Efficacy of mirikizumab versus azathioprine in newly diagnosed patients with moderate-to-severe Crohn’s disease: a 52‑week randomized trial

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What is this study about?

Crohn’s disease is a long‑lasting condition that causes inflammation of the digestive tract, leading to abdominal pain, diarrhea, weight loss and fatigue. In this study, the experimental medication mirikizumab is given by injection under the skin or into a vein, while the standard therapy uses the oral drug azathioprine together with a type of steroid called glucocorticoids. The goal is to compare how well each approach controls the disease over a year.

The purpose of the study is to determine whether the mirikizumab regimen can achieve a higher rate of deep remission than the standard treatment. Participants receive an initial series of doses to start treatment, followed by regular maintenance doses for up to 52 weeks, with periodic clinic visits to monitor symptoms, perform a camera‑based exam of the intestine (endoscopic assessment), and check for any need for steroids, surgery, or complications such as abnormal connections (fistulas) or narrowings (stenoses). Clinical remission is defined as having few or no symptoms, and the combination of these factors constitutes deep remission.

1 enrollment and randomization

after signing the consent form, you are entered into the study and assigned by the study system to one of two treatment groups. the assignment is random and you will receive either the test medication or the standard medication.

2 baseline assessments

before any medication is given, you will undergo a series of evaluations that include a physical exam, blood tests, and imaging of the intestine. these assessments establish the severity of your crohn’s disease and provide a reference point for later comparison.

3 start of treatment – induction phase

if you are assigned to the test group, you will receive mirikizumab by subcutaneous injection (under the skin) at a dose of 200 mg. the injection is given on the first day of the induction phase.

the test group may also receive a single intravenous (through a vein) dose of mirikizumab at 900 mg, administered on the first day as part of the induction protocol.

if you are assigned to the standard‑care group, you will start oral azathioprine at a dose of 2.5 mg per kilogram of body weight each day. you will also receive an oral glucocorticoid (a type of steroid) at a dose of 60 mg per day. these medications are taken by mouth as directed.

4 maintenance therapy – weeks 1 to 52

for patients receiving mirikizumab, the maintenance schedule includes subcutaneous injections of 100 mg at regular intervals defined by the study protocol. the injections continue for the remainder of the 52‑week study period.

for patients receiving azathioprine, the oral dose of 2.5 mg per kilogram is continued daily for the entire 52‑week period. the oral glucocorticoid may be tapered according to the study schedule, with the goal of stopping the steroid use as early as possible while remaining under medical supervision.

5 regular clinic visits

throughout the 52‑week period you will attend scheduled visits at the study site. during each visit you will have physical examinations, blood tests, and questionnaires to monitor disease activity and any side effects. the timing of these visits follows the study schedule, typically occurring every few weeks.

6 final assessment at week 52

at the end of week 52, a comprehensive evaluation is performed to determine whether deep remission has been achieved. this includes clinical assessment, endoscopic examination of the intestine, and review of medication use to confirm that no steroids have been taken in the previous eight weeks.

Who Can Join the Study?

Give written informed consent before any study procedures.
Stop taking oral budesonide at least 2 weeks before the screening colonoscopy; you may switch to prednisolone if needed.
Stop taking oral mesalamine at least 2 weeks before the screening colonoscopy.
Show active Crohn’s disease by meeting all three of the following:
- Have a CDAI (Crohn’s Disease Activity Index) score between 220 and 500.
- Have a blood test called CRP that is higher than normal, or a stool test called fecal calprotectin that is above 250 µg/g.
- Have an endoscopy called an ileocolonoscopy that shows disease activity: a score of 4 or more if the disease is only in the small intestine, or a score of 6 or more if the disease involves the colon or both.
Have no actively draining fistula (an abnormal tunnel that leaks fluid) at screening.
Have had no previous Crohn’s disease‑related surgery.
Be willing and able to complete all study visits, including the colonoscopy and daily diary entries.
Agree to follow the study’s contraception requirements.
Be between 18 and 75 years old.
Never have used thiopurines (such as azathioprine or 6‑mercaptopurine) or methotrexate before.
Never have used advanced Crohn’s disease medicines (targeted biologic or small‑molecule therapies) for Crohn’s disease or any other condition.
Have been diagnosed with Crohn’s disease no more than 12 months ago and at least 4 weeks before randomization, according to DGVS/ECCO criteria.
Have previously taken a 5‑aminosalicylate (5‑ASA) medicine and/or oral glucocorticoid (steroid) but had an inadequate response, loss of response, or could not tolerate it.
If you are taking systemic steroids at screening, you must have used them for no more than 8 weeks total, and your prednisolone dose must be 20 mg per day or less and stable for at least 2 weeks before the colonoscopy.

Who Cannot Join the Study?

Having a very severe flare of Crohn’s disease that needs emergency hospital care or immediate surgery (such as a blockage, a hole in the gut, a draining fistula, uncontrolled infection, or a dangerous swelling of the colon called toxic megacolon).
Having latent tuberculosis (TB) – a hidden TB infection that is not currently active.
Planning to receive any live or weakened (live‑attenuated) vaccines, such as the BCG vaccine for TB, during the screening period or while in the study.
Having a serious fungal infection (systemic mycoses) or a parasite infection (parasitosis) anywhere in the body.
Having an unstable or uncontrolled illness that could raise risk or affect the study results, including serious heart, brain, lung, liver, kidney, hormone, blood, or nerve problems, or an active cancer.
Being known to have a severe allergic reaction (systemic hypersensitivity) to any of the study medicines, their ingredients, or to similar antibody drugs in the past.
Being a woman who is pregnant, breastfeeding, or planning to become pregnant.
Being an employee of the drug company Lilly, any organization running the study, the study site staff, or an immediate family member of those people.
Having taken part in another clinical trial with an experimental drug or non‑approved use of a drug within the past 12 weeks, or being enrolled in any other study at the same time.
Being unable or unwilling to use the electronic diary (eDiary) or follow other study procedures for the whole study period.
Being under a court or government order that places you in an institution (such as jail or a mandated care facility).
Using oral or rectal 5‑ASA medications or rectal steroids within two weeks before the screening colonoscopy.
Having a history of cancer, except for a non‑melanoma skin cancer that has been completely treated and is considered cured.
Planning to have surgery before the randomization visit (Week 0) or expecting surgery soon after.
Having a known deficiency of the enzyme thiopurine methyltransferase or a known mutation in the NUDT15 gene, which affect how certain drugs are processed.
Having inherited problems such as galactose intolerance, total lactase deficiency, or glucose‑galactose malabsorption, which affect how sugars are digested.
Having a diagnosis that is not Crohn’s disease, such as ulcerative colitis, indeterminate colitis, microscopic colitis, or other inflammatory bowel conditions.
Having a clinically important active infection, including hepatitis B, hepatitis C, HIV/AIDS, or active tuberculosis.
Having detectable hepatitis B virus DNA or hepatitis C virus RNA in the blood at the time of screening.

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country	Status
Gastropraxis Magdeburg	Magdeburg	Germany
CED Studienzentrum Karlshorst, Dr. med., Thomas Brunk, Gastroenterologie Berlin	Berlin	Germany

Other Sites

Site Name	City	Country
Specialist Internal Medicine Practice	Hamburg	Germany
Gastropraxis an der St. Barbara-Klinik	Hamm	Germany
Universitaetsklinikum Schleswig-Holstein AöR	Kiel	Germany
Pteivvny fzd Graqxgffplmtfuvs	Hanover	Germany

Trial status

Country	Status	Recruitment Start
Germany	Not yet recruiting	01.07.2026

Trial locations

Investigated drugs:

Mirikizumab is a biologic medicine given by injection under the skin or into a vein. It works by targeting a specific part of the immune system that causes inflammation in the gut. In this trial, patients received mirikizumab to see if it could bring deeper and longer-lasting remission of Crohn’s disease compared with standard treatments.

Azathioprine is an oral medication that weakens the immune system to help control the inflammation of Crohn’s disease. It is taken as a pill and is part of the usual care for patients with this condition. In the study, it was used as the standard treatment that mirikizumab was compared against.

Glucocorticoids are short‑term oral steroids that quickly reduce inflammation in the intestines. They are often used at the start of treatment to bring symptoms under control. In this trial, glucocorticoids were given together with azathioprine as part of the standard care regimen.

Crohn’s disease – Crohn’s disease is a long‑lasting condition that causes inflammation of the digestive tract. It can affect any part from the mouth to the anus, but most often involves the lower small intestine and colon. The inflammation may start in small patches and grow larger over time, leading to abdominal pain, diarrhea, and weight loss. As the disease continues, the intestinal wall can become thickened, which may narrow the passage and make it harder for food to move through. In some cases, the inflamed areas can develop small ulcers or deeper sores that may bleed or become scarred. The pattern of flare‑ups and quieter periods can vary from person to person.

Trial ID:

2026-525191-26-00

Protocol code:

MIRAGE

Trial Phase:

Therapeutic confirmatory (Phase III)

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Efficacy of mirikizumab versus azathioprine in newly diagnosed patients with moderate-to-severe Crohn’s disease: a 52‑week randomized trial

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?