Background:  It is not known whether the early HBV plasma dynamics in HIV/HBV-co-infected patients is different according to treatment with tenofovir (TDF) or adefovir (ADV).

Methods:  HIV/HBV-co-infected patients recruited in the HIV/HBV French cohort study were prospectively followed and assessed for biochemical and virological responses to ADV or TDF. Patients were HBV treatment-naive at inclusion, except for past or current lamivudine, as part as ART regimen. Plasma viral dynamics were modelled using random-effects, mixed-linear models.

Results:  A total of 85 patients were included, 29 in the ADV arm and 56 in the TDF arm. Both groups did not differ at inclusion, except for HBV genotypes (41.7% of genotype G in ADV group vs 5.4% in TDF group, p <0.003). During the first 6 months, there was an overall decrease of HBV load by 1 log unit (95%CI 0.9 to 1.2) per month. Individuals in the TDF group presented a more rapid decline, with a declining slope estimated at 1.1 (95%CI 0.9 to 1.3) compared to 0.8 (95%CI 0.6 to 1.0) in the ADV group (p = 0.036). After 12 months of treatment, the HBV DNA load, although similar at baseline (7.98 log and 7.30 log in the ADV and TDF groups, respectively), declined to a lower level in patients treated with TDF (2.45 log vs 3.97 log, p <0.0001). A marked decrease in the rate of transaminases was noted in the TDF group but not in the ADV group (mean ALT [TDF] = 46 UI/mL vs mean ALT [ADV] = 83 UI/mL, p = 0.001). The proportion of patients with HBe seroconversion was identical in both groups (4 of 29 with ADV vs 7 of 56 with TDF).

Conclusions:  The HBV DNA declined less rapidly under ADV than TDF treatment. The use of TDF was associated with a better biochemical and antiviral response. Viral HBV dynamics under both treatments are in favour of using TDF rather than ADV when controlling the HBV replication in HIV-infected patients is concerned.