To evaluate the efficacy, safety and immunogenicity of QCL7401 subcutaneous administration in patients with primary hypercholesterolemia or mixed hyperlipidemia with poorly controlled LDL-C elevated on optimized lipid-lowering therapy.

Inclusion Criteria:

1. Male or female participants aged ≥18 years of age.
2. Serum low density lipoprotein cholesterol (LDL-C) ≥1.8mmol/L for participants with atherosclerotic cardiovascular disease (ASCVD) or ≥2.6mmol/L for other participants at screening.
3. Fasting Total Cholesterol (TG) ≤400mg/dL (≤4.5mmol/L) at screening.
4. Stable lipid-lowering therapy for ≥4 weeks at randomization.
5. Understand the study procedures and methods, volunteer to participate in the study, and sign the informed consent.

Exclusion Criteria:

1. Having the following diseases or treatment history: (1) cardiac function as defined by the New York Heart Association (NYHA) grade III-IV at screening or randomization ; (2) Cardiovascular diseases within 3 months; (3) uncontrolled severe hypertension; (4) previous diagnosis of familial hypercholesterolemia; (5) have known allergic reaction to experimental drug, or have severe allergic reaction to other drugs; (6) inadequate organ functions or malignancy history; (7) prior exposure to other RNA inhibitors within 2 years.
2. Any of the laboratory indicators met the following criteria at screening or at randomization: (1) ALT or AST exceeding 3 times the upper limit of normal (ULN), or total bilirubin exceeding 2 times ULN; (2) creatine kinase (CK) exceeding 3 times ULN; (3) TSH is less than the lower limit or normal (LLN) or exceeds 1.5 times ULN.
3. General conditions: (1) male or female participants who do not agree to use high-efficiency contraceptives during the trial and for 6 months after the last dosing; (2) women who are pregnant or lactating.
4. The investigator determines that the participants have poor compliance or have any factors that may prevent them from participating in the study.