RecruitingPhase IIIInterventional

A study of JNJ-78934804 in participants with moderately to severely active ulcerative colitis (DUET ENCORE-UC)

Ulcerative colitis is a long-term condition causing swelling and sores in the lining of the large bowel. Current treatments can help, but they do not work for everyone, and some people find their medicine stops working over time. This Phase 3 trial tests a new drug called JNJ-78934804. It combines two medicines (guselkumab and golimumab) that block two different proteins responsible for gut inflammation. The trial compares this combined treatment directly against guselkumab given on its own. Participants will receive regular injections under the skin over a 48-week period, with the option to continue in a longer extension study. There is no dummy drug (placebo) in this trial, meaning every participant receives an active treatment. The total study lasts around three years, including regular health checks and safety monitoring. Travel expenses are reimbursed.

At a glance

Status

Recruiting

Phase

Phase III

Sponsor

Janssen-Cilag International N.V.

Enrolment target

644

Start

28 May 2026

Estimated completion

31 Jul 2027

Moderately to Severely Active Ulcerative Colitis

What is this study about?

Ulcerative colitis is a long-term condition where the large bowel becomes swollen and inflamed. This can cause frequent diarrhoea, tummy pain, bleeding, and deep tiredness. Although there are several treatments available on the NHS and worldwide, many people find that their symptoms do not fully settle, or that a treatment which worked well at first gradually stops helping.

To address this, researchers are testing a new approach: combining two targeted medicines into a single treatment called JNJ-78934804. Normally, the body produces natural proteins that trigger inflammation to fight off illness. In ulcerative colitis, some of these proteins—called IL-23 and TNF-alpha—become overactive and damage the gut. JNJ-78934804 is designed to block both proteins at the same time, which scientists hope will calm the inflammation more effectively than blocking just one.

This study is a Phase 3 clinical trial, which means researchers are comparing the new combination medicine against a single active medicine (guselkumab) in a large group of patients. By comparing the two, doctors hope to find out whether targeting two inflammatory pathways at once leads to better symptom relief and gut healing for people with difficult-to-treat colitis.

Key takeaways

Tests a new two-in-one injection (JNJ-78934804) against a single treatment for ulcerative colitis.
Open to adults with moderate to severe colitis who have not had success with other treatments.
There is no placebo; all participants receive an active medication.
Medication is given as an injection under the skin every four weeks after initial starting doses.
The total study commitment is around three years, including long-term follow-up.

Who may be eligible?

This trial is open to adults aged 18 and over who have been diagnosed with moderate to severe ulcerative colitis for at least 12 weeks. It is designed for people whose condition has not improved enough on standard approved treatments, or who could not continue their previous medications due to unpleasant side effects.

You cannot join this study if your inflammation is only in the rectum (a type called isolated proctitis), or if you have a different bowel condition such as Crohn's disease. People with serious ongoing infections, or those who have previously taken guselkumab or golimumab without success, will also not be able to participate.

Because the study medicines may affect an unborn baby, you cannot take part if you are pregnant, breastfeeding, or planning a pregnancy. Men and women taking part must agree to use effective contraception during the study and for six months after their final dose.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

I am aged 18 or older.
I have had a confirmed diagnosis of ulcerative colitis for at least 12 weeks.
My colitis is currently moderately to severely active.
Previous standard treatments have not worked well enough or caused difficult side effects.
I have not previously taken guselkumab or golimumab.
I am not pregnant, breastfeeding, or planning a pregnancy in the near future.

Answer every question to see your result.

What does participation involve?

Taking part in this trial lasts for around three years in total. It begins with a screening period of up to six weeks to check that the study is safe and suitable for you. If you join, you will be placed into one of two groups: one receives the combination medicine (JNJ-78934804) and the other receives guselkumab alone. Neither you nor your doctor will choose or know which group you are in. Both medicines are given as injections under the skin, starting with doses at weeks 0, 4, and 8, followed by a dose every four weeks.

If your symptoms do not improve as hoped, there is a 'rescue' option that allows you to switch to the combination medicine. After the first 48 weeks, you may be able to enter a long-term extension period for up to 96 weeks. Throughout the trial, you will attend regular clinic visits for blood and urine tests, heart traces (ECGs), and camera checks of your bowel (endoscopies). You will also have a final safety follow-up visit about 12 weeks after your last injection.

Potential risks and benefits

You may experience an improvement in your colitis symptoms, but this cannot be guaranteed as the combination medicine is still being tested. A clear benefit is that your health and bowel condition will be closely monitored by a specialist medical team throughout the study. However, there are potential risks and side effects. Because these medicines lower parts of your immune system, you may have a higher risk of infections. Other possible risks include allergic reactions, liver problems, worsening bowel symptoms, or discomfort and bruising from injections and bowel camera tests. Your safety will be tracked closely at every visit, and you are free to leave the trial at any time without your normal NHS care being affected.

Locations (12)

St George's Hospital
Approximate
London, England
Fairfield General Hospital
Approximate
Bury, England
John Radcliffe Hospital
Approximate
Oxford, England
Whipps Cross University Hospital
Approximate
London, England
Guy's and St Thomas' Hospitals
City only
London, England
Kings College Hospital
Unverified
London, England
Royal Devon & Exeter Foundation Hospital
Unverified
Exeter, England
Ninewells Hospital
Unverified
Dundee, Scotland
University Hospital of Wales
Unverified
Cardiff, Wales
Addenbrookes Hospital
Unverified
Cambridge, England
Russells Hall Hospital
Unverified
Dudley, England
Royal Victoria Infirmary
Unverified
Newcastle upon Tyne, England

Common questions

Will I receive a dummy drug (placebo)?

No. Every participant in this study receives an active treatment. You will receive either the new combination medicine or guselkumab on its own.

How is the study medicine given?

Both study treatments are given as injections just under the skin (subcutaneous injections), similar to how insulin is given.

What happens if my colitis gets worse during the trial?

The study includes 'rescue criteria'. If your symptoms do not improve or get significantly worse, your study doctor can move you onto the combination medicine to help get your condition under control.

Do I have to pay to take part?

No. The study medication and all study-related medical tests are provided free of charge. You will also be reimbursed for reasonable travel and parking expenses.

Can I leave the study if I change my mind?

Yes. Taking part is completely voluntary. You can withdraw from the study at any point, for any reason, and it will not affect the standard of care you receive.

How to find out more

- Medical Information and Product Information Enquiry

medinfo@its.jnj.com +44 800 731 8450 / 10494 567 444 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.