No Genotypic Resistance Detected In Clinical Trials Through 48 and 108 Weeks With Abbott Laboratories' Kaletra(TM) (Lopinavir/Ritonavir) in Patients Without Previous HIV Therapy
GLASGOW, Scotland, Oct. 24 /PRNewswire/ -- Data presented at the Fifth International Congress on Drug Therapy in HIV
Infection in Glasgow show that to date, patients new to HIV therapy have not developed genotypic resistance to Abbott
Laboratories' (NYSE: ABT - news) protease inhibitor (PI), Kaletra(TM) (lopinavir/ritonavir) (pronounced kuh-LEE-tra), even after 48 weeks of treatment in an ongoing Phase III clinical trial, and in an ongoing, smaller, dose-ranging study with no comparator group through two years. These analyses, conducted across studies using Kaletra as part of a first-line antiviral regimen, indicate that Kaletra has not been associated with the development of resistance in patients new to HIV therapy. Genotypic testing examines a viral sample for specific mutations, or changes, in the virus that are known to cause resistance to certain drugs.
Kaletra, formerly known as ABT-378/r, is indicated for the treatment of HIV infection in adults and children as young as six months in combination with other antiretroviral medications. Accelerated approval of Kaletra is based on the response of viral load (amount of virus in the blood) measurements and CD4 cell count, both surrogate markers, from a 24-week controlled Phase III clinical trial and additional smaller open-label studies of 72 weeks in duration. The 72-week studies were designed to evaluate different doses of Kaletra and had no comparator groups. At present, there are no results from controlled trials
evaluating the effect of Kaletra on the progression of HIV.
``Although Kaletra resistance may be observed with longer study, the lack of genotypic resistance detected to date with Kaletra in clinical trials in patients new to therapy is promising,'' said Eugene Sun, M.D., head of antiviral development, at Abbott Laboratories.
In an ongoing, international, multi-center, double-blind, randomized clinical trial of 653 patients new to HIV therapy, the Kaletra regimen was compared to a regimen containing Viracept® (nelfinavir), a widely-used protease inhibitor. In addition to the protease inhibitor, patients in each of the treatment groups also received two nucleoside reverse transcriptase inhibitors (3TC and d4T). In this study, 326 patients received the Kaletra regimen and 327 patients received the nelfinavir regimen.
Drug Resistance Analyses at 24 or 48 Weeks
Plasma viral isolates from all patients on treatment who had detectable HIV (>400 copies/mL) at either week 24 or 48 were
analyzed for evidence of genotypic resistance. Of those, genotypic analysis results were available for 31 Kaletra patients and 64 nelfinavir patients. Viral resistance is one of the causes of viral rebound and subsequent treatment failure for people with