The purpose of this study is to determine the safety and efficacy of different doses of CAT-2003 in patients with hyperlipidemia when CAT-2003 is taken for 4 weeks. The study will evaluate effects of CAT-2003 on (1) fasting triglycerides and non-HDL-C in patients with moderate hypertriglyceridemia and (2) fasting LDL-C levels in combination with a statin in patients with hypercholesterolemia who are on a statin.

Inclusion Criteria:

• Between 18 and 69 years at Screening
• Hypertriglyceridemia (TG ≥ 200 mg/dL and < 500 mg/dL and non-HDL-C ≥ 100 mg/dL and < 220 mg/dL) OR
• Hypercholesterolemia (LDL-C ≥ 100 mg/dL and < 190 mg/dL and TG value < 200 mg/dL) plus a stable dose of statin for at least 4 weeks prior to Screening.
• Body mass index (BMI) ≤ 45 kg/m2

Exclusion Criteria:

• History of any major cardiovascular event within 6 months of Screening
• Type I diabetes mellitus
• Any condition that may predispose the patient to secondary hyperlipidemia, such as uncontrolled hypothyroidism
• Any statin at the highest approved dose
• Non-statin lipid-altering drugs other than cholesterol absorption inhibitors.
• Active peptic ulcer disease or a history of muscle disease or myopathy