ARC-520

ARC-520 is an investigational RNA interference (RNAi) therapeutic developed for the treatment of chronic hepatitis B virus (HBV) infection. It consists of two small interfering RNAs (siRNAs), AD0009 and AD0010, which specifically target and degrade all viral mRNA transcripts derived from covalently closed circular DNA (cccDNA) in HBV-infected hepatocytes. By silencing these transcripts, ARC-520 effectively reduces the production of viral proteins—including hepatitis B surface antigen (HBsAg)—and HBV DNA, aiming to achieve a functional cure characterized by HBsAg loss with or without seroconversion. The drug uses a polymer-based excipient to facilitate endosomal escape and delivery of siRNAs into the cytoplasm where RNAi occurs. Clinical studies have shown that ARC-520 can significantly reduce levels of HBsAg and other viral antigens in patients with chronic HBV infection[1][2][3][5]. The primary developer is Arrowhead.