An open-label study of tenofovir in HIV-1 and Hepatitis B virus co-infected individualsNelson, M; Portsmouth, S; Stebbing, J; Atkins, M; Barr, A; Matthews, G; Pillay, Da; Fisher, Mb; Bower, M; Gazzard, BAIDS: 3 January 2003 - Volume 17 - Issue 1 - pp F7-F10 Fast Track Abstract Author Information Background: Tenofovir is a novel nucleotide analogue recommended for use in HIV-1 infected treatment-experienced patients. Recent data suggest an effect on Hepatitis B virus (HBV) replication. We therefore investigated the use of tenofovir in HIV-1 and HBV co-infected individuals. Methods: Twenty HIV-1/HBV co-infected patients with a median of 108 weeks lamivudine experience (range, 0–270 weeks) received tenofovir 245 mg daily in addition to or as part of their combination antiretroviral therapy. Their immunologic parameters and HIV-1 RNA and HBV DNA viral loads were followed over a period of 52 weeks. In addition, their HBV DNA polymerase was sequenced at baseline to measure the frequency of YMDD mutations that are associated with lamivudine resistance. Findings: A significant decrease in HBV DNA viral load (4 × log10) and alanine aminotransferase levels was observed. There were no significant overall differences between the lamivudine-experienced (n = 15) and -naive (n = 5) individuals and tenofovir was well tolerated. Five patients (25%) underwent HBe antigen seroconversion during the study period. Out of the 15 lamivudine-experienced individuals, 10 had YMDD mutations and one had YIDD mutations in HBV DNA. Interpretation: These results indicate that 52 weeks of tenofovir in addition to antiretroviral therapy is active against HBV, and it appears to overcome lamivudine resistance. From The Chelsea and Westminster Hospital, London, UK; aPHLS, Anti-Viral Susceptibility Unit, University of Birmingham and bRoyal Sussex County Hospital, Brighton, UK. Correspondence to M. Nelson, The Chelsea and Westminster Hospital, 369 Fulham Road, London, SW10 9NH, UK. Received: 29 October 2002; accepted: 30 October 2002. © 2003 Lippincott Williams & Wilkins, Inc.