Introduction

The intestinal epithelium is the most regenerative tissue in the human body and an essential interface between the microbial ecosystem and the underlying mucosa, orchestrating both immune-mediated and metabolic functions. Mitochondrial signaling and metabolism controls the phenotype and function of intestinal epithelial cells (IECs) and mitochondrial perturbation is associated with chronic inflammation. We hypothesize that disruption of microbial-metabolic circuits and impaired metabolic flexibility of IECs contribute to the initiation and progression of tissue injury underlying chronic inflammation. Our aim is to identify key players of the intestinal microbiota crucial in, respectively, metabolic mutualism or disrupted homeostasis.

Aims & Methods

To address the role of mitochondrial impairment in epithelial homeostasis, conditional deletion of the mitochondrial chaperone Heat shock protein 60 (Hsp60) was induced in IECs of both specific-pathogen free and germ-free (GF) Hsp60^Δ/ΔIEC mice as well as in a colitis mouse model (Hsp60^Δ/ΔIEC;Il10^-/-) and in AhR-deficient mice (Hsp60^Δ/ΔIEC;AhR^-/-). Histological analysis, 16S rRNA and shallow shotgun sequencing were performed. Nanostring analysis and single-cell RNA sequencing (scRNA-seq) were used to investigate respectively the intestinal tissue response and cell population gene signatures. Different molecular mechanisms were analyzed in Hsp60-deficient organoids.

Results

Hsp60 deletion in IECs induces metabolic injury, defined as a disrupted mitochondrial metabolism accompanied by an irregular crypt architecture indicative of transient tissue injury. Tissue lesions are completely absent in the distal colon of GF mice, indicating bacterial contribution to metabolic injury. Furthermore, mitochondrial perturbation is associated with microbial dysbiosis including a rapid drop in species richness and changes in the bacterial community profile of Hsp60^Δ/ΔIEC mice with an increased abundances of Bacteroides spp. in Hsp60^Δ/ΔIEC;Il10^-/- mice. Mitochondrial impairment of the epithelium accelerates inflammation, paralleled by a persistent Bacteroides spp. expansion. Accordingly, B. caecimuris expands during metabolic injury in GF Hsp60^Δ/ΔIEC animals colonized with the synthetic minimal consortium OligoMM¹². Consistently, B. caecimuris triggers tissue aberration in monocolonized-Hsp60^Δ/ΔIEC mice, supporting its deleterious role in tissue homeostasis. Importantly, clinical relevance of mitochondrial stress signaling of the epithelium and increased abundance of Bacteroides spp. are confirmed in a combined analysis of three IBD cohorts (N=560 patients). On the host side, lack of Aryl hydrocarbon Receptor (AhR) signaling upon metabolic injury is lethal in Hsp60^Δ/ΔIEC;AhR^-/- mice, yet antibiotic exposure abrogates the severity of the phenotype, highlighting that AhR ligands modulate metabolic injury, which we also show in ex vivo intestinal organoids. Nanostring analysis of a metabolic gene panel points out changes in the profile of Hsp60^Δ/ΔIEC intestinaltissue, including tryptophan metabolism. Moreover, IEC scRNA-seq data confirms that clusters of cells repopulating the epithelium show expression of key enzymes of tryptophan metabolism.

Conclusion

Bacteroides spp. profit from a selection advantage under conditions of epithelial metabolic injury and aggravate tissue pathology. Furthermore, bacterial and metabolic sensing by the host critically affect the outcome of metabolic injury, strengthening the hypothesis of unresolved metabolic injury as a novel concept in the pathogenesis of intestinal inflammation.

Introduction

Fistulizing perianal Crohn’s disease (CD) remains a significant therapeutic challenge, with limited randomized controlled trials to date, restricted so far to infliximab and, more recently, filgotinib. The USTAP (NCT04496063) trial aimed to evaluate the efficacy and safety of UST in patients with actively draining perianal fistulas through a multicenter randomized controlled design.

