A Study to Evaluate the SYH2053 Injection in Patients With Heterozygous Familial Hypercholesterolemia (HeFH)

Inclusion criteria

• Male or female participants ≥18 years of age.
• HeFH.
• Stable moderate-to-high intensity statin therapy (± cholesterol absorption inhibitors) .
• Maintained a low-fat diet for ≥4 weeks before signing the ICF.
• Fasting LDL-C at screening ≥ 2.6 mmol/L or ≥ 1.4 mmol/L without ASCVD or with ASCVD.
• Fasting TG ≤5.6 mmol/L at screening.

Exclusion criteria

• HoFH or suspected HoFH.
• Use of medications that significantly affect LDL-C levels.
• Hypersensitivity or suspected allergy to oligonucleotide drugs or excipients of the investigational product.
• Major adverse cardiovascular events (MACE) within 180 days before signing the ICF; history of hemorrhagic stroke; or extreme-risk ASCVD at screening.
• Uncontrolled (by medication/ablation) or severe arrhythmias within 180 days before signing the ICF.
• NYHA Class III-IV heart failure or LVEF \<40% within 1 year before signing ICF or at screening.
• Type 1 diabetes.
• Uncontrolled severe illness or conditions that may interfere with study results/increase risk at screening, according to investigator's judgment.
• History of malignancy or underlying malignancy within 5 years before signing ICF or at screening.
• Major surgery within 180 days before signing ICF or planned during the study.
• History of drug/alcohol abuse within 5 years before signing ICF.
• Participation in another clinical trial within 90 days or 5 half-lives (whichever is longer) before signing ICF, or planned during the study.
• Any of the following at screening:
• ）SBP ≥160 mmHg or DBP ≥100 mmHg. 2）ALT/AST \>3× ULN, or total bilirubin \>1.5× ULN. 3）CK \>2.5× ULN. 4）QTcF interval: \>450 ms for male, \>470 ms for female. 5）eGFR \<30 mL/min/1.73 m². 6）HBsAg positive with HBV DNA positive; or HCV/syphilis/HIV antibody positive. 7）TSH\<LLN, or TSH\>ULN. 8）HbA1c \>8.5%. 14.Pregnancy/lactation or planned parenthood, and/or without effective contraception for female and male participants of childbearing potential from the study to 3 months after the end of treatment.