Apolipoprotein CIII is a small secreted protein encoded by the APOC3 gene, primarily synthesized and secreted into the plasma by the liver. It is a component of lipoprotein particles such as high-density lipoprotein and very-low-density lipoprotein. Its main physiological function is to regulate lipid metabolism by inhibiting the activity of lipoprotein lipase and interfering with hepatic uptake of triglyceride-rich lipoproteins, thereby delaying the clearance of plasma triglycerides. Research indicates that elevated APOCIII levels are an independent risk factor for severe hypertriglyceridemia, insulin resistance, and atherosclerosis, and are closely associated with cardiovascular events. Consequently, APOCIII has become a critical therapeutic target for managing metabolic syndrome and cardiovascular diseases, with targeted drugs such as the antisense oligonucleotide Volanesorsen already in clinical use.