• Anti-HBV Activity of Emtricitabine (FTC) in Patients Co-Infected With HIV and Hepatitis B Virus (Forum 215)
  Authored by F. Raffi, A. Snow, K. Borroto-Esoda, A. Shaw, J. Anderson, J. Sorbel, J. Quinn, E. Mondou, F. Rousseau
  

FTC (emtricitabine, Emtriva) was recently approved by the FDA for the treatment of HIV infection. This agent is a nucleoside reverse transcriptase inhibitor (NRTI) similar to 3TC (lamivudine, Epivir), but with a longer half life. Sharing another similarity with 3TC, FTC also has potent activity against the hepatitis B virus (HBV).

Previous studies of FTC have shown in vitro activity against HBV with IC50 in the 0.01 micromolar range. These IC50 levels are comparable to those found with 3TC. In this study, the virologic response of patients co-infected with HBV and HIV and given FTC was presented. Two prior controlled trials with different dose ranges of FTC were presented (FTCB-101 and FTCB-102). These studies looked at FTC in doses of 25-300 mg daily in a total of 147 patients in total and showed a 3.4 log reduction of HBV viral load.

The anti-HBV activity of FTC was evaluated from data obtained in the phase III, randomized, controlled studies done for the treatment of HIV. In these studies there was a 3.12 reduction in HBV viral load in patients taking 100 mg of FTC and 2.92 log reduction with the 200-mg dose.

A total of 52 patients were in these phase III trials. With 48-week data available, more than 50 percent of the patients in the study had undetectable HBV viral loads. Regarding the tempo of virologic response, 36 percent were undetectable for HBV at week 12, 45 percent at week 24 and 59 percent at week 48. These results were comparable to data from previous studies in HIV-negative patients.

These data were obtained from studies done on HIV/HBV treatment-naive patients. FTC does not have activity against HBV that is resistant to 3TC.

This study was presented by researchers from the CHU de Nantes center in Nantes, France, and was funded by Gilead Sciences, the maker of FTC. It is an important addition to the literature on the treatment of HIV/HBV co-infected patients -- which occurs in about 5-8 percent of patients with HIV; HBV-related liver cirrhosis and hepatocellular carcinoma are now major concerns in co-infected patients and significantly contribute to morbidity and mortality.

Although not approved for the treatment of HBV, tenofovir (TDF, Viread) has excellent activity against HBV and many co-infected patients have been treated with tenofovir plus 3TC for the management of both HIV and HBV infections. With the recent approval of FTC, it is likely that we will soon see studies looking at the combination of FTC and tenofovir for the management of these patients as well.