Hertogh, Gert D.

Abstract Background Histologic inflammation persists in up to 1/4 of patients with Crohn’s disease (CD) despite endoscopic mucosal healing. Histologic and combined endoscopic-histologic endpoints are evolving measures of treatment efficacy in CD; however, the impact of histologic healing on long-term outcomes and disease progression is unknown. Week (W) 52 data comparing mirikizumab (Miri) vs placebo (PBO) in the randomized, double-blind, placebo- and active-controlled, treat-through Phase 3 VIVID-1 trial in patients with moderately-to-severely active CD (NCT03926130) were reported previously.1 Methods The main objective was to evaluate the association of W12 histologic response and W12 histologic remission with W52 clinical and endoscopic outcomes in VIVID-1. Two biopsy specimens from each of 5 intestinal segments (1 ileal and 4 colonic) were obtained from the edge of the ulcers, or the most inflamed mucosa from randomized patients at screening, W12, and W52. All analyses were post hoc and among patients with active histologic disease (defined as a Robarts Histopathology Index >0 and a Global Histologic Disease Activity Score >0) at baseline. Results At W12, treatment with Miri resulted in statistically significantly higher rates of achieving histologic response and histologic remission vs. PBO (Figure). At W12, 62.1% of patients had agreement (k=0.27 [fair]) between histologic response and endoscopic response, with a greater percentage achieving histologic over endoscopic response (59.0% vs. 38.8%)*. Significantly greater proportions of patients who achieved histologic response at W12 also achieved histologic response, histologic remission, endoscopic response, endoscopic remission, combined CDAI (Crohn’s Disease Activity Index) remission and endoscopic response, and normalisation of faecal calprotectin levels ≤250 µg/g and ≤150 µg/g at W52 (Table). Similar associations were observed between W12 histologic remission and W52 outcomes. Conclusion Histologic response seems to be an early objective sign of anti-inflammatory response and was significantly associated with one-year endoscopic and histologic outcomes, as well as biomarker normalisation. *Observed data References 1.Jairath V, et al. Presented at: UEGW 2024. OP131.

AimsPatients with Crohn's disease (CrD) have an elevated risk for the development of small bowel adenocarcinomas (SBAs). Actionable isocitrate dehydrogenase 1 (IDH1) mutations have been reported to be more frequent in CrD‐SBAs than in sporadic SBAs. The present study aimed to investigate the clinicopathological and immunophenotypical features, as well as methylation profiles, of IDH1‐mutated CrD‐SBAs.Methods and resultsAn international multicentre series of surgically resected CrD‐SBAs was tested for IDH1 mutation. Clinicopathological features, immunophenotypical marker expression and O6‐methylguanine‐DNA methyltransferase (MGMT) and long interspersed nuclear element‐1 (LINE‐1) methylation were compared between IDH1‐mutated and IDH1 wild‐type CrD‐SBAs. Ten (20%) of the 49 CrD‐SBAs examined harboured an IDH1 mutation and all the mutated cancers harboured the R132C variant. Compared to IDH1 wild‐type cases, IDH1‐mutated CrD‐SBAs showed significantly lower rates of cytokeratin 7 expression (P = 0.005) and higher rates of p53 overexpression (P = 0.012) and MGMT methylation (P = 0.012). All three dysplastic growths associated with IDH1‐mutated SBAs harboured the same IDH1 variant (R132C) of the corresponding invasive cancer, and all were of non‐conventional subtype (two serrated dysplastic lesions and one goblet cell‐deficient dysplasia). In particular, non‐conventional serrated dysplasia was significantly associated with IDH1‐mutated CrD‐SBAs (P = 0.029). No significant cancer‐specific survival difference between IDH1‐mutated CrD‐SBA patients and IDH1 wild‐type CrD‐SBA patients was found (hazard ratio = 0.55, 95% confidence interval = 0.16–1.89; P = 0.313).ConclusionsIDH1‐mutated CrD‐SBAs, which represent approximately one‐fifth of total cases, are characterised by distinctive immunophenotypical features and methylation profiles, with potential therapeutic implications. Moreover, IDH1‐mutated non‐conventional, serrated dysplasia is likely to represent a precursor lesion to such CrD‐SBAs.