p < 0.001). Similarly, patients with subepithelial collagen band thickness <20 µm showed more rapid improvement than those with ≥20 µm (median time to improvement: 2 weeks vs. 6 weeks; p < 0.002).
Regarding treatment, 49 patients (90.7%) received budesonide, while 5 (9.3%) were managed with loperamide. A follow-up histological assessment performed 12 months after treatment initiation showed complete normalization of the colonic mucosa in all patients.

Conclusion

Microscopic colitis is a common cause of chronic diarrhea and represents a treatable condition. Accurate diagnosis relies on the recognition of characteristic histopathological features, highlighting the importance of a thorough histological assessment. The integration of clinical context with microscopic findings enables the pathologist to establish a confident diagnosis in most cases and to provide the gastroenterologist with precise and clinically relevant information.