To print: Select File and then Print from your browser's menu --------------------------------------------------------------------------------------- Title: DT-HIV: Low Rate of Resistance Mutations Related to Tenofovir DF in Treatment-Naïve HIV-Infected Patients URL: http://www.pslgroup.com/dg/22384A.htm Doctor's Guide November 20, 2002
By Jay Owens GLASGOW, SCOTLAND -- November 20, 2002 -- Resistance testing of blood samples from HIV-infected patients experiencing virologic failure while being treated with their first antiretroviral regimen containing tenofovir disoproxil fumarate (DF) showed a low incidence of K65R resistant mutation without any new patterns of resistance. The K65R mutation is known as the signature mutation of tenofovir DF, occurring in approximately 3 percent of treatment-experienced patients. Damian McColl, PhD, from Gilead Sciences, in Foster City, California, United States, presented the study results here November 18 during the Sixth International Congress on Drug Therapy in HIV Infection (DT-HIV) held here November 17-21. In an interim analysis of an ongoing phase III clinical trial of tenofovir DF as part of initial therapy, plasma samples from the 29 patients in the tenofovir DF/lamivudine/efavirenz treatment arm who experienced virologic failure during the first 48 weeks of the study were analyzed for genotype and phenotype. The researchers defined virologic failure as HIV RNA levels above 400 copies/mL or discontinuation of treatment for any reason by Week 48. Seven of the 29 patients had the K65R mutation, which is an incidence rate of 2.3 percent when including all 299 patients in the tenofovir DF-treatment arm of the clinical trial. Resistance mutations associated with efavirenz were the most common (4.3 percent), followed by wild-type (3.6 percent) or the M184V mutation, which is associated with lamivudine. Phenotypic analyses indicated that virus with the K65R mutation remained susceptible to zidovudine, stavudine, and abacavir. No new patterns of resistance were seen and none of the patients had developed thymidine-analog mutations All seven patients had regimen changes following virologic failure, and median follow-up at 50 weeks showed that five had achieved an undetectable viral load (<50 HIV RNA copies/mL). Of the remaining two patients, one was lost to follow-up and the other had a viral load rebound due to nonadherence. Two of the five successfully re-treated patients had maintained tenofovir DF in their regimen. --------------------------------------------------------------------------------------------- Copyright © 1999 P\S\L Consulting Group Inc. All rights reserved. Republication or redistribution of P\S\L content is expressly prohibited without the prior written consent of P\S\L. P\S\L shall not be liable for any errors, omissions or delays in this content or any other content on its sites, newsletters or other publications, nor for any decisions or actions taken in reliance on such content. --------------------------------------------------------------------------------------------- This news story was printed from *Doctor's Guide to the Internet* located at http://www.docguide.com --------------------------------------------------------------------------------------- Return to News Story Page This site is maintained by webmaster@pslgroup.com Please contact us with any comments, problems or bugs. All contents Copyright (c) 1998 P\S\L Consulting Group Inc. All rights reserved.