A 2-Part, Phase 1, Single and Multiple Ascending Dose Study to Assess the Safety, Pharmacokinetics, and Pharmacodynamics of CAT-2054 in Healthy Subjects

Inclusion Criteria: * Provision of written informed consent before any study-specific procedure * Good health as determined by medical history, physical examination, vital sign measurements, ECG, and clinical laboratory measurements * Satisfies one of the following: 1. Females not of childbearing potential: non-pregnant and non-lactating surgically sterile or postmenopausal 2 years or less with a follicle-stimulating hormone assessment greater than or equal to 40 IU/L 2. Males: surgically sterile, abstinent, or subject or partner is utilizing an acceptable contraceptive method during and 3 months after the last study dose * For Part B only, measured at Screening: Fasting LDL-C ≥100 mg/dL; or (Cohort B6 only) fasting LDL-C ≥130 mg/dL * Body mass index (BMI) between 18 and 30 kg/m², inclusive, for Part A and between 18 and 40 kg/m², inclusive, for Part B, and body weight \>50 kg at Screening Exclusion Criteria: * Use of prescription drugs or non-prescription drugs including herbals, and dietary supplements (including multivitamins and any product containing niacin or omega-3 fatty acids above the Recommended Daily Allowance) within 2 weeks before dosing. Additionally for Part B only, use of any lipid-regulating prescription drug, non-prescription drug, herbal, or dietary supplement within 6 weeks before dosing * Clinically significant disease that requires a physician's care and/or would interfere with study evaluations * Clinically significant electrocardiogram (ECG) abnormalities or laboratory results as assessed by the investigator, such as QTcF \>450 * Use of any investigational drug or participation in any investigational study within 30 days prior to screening or 5 half-lives of the study agent, whichever is longer