A Study to Test Bioavailability of of 2 New Formulations of UCB0599 in Healthy Participants in Part A and to Test Safety, Tolerability, and Pharmacokinetic (PK) of UCB0599 in Healthy Japanese and Chinese Participants in Part B

A 2-Part Study to Evaluate the Relative Bioavailability of 2 New Formulations of UCB0599 and the Effect of Esomeprazole on the PK of UCB0599 in Healthy Participants (Part A, Open-Label) and to Assess the Safety/Tolerability and PK of UCB0599 in Healthy Participants of Japanese and Chinese Origins (Part B, Double-Blind)

The purpose of the study is to estimate the relative bioavailability of 2 new UCB0599 formulations under elevated and normal gastric pH conditions in healthy participants (Part A) and to asess the safety, tolerability and pharmacokinetics of UCB0599 in healthy participants of Japanese and Chinese origins (Part B).

Inclusion Criteria:

• Part A only: all healthy study participants except for those participants who are eligible for Part B of the study
• For participants of Japanese origin (Part B): study participant is of Japanese descent as evidenced by appearance and verbal confirmation of familial heritage (a participant has all 4 Japanese grandparents born in Japan). For participants of Chinese origin (Part B): study participant is of Chinese descent as evidenced by appearance and verbal confirmation of familial heritage (a participant has all 4 Chinese grandparents born in China).
• Body weight within 45 to 100 kg (female) and 50 to 100 kg (male) and body mass index (BMI) within the range 18 to 30 kg/m^2 (inclusive at screening)
• Healthy male and female study participants

Exclusion Criteria:

• Participant has any medical or psychiatric condition that, in the opinion of the Investigator, could jeopardize or would compromise the study participant's ability to participate in this study
• Participant has a history or presence of/significant history of cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrinological, hematological, or neurological disorders capable of significantly altering the absorption, metabolism, or elimination of drugs; constituting a risk when taking the study intervention; or interfering with the interpretation of data
• Participant has had lymphoma, leukemia, or any malignancy within the past 5 years, except for basal cell carcinomas that have been resected, squamous epithelial carcinomas of the skin that have been resected with no evidence of metastatic disease for 3 years
• Participant has had breast cancer within the past 10 years
• Participant has a history of alcohol or drug abuse within the last 1 year from Screening, as defined according to the Diagnostic and Statistical Manual of Mental Disorders
• Participant has a known hypersensitivity to any components of the study medication or comparative drugs as stated in this protocol
• Participant has a consumption of more than 600 mg of caffeine/day at screening and throughout the study
• Participant has consumed any grapefruit, grapefruit juice, grapefruit-containing products, or star fruit within 14 days prior to administration of study medication or is not willing to refrain from consuming these products for the duration of the study
• Participant has previously participated in this study or participant has previously been assigned to treatment in a study of the medication under investigation in this study
• Participant has participated in another study of a study medication (and/or an investigational device) within the previous 30 days or 5 half-lives, whichever is greatest, or is currently participating in another study of an study medication (and/or an investigational device)
• Presence of hepatitis B surface antigen (HBsAg) at screening or within 3 months prior to dosing
• Positive hepatitis C antibody test (HCVAb) result at screening or within 3 months prior to starting study intervention
• Positive hepatitis C ribonucleic acid (RNA) test result at screening or within 3 months prior to first dose of study medication
• Current or chronic history of liver disease or known hepatic or biliary abnormalities (with the exception of Gilbert's syndrome or asymptomatic gallstones)
• For women of childbearing potential, study participant is pregnant, planning on becoming pregnant during the study, or is breastfeeding
• Participants who may have a history of confirmed gastric ulceration