 Although REP 2139-Ca has been shown to be safe in human patients, it shares the same class effect as other phosphorothioate oligonucleotides in that it accumulates in the liver with repeated dosing. REP 2165 is a version of REP 2139 which is designed to have an increased rate of degradation to slow down liver accumulation while keeping its antiviral activity intact. The antiviral efficacy of REP 2165 has been shown to be comparable to REP 2139 in a pre-clinical model of HBV infection with significantly less accumulation in the liver. As such, REP 2165 is expected to have comparable antiviral efficacy in human patients with reduced liver accumulation during treatment. 