Background: Phase 3 studies in patients with chronic hepatitis B have shown tenofovir alafenamide to have non-inferior efficacy to tenofovir disoproxil fumarate, with improved renal and bone safety. We conducted this study to evaluate the safety and efficacy of switching to tenofovir alafenamide in participants with chronic hepatitis B and renal or hepatic impairment.
Methods: This open-label, multicentre, phase 2 study was done in eight countries or territories at 30 sites. We recruited adults (≥18 years) with chronic hepatitis B who were virally suppressed on nucleoside or nucleotide analogues and had renal impairment (part A: moderate or severe in cohort 1 [estimated glomerular filtration rate by the Cockcroft-Gault formula (eGFRCG) 15-59 mL/min] or end-stage renal disease [eGFRCG <15 mL/min] on haemodialysis in cohort 2) or hepatic impairment including decompensation (part B: Child-Turcotte-Pugh score 7-12). Participants switched to 25 mg of tenofovir alafenamide given orally once daily for 96 weeks. The primary endpoint was the proportion of participants with viral suppression (HBV DNA <20 IU/mL) at week 24 by missing-equals-failure analysis. Efficacy (full analysis set) and safety (safety analysis set) analyses included all enrolled participants who received at least one dose of the study drug. Week 96 safety was assessed, including renal and bone parameters. This trial is registered at ClinicalTrials.gov, NCT03180619, and is completed.
Findings: 124 participants (93 in part A [78 in cohort 1 and 15 in cohort 2] and 31 in part B) were enrolled between Aug 11, 2017, and Oct 17, 2018, and included in the full and safety analysis sets. 106 (85%) participants completed the study. There were 69 (74%) men and 24 (26%) women in part A and 21 (68%) men and ten (32%) women in part B. At week 24, 91 (97·8%, 95% CI 92·4 to 99·7) of 93 individuals in part A (76 [97·4%, 91·0 to 99·7] of 78 in cohort 1 and 15 [100·0%, 78·2 to 100·0] of 15 in cohort 2) and 31 (100·0%, 88·8 to 100·0) in part B had HBV DNA of less than 20 IU/mL. By week 96, the most common adverse event was upper respiratory tract infection, which occurred in 14 (15%) participants in part A and in six (19%) participants in part B. Serious adverse events occurred in 20 (22%) part A participants and in ten (32%) part B participants; none were related to treatment. No treatment-related deaths occurred. At week 96, median change in estimated glomerular filtration rate (Cockcroft-Gault method) was 1·0 mL/min (IQR -2·8 to 4·5) in cohort 1 and -2·4 mL/min (-11·4 to 10·7) in part B. Mean changes in spine and hip bone mineral density were 1·02% (SD 4·44) and 0·20% (3·25) in part A and -0·25% (3·91) and 0·28% (3·25) in part B.
Interpretation: Tenofovir alafenamide might offer continued antiviral efficacy and a favourable safety profile for patients with renal or hepatic impairment and chronic hepatitis B switching from tenofovir disoproxil fumarate or other antivirals.
Funding: Gilead Sciences.
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