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

Prior treatment

• A positive urine drug test. A single repeat for positive drug screen may be allowed.

Other illness

• 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).
• History of any lymphoproliferative disorder such as Epstein-Barr virus (EBV) related lymphoproliferative disorder, history of lymphoma, history of leukemia, or signs or symptoms suggestive of current lymphatic or lymphoid disease. Known present or a history of malignancy other than a successfully treated or excised nonmetastatic basal cell or squamous cell cancer of the skin or cervical carcinoma in situ.
• Evidence of active Mycobacterium tuberculosis (TB) infection in the past. Adequately treated latent TB will be permitted.
• Participants who in the last 6 months experienced myocardial infarction, unstable angina pectoris, stroke, transient ischemic attack (TIA), decompensated heart failure requiring hospitalization, or New York Heart Association (NYHA) Class III/IV heart failure.
• Participants with history or presence of second-degree or third-degree atrioventricular (AV) block, sick sinus syndrome, or sinoatrial block.
• 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.
• Participants with any of the acute or chronic infections or infection history.

Lab values

• Any medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality or other conditions that may increase the risk of study participation or, in the investigator’s judgment, make the participant inappropriate for the study.
• Participants with ANY of the abnormalities in clinical laboratory tests at screening or Day -1, as assessed by the study-specific laboratory and confirmed by a single repeat test, if deemed necessary. - White blood cell (WBC) <3500/mm3 (<3.5 × 109 cells/L) - Absolute neutrophil count (ANC) <1500/mm3 (<1.5 × 109 cells/L) - Absolute lymphocyte count (ALC) <800/mm3 (<0.8 × 109 cells/L) - Aspartate aminotransferase (AST) or Alanine aminotransferase (ALT) level >2 × upper limit of normal (ULN) - Total bilirubin level > 1.5 × ULN; participants with a history of Gilbert’s syndrome may have direct bilirubin measured and would be eligible for this study provided the direct bilirubin level is ≤ ULN; - Estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 based on the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. - In the opinion of the investigator, have any clinically significant laboratory abnormality that could affect interpretation of study data or the participant’s participation in the study.

Age

• Standard 12-lead ECG that demonstrates clinically relevant abnormalities that may affect participant safety or interpretation of study results (eg, QTcF >470 ms, complete LBBB, signs of an acute or indeterminate age myocardial infarction, ST segment and/or T wave changes suggestive of myocardial ischemia, second- or third-degree AV block, or serious bradyarrhythmias or tachyarrhythmias). If QTcF exceeds 470 ms, or QRS exceeds 120 ms, the ECG should be repeated twice and the average of the 3 QTcF or QRS values used to determine the participant’s eligibility. Computer interpreted ECGs [with abnormal findings] should be overread by an investigator experienced in reading ECGs before excluding a participant.

Other

• 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.
• A positive pregnancy test.
• Screening supine blood pressure (BP) ≥140 mm Hg (systolic) or ≥90 mm Hg (diastolic), following at least 5 minutes of supine rest. If systolic BP is ≥140 mm Hg or diastolic ≥90 mm Hg, the BP should be repeated 2 more times and the average of the 3 BP values should be used to determine the participant’s eligibility.

• 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.