Aims & Methods

This double-blind, placebo-controlled, multicenter trial enrolled adult patients with active draining fistulizing perianal CD. Between April 2020 and June 2024, eligible patients with persistent fistula drainage were randomized 1:1, after seton placement when necessary, to receive either UST (6 mg/kg IV at baseline followed by 90 mg SC at week 8, then every 8 weeks) or placebo. Steroids were allowed at baseline with a standardized steroid taper. Seton removal was planned at week 6. The primary endpoint was combined clinical remission (absence of drainage from all external fistula openings) and radiological remission (defined as the absence of abscesses >2 cm confirmed by blinded central pelvic MRI) at week 12. Secondary endpoints included clinical remission, radiological remission, changes in disease activity (CDAI, PDAI), IBD-DI, and safety. Endpoints were independently reviewed by a blinded adjudication committee. Randomization was stratified by prior anti-TNF exposure and study center. The intended sample size was 73 patients per group to detect a 20% difference in remission rates (power 80%, alpha 5%). Due to slow recruitment, the study was discontinued in June 2024 after randomizing 32 patients, without unblinding the study data. Patients were subsequently followed until week 48.

Results

Thirty-three patients consented to participate with 32 patients (women: 41%; median age: 42) ultimately randomized (UST: 16; placebo: 16) across 10 French centers. Seventy percent had prior anti-TNF exposure (50% in UST arm, 50% in placebo arm), and 23% had previously failed two or more anti-TNF therapies. At baseline, 84% had one draining fistula, 16% had two, and 25% had associated abscesses. At week 12, combined remission was achieved in 62% in the UST group versus 25% in the placebo group (Table). Clinical remission was observed in 69% in the UST group vs. 31% in the placebo group, while radiological remission rates were 87.5% in the UST group and 75% in the placebo group. In the UST arm, mean change in CDAI, PDAI and IBD-DI from baseline to week 12 was -56.3, -2.2 and -4.9, (vs. -9.8, -1.6 and +4.9, in the placebo arm, respectively). Adverse events (AE) and serious adverse events (SAE) were similar in both treatment groups: 23 AE (62%) occurred in the placebo group, and 14 AE (38%) in the UST group. Six SAEs were reported overall, including two gastrointestinal events, one renal disorder, and one anal abscess. Two patients in the placebo group discontinued study by week 6 due to SAEs (an anal abscess and a peri-ileal abscess).

Endpoints	Overall (N=32)	Placebo (N=16)*	Ustekinumab (N=16)	OR (IC 95%)
Primary endpoints, n (%)
Combined Remission	14 (44%)	4 (25%)	10 (62%)	5.1 [1.07-24.4]
Secondary endpoints, n (%)
Clinical Remission (100% of the fistulas tracts showing no drainage)	16 (50%)	5 (31%)	11 (69%)	0.27 [0.06-1.17]
Radiological Remission (absence of collections >2 cm confirmed by masked central MRI)	26 (81.2%)	12 (75%)	14 (87.5%)	2.7 [0.34-21.1]
Absence of abscess at pelvic MRI	22 (69%)	11 (69%)	11 (68%)	1.51 [0.3-7.46]

*Two patients discontinued study by week 6 in the placebo group

Conclusion

In this trial, where the majority of patients had prior anti-TNF exposure, the observed short-term clinical benefit of UST supports its use in fistulizing perianal CD.

