A Phase 2, Randomized, Open Label Study to Evaluate the Efficacy and Safety of Tenofovir Alafenamide (TAF) versus Tenofovir Disoproxil Fumarate (TDF)–containing Regimens in

INTERVENTION: Approximately 60 subjects with chronic hepatitis B and Stage 2 or greater chronic kidney disease and have received a liver transplant will be assigned to one of the two treatment arms (A:B) for 48 weeks. Randomization will be stratified by baseline renal function. ‐ Treatment Arm A: approximately 30 subjects administered Tenofovir Alafenamide (TAF) 25 mg oral daily ‐ Treatment Arm B: approximately 30 subjects to continue administration of Tenofovir Disoproxil Fumarate (TDF) alone or in combination with other approved antivirals per local practice; After Week 48, during the optional treatment extension phase, subjects in treatment arms A and B will be eligible to receive TAF 25 mg daily and will be followed for an additional 96 weeks. An accountability check at each visit, Drug tablet return and lab tests are all part of the protocol to manage and monitor adherence. CONDITION: Chronic Hepatitis B Chronic Kidney Disease PRIMARY OUTCOME: Change from baseline in renal function of TAF 25 mg daily versus TDF‐containing regimens at Week 24. ; eGFR is calculated by assessing Cystatin C and estimated serum creatinine clearance. Proportion of subjects with HBV DNA < 20 IU/mL at Week 24. ; The subject's HBV DNA will be assessed using a plasma assay. ; SECONDARY OUTCOME: Change from baseline in renal function of TAF 25 mg daily versus TDF‐containing regimens at Week 48. ; eGFR is calculated by assessing Cystatin C and estimated serum creatinine clearance. Change from baseline in serum creatinine of TAF 25 mg daily versus TDF‐containing regimens at Weeks 24 and 48 Percent change from baseline in hip and spine bone mineral density (BMD) of TAF 25 mg daily versus TDF‐containing regimens at Weeks 24 and 48. The outcome is assessed using a DEXA scan. Proportion of subjects with HBV DNA < 20 IU/mL at Week 48. ; The subject's HBV DNA will be assessed using a plasma assay. INCLUSION CRITERIA: 1) Must have the ability to understand and sign a written informed consent form; consent must be obtained prior to initiation of study procedures 2) Adult male or non‐pregnant female subjects, over 18 years of age based on the date of the screening visit 3) Documented evidence of chronic HBV infection prior to transplantation 4) Primary or secondary (re‐transplant), liver alone or liver and kidney transplant recipient from deceased or living donor 5) Liver Transplant =>12 weeks prior to screening 6) Maintained on TDF alone or in combination with other approved antivirals for HBV prophylaxis or treatment 7) Have been on approved HBV OAV treatment for at least 12 weeks post‐transplant prior to screening, with HBV DNA < LLOQ at screening 8) Screening renal function < 90 ml/min/1.73m^2 9) Male subjects and female subjects of childbearing potential who engage in heterosexual intercourse must agree to use protocol specified method(s) of