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A study of mirikizumab levels in breast milk of breastfeeding women with ulcerative colitis or Crohn's disease

Verified siteRegistered drugNo placebo
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What is this trial about?

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

This study is designed to assess the concentration of mirikizumab in breast milk. The research focuses on individuals who are currently receiving this medication to treat conditions such as Ulcerative Colitis or Crohn's Disease, which are types of inflammatory bowel diseases that cause swelling and irritation in the digestive tract.

Participants in the study will receive mirikizumab through a subcutaneous injection, which is a method of delivering medication into the fatty layer of tissue just under the skin. During the course of the study, levels of the drug will be measured in breast milk to understand how much of the substance is present.

The research process

The trial runs in 3 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Medication administration

    The participant receives mirikizumab via subcutaneous injection, which is an injection administered just under the skin.

    This medication is used for the maintenance treatment of ulcerative colitis or crohn's disease, which are types of inflammatory bowel disease.

  2. Step 2

    Breast milk collection

    breast milk is collected to measure the concentration of mirikizumab.

    Collection occurs on day 0 before the dose is given, and on other specific days as indicated by the study protocol.

  3. Step 3

    Infant monitoring

    The weight of the infant is monitored during the study.

    Any adverse events, which are unexpected or harmful medical occurrences, are reported by the caregiver or a healthcare professional.

Who can join the trial?

13 criteria

  • The mother must be at least 18 years old at the time of joining the study.
  • The baby must have been born after at least 36 weeks of pregnancy and must be at least 3 weeks old by the start of the study.
  • A healthcare professional (a doctor or nurse) must agree that there are no health issues preventing the mother or baby from participating.
  • The choice to use mirikizumab (the study medication) or to breastfeed must have been made before joining the study.
  • The mother must agree to use only the specific nipple cream or emollient (a soothing cream used to soften or protect the skin) recommended by her doctor.
  • The mother must be exclusively breastfeeding, meaning the baby receives only breast milk and no more than one bottle of formula (milk substitute) per day.
  • The mother must be receiving mirikizumab to treat a medical condition that has been officially approved for use in her location.
  • The mother must have been assigned female at birth and must use contraception (methods used to prevent pregnancy) according to local medical rules.
  • The mother must be able to provide informed consent, which means she understands the study and agrees to follow all the rules and requirements.
  • The mother must not be pregnant, as confirmed by a test, and must agree not to become pregnant during the study.
  • The baby must be able to drink from a bottle using either stored breast milk or formula.
  • The mother must be on an established maintenance therapy (a regular treatment plan to keep a disease under control) using mirikizumab SC, which is a version of the medicine injected just under the skin.
  • The mother must have already received at least two doses of this medicine every 4 weeks before the study begins.

Who cannot join the trial?

18 criteria

  • You have a hypersensitivity, which means an allergic reaction, to mirikizumab or any of the other ingredients used to make the medicine.
  • You have taken an experimental medicine in a clinical study within the last 30 days or within a period of 5 half-lives, which is the time it takes for the amount of a drug in your body to reduce by half.
  • If your previous study used biologic agents, such as monoclonal antibodies (medicines made from proteins that target specific parts of the immune system), you must have waited at least 3 months or 5 half-lives before starting this study.
  • You have a history of, or currently have, alcohol use disorder or substance use disorder, which refers to problems with using alcohol or drugs.
  • You have important liver disease, such as advanced fibrosis (scarring of the liver) or cirrhosis (permanent scarring and damage to the liver).
  • You are unable to attend all the required study visits or follow the rules and steps of the study.
  • You or your immediate family members, such as a spouse, parent, child, or sibling, work for the people running this study.
  • The healthcare provider (your doctor) or the study sponsor decides you are not a good fit for the study.
  • You are an employee of Eli Lilly and Company or work for another company involved in this research.
  • You have other medical conditions, known as comorbidities, that could change how your body absorbs, processes, or removes medicine, or that could make taking this medicine risky.
  • You have any medical condition that is listed as a contraindication, which means a reason why a specific treatment should not be used because it may be harmful.
  • If you have breastfed before, you have a history of inadequate lactation, which means not being able to produce enough breast milk.
  • You have had breast augmentation (surgery to increase breast size), breast reduction, or have certain breast implants that might make it hard to collect breast milk.
  • You have a current, important infection, such as human immunodeficiency virus (HIV), hepatitis B, hepatitis C, or tuberculosis (a serious bacterial infection).
  • You had a significant infection that has since cleared up, such as pneumonia (lung infection) or pyelonephritis (kidney infection), within the last 14 days.
  • You have received a live vaccine (a vaccine using a weakened form of a germ) within the last 4 weeks, or an inactivated vaccine (a vaccine using a killed form of a germ) within the last 2 weeks.
  • You plan to get a vaccine during the study or an inactivated vaccine within 2 weeks after your dose.
  • You are currently participating in, or planning to join, another medical research study that is not compatible with this one.
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Investigated drugs

Mirikizumab is a medication administered through a small needle under the skin. In this study, it is being studied to see how much of the medicine passes into breast milk in breastfeeding mothers who are already using it to treat their medical condition.

What is already known about the treatment

Mirikizumab - This medication is an injectable solution administered through a shot under the skin. It is a specialized biological medicine currently used to treat inflammatory conditions like ulcerative colitis and Crohn's disease. It works by targeting and blocking a specific protein in the body that triggers inflammation, effectively calming the immune system's overactive response. This drug belongs to a class of medicines known as interleukin-23 inhibitors.

Investigated diseases

  • Ulcerative colitis

    This is a condition where inflammation and sores develop in the inner lining of the large intestine and rectum. The inflammation typically occurs in a continuous pattern. Over time, the irritation can cause the lining of the bowel to become swollen and damaged. It often progresses through periods of active symptoms followed by periods of calm.

  • Crohn’s disease

    This is a type of long-term inflammation that can affect any part of the digestive tract. It often occurs in patches, where healthy sections of the intestine are mixed with diseased areas. The inflammation can penetrate through all layers of the intestinal wall. As the condition progresses, it can cause thickening or narrowing of the digestive tract.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-522362-78-00Protocol codeI6T-MC-AMCAEstimated enrolment27 patientsSponsorEli Lilly & Co.

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