Disclosure

This work was supported by a grant from Johnson & Johnson
Pauline Wils : Johnson & johnson, Takeda, Amgen, Abbvie, Celltrion, Ferring
S Nancey: Abbvie, Johnson and Johnson, Fresenius Kabi, Biogen, Takeda, Medac, Celltrion, MSD, Pfizer, Sandoz, Lilly,Ferring, Amgen
E. Messmer: No conflict of interest for this study
A Bourreille: Johnson and Johnson
A Buisson: Consulting fees from: Abbvie, Amgen, Arena, Biocon, Biogen, Celltrion Healthcare, CTMA, Ferring, Galapagos/AlfaSigma, GutyCare/Resilience Janssen, Lilly, MSD, Nexbiome, Pileje, Pfizer, Roche, Sandoz, Takeda et Tillotts. Lecture fees from: Abbvie, Amgen, Biogen, Celltrion Healthcare Galapagos/AlfaSigma, Ferring, Janssen, Lilly, Mayoli-Spindler, MSD, Nordic Pharma, Norgine, Pfizer, Roche, Takeda, Tillotts and Vifor Pharma. Research grants/fundings from: Abbvie, Celltrion Healthcare, Janssen, Lessaffre, Lilly, Pfizer, Sandoz and Takeda
L Caillo: No conflict of interest for this study
L Vuitton: abbvie amgen J&J Pfizer Takeda Lilly MSD Mayoli Ferring Dr Falk Alpha Sigma
R Altwegg: Abbvie, Johnson ans Johnson, Takeda, Pfizer, Lilly, Alphasigma, Celltrion, Amgen, Biogen, Sandoz, Ferring
X Hébuterne reports clinical research funding from Abbvie, Abivax, Amgen, Celltrion, Lilly, Fresenius-Kabi, J&J, InDex Pharmaceuticals, Pfizer, Prometheus, MSD, Roche, Takeda, serving on advisory boards for Abbvie, Biogen, Celltrion, Lilly, J&J, and participating in lectures and educational activities for Abbvie, Amgen, Celltrion, Lilly, Fresenius-Kabi, Galapagos, J&J, MSD, Nestlé Health Sciences, Nutricia, Pfizer, Tillots, Takeda.
O Ernst: No conflict of interest for this study
P Meunier: No conflict of interest for this study
V Laurent: No conflict of interest for this study
D Laharie: received board and lecture fees from: Abbvie, Alfasigma, Amgen, Biogen, Celltrion, Ferring, Fresenius-Kabi, Janssen, Lilly, MSD, Pfizer, Roche, Sandoz, Takeda
E Vicaut: No conflict of interest for this study
L Peyrin-Biroulet: Consulting : Abbvie, Abivax, Adacyte, Alimentiv, Amgen, Applied Molecular Transport, Arena, Banook, Biogen, BMS, Celltrion, Connect Biopharm, Cytoki Pharma, Enthera, Ferring, Fresenius Kabi, Galapagos, Genentech, Gilead, Gossamer Bio, GSK, IAC Image Analysis, Index Pharmaceuticals, Inotrem, Janssen, Lilly, Medac, Mopac, Morphic, MSD, Nordic Pharma, Novartis, Oncodesign Precision Medicine, ONO Pharma, OSE Immunotherapeuthics, Pandion Therapeuthics, Par' Immune, Pfizer, Prometheus, Protagonist, Roche, Samsung, Sandoz, Sanofi, Satisfay, Takeda, Telavant, Theravance, Thermo Fischer, Tigenix, Tillots, Viatris, Vectivbio, Ventyx, Ysopia ; lecture : Abbvie, Amgen, Arena, Biogen, Celltrion, Ferring, Galapagos, Genentech, Gilead, Janssen, Lilly, Medac, MSD, Nordic Pharma, Pfizer, Sandoz, Takeda, Tillots, Viatris

Introduction

Obefazimod is an oral small molecule that modulates inflammation by upregulating a specific anti-inflammatory micro-RNA (miR-124). Obefazimod has demonstrated safety and efficacy in patients with moderate-to-severe ulcerative colitis (UC) in the randomized, placebo-controlled, phase 2b induction study (1). This analysis presents data at week 96 after subjects enrolled in the open-label (OL) maintenance study.

Aims & Methods

Patients received placebo or obefazimod 25mg, 50mg or 100mg once daily (od) during the 16-week induction Phase 2b and, irrespective of their clinical response, could enter the optional OL 96-week maintenance study with obefazimod 50mg od. A total of 217 patients were enrolled into this study from January 13, 2020 onwards. Patients were followed monthly for safety and efficacy. Non-responder imputation (NRI) was used for missing efficacy data.

Results

Of 222 patients who completed the phase 2b induction study, 217 (97.7%) were enrolled in the OL maintenance study. 30/217 (13.8%) subjects dropped out prior to week 48, 6 subjects did not qualify the second year of treatment (non-responders) and 17/181 (9.4%) subjects dropped out between week 48 and week 96. All dropouts were considered as treatment failures for this analysis. 164 subjects completed the second year of treatment. Main efficacy results are presented in the Table below.

