Part B will utilize an open-label, randomized, combination therapy design. The study is designed to evaluate the safety, tolerability, and antiviral response of the chosen dose and regimen from Part A administered for 12 weeks, either alone or in combination with tenofovir 300 mg QD. Randomization will be stratified based on HBeAg status (+/-), HBV viral load (< 10(6) or ≥ 10(6) IU/mL), and HBsAg baseline levels (< 10(3) or ≥ 10(3) IU/mL).