BMJ Open Gastroenterol. 2026 Mar 23;13(1):e002153. doi: 10.1136/bmjgast-2025-002153.
ABSTRACT
OBJECTIVE: Selective inhibition of interleukin (IL)-23 through antagonism of the IL-23p19 subunit has demonstrated clinical efficacy in inflammatory bowel disease, but the molecular changes underlying the efficacy outcomes have not yet been described. Here, we provide a detailed evaluation of the cellular and molecular changes associated with guselkumab treatment in patients with moderately to severely active ulcerative colitis (UC) from the QUASAR Phase IIb induction study.
METHODS: In this double-blind, placebo-controlled, dose-ranging induction study, patients (n=313) were randomised (1:1:1) to receive intravenous guselkumab 200 or 400 mg or placebo at weeks 0, 4, and 8. Colon biopsy samples were collected at weeks 0 and 12, enabling molecular profiling by bulk RNA sequencing (RNA-seq, n=257), single-cell RNA sequencing (n=52), and flow cytometry (n=30). Serum proteomic profiling was also performed at weeks 0, 4, and 12 (n=302).
RESULTS: Guselkumab treatment significantly reduced pro-inflammatory serum proteins by week 4 with continued decline through week 12, compared with placebo. Unsupervised analysis of tissue gene modules revealed significant changes in transcriptional states related to pro-inflammatory and epithelial repair pathways, which were most pronounced in patients who achieved histological-endoscopic mucosal improvement (HEMI) at week 12, an important tissue-based end point. Single-cell analyses supported a decrease in the cellular abundance of pro-inflammatory and an increase in mucosal cell types in tissue following treatment.
CONCLUSION: This analysis of guselkumab in UC demonstrated changes in key pathways and cell types that are associated with achieving important clinical end points including HEMI at week 12.
TRIAL REGISTRATION NUMBER: NCT04033445.
PMID:41871904 | DOI:10.1136/bmjgast-2025-002153
