The inclusion of 3TC or tenofovir in antiretroviral treatment regimens reduces the risk of infection with hepatitis B virus (HBV) for gay men living with HIV who have not been vaccinated against HBV, Japanese investigators report in the online edition of Clinical Infectious Diseases. The authors believe that both 3TC and tenofovir had a prophylactic effect and reduced the risk of incident HBV infections by up to 90%.
“The results of this serological follow-up study indicated that LAM- [lamivudine, 3TC, Epivir, also in the combination pills Kivexa and Trizivir) and TDF- (tenofovir, Viread, also in the combination pills Truvada, Atripla and Eviplera) containing ART regimens seem to protect against HBV incident infections,” write the researchers.
HBV is a sexually transmissible infection and many people with HIV, especially gay and other men who have sex with men (MSM), are co-infected with HIV and HBV.
People who have or are at risk of HIV are recommended to be vaccinated against HBV. However, immunisation uptake rates are often poor, and the protective effect of the vaccine can be reduced in the context of immune suppression and a low CD4 cell count.
Most recommended antiretroviral treatment regimens include either 3TC or tenofovir, drugs which are also active against HBV.
Investigators in Tokyo therefore wished to see if the inclusion of either of these drugs in HIV treatment combinations reduced the incidence of HBV infections among gay men who had not been vaccinated against HBV.
They therefore examined stored serum samples obtained between 1997 and 2009.
A total of 354 non-vaccinated, HBV-uninfected gay men with HIV were identified and included in the study.
They were placed into three categories according to their use of antiretroviral therapy: therapy containing 3TC or tenofovir; other HIV treatment regimen; no therapy.
Incidence of HBV infection was compared between these three groups.
A total of 43 people (12%) were newly infected with HBV during follow-up. Most infections (30) involved people who were not taking any HIV therapy; six occurred in people taking other antiretroviral combinations; and there were seven infections among people treated with 3TC or tenofovir (all involved treatment with 3TC).
The incidence of HBV infection was 0.669 per 100 person years for people taking either 3TC or tenofovir, compared to an incidence of 6.726 per 100 person years among people not taking HIV therapy and a rate of 5.263 per 100 person years for people treated with other antiretroviral regimens.
“ART regimens with anti-HBV activity can reduce HBV incident infections by 90%,” comment the investigators.
Five of the HBV infections in people taking 3TC-based therapy were transient. However, the other two infections became chronic, and both cases involved exposure to 3TC-resistant strains of HBV.
“LAM seems to prevent acquisition of HBV infection, progression to symptomatic hepatitis, and development of chronic infection even after the development of infection,” write the authors. “These effects may be less pronounced in patients with LAM-resistant strains.”
The results could have implications for patient care, and the investigators believe they further support arguments for the initiation of early antiretroviral therapy.
Gatanaga H et al. Prophylactic effect of antiretroviral therapy on hepatitis B virus infection. Clin Infect Dis, online edition, 2013.