A Study of PCSK9 Inhibitor AK102 in Patients With Heterozygous Familial Hypercholesterolemia (HeFH)

Inclusion Criteria: * Subjects with heterozygous familial hypercholesterolemia diagnosed by genetic confirmation or clinical diagnosis criteria. * Stable on pre-existing, lipid-lowering therapies (statins with or without ezetimibe) for at least 4 weeks with no planned medication or dose change for the duration of study participation. * Fasting Low-Density Lipoprotein Cholesterol (LDL-C) ≥ 70 mg/dL in patients with history of Atherosclerotic Cardiovascular Disease (ASCVD) or Fasting Low-Density Lipoprotein Cholesterol (LDL-C) ≥ 100 mg/dL in patients without history of Atherosclerotic Cardiovascular Disease (ASCVD). * Fasting triglycerides ≤ 400 mg/dL. * Body weight ≥ 40kg. Key Exclusion Criteria: * Subjects with homozygous FH (clinically or by genotyping). * Receipt of LDL apheresis within 12 months prior to the first dose of Investigational product. * Receipt of Lomitapide or Mipomersen within 5 months prior to the first dose of Investigational product. * Prior use of PCSK9 inhibitors. * Creatine kinase (CK) \>3 times of the upper limit of normal (ULN). * Aspartate Aminotransferase (AST) ≥ 2 x ULN. * Estimated Glomerular Filtration Rate (eGFR)≤ 30 mL/min/1.73m\^2. * Thyroid-Stimulating Hormone (TSH)\> 1.5 x ULN or \<1 x LLN. * Type 1 diabetes, or type 2 diabetes that is or poorly controlled（HbA1c\> 8.5%). * Subjects with untreated or active chronic hepatitis B or active hepatitis C virus infections.