PO-026 : Improvement in Renal Parameters in CHB Patients Treated with Tenofovir Alfenamide (TAF) versus Tenofovir Disoproxil Fumarate (TDF) over 96 Weeks

Aims: In Phase 3 studies in CHB patients the efficacy of TAF was found smaller changes in renal parameters compared with TDF treatment. This benefit was particularly evident in patients with risk factors for renal impairment.Here, we present renal safety results after 96 weeks of treatment. Methods: In Phase 3 studies (HBeAg positive patients [N=873] and HBeAg negative patients [N=425]), patients were randomized 2:1 to TAF 25 mg QD or TDF 300 mg QD, and treated for 144 weeks. Renal parameters including estimated glomerular filtration rate (eGFR) calculated by the Cockcroft-Gault method were evaluated. Chronic kidney disease (CKD) staging was categorized by the National Kidney Foundation KDOQI guidelines. Evaluated risk factors for kidney disease included older age (age ≥ 50), female gender, renal impairment (eGFR <90mL/min) and presence of comorbidities (hypertension, cardiovascular disease and diabetes). Urine markers of renal glomerular dysfunction (urine protein and albumin to creatinine ratio) and tubular dysfunction (retinol binding protein (RBP) and beta-2 microglobulin [B2M] to creatinine ratio) were serially assessed. Results: Patients treated with TAF continued to show smaller changes in serum creatinine (p=0.001) and eGFRCG (p<0.001) at 96 weeks. Similarly, median percentage changes in renal tubular markers, were also smaller in TAF-treated patients compared with TDF patients at Week 96; RBP/Cr (p<0.0001) and B2M/Cr (p<0.0001). A lower percentage of patients experienced ≥1 stage worsening in NKF CKD stage when treated with TAF compared with TDF at Week 96 overall and when evaluated by risk factors for kidney disease.Furthermore, CKD stage progression increased disproportionately in the TDF group in patients with ≥2 risk factors (Table). Conclusions: Treatment with TAF for 96 weeks continued to be associated with smaller changes in renal parameters compared with TDF treatment. The benefits of TAF are particularly evident in patients with risk factors for kidney disease.