AuthorisedTherapeutic exploratory (Phase II)Interventional

A Phase 2b, Double-Blind, Placebo-Controlled, Multicenter Proof of Concept Clinical Study to Evaluate the Efficacy and Safety of ATH-063 Induction Therapy in Patients with Biologic Relapsed/Refractory Moderately to Severely Active Ulcerative Colitis (UC)

Ulcerative colitis is a long-term condition that causes painful inflammation and ulcers in the bowel. While biologic treatments help many people, these medicines do not work for everyone, or they can stop working over time. This study tests a new experimental oral medicine called ATH-063 to see if it can help adults with active ulcerative colitis achieve remission (a period where symptoms clear up). Participants will take three capsules once a day for 12 weeks. To find out how well ATH-063 works, doctors will compare it against a placebo, which is a dummy pill with no active ingredients. Neither you nor the study team will know which one you receive. Throughout the 12 weeks, the research team will closely monitor your gut symptoms, general health, heart, and blood tests to check both the effectiveness and safety of the treatment.

At a glance

Status

Authorised

Phase

Therapeutic exploratory (Phase II)

Sponsor

Athos Therapeutics Inc.

Enrolment target

Start

24 Sep 2026

Active Ulcerative Colitis

What is this study about?

Ulcerative colitis causes chronic swelling and irritation along the lining of the large bowel. Many patients rely on advanced treatments called biologics to control their flare-ups. However, when these medicines stop working or fail to bring relief, finding another effective treatment can be challenging. This trial is investigating whether a new medicine, ATH-063, can offer a new solution.

ATH-063 is an oral medication taken by mouth as three capsules each morning. The purpose of this study is to test how well it calms inflammation during a flare-up and whether it can guide the bowel into clinical remission within 12 weeks. Remission means that common symptoms, such as urgent diarrhoea, bleeding, and tummy cramps, significantly reduce or fade away entirely.

This is a 'double-blind, placebo-controlled' study. This means some participants will take ATH-063, while others will take dummy capsules that look identical but contain no medicine. Comparing the real drug to a placebo is the standard medical way to prove whether a treatment truly works and what side effects it might cause. A computer randomly decides who gets the medicine and who gets the placebo, and neither you nor your doctor will know your group until the study is over.

Taking part helps medical researchers understand if ATH-063 could become a safe and useful new therapy for people living with difficult-to-treat colitis in the UK and worldwide.

Key takeaways

Tests a new daily capsule called ATH-063 for moderate to severe ulcerative colitis.
Designed for adults whose colitis has not responded well to previous biologic drugs.
Treatment lasts for 12 weeks and involves regular clinic visits and health checks.
Participants are randomly assigned to receive either the active medicine or a dummy pill (placebo).
Taking part is completely voluntary and you can leave the study at any point.

Who may be eligible?

This study is open to men and women aged 18 and older who are currently experiencing moderate to severe symptoms of active ulcerative colitis.

To be considered, you must have previously tried biologic medicines that either did not control your colitis well enough or stopped working for you over time. Your study doctor will carry out standard health checks to confirm that your bowel inflammation is currently active before you join.

Because this is a clinical trial, you may not be able to join if you have certain other serious medical conditions, ongoing severe infections, or are pregnant or planning a pregnancy. The trial team will review your full medical history and current prescription medicines to make sure taking part is safe for you.

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 been diagnosed with moderate to severe active ulcerative colitis.
I have previously taken biologic treatments that stopped working or did not help enough.
I am able to swallow three capsules once every day.
I can attend regular clinic appointments and health checks over a 12-week period.

Answer every question to see your result.

What does participation involve?

If you take part, your participation will last around 12 weeks. You will take three capsules once daily with water. You will collect a fresh supply of capsules from the clinic on Day 1, at Week 4, and at Week 8. During the 12 weeks, you will attend regular hospital appointments so the medical team can track your progress. These visits will involve standard checks, including blood and urine tests, physical examinations, heart tracings (an ECG), and monitoring your blood pressure. You will also be asked about your daily bowel habits, how you feel, and whether you are taking any other medications. After completing the 12 weeks of treatment, you will have a final check-up to see how your bowel has responded.

Potential risks and benefits

A potential benefit of joining is that the trial medicine may help calm your ulcerative colitis symptoms and bring about remission, although this cannot be guaranteed. You will also receive frequent, thorough health checks from specialist doctors. The risks include possible side effects from the study drug, which the team will explain in detail, as well as the chance that you receive the placebo instead of active medicine. Having blood taken may also cause minor bruising. Taking part is completely your choice, and you can withdraw from the study at any time without giving a reason and without it affecting your standard NHS care.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

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Unverified
Poland

Common questions

What is a placebo and why is it used?

A placebo is a capsule that looks just like the real medicine but contains no active drug. Researchers use it to ensure that any improvements or side effects seen in the trial are genuinely caused by ATH-063.

Will I know if I am taking ATH-063 or the placebo?

No. The trial is double-blind, meaning neither you nor the doctors will know which treatment you are taking. However, in an emergency, the doctors can quickly find out.

How long will I be in the study?

The main treatment phase lasts 12 weeks, with clinic appointments scheduled at regular intervals during this time.

Can I carry on taking my usual medicines?

Some medicines can be continued, while others may interfere with the trial drug. The study doctor will carefully review all your current prescriptions to ensure they are safe to use together.

What happens if my symptoms get worse during the trial?

Your health and safety come first. If your colitis flares up or you feel unwell, the study team can change your treatment or withdraw you from the study to ensure you receive the care you need.