Infliximab was the first-in-class anti-TNF agent approved for treating patients with IBD, both for Crohn's disease (CD)1 and ulcerative colitis (UC)2. Infliximab is administered by intravenous infusions and demonstrated its superiority over placebo to induce and maintain steroid-free clinical remission. Besides, SONIC and SUCCESS trials showed that combination therapy (infliximab + immunosuppressant) was more effective than infliximab alone to induce clinical remission3,4. Moreover, the PANTS cohort confirmed the benefits of combination therapy to induce remission and to prevent immunogenicity over time5. Accordingly, current guidelines recommend to use infliximab in combination with an immunosuppressive therapy. Recently, subcutaneous (SC) infliximab has been developed and is now approved for patients with CD and UC6. The LIBERTY-CD and LIBERTY-UC trials showed that SC infliximab is more effective than placebo to maintain clinical remission7. Real-world evidence studies, such as the REMSWITCH program8,9, reported that switching from IV to SC infliximab is feasible, safe and well accepted leading to a low risk of relapse including in patients with intensified IV doses. In addition to its better acceptability compared to IV regimen, SC infliximab seems to have a better pharmacokinetic profile that can lead to reduced risk of immunogenicity and thus question the need for using combination therapy with SC infliximab6-9. No data enables to draw any firm conclusion on this topic10.

In the REMONO studies (REMONO-UC and REMONO-CD), we aim to show the non-inferiority of SC infliximab monotherapy to maintain steroid-free clinical remission compared to combination therapy in patients with CD and UC.

It will be a retrospective multicentre study (22 centres). Data will be collected from the electronic medical records and pseudonymized from routine clinical care between 01/01/2023 and 01/07/2025. Data will be entered the electronic CRF (RedCAP).

The main data collected at the different time points : age, disease duration, smoking status, prior bowel resection, Montreal classification (location, behaviour, extent), perianal lesions, upper GI involvement, previous IBD medications, concomitant IBD medications (including doses and intervals), disease activity (stool frequency, abdominal pain, bowel urgency, CRP level, faecal calprotectin level, endoscopic activity, MRI scores, IUS lesions), side effects, pharmacokinetics (infliximab serum level, anti-infliximab antibodies).

Inclusion Criteria:

• Patients with UC (REMONO-UC) or with CD (REMONO-CD) ≥ 18 years
• Who received at least one SC injection of infliximab after IV induction (5 mg/kg at week 0, week 2 ± week 6)
• Infliximab started for symptomatic CD (PRO2: abdominal pain > 1 or stool frequency >3) or UC (partial Mayo score >2)
• Follow-up of at least 3 months (except for those who failed or were intolerant to SC infliximab before 3 months)

Exclusion Criteria:

• Unclassified colitis
• Infliximab started for isolated perianal CD, to prevent CD endoscopic postoperative recurrence or for acute severe colitis
• Permanent stoma
• Total colectomy with IPAA
• Concomitant other biological therapy or small molecule

Patients with Crohn's disease or ulcerative colitis treated in the day care unit at Clermont-Ferrand University Hospital.