Introduction

Real-world data on the speed of onset of ustekinumab (UST) in patients with ulcerative colitis (UC) are limited. Current information regarding early response in these patients comes from the UNIFI trial.

Aims & Methods

The primary outcome of this study was to evaluate the response to UST in patients with moderate-to-severe UC by assessing PRO2 at 14 days after the first intravenous dose (6mg/kg).
Methods: A multicenter, prospective observational study was designed in patients ≥18 years old with moderate-to-severe UC (partial Mayo score ≥6) who initiated UST 6mg/kg between June 2023 and September 2024. Patients received a diary to record the stool frecuency and rectal bleeding during first 14 days after first dose of induction. The proportion of patients achieving the combined outcome of rectal bleeding score = 0 and stool frequency score ≤ 1 (PRO-2: patient-reported outcome 2 remission) was assessed. FC was measured at baseline and at day 7 and 14. Health-Related Quality of Life was evaluated using the disease-specific shortened Spanish version of the IBDQ (SIBDQ-9) at baseline and at 4 weeks. Patients with previous panproctocolectomy with ileostomy or pouch and those who had received cyclosporine within one month prior to starting UST were excluded. Descriptive statistics are presented as frequencies with percentages for categorical variables.

Results

A total of 54 patients were included across 14 hospitals in Spain. Of these, 29 (53.7%) were men, with a mean age of 54 (± SD 16.1) years. Thirty (55.6%) patients had pancolitis, 20 (37%) had left-sided colitis, and 4 (7.4%) had proctitis. Five (9.3%) patients were bio-naïve, 32 (59.3%) had previously received one biological therapy, 10 (18.5%) had received two, and 7 (13%) had received three biologics prior to starting UST. By day 14, 26% of patients had achieved clinical remission. No significant differences in clinical remission were observed based on disease extent (p = 0.11) or the number of prior biologics (p = 0.39). By day 7, 12/31 (38.7%) patients with baseline bloody stools had achieved a rectal bleeding score = 0. A reduction in FC >50% was observed in 14/48 (29%) patients by day 7 and in 20/47 (43%) patients by day 14. The SIBDQ9 average score was 54.9 (± SD 6.2) at baseline and 61.3 (± SD 7.4) at week 4.

Conclusion

One-quarter of patients with moderate-to-severe UC achieved clinical remission by day 14 following the first induction dose of UST. Nearly 40% of patients achieved a rectal bleeding score = 0 (PRO2) by day 7. A reduction in FC >50% was observed in 43% of patients by day 14.

Disclosure

Manuel Barreiro de Acosta: speaker, consultant and advisory member for or have received research funding from AbbVie, Janssen, Takeda, Pfizer, Lilly, Alphasigma, Sandoz and Oncostellae

Introduction

Ulcerative colitis (UC) is a chronic, relapsing-remitting inflammatory bowel disease (IBD) with increasing global prevalence. The FDA has emphasized the importance of histologic endpoints in clinical trials, noting mucosal healing claims should be supported by more than just endoscopic findings. However, there are many challenges to achieving a standardized assessment of histologic disease activity in a UC clinical trial, including: the heterogeneity in the collection of mucosal biopsies (number, location) from study to study, a lack of fully validated histology scoring systems and an absence of community standards for definitions of histologic improvement or histologic remission.

Aims & Methods

This work was conducted by the FNIH Biomarkers Consortium Mucosal Healing in UC Project, a collaborative initiative involving academic institutions, pharmaceutical companies, patient advocacy organizations, and regulatory agencies to foster consensus, encourage adoption of findings, and support regulatory decision-making.
Aim 1: McBride et al. analyzed 994 biopsies from UC colectomy specimens to determine optimal biopsy sampling strategies for histologic grading.
Aim 2: A prospective study enrolled 153 UC patients to compare targeted versus non-targeted biopsy strategies across four colonic segments, assessing both endoscopic and histologic remission.
Aim 3: Data from three clinical trials (NCT02840721, NCT02958865, NCT02065622) and four independent datasets were compiled, yielding 9,652 whole slide images (WSIs) were used to train two AI tools:
• AIM-HI UC: Multiple instance learning models for predicting Geboes Score (GS) subgrades directly from H&E-stained WSIs.
• IBD Explore: A suite of convolutional neural networks (CNNs) for segmentation and classification of histologic features, including tissue types, crypt architecture, and cells. Performance was evaluated using a held-out test set (N=578 WSIs) and inter-pathologist agreement metrics.

Results

Aim 1: Sampling 2–3 biopsies per colonic region most effectively captured histologic heterogeneity and improved grading reliability. Agreement across histologic indices increased with biopsy number, particularly after the second and third biopsies.
Aim 2: Rectal histologic remission was highly predictive of proximal colonic remission (93% endoscopic, 88% histologic concordance). Histologic scores showed high correlation between targeted and non-targeted biopsies (ρ = 0.80–0.86), especially in remission.
Aim 3: Most AIM-HI UC models outperformed individual pathologists in predicting GS subgrades. IBD Explore generated interpretable histologic features—such as epithelial-to-lamina propria ratio, crypt distortion, and lymphocyte density—supporting advanced spatial analysis beyond conventional scoring systems.

