The rate of complete virus suppression (CVS) was found in patients with hepatitis B virus (HBV) infection from 91.9% to 97.2% 96 weeks after switching from entecavir (ETV) to tenofovir alafenamide (TAF), according to the results of a study published in American Journal of Gastroenterology.
Both ETV and TAF are first-line treatments for HBV, but data associated with switching from prolonged ETV to TAF are limited. In this study, 425 patients with chronic hepatitis B virus who were treated with ETV for at least 12 months were switched to TAF. Patients were located in the United States, Korea, Japan and Taiwan. The mean duration of ETV treatment before the switch was 6.16 ± 3.17 years.
Approximately half of patients (55.6%) have stage 1 chronic kidney disease (CKD). 35.7% had stage II CKD and 8.8% had stage 3-5 CKD. The baseline mean glomerular filtration rate (eGFR) was 89 ± 19 mL/min/1.73 m.2.
After switching from ETV to TAF, CVS rate increased significantly; CVS was 95.3% (385/404; s = .05) at 24 weeks, 97.0% (288/297; s = .01) at 72 weeks, 97.2% (174/179; s = .02) at 96 weeks. Approximately half of patients who were not virologically suppressed before the switch achieved CVS at 48 weeks. The trend for increased CVS rates was significant (s <.001) as was the trend of decreasing mean HBV DNA (s <.001). However, there was no change in the rate of normalization of alanine aminotransferase (ALT) (s = .48) or mean ALT level)s = .97).
There were no significant changes in CKD stage over time. At week 96, 11% (26/235) of patients with stage 1 CKD moved to stage 2, and 8% (12/151) of patients with stage 2 CKD moved to stage 3 or Top. An improvement in CKD stage was seen with 18% (27/151) of patients with stage 2 improving to stage 1, and 19% (7/37) moving from stage 3-5 to stage 2. No overall change in mean eGFR Adjustment for age, sex, diabetes, hypertension, and cirrhosis has been reported.
The factors that predicted change in GFR were age (s <.001) and base eGFR either 60 to 89 mL/min/1.73 m2 (s <.001) or <60 ml/min/1.73 m2 (s <.001). Using logistic regression, deterioration of CKD was only associated with baseline eGFR (adjusted odds ratio: 0.96; 95% CI 0.94–0.99; s = .002).
The investigators highlighted several study limitations including missing data due to the retrospective nature of the study and a lack of understanding of patient experience, adherence, or the reason for the switch. The study also lacked a control arm, and the group was not closed (that is, not everyone reached the 96-week end point). The study was augmented by the use of real-life data, naive patients receiving ETV, and long-term follow-up including several analyses and sub-analyses.
The authors concluded that CVS, HBV DNA, and surface antigen levels improved during the switch from ETV to TAF, with no significant change in renal function. Although the switch appears to be safe and effective, they caution that due to the scale of incremental changes, costs and benefits must be weighed before automatically switching these systems out. The researchers also recommended additional studies to examine the long-term effects of treatment with TAF.
The study was supported by an investigator-initiated grant from Gilead Sciences. For full disclosure details, please refer to the original reference.
Nguyen MH, Atsukawa M, Ishikawa T, et al. Results of sequential treatment with tenofovir alafenamide after long-term entecavir. I am Gastroenterol. Published online February 2, 2021. doi: 10.14309/ajg.0000000000001157