Improved Renal Laboratory Parameters In CHB Patients Treated With TAF Compared With Tenofovir Disoproxil Fumarate (TDF)

초록

Background: TDF treatment results in high rates of viral suppression with no described resistance; however its use has been associated with declines in eGFR over time. Phase 3 studies of TAF in CHB demonstrated lower declines in eGFR compared to TDF over 48 weeks of treatment. Here, we further characterize the clinical renal benefits of TAF compared to TDF. Methods: In two identically-designed Phase 3 studies of TAF (Study 110 in HBeAg positive and Study 108 in HBeAg nega-tive patients), patients were randomized 2:1 to TAF 25 mg QD or TDF 300 mg QD, each with matching placebo, and treated for 96 weeks. After Week 96, patients receive open label TAF for 48 weeks. Renal parameters including eGFR calculated by Cockcroft-Gault and CKD-EPI were evaluated throughout the study period. Chronic kidney disease (CKD) staging was categorized according to the NKF KDOQI guidelines (Stage 1: eGFR ≥ 90mL/min; Stage 2: eGFR 60-90 mL/min; Stage 3 eGFR 30-59 mL/min). Evaluated risk factors for kidney disease included older age (age ≥ 50) and comorbidities of hypertension (HTN), cardiovascular disease (CVD) and diabetes (DM). Multivariate analysis was performed using backwards stepwise approach. Results: Baseline demographics between TAF and TDF groups in both studies were generally balanced for risk factors for kidney disease. At week 48, patients treated with TAF had smaller changes in creatinine (median change 0.01 mg/dL for TAF and 0.02 mg/dL for TDF; p=0.012) and eGFRCG (median change -1.2 mL/min for TAF and -5.4 mL/min for TDF; p<0.001) during 48 weeks of treatment. The number of patients who had >25% eGFRCG reductions was also greater in the TDF arm versus the TAF arm (14.5% vs 8.7%, p=0.002). Using stages of CKD, a higher percentage of patients treated with TDF had one or more stage worsening in renal function at Week 48 (10.6% vs 6.7%; p=0.002; table). Among patients at highest risk for kidney disease (older age and comorbidities of HTN, CVD or DM), significantly more TDF-treated patients had worsening of renal function compared to TAF-treated patients. Multivariate analysis of worsening renal function by CKD stage identified lower baseline eGFR, lower baseline BMI, and Age ≥ 50 as independent predictors. Conclusions: In patients with CHB, TAF therapy is associated with less effects on renal parameters compared with TDF treatment. The benefits of TAF may be particularly evident in patients at higher risk of eGFR decline.