A Study to Learn How the Body Processes BIIB141 (Omaveloxolone) When Taken as a Capsule or as a Tablet Dissolved in Liquid, and to Learn About Its Safety in Healthy Adults Ages 18 to 55

A Phase 1, Randomized, Open-Label, Single-Dose, Crossover, Bioequivalence Study of Omaveloxolone Tablets for Oral Suspension Versus Capsules in Healthy Adult Participants

In this study, researchers will learn more about BIIB141, also known as omaveloxolone or SKYCLARYS®. This drug has been approved, or made available for doctors to prescribe, for people with Friedrich's Ataxia (FA) who are at least 16 years old. Currently, BIIB141 is taken by mouth as capsules or capsule contents sprinkled over applesauce. But, there may be some people who have trouble swallowing capsules. In this study, the main goal was to learn if BIIB141 is processed similarly in the body of healthy adults when taken as tablets that dissolve in liquid compared to the currently available capsules.

The main question researchers want to answer in this study is :

• How does the body process BIIB141 when taken as a tablet dissolved in liquid compared to capsules?

Researchers will also learn more about:

• How many participants have adverse events during the study. An adverse event is a health problem that may or may not be caused by the study drug.
• If there are any changes in the participants' overall health during the study.

This study will be done as follows:

• Participants will be screened to check if they can join the study. The screening period will be up to 28 days, after which participants will check into their study research center.
• Participants will stay at the study research center for about 30 days.
• This is an "open label" study. In this kind of study, the participants, study doctor, and site staff know which study drug the participant is taking. In this study, all participants will take BIIB141.
• This study also has a "crossover" design. This means that all of the participants will take BIIB141, once as a tablet that dissolves in liquid and once as a capsule. But the order in which the participants take them will be different. There will be a break of about 14 days between the 2 doses.
• Throughout the study, researchers will take participants' blood and urine samples. Researchers will also do other tests to check the participants' overall health and will ask participants how they are feeling.
• Each participant will be in the study for up to 57 days.

The primary objective of the study is to assess the bioequivalence (BE) of omaveloxolone tablets for oral suspension (TOS) compared to capsules in healthy adult participants. The secondary objective of the study is to assess the safety and tolerability of a single dose of omaveloxolone when administered as TOS or capsule in healthy adult participants.

Key Inclusion Criteria:

• All female participants of childbearing potential must have negative results for pregnancy tests as follows:

  1. At screening, based on a serum sample obtained within 28 days prior to initial study drug administration; and
  2. Prior to dosing, based on a serum sample obtained on Study Day -1.

• Body Mass Index (BMI) at screening between 18 and 32 kilograms per meter square (kg/m^2), inclusive.

• Participants must be in good health.

Key Exclusion Criteria:

• History of any clinically significant cardiac, endocrine, gastrointestinal, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, psychiatric, or renal disease, or other major disease, as determined by the Investigator.
• Clinically significant, as determined by the Investigator, 12-lead electrocardiogram (ECG) abnormalities.
• History of, or positive test result for human immunodeficiency virus (HIV).
• History of hepatitis C infection or positive test result at Screening for hepatitis C virus antibody (HCV Ab).
• Current hepatitis B infection [defined as positive for hepatitis B surface antigen (HBsAg) and/or total hepatitis B core antibody (anti-HBc)]. Participants with immunity to hepatitis B from previous natural infection (defined as negative HBsAg, positive anti-HBc, and positive anti-HBs) or vaccination (defined as negative HBsAg, negative anti-HBc, and positive anti-HBs) are eligible to participate in the study.
• Chronic, recurrent, or serious infection (e.g., pneumonia, septicemia), as determined by the Investigator, within 90 days prior to Screening or between Screening and Day -1.
• Prior exposure to the study treatment.
• Any clinically significant abnormal laboratory test value as determined by the Investigator, as Screening or Day-1.

NOTE: Other protocol-defined Inclusion/Exclusion criteria may apply.