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Efficacy and safety of ontunisertib in patients with fibrostenosing Crohn’s disease: a phase 2b randomized, double‑blind, placebo‑controlled dose‑ranging trial

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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study focuses on Fibrostenosing Crohn’s Disease, a form of Crohn’s disease where scar tissue causes narrowing and blockage of the intestine. The investigational medicine being examined is ontunisertib, given as oral capsules in two strength levels (200 mg and 800 mg). Participants will be randomly assigned to receive either one of the active doses or a matching placebo that looks the same but contains no active drug.

The aim is to determine whether the drug improves the ability of the intestine to open up and reduces disease activity, and to see how the different doses compare. Over a period of up to one year, participants will take the study medication each day, undergo an endoscopic examination of the intestine and a special imaging test called MRE at approximately 24 and 52 weeks, and have routine safety checks that include blood tests, vital‑sign measurements, an ECG, and physical examinations. Researchers will also track side effects, referred to as TEAEs, and use a scoring system known as SES‑CD to evaluate changes in disease severity.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment and consent

    After joining the study, you will sign an informed consent form and complete the screening procedures required to confirm eligibility.

  2. Step 2

    Baseline assessments

    The study team will perform an endoscopic examination of the ileum, imaging studies, and laboratory tests to record your condition before any medication is given.

  3. Step 3

    Randomization to study group

    You will be randomly assigned, without knowing the result, to receive either ontunisertib 200 mg, ontunisertib 800 mg, or a placebo capsule. the assignment is double‑blind, meaning neither you nor the investigators will know which group you are in.

  4. Step 4

    Start of study medication

    You will take one oral capsule each day. the capsule contains either 200 mg of ontunisertib, 800 mg of ontunisertib, or no active drug (placebo).

    The daily dosing will continue for up to 52 weeks unless the study team advises otherwise.

  5. Step 5

    Mid‑study evaluation (week 24)

    At week 24, you will return for a follow‑up visit that includes another endoscopic examination to see if the ileal stricture is passable, imaging studies, and safety assessments such as lab tests and vital‑sign checks.

  6. Step 6

    Final evaluation (week 52)

    At week 52, a final visit will be scheduled. the same endoscopic and imaging assessments performed at week 24 will be repeated, along with safety evaluations and questionnaires about symptom severity.

    After the week 52 assessments, the study medication will be discontinued.

Who can join the trial?

8 criteria

  • Have a diagnosis of Crohn’s disease that affects the ileum (the end part of the small intestine) or both the ileum and colon, confirmed by a doctor using symptoms and an endoscopic (camera‑based) or radiological (scan‑based) exam at least 12 weeks before signing the consent form.
  • Have at least one narrowing, called a stricture, in the ileum that an endoscope cannot pass through.
  • The narrowing can be a new (naïve) stricture or one that formed at a previous surgical connection (an anastomotic stricture), and it must be confirmed by a centrally reviewed magnetic resonance enterography (MRE) scan.
  • Experience symptoms of partial blockage (such as abdominal pain, cramping, feeling full quickly) or need to limit the amount or type of food they can eat.
  • Be taking a stable dose of medication that reduces inflammation for Crohn’s disease and agree to keep this medication unchanged for the whole study.
  • Not be expected, in the doctor’s opinion, to need hospitalization, an endoscopic balloon dilation (a procedure that widens a stricture with a small balloon), surgical removal of part of the intestine (surgical resection), or a stronger anti‑inflammatory treatment during the first four weeks of the trial.
  • Have a body mass index (BMI) of at least 18 and less than 35 kg/m², which is a measure of weight relative to height.
  • Be a male or female patient who meets the age requirements set by the study.

Who cannot join the trial?

6 criteria

  • You have ever had or currently have any type of colon inflammation (colitis), such as ulcerative colitis, indeterminate colitis, ischemic colitis, NSAID‑induced colitis, idiopathic colitis, radiation colitis, microscopic colitis, colonic mucosal dysplasia, untreated bile‑acid malabsorption, or infectious colitis.
  • You have major Crohn’s disease complications, including a very short remaining small intestine (short bowel syndrome with less than 200 cm left), surgical openings like an ileostomy, colostomy, small‑bowel stoma, or ileoanal pouch, internal abnormal connections (fistulas or sinus tracts) from the narrowed area, untreated abdominal or perianal abscess, severe widening of the colon (toxic megacolon), or anal/perianal narrowing (stricture).
  • You have had an endoscopic balloon dilation or surgery on the same small‑bowel narrowing within the last six months.
  • You have current or past heart valve disease (valvulopathy) or moderate to severe valve problems, or a reduced heart pumping ability (left ventricular ejection fraction below 50%).
  • You have any other serious acute or chronic medical condition, psychiatric disorder, abnormal laboratory test, or infection that could increase risk or affect the study’s results.
  • You have significant abnormal lab values or heart‑electrical test (ECG) findings at screening, such as abnormal blood counts, liver function tests, vital signs, or ECG measures like a PR interval ≥ 220 ms, QRS ≥ 120 ms, prolonged QTc (>450 ms for men or >470 ms for women), very slow heart rate, ST‑segment changes, bundle‑branch block, or any other ECG abnormality that would interfere with measuring the QT interval.
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Investigated drugs

Ontunisertib is an experimental oral medication given in capsule form that is being studied in this trial. It is designed to affect the biological processes that cause inflammation and narrowing of the intestine in fibrostenosing Crohn’s disease. The study is testing different amounts of the drug to learn how well it works and how safe it is for patients.

What is already known about the treatment

Ontunisertib - Ontunisertib is taken as an oral capsule, swallowed with water. It is still an investigational drug being studied in phase 2b trials and has not yet been approved for routine use. The drug is being tested for treating fibrostenosing Crohn’s disease, a condition where scar tissue narrows the intestine. It works by blocking a protein called TGF‑beta receptor I, which reduces the signals that lead to excess scar tissue and inflammation, and it belongs to the class of small‑molecule kinase inhibitors.

Investigated diseases

Fibrostenosing Crohn’s disease - It is a form of Crohn’s disease where ongoing inflammation produces scar tissue that narrows the intestine. The condition progresses with repeated flare‑ups that increase the thickness of the bowel wall. Over time the narrowed segments, called strictures, can become more fibrotic and may impede the passage of food. As strictures develop, people often feel abdominal pain, cramping, and changes in bowel habits. The disease can affect any part of the gastrointestinal tract, most commonly the ileum.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2026-525197-19-00Protocol codeAGMB129-01-CL-201Estimated enrolment320 patientsSponsorAgomab Spain S.L.U.

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