Objective: To compare the 2-year efficacy and safety of combination therapy with entecavir (ETV) and adefovir dipivoxil (ADV) to that of tenofovir disoproxil fumarate (TDF) monotherapy in treatment of patients with adefovir drug-resistant chronic hepatitis B. Methods: HBeAg-positive CHB patients (n = 100) with adefovir-resistance (rtA181T/V and/or rtN236T) were enrolled. Patients were treated with either ETV 0.5 mg plus ADV 10 mg per day (n = 52) or TDF 300 mg per day (n = 48) for 48 weeks. Tests for liver and kidney function, Serum Phosphorus, HBV serum markers, HBV DNA load and ultrasonography of liver were performed every 3 months. Student's t-test and χ2 test were used to compare the efficacy, side effects in the two groups. Results: Fifty-two patients in ETV + ADV group and forty-eight patients in TDF group were followed-up for 96 weeks. HBV DNA undetectable rate were 76.9% versus 81.3% (P = 0.631) at week 48, and 92.3% versus 95.8% (P = 0.679) at week 96 in ETV + ADV combination therapy and TDF monotherapy group respectively. Serum ALT normalized rate were 84.6% versus 87.5% (P = 0.777) at week 48, and 92.3% versus 95.8% (P = 0.679) at week 96 in ETV+ADV combination therapy and TDF monotherapy group respectively. But the level of serum Phosphorus was significantly lower in ETV + ADV combination therapy group compare with TDF monotherapy group (1.13 ±0.15 versus 1.22 ±0.16, P = 0.004) at week 96. Conclusion: Both ETV + ADV combination therapy and TDF monotherapy provided effective treatments in chronic hepatitis B with adefovir-resistant. However, it was associated with poor serological responses up to week 96. The long term treatment of hepatitis B with ETV (0.5 mg/day) combination of ADV (10 mg/day) can potentially cause hypophosphatemia and renal impairment, so regular monitoring of serum phosphate, serum creatinine and evaluation of eGFR is needed.
Keywords: adefovir dipivoxil; adefovir-resistant; chronic hepatitis B; combination therapy; entecavir; hypophosphatemia; tenofovir disoproxil fumarate.