Criteria	Definition	All patients (NRI) N=217
Clinical remission	MMS : stool frequency sub-score ≤1, RBS = 0 and endoscopic sub-score ≤1	52.5%
Endoscopic improvement	Endoscopic sub-score ≤1	59.0%
Endoscopic remission	Endoscopic sub-score = 0	35.9%
Clinical response	Decrease from baseline in the MMS ≥ 2 points and ≥30% from baseline, plus a decrease in RBS ≥ 1 or an absolute RBS ≤ 1	70.5%

MMS: Modified Mayo score ; NRI: Non-responder imputation ; RBS: rectal bleeding sub-score
Among the 168 patients with no clinical remission after week 16 induction, 81 (48.2 %) achieved de novo clinical remission at week 96 of the OL maintenance study. Among the 49 patients with clinical remission after induction, 33 (67.3 %) maintained remission at week 96.
In total, 149 /217 subjects (68.7 %) reported at least one treatment emergent adverse events (TEAE) over 2 years of treatment. TEAEs leading to study discontinuation were reported in 17 subjects (7.8 %) and serious adverse events (SAEs) were reported in 18 subjects (8.3 %). The most frequent TEAEs (≥ 5 %) were COVID-19 (14.3 %), headache (11.5%), ulcerative colitis (7.8 %) and nasopharyngitis (6.9 %). No new safety risks were identified over these 96 weeks.

Conclusion

Results from this 96-week analysis of the OL maintenance Phase 2b study confirmed long-term efficacy of obefazimod 50 mg od, with durable clinical remission, as well as a favorable long-term safety profile.

References

1. Vermeire S, Sands B, Tilg H et al. ABX464 (obefazimod) for moderate-to-severe, active ulcerative Colitis: a phase 2b, double-blind, randomised, placebo-controlled induction trial and 48 week, open-label extension. Lancet Gastroenterol Hepatol 2022, 7 (11): 1024-1035

Disclosure

Bruce E Sands reports consulting fees from Abbvie, Alimentiv , Amgen, Arena Pharmaceuticals, Artugen Therapeutics, Astra Zeneca, Boehringer Ingelheim, Boston Pharmaceuticals, Calibr, Celgene, Celltrion, ClostraBio, Equillium, Enthera, Evommune, Fresenius Kabi, Galapagos, Genentech (Roche), Gilead Sciences, GlaxoSmithKline, Gossamer Bio, Index Pharmaceuticals, Innovation Pharmaceuticals, Inotrem, Kaleido, Kallyope, Merck, Morphic Therapeutics, MRM Health, Progenity, Prometheus Biosciences, Prometheus Laboratories, Protagonist Therapeutics, Q32 Bio, Sun Pharma, Surrozen, Target RWE,Teva, TLL Pharmaceutical, Ventyx Biosciences; consulting and speaking fees from Abivax; consulting and speaking fees and other support from Lilly; research grants, consulting and speaking fees and other support from Bristol Myers Squibb, Janssen, Pfizer, Takeda; research grants and consulting fees from Theravance Biopharma; and stock options from Ventyx Biopharma.
Séverine Vermeire has received grants from AbbVie, J&J, Pfizer, Takeda and Galapagos; Séverine Vermeire has received consulting and/or speaking fees from: AbbVie, Abivax, AbolerIS Pharma, AgomAb, Alimentiv, Arena Pharmaceuticals, AstraZeneca, Avaxia, BMS, Boehringer Ingelheim, Celgene, CVasThera, Cytoki Pharma, Dr Falk Pharma, Ferring, Galapagos, Genentech-Roche, Gilead, GSK, Hospira, Imidomics, Janssen, J&J, Lilly, Materia Prima, MiroBio, Morphic, MrMHealth, Mundipharma, MSD, Pfizer, Prodigest, Progenity, Prometheus, Robarts Clinical Trials, Second Genome, Shire, Surrozen, Takeda, Theravance, Tillots Pharma AG, Zealand Pharma.