FTC (emtricitabine, Emtriva) has potent anti-hepatitis B virus (HBV) and anti-HIV activity when included in the HAART regimens of individuals coinfected with HBV and HIV, according to a study presented as a poster to the Eleventh Conference on Retroviruses and Opportunistic Infections in San Francisco. Investigators (from the drug’s manufacturer, Gilead Sciences) also found that after a year of treatment with the antiviral, few patients developed HBV resistant to the drug.
The investigators analysed data from three 48-week studies designed to evaluate the safety and efficacy of FTC as part of HAART in treatment-naïve individuals. They extracted data for individuals coinfected with HIV and HBV at baseline and looked at the anti-HIV and anti-HBV effects of FTC in these individuals. Genotypic assays were performed on HBV plasma samples that at week 48 showed detectable HBV (above 4700 copies/ml), to assess the prevalence of FTC-resistant HBV.
A total of 39 patients from the three studies met the investigators' criteria. At baseline their median HBV viral load was over 500,000 copies/ml, and 24 patients (62%) had a detectable HBV viral load.
By week 24, 45% of these patients experienced a fall in their HBV load to below the limit of detection (4,700 copies/mL). By week 48, 59% had an undetectable HBV load. The anti-HIV potency of FTC was indicated by data showing that 97% of individuals had an HIV viral load below 400 copies/mL at week 24, and 94% at week 48.
The investigators compared the results of the three studies looking at the anti-HBV efficacy of FTC in HIV/HBV coinfected patients with a study looking at the effectiveness of FTC in patients infected only with HBV. They established that at week 48, FTC was as effective against HBV in individuals coinfected with HBV and HIV as it was in patients just infected with HBV, with 55% of coinfected patients achieving an undetectable HBV viral load compared to 59% of monoinfected individuals.
Finally, the investigators looked at the 48 week incidence of drug resistant HBV in coinfected individuals who had detectable HBV viral load at baseline. By week 48 two of these individuals (12%) had developed resistance mutations.
The Gilead investigators conclude that FTC has potent anti-HBV and anti-HIV effects in treatment-naïve individuals coinfected with the two viruses, and that the drug has similar efficacy in coinfected patients as it does in monoinfected individuals. In addition, they conclude that a low incidence of HBV resistance was observed.
Further information on this website
FTC – overview
Hepatitis B - overview
Hepatitis B - factsheet
HIV and hepatitis 2003 edition of the booklet in the information for HIV-positive people edition (2004 version available by e-mailing email@example.com).
Harris J et al. Emtricitabine therapy for hepatitis infection in HIV-1 patients co-infected with hepatitis B: antiviral response and genotypic findings in antiretroviral treatment naïve patients. Eleventh Conference on Retroviruses and Opportunistic Infections, poster 836, 2004.