YKYY-015

Phase Ib: Primary Objective: To evaluate the safety and tolerability of YKYY015 injection after multiple subcutaneous administration in participants with elevated low-density lipoprotein cholesterol (LDL-C). Secondary Objectives: To evaluate the pharmacokinetic (PK) characteristics of YKYY015 injection after multiple subcutaneous administration; to evaluate the pharmacodynamic characteristics of YKYY015 injection in participants with elevated low-density lipoprotein cholesterol (LDL-C); and to evaluate the immunogenicity of YKYY015 injection in participants with elevated low-density lipoprotein cholesterol (LDL-C). To evaluate the efficacy of YKYY015 injection in participants with elevated low-density lipoprotein cholesterol (LDL-C) on statin therapy. Phase IIa: Primary Objective: To evaluate the efficacy of YKYY015 injection in participants with elevated low-density lipoprotein cholesterol (LDL-C) on statin therapy. Secondary objectives: To evaluate the safety of YKYY015 injection in participants with elevated low-density lipoprotein cholesterol (LDL-C) under statin treatment; to evaluate the immunogenicity of YKYY015 injection in participants with elevated low-density lipoprotein cholesterol (LDL-C) under statin treatment.