Dicerna Pharmaceuticals, Inc. announced the dosing of the first human volunteer in its Phase 1 clinical trial of DCR-HBVS, the Company’s investigational GalXCTM-based therapy for the treatment of chronic hepatitis B virus (HBV) infection in adults. The Company anticipates human proof-of-concept data from the Phase 1 trial, which is known as DCR-HBVS-101, in the second half of 2019. DCR-HBVS is comprised of a single GalXC molecule that targets HBV messenger RNAs (mRNAs) within the hepatitis B surface antigen (HBsAg) gene sequence region. Preclinical studies with a standard mouse model of HBV infection showed DCR-HBVS led to greater than 99% reduction in circulating HBsAg, suggesting superior HBsAg suppression (both in magnitude and duration of suppression), compared to targeting within the X gene sequence region. The DCR-HBVS-101 clinical trial is a randomized, placebo-controlled study designed to evaluate the safety and tolerability of DCR-HBVS in normal healthy volunteers (NHVs) and in patients with non-cirrhotic chronic HBV. Secondary objectives are to characterize the pharmacokinetic (PK) profile of DCR-HBVS and to evaluate preliminary pharmacodynamics (PD) and antiviral efficacy on plasma levels of HBsAg and HBV in blood. The study is divided into three phases or groups: In Group A, 30 NHVs are to receive a single ascending-dose of DCR-HBVS (0.1, 1, 1.5, 3, 6, or 12 mg/kg), with a four-week follow-up period. Group B is a single-dose study of DCR-HBVS (3 mg/kg) in eight patients with HBV who are naïve to nucleoside analog therapy; these patients will be followed for at least 12 weeks. The Company expects to initiate Group B dosing in the third quarter of 2019. Group C is a multiple ascending-dose study of DCR-HBVS (1.5, 3, or 6 mg/kg) in 18 patients with HBV previously treated with nucleoside analogs with a follow-up period of 24 weeks or more. The Company expects to initiate Group C dosing in the second quarter of 2019.