Conclusion

This consortium-based endeavor generated several key findings: 1) Up to 3 biopsy samples per region of interest are required to overcome microscopic heterogeneity and ensure accurate histological grading in active colitis; 2) Targeted and random biopsies provide comparable histologic information, supporting the use of random biopsies in future clinical trials and practice; 3) Rectal endoscopic and histologic remission are highly predictive of pancolonic remission in extensive UC, supporting assessment limited to rectum in stable disease. Development of a ML-based approach for predicting GS subgrades, combined with these sampling insights, has the potential to improve standardization and automation of GS histological assessment, enhancing measurement of histological treatment response and endpoints in clinical trials.

References

IBD Explore and AIM-HI UC are for Research Use Only. Not for use in diagnostic procedures
McBride, R. B., Suarez-Farinas, M., Ko, H. M., Chen, X., Liu, Q., & Harpaz, N. (2023). Density of Biopsy Sampling Required to Ensure Accurate Histological Assessment of Inflammation in Active Ulcerative Colitis. Inflammatory bowel diseases, 29(11), 1706–1712. https://doi.org/10.1093/ibd/izad063
Danese S, Klopocka M, Scherl EJ, et al. Anti-TL1A Antibody PF-06480605 Safety and Efficacy for Ulcerative Colitis: A Phase 2a Single-Arm Study. Clin Gastroenterol Hepatol. 2021;19(11):2324-2332.e6. doi:10.1016/j.cgh.2021.06.011
Sandborn WJ, Danese S, Leszczyszyn J, et al. Oral Ritlecitinib and Brepocitinib for Moderate-to-Severe Ulcerative Colitis: Results From a Randomized, Phase 2b Study. Clin Gastroenterol Hepatol. 2023;21(10):2616-2628.e7. doi:10.1016/j.cgh.2022.12.029
Panés J, Colombel JF, D'Haens GR, et al. Higher vs Standard Adalimumab Induction and Maintenance Dosing Regimens for Treatment of Ulcerative Colitis: SERENE UC Trial Results. Gastroenterology. 2022;162(7):1891-1910. doi:10.1053/j.gastro.2022.02.033

Disclosure

Disclosures of Primary Authors
Autumn Jones: None
Russell McBride: None
Stephen Laroux: holds shares of stock in AbbVie
Christina Jayson: PathAI stock holder
Noam Harpaz: has served as an advisory board member or consultant for Lilly, Inc., Abbvie Inc., Bristol Meyer Squibb, Inc., and PathAI, Inc.

All listed organizations are financially contributing partners and/or consulting partners of the Foundation for the National Institutes of Health Biomarkers Consortium project team.
PathAI employees, previous and current are PathAI stock holders.

Introduction

Tumor necrosis factor-like ligand 1A (TL1A) is a member of the Tumor necrosis factor (TNF) superfamily implicated in the pathogenesis of inflammatory bowel disease (IBD) as a key amplifier of the effector function of several immune cells. TL1A can be expressed by various immune cells, including macrophages, dendritic cells, and some T cell subsets, and exists either as a membrane-bound or as a cleaved soluble trimer. TL1A signals predominantly by activating NF-kB pathway via the only known functional receptor, death receptor 3 (DR3), which has restricted expression mostly on effector T cells and innate lymphoid cells (ILCs). Afimkibart is a fully human anti-TL1A antibody that has shown clinical benefit in Phase 2 clinical studies and specifically blocks the activity of trimeric forms of TL1A. Monomeric TL1A has also been described; however, the relevance of monomeric TL1A in DR3 signaling and disease is unclear. This study aimed to understand the functional characteristics of both monomer and trimer TL1A species in primary cells and cell lines.

Aims & Methods

Immunoassays were used to measure the detection of TL1A species in IBD serum. Recombinant human monomeric and trimeric TL1A proteins were assessed for binding to afimkibart using SPR and in cellular assays using primary immune cells and cell lines for nuclear factor-kappa B (NF-κB) signaling and interferon-gamma (IFNγ) production.

Results

In functional cellular assays with primary immune cells, we demonstrate that trimeric recombinant human TL1A (rhTL1A) protein causes significant NF-κB signaling in human peripheral T lymphocytes, and in the presence of interleukin 12 (IL12) and interleukin 18 (IL18) co-stimulation, a significant increase of IFNγ production by human primary peripheral blood mononuclear cells (PBMCs). In line with the mechanism of action, both the NF-κB signaling and IFNγ production are blocked by afimkibart. In contrast, only high concentrations of monomeric rhTL1A, >100 ng/ml, induced moderate NF-κB signal and demonstrated a minimal increase in IFNγ production above IL12 + IL18 stimulation alone. However, this activity was blocked by afimkibart. Lastly, afimkibart blocks endogenous soluble and membrane-bound TL1A.

Conclusion

Herein, we demonstrate that afimkibart blocks NF-kB signaling and IFNγ production induced by TL1A stimulation. While some signaling activity was observed at high concentrations of monomeric TL1A protein, we hypothesize that any signaling observed with monomeric form is likely due to the formation of trimers, which are efficiently blocked by afimkibart. Overall, any monomeric TL1A present should not be functionally active nor be available as a sink for afimkibart, thus preserving the optimal pharmacokinetic (PK) and pharmacodynamic (PD) properties needed for effective target inhibition.

Disclosure

All the authors are employees of Genentech-Roche.