Arrowhead Pharmaceuticals Inc., of Pasadena, Calif., reported new data from its phase II trial testing ARC-520, the company's prior-generation RNAi-based drug against chronic hepatitis B (HBV) infection, at the 22nd biennial HEP DART meeting held in Kona, Hawaii. Seven months after the last dose of ARC-520 was administered, patients experienced up to a 5 log10 reduction of HBV surface antigen (HBsAg ) from baseline.