Maintenance Study to Investigate the Efficacy and Safety of Duvakitug Maintenance Therapy in Participants with Moderate to Severe Active Ulcerative Colitis

Summary description of the study

This study aims to determine whether long-term use of Duvakitug in adults with moderate to severe ulcerative colitis (UC) who have completed study EFC18325 (SUNSCAPE-1) and shown symptom improvement is safe and effective. The study will assess how safe Duvakitug is and how effective it is compared to placebo in people with moderate to severe UC who have completed the induction study and shown improvement. Duvakitug is not approved for the treatment of UC outside of studies. Duvakitug will be administered in this study as an injection under the skin (as a subcutaneous injection). Self-administration at home may be possible. The study will last for participants up to 286 weeks (approximately 5 years and 9 months). The study includes 2 parts: Participants will start with Part 1, where they will be randomly assigned to 3 treatment groups and receive one of two Duvakitug doses or a placebo for 40 weeks (10 months). After that, participants may switch to a longer Duvakitug treatment for 240 weeks (approximately 4 years and 9 months) in Part 2. In Part 2, all participants will receive Duvakitug (no placebo). Participants will undergo regular tests and examinations, including colonoscopies, as well as collection of tissue, blood, stool, and urine samples for laboratory tests. Participants must record their UC symptoms daily in an electronic diary, including rectal bleeding and the frequency of bowel movements, and regularly complete quality of life questionnaires to assess UC symptoms such as fatigue or pain. Approximately 671 participants will take part at about 450 study centers in approximately 40 countries worldwide.

(BASEC)

Intervention under investigation

This is a randomized, double-blind, placebo-controlled Phase III maintenance study (SUNSCAPE-2 or EFC18359). All participants who have shown a response in the induction study (SUNSCAPE-1 or EFC18325) may participate in this study and receive treatment with Duvakitug or placebo, with treatment assigned randomly by a computer program. A placebo looks like the investigational drug but contains no active ingredient.

The investigational drug is Duvakitug. It is an investigational medication intended to reduce UC symptoms. "Investigational" means that Duvakitug is not yet approved for the treatment of UC outside of clinical studies like this one. Participants will receive either the investigational drug Duvakitug or a placebo. The medication will be administered as an injection under the skin (as a subcutaneous injection). Self-administration by participants or a caregiver at home may be possible after appropriate training.

The duration of this maintenance study for individual participants is up to 286 weeks (approximately 5 years and 9 months): Duvakitug or placebo treatment for 40 weeks (10 months; Part 1), followed by Duvakitug treatment for an additional 240 weeks (approximately 4 years and 9 months; Part 2) and a follow-up visit 45 days after the last dose of the investigational drug.

Part 1 (randomized, double-blind): Treatment phase lasting 40 weeks (10 months), during which participants are randomly assigned by a computer program into three groups (treatment arms) and receive either a lower Duvakitug dose, a higher Duvakitug dose, or a placebo. This part of the study is "double-blind," meaning that neither the participants nor the medical staff will know which group the participants have been assigned to. All participants who complete the 40-week treatment may be enrolled for a longer Duvakitug treatment in Part 2.

Part 2 (open-label extension): Duvakitug treatment for 240 weeks (approximately 4 years and 9 months). Participants will be randomly assigned to 3 groups (treatment arms) with 3 different Duvakitug doses. All participants will receive Duvakitug. This part of the study will assess the safety of long-term use of Duvakitug in participants with moderate to severe active UC.

The total number of center visits will be up to 43, with 21 visits in Part 1 and, if participating, 22 additional visits in Part 2. Participants who are eligible for self-administration at home will require fewer visits to the study center.

(BASEC)

Disease under investigation

Moderate to severe active ulcerative colitis

(BASEC)

Sponsor

Sanofi-Aventis Recherche & Développement SANOFI AVENTIS (SUISSE) SA

(BASEC)

Name of the authorising ethics committee (for multicentre studies, only the lead committee)

Ethics Committee Bern

(BASEC)

Date of authorisation

22.12.2025

(BASEC)

Results of the trial