This is a first-in-human (FIH study designed to evaluate safety, tolerability, pharmacokinetic, and pharmacodynamic effects of AKB-9090 in healthy adult participants. The study consists of two stages: Stage 1, a single ascending dose (SAD) phase with five dose cohorts, and Stage 2, a multiple ascending dose (MAD) phase with three dose cohorts. Approximately 40 participants in SAD and 30 in MAD are planned to be enrolled.

Key Inclusion Criteria:

• Healthy adult participants with no clinically significant findings, as judged by the investigator, based on physical examination, 12-lead ECG, alcohol breath test, and clinical laboratory tests (including serum chemistry, hematology, coagulation, urine drug screen, and urinalysis).
• Body mass index (BMI) greater than 18.5 and less than 32.0 kg/m^2 at screening.
• In the Investigator's opinion, willing and able to provide written informed consent and comply with the all protocol requirements, including required confinement, outpatient visits, and protocol-specified restrictions (including refraining from major lifestyle changes) from signature of the informed consent form (ICF) through the last study visit.

Key Exclusion Criteria:

• Clinically significant metabolic, hepatic, renal, hematologic, pulmonary, cardiovascular, gastrointestinal, musculoskeletal, dermatologic, urogenital, ophthalmologic, ear/nose/throat, psychiatric, or neurologic disorder.

• History of active or recurrent malignancy within 2 years before screening or during the screening period, or currently receiving treatment or suppressive therapy for cancer, except for:

  1. Treated basal cell carcinoma of the skin
  2. Curatively resected squamous cell carcinoma of the skin
  3. Treated colonic or cervical carcinoma in situ

• Abnormal ECG findings at screening, including:

  1. Severe bradycardia (heart rate <40 beats per minute) on any measurement
  2. Mean QT Interval Using Fridericia's Formula (QTcF) >450 msec for males or >470 msec for females

• Elevated laboratory values (>1.25 × upper limit of normal [ULN]) for alanine aminotransferase (ALT), aspartate aminotransferase (AST), or creatinine at the screening visit or at check-in.

• Evidence of acute or chronic hepatitis B (positive hepatitis B surface antigen) or hepatitis C infection (positive hepatitis C antibody and positive hepatitis C ribonucleic acid [RNA] test).

• Use of nicotine-containing products (including cigarettes, cigars, tobacco, gum, patches, vaping, and e-cigarettes), caffeine-containing foods or beverages, and alcohol-containing foods or beverages during study.