A Relative Bioavailability Study and Food Effect Study of AB521 in Healthy Adult Volunteers

Key Inclusion Criteria:

• Continuous non-smoker who has not used nicotine- and tobacco-containing products for at least 3 months prior to the first dosing based on volunteer self-reporting
• Body mass index (BMI) ≥ 18.0 and ≤ 32.0 kilogram (kg)/square meter (m^2) at the screening visit, with body weight ≥ 45 kg
• Medically healthy with no clinically significant medical history, physical examination, laboratory profiles, vital signs, and ECGs, as deemed by the study physician
• Able to swallow multiple capsules and tablets
• Has adequate peripheral venous access

Key Exclusion Criteria:

• Has active neoplastic disease or history of neoplastic disease within 5 years of the screening visit (except for basal or squamous cell carcinoma of the skin or carcinoma in situ that has been definitively treated with standard of care)
• Has abnormal liver enzyme test results or hematology values at the time of enrollment
• Has a history of additional risk factors for Torsades de pointes (example: heart failure, hypokalemia, family history of Long QT Syndrome)
• Malabsorption condition that would alter the absorption of orally administered medications at the discretion of the study physician
• Participation in another clinical study within 90 days or within 5 half-lives (if known), prior to the first dosing, whichever is longer. The 90-day window will be derived from the date of the last blood collection or dosing, whichever is later, in the previous study to Day 1 of the current study

Note: Other protocol defined Inclusion/Exclusion criteria may apply.