HIV Coinfection Has Little Effect on Response to Chronic Hepatitis B Treatment

By Liz Highleyman

Hepatitis B Virus

HIV Virus

Antiviral therapy for chronic hepatitis B virus (HBV) infection is similarly effective in HIV negative and HIV positive patients, according to a study published in the April 2009 issue of Hepatology.

Studies have consistently shown that HIV-HCV coinfected patients do not respond as well to interferon-based therapy as those with HCV monoinfection. While interferon stimulates the natural immune response, and therefore its effectiveness may be impaired by HIV-related immune deficiency, antiviral therapy for HBV directly targets the virus. Furthermore, some nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) -- including lamivudine (3TC, Epivir), emtricitabine (Emtriva), and tenofovir (Viread, also in the Truvada and Atripla combination pills) -- have dual activity against both HBV and HIV.

After starting antiviral treatment for hepatitis B, there is a biphasic clearance of HBV, similar to that seen with HIV and HCV therapy, Sharon Lewin from Alfred Hospital in Melbourne, Australia, and colleagues noted as background. However, little is known about the effect of combination NRTIs and the influence of HIV coinfection on HBV viral kinetics following the initiation of dually active HAART.

In the current study, 21 treatment-naive HIV-HBV coinfected patients in Thailand were enrolled in a viral kinetics sub-study of the TICO (Tenofovir in HIV-1-HBV Coinfection) study, a randomized trial comparing 300 mg tenofovir versus 300 mg lamivudine versus tenofovir plus lamivudine, as part of an efavirenz (Sustiva)-based HAART regimen.
The researchers measured HBV DNA frequently over the first 56 days of treatment. To fit the viral load data, they used a model of HBV kinetics that allows for the estimation of treatment effectiveness, viral clearance, and infected cell loss.

Results

	A biphasic decline in HBV DNA was observed in almost all patients.
	There were no significant differences in HBV viral dynamic parameters between the 3 treatments groups.
	Overall HBV treatment effectiveness was 98%.
	The median HBV virion (single virus particle) half-life was 1.2 days.
	The median half-life of an HBV-infected cell was 7.9 days.
	Hepatitis B "e" antigen (HBeAg) positive individuals had a significantly longer infected-cell half-life than HBeAg negative patients (9.0 vs 6.2 days; P = 0.02).

"HBV viral dynamic parameters are similar following anti-HBV NRTI monotherapy and dual combination therapy in the setting of HIV-1-HBV coinfection," the study authors concluded. "HIV-1 coinfection has minimal effect on HBV viral dynamics, even in the setting of advanced HIV-1-related immunosuppression."

Infectious Diseases Unit, Alfred Hospital, Melbourne, Australia; Monash University, Melbourne, Australia; Los Alamos National Laboratory, Los Alamos, NM; HIV Netherlands Australia Thailand Research Collaboration, Thai Red Cross Bangkok, Thailand; Victorian Infectious Diseases Reference Laboratory, Melbourne, Australia; National Centre in HIV Epidemiology and Clinical Research, University of New South Wales, Sydney, Australia; Chulalongkorn University, Bangkok, Thailand.

6/16/09

Reference
SR Lewin, RM Ribeiro, A Avihingsanon, and others. Viral dynamics of hepatitis B virus DNA in human immunodeficiency virus-1-hepatitis B virus coinfected individuals: Similar effectiveness of lamivudine, tenofovir, or combination therapy. Hepatology 49(4): 1113-1121. April 2009.