Phase 2b Study of ATH-063 in Adults with Biologic‑Relapsed/Refractory Moderately to Severely Active Ulcerative Colitis

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What is this study about?

The study focuses on individuals with moderately to severely active Ulcerative Colitis, a condition that causes inflammation and ulcers in the lining of the colon, leading to symptoms such as frequent diarrhea, abdominal pain, and bleeding. Participants will receive either the investigational oral medication ATH-063 in capsule form or a matching placebo capsule taken once daily for a period of about three months.

The purpose of the study is to determine whether the test drug can bring about meaningful improvement in disease activity. After an initial screening visit, participants will begin the assigned treatment and attend regular clinic visits where vital signs, simple heart recordings, and basic laboratory tests are checked. The treatment phase lasts approximately twelve weeks, after which the study concludes for each participant.

Researchers will look for a state called clinical remission, meaning the signs and symptoms of the disease have reduced to a level where the patient feels essentially normal and does not need additional medication for the condition. Throughout the trial, any side effects or health problems that arise will be recorded and evaluated to ensure the safety of the participants.

1 screening and randomization

after joining the study, eligibility is confirmed based on a diagnosis of active ulcerative colitis that has not responded to previous biologic therapy.

once eligibility is confirmed, you are assigned to receive either ATH-063 or a matching placebo without knowing which one you will receive.

2 baseline assessments

a series of baseline measurements are performed, including a clinical evaluation of ulcerative colitis activity, laboratory blood tests, an electrocardiogram (ecg) that records the heart’s electrical activity, a physical examination, and vital‑sign measurements such as blood pressure and heart rate.

information about any current medications you are taking is recorded.

3 first dose administration

on day 1 you receive a bottle containing 30 capsules.

if you are assigned to ATH-063, each capsule contains 150 mg of ATH‑063 hydrochloride and is taken orally.

if you are assigned to the placebo, the capsules contain microcrystalline cellulose and have no active drug.

the instruction is to take three capsules once daily (qd) for the duration of the study.

4 monthly dispensing visits

at week 4 and again at week 8 you return to the study site to receive a new bottle of 30 capsules.

the same dosing schedule—three capsules once daily—continues during each month.

5 regular study visits

throughout the 12‑week treatment period you attend scheduled clinic visits.

at each visit the study team records any side effects, repeats laboratory tests, checks vital signs, and may repeat the ecg and physical examination.

any changes to other medications you are taking are also documented.

6 week 12 primary endpoint assessment

at the end of week 12 a final clinical assessment is performed to determine whether clinical remission of ulcerative colitis has been achieved.

the same laboratory, ecg, physical examination, and vital‑sign measurements are repeated.

any adverse events that occurred during the study are reviewed.

7 study completion and safety follow‑up

after the week 12 assessment the study medication is stopped.

you may be asked to attend a short safety follow‑up visit to ensure that no new problems have arisen after stopping the medication.

Who Can Join the Study?

Can understand the study information, agree to take part by signing an informed consent form, and follow all study procedures.
Is 18 to 75 years old and identifies as male or female (any gender identity).
Is either postmenopausal, surgically sterile, sexually abstinent, or uses two forms of contraception: one physical barrier method (such as a condom or diaphragm) plus one highly effective method (like hormonal birth control, an intrauterine device, vasectomy, or complete abstinence). Women who could become pregnant must not be pregnant and must not be breastfeeding.
Has a diagnosis of ulcerative colitis that was confirmed by an endoscopy (a camera exam of the colon) and a tissue (histologic) test at least four months before screening, or the study’s own screening tests can be used as proof.
Has moderately to severely active ulcerative colitis, measured by a disease activity score called UCDSS that is between 5 and 9, with an EMA subscore of 2 to 3.
The ulcerative colitis affects more than 15 cm of the colon beyond the anus, as seen during a colonoscopy.
Has documented inadequate response or loss of response to one or two previously approved biologic or advanced ulcerative colitis therapies, and at least one of those must have been an anti‑TNF drug (a type of biologic that blocks tumor‑necrosis factor).
Has documented inadequate response, loss of response, or intolerance to standard ulcerative colitis medicines such as corticosteroids (e.g., prednisone), 5‑ASAs (e.g., mesalamine or sulfasalazine), or other immunomodulators (e.g., thiopurines, methotrexate, cyclosporine, tacrolimus).
Any prior medication that is not allowed as a standard treatment must have been stopped at least four weeks (or five drug “half‑lives,” whichever is longer) before screening, and no active drug should be detectable at the start of screening.
Screening laboratory results must be within the required ranges: hemoglobin ≥ 8 g/dL, white blood cell count ≥ 3 × 10³/µL, neutrophil count ≥ 1.5 × 10³/µL, platelet count ≥ 100,000/µL, serum creatinine ≤ 1.5 mg/dL (or creatinine clearance > 80 mL/min), ALT and AST values ≤ 2 times the normal upper limit, and total bilirubin ≤ 1.5 times the normal upper limit (or ≤ 2 times if the person has Gilbert’s syndrome).

Who Cannot Join the Study?

Any serious medical problem or abnormal test result (such as unusual vital signs, ECG, or lab values) that the doctor thinks could affect the study’s goals or your safety.
Recent surgery (for example, stomach bypass) or a condition that might prevent oral medicines from being absorbed properly.
Hospital stay for a severe ulcerative colitis flare that required IV steroids within the past 12 weeks.
Current signs of very severe colitis (fulminant colitis) or a dangerous swelling of the colon (toxic megacolon), or a history of toxic megacolon or a hole in the bowel (bowel perforation) within the last 6 months.
The doctor believes you may need removal of the colon (colectomy) within 12 weeks of starting the study medication.
Ulcerative colitis that is only in the rectum or only in the right side of the colon.
Having an abnormal connection between the intestines (enteric fistula) that is typical of Crohn’s disease.
History of reduced blood flow to the colon (ischemic colitis).
History of unclear type of colitis (indeterminate colitis) or microscopic colitis (a form that can only be seen under a microscope).
Use of medicines that destroy immune cells called B or T cells (for example, rituximab) within the past 12 months.
Active hepatitis B infection, risk of hepatitis B re‑activation, hepatitis C infection (unless fully cleared for more than 2 years), or HIV infection at the screening visit.
History of colon damage caused by radiation (radiation colitis).
Severe, worsening, or uncontrolled disease of the kidneys, liver, blood, hormones, lungs, heart, nerves, mind, or brain, or any signs of these problems.
Unstable heart disease caused by reduced blood flow (ischemic heart disease) or severe heart failure classified as NYHA Class III or IV (meaning the heart cannot pump enough blood).
Alcohol or drug abuse or dependence within the past year that could make it hard to follow the study rules.
Women who are pregnant, breastfeeding, or planning to become pregnant during the study.
Receiving nutrition through a feeding tube, special formula diets, or receiving all nutrition directly into a vein (total parenteral nutrition).
History of bleeding problems or recent use of medicines that prevent clotting (antiplatelet or antithrombotic drugs) that would make colonoscopy and biopsy unsafe.
Taking medicines that block transport proteins called P‑glycoprotein (P‑gp) or breast cancer resistance protein (BCRP), such as amiodarone, clarithromycin, cyclosporine, ketoconazole, ritonavir, verapamil, tacrolimus, or gefitinib.
Any condition that makes it hard for you to understand, cooperate with, or follow the study procedures, or any known allergy to the study drug.
History of Crohn’s disease (CD).
History of a narrowing (stricture) in the colon.
Positive stool test for Clostridioides difficile (C. difficile), other bacterial infection, or parasites, unless the infection does not need antibiotics.
Extensive removal of part or all of the colon (large bowel resection) or a subtotal/total colectomy (with or without a stoma or ileoanal pouch) that would prevent proper assessment of the study drug.
Current colon polyps (adenomas) or abnormal cell changes (dysplasia) that have not been completely removed, or a past diagnosis of dysplasia that was not fully treated.
Any current cancer that is not completely in remission, except fully removed basal cell skin cancer or in‑situ squamous cell skin cancer; any previous cancer must have been in remission for more than 2 years.
Have already tried more than two approved biologic or advanced ulcerative colitis medicines at the approved doses.

Where you can join this trial?

Verified and Recommended Sites

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Verified Sites

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Other Sites

Site Name	City	Country
Centrum Badan Klinicznych Piotr Napora Lekarze sp.p.	Wroclaw	Poland
Vita Longa Sp. z o.o.	Katowice	Poland
Hi5Clinic Sp. z o.o.	Lublin	Poland
Gmacizi Exqvhdiipr Pllrnhbm Pszoskcngpv	Cracow	Poland
Aboeddr Ssj z obtb Sscw	Lodz	Poland
Vpuyylq Gusyq I Copieaazr Shl ja	Bydgoszcz	Poland
Taotxkwa Svk z obhz	Poznan	Poland
Eihyevijjs Sml z obhe	Sopot	Poland
Pvdwablgk Sdy z oftg	Wroclaw	Poland
Mr Kvbhmrtmsg Bbeosus Gpncbny Lottduyb	Rzeszow	Poland
Mmuzyudt Ssr z ogos	Oświęcim	Poland
Wan Wkhahe Ilk Phiyq Pthsxkui Kibqpeh	Warsaw	Poland

Trial status

Country	Status	Recruitment Start
Poland	Not yet recruiting	16.09.2026

Trial locations

ATH-063 is an experimental oral capsule being tested as an induction therapy for people with ulcerative colitis that has not responded to other biologic medicines. In this study, participants take the capsule once a day for several weeks. Researchers are looking to see whether the medication can reduce the signs and symptoms of active ulcerative colitis and improve patients’ overall health compared with a placebo.

Investigated Diseases:

Colitis ulcerative

Ulcerative colitis – It is a chronic inflammation of the large intestine that causes the lining to develop ulcers. The condition usually starts in the rectum and can spread upward to involve more of the colon. Inflammation leads to frequent loose stools, often with blood or mucus. Over time, the bowel wall may become thinner and develop scar tissue that can narrow the passage. Flare‑ups can appear suddenly, followed by periods when symptoms lessen.

Trial ID:

2024-520183-33-00

Protocol code:

ATH-002-000

NCT ID:

NCT07513181

Trial Phase:

Therapeutic exploratory (Phase II)

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Phase 2b Study of ATH-063 in Adults with Biologic‑Relapsed/Refractory Moderately to Severely Active Ulcerative Colitis

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?