S-556971

S-556971 is an investigational, orally bioavailable small molecule inhibitor of proprotein convertase subtilisin/kexin type 9 (PCSK9) developed by Shionogi & Co., Ltd. for the treatment of dyslipidemia. PCSK9 is a key regulator of cholesterol metabolism that binds to low-density lipoprotein receptors (LDLR) on the surface of hepatocytes, promoting their internalisation and lysosomal degradation. By inhibiting the interaction between PCSK9 and LDLR, S-556971 increases the density of LDLR on the liver cell surface, thereby enhancing the clearance of LDL cholesterol (LDL-C) from the bloodstream. As an oral agent, S-556971 offers a potential alternative to the currently available injectable PCSK9 monoclonal antibodies, potentially improving patient convenience and adherence in the management of primary dyslipidemia and hypercholesterolemia.