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Healthy ParticipantPhase 1NCT07153159

A Study to Learn How the Study Medicine Called Etrasimod is Taken up Into Blood and Breastmilk of Healthy Breastfeeding Women

A Phase 1 study testing Etrasimod in people with Healthy Participant, run by Pfizer at 1 site in Belgium.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

This study aims to figure out how much etrasimod, a medication, ends up in breast milk after taking it for several days. To do this, the researchers will work with at least 8 healthy women who are breastfeeding. These women will take a 2 mg dose of etrasimod every day for 7 days while staying at the testing site. Read more about this study

Who is it for?
Ages 18 to 55 years, women onlyHealthy volunteers can take part
Conditions the study is for
Healthy Participant
What is being tested?
Etrasimod
Type of treatment
Pill or oral medicine
Could I receive a placebo?
No, everyone receives an active treatment
How many people
8 participants
Where
1 siteBelgium
Study dates
7 Aug 2025to 15 Oct 2026
Phase
Phase 1
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 55 years
  • Women only
  • Healthy volunteers accepted
  • Adult

Who may be able to join

  • Healthy (as determined by medical evaluation including medical history, physical examination, laboratory tests, vital signs and 12-lead ECGs) lactating women who are actively breastfeeding or expressing breast milk, who are at least 12 weeks post partum and not currently pregnant (must have a negative pregnancy test), and must be 18 to 55 years of age, inclusive, at the time of signing the informed consent document (ICD).
  • Body mass index (BMI) of 16-35 kg/m2; and a total body weight >45 kg (99 lb).
  • Participants must be willing to temporarily discontinue breastfeeding their infants for a total of 21 days, ie, from the evening of the day before Day 1 through to 14 days after the last dose (approximately 8 AM the morning of Day 21). Participants must be willing to regularly pump breasts throughout the study and express breast milk according to a schedule designed to maintain lactation until the completion of breast milk collection

Who cannot join

  • Evidence or history of clinically significant hematological, renal, endocrine, pulmonary (such as moderate or severe chronic pulmonary disorders like asthma or chronic obstructive pulmonary disease [COPD]), gastrointestinal, cardiovascular, hepatic, neurological/psychiatric, anaphylactic, ophthalmologic disorders (such as macular edema, uveitis, retinopathy), or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at the time of dosing).
  • Participants with history or presence of second-degree or third-degree atrioventricular (AV) block, sick sinus syndrome, or sinoatrial block.
  • Resting HR <50 bpm at Screening or pre-randomization on Day 1. Measurement can be repeated up to 3 times to confirm the finding. Mean values will be used if repeated.
  • Recurrent symptomatic bradycardia or recurrent cardiogenic syncope
  • Any condition possibly affecting drug absorption (eg, gastrectomy, cholecystectomy).
  • Known immunodeficiency disorder, including positive serology for human immunodeficiency virus (HIV), or a first degree relative with a hereditary immunodeficiency, and history of organ transplant (except corneal transplant).
  • History or evidence of hepatitis B or hepatitis C viruses. Hepatitis B vaccination is allowed.89.
  • Participants with any of the acute or chronic infections or infection history

Trial locations and contacts

1 site in 1 country.

Belgium1 site

  • Pfizer Clinical Research Unit - Brussels

    Brussels, Bruxelles-capitale, Région de, B-1070

Other trials in Belgium

About this study

Official title: A PHASE 1 MULTIPLE-DOSE, OPEN-LABEL PHARMACOKINETIC STUDY OF ETRASIMOD IN HEALTHY LACTATING WOMEN

This study aims to figure out how much etrasimod, a medication, ends up in breast milk after taking it for several days. To do this, the researchers will work with at least 8 healthy women who are breastfeeding. These women will take a 2 mg dose of etrasimod every day for 7 days while staying at the testing site. During the study, they won't be allowed to breastfeed their babies to keep the babies safe. Instead, they need to have another plan for feeding their babies during this time. The study will look at how the medication is absorbed and how it moves through the body, checking things like the highest level in the blood and how long it takes to reach that level. The researchers will also see how much of the drug is in the breast milk compared to the blood and whether it's safe for the women to take. After the last dose, the women will stay at the site for at least another 24 hours before going home, and follow-up safety calls will be made about 14 and 28 to 35 days later. The whole process from start to finish will take about 10 weeks

Being tested
Etrasimod
Keywords
Breast feeding women

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • EtrasimodDrug

    Oral 2 milligrams tablet, once a day for 7 days

Study groups in NCT07153159
Study groupRoleWhat they receive
healthy breast feeding volunteersExperimentalNot described
Receives: Drug: Etrasimod

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Area under the etrasimod concentration-time curve in breast milk

    Measured: Baseline (Day -1), Day 1, Day 7 and Day 8.

  2. Maximum observed concentration of etrasimod in breast milk

    Measured: Baseline (Day -1), Day 1, Day 7 and Day 8.

  3. Amount of etrasimod excreted in breast milk

    Measured: Baseline (Day -1), Day 1, Day 7 and Day 8.

  4. Percent of etrasimod dose excreted in breast milk

    Measured: Baseline (Day -1), Day 1, Day 7 and Day 8.

  5. Breast milk clearance of etrasimod

    Baseline (Day -1), Day 1, Day 7 and Day 8.

    Measured: Baseline through Day 8

  6. Time to maximum observed concentration of etrasimod

    Measured: Baseline (Day -1), Day 1, Day 7 and Day 8.

Secondary outcomes (11)

  1. Area under the etrasimod concentration-time curve in plasma

    Measured: Day 1 hour 0, Day 7 hour 0, 1, 2, 4, 6, 8 and 12, Day 8 hour 24

  2. Maximum observed concentration of etrasimod in plasma

    Measured: Day 1 hour 0, Day 7 hour 0, 1, 2, 4, 6, 8 and 12, Day 8 hour 24

  3. Time to maximum observed concentration of etrasimod in plasma

    Measured: Day 1 hour 0, Day 7 hour 0, 1, 2, 4, 6, 8 and 12, Day 8 hour 24

  4. Breast milk to plasma ratio for area under the concentration-time curve

    Measured: Baseline (Day -1), Day 1, Day 7 and Day 8.

  5. percentage of treatment emergent adverse events in participants

    Measured: Baseline through Day 35

  6. Number of Participants With Clinically Significant Change From Baseline in Laboratory Abnormalities

    Measured: Baseline through Day 8

  7. Number of Participants With Clinically Significant Change From Baseline in vital signs (blood pressure and heart rate)

    Measured: Baseline through Day 8

  8. Number of Participants With Clinically Significant Changes From Baseline in 12-Lead Electrocardiogram (ECG) Parameters

    Measured: Baseline through Day 8

  9. Body weight normalized infant dose in μg/kg/day

    Measured: Baseline through Day 8

  10. Body weight normalized maternal dose in μg/kg/day

    Measured: Baseline through Day 8

  11. Infant dose expressed as % of body weight normalized maternal dose

    Measured: Baseline through Day 8

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted3 Sep 2025
  2. Study start7 Aug 2025
  3. Primary completion18 Sep 2026
  4. Study completion15 Oct 2026

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1
Primary purpose
Basic science
Allocation
Non-randomised
Intervention model
Single group
Masking
None (open label)
Enrolment
8 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07153159
Sponsor's protocol ID
C5041053
Other IDs
2025-520930-44-00, 2025
Status last verified
Oct 2026
First submitted
5 Aug 2025
Last updated
20 Oct 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
No: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.
Expanded access
Available

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing Etrasimod in people with Healthy Participant, run by Pfizer at 1 site in Belgium.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 3 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 20 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Belgium. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Area under the etrasimod concentration-time curve in breast milk (time frame: Baseline (Day -1), Day 1, Day 7 and Day 8.). The study lists 6 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07153159.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 20 Oct 2026.

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