Background:   Tenofovir disoproxil fumarate (TDF) is a nucleotide analogue with dual activity against both HIV and HBV. Small sample sized, pilot open studies have suggested TDF efficacy against wild-type, precore and lamivudine resistant HBV. The objective was to evaluate efficacy of TDF (300 mg once a day), administered as a part of antiretroviral therapy, in a large cohort of HIV/HBV co-infected patients.

Methods: HIV/HBV co-infected patients who received TDF for at least 2 weeks and who had stored serum samples at the beginning and during TDF therapy were included. Clinical, biological and virological data were retrospectively recorded. Serum HBV DNA was measured on store samples by the Amplicor Monitor Roche 2.0 (sensitivity 2.3 log_{10<.sub> copies/mL). Baseline was the day of TDF initiation and the end point was the day of the last available stored serum sample during TDF therapy.}

_{Results: A total of 119 patients  (mean age 42.4 +7.1 years) were included. The median follow-up period was 8.0 (1 to 24) months. All the patients but 5 (97%) were receiving lamivudine (150 mg twice daily) at baseline. Median CD4 count and HIV RNA at baseline were 337 (3 to 1174) cells/µL and 2.8 (1.3 to 6.1) log10} copies/mL, respectively. Fifty-two patients (48%) had an HIV RNA <400 copies/mL. HBeAg and anti-HBe Ab were positive at baseline in 73 patients (68%) and 29 patients (27%), respectively. HBV DNA was detectable at baseline in 88 patients (84%). Of these patients, 83 (95%) were receiving lamivudine at TDF initiation. After a median period of 9 (1 to 24) months HBV DNA became undetectable in 28 (32%) patients. In this group of patients, the median reduction from baseline of serum HBV DNA (8.0; 2.4 to 8.8 log₁₀ copies/mL) was -3.8 (-6.4; -2.5) log₁₀ copies/mL (p <0.0001). Serum HBeAg became negative in 5 patients after > 6 months of treatment, 3 of them seroconverted to anti-HBe Ab. Serum HBV DNA remained undetectable in the 16 of 17 patients with negative PCR at baseline during TDF therapy (5.0; 1 to 17 months).

Conclusions: The results of this large cohort demonstrate the anti-HBV efficacy of TDF (300 mg once daily), given for a median period of 9 months as a part of antiretroviral therapy, in HIV infected patients with HBV replication and mostly receiving lamivudine.

Keywords: Tenofovir; HBV coinfection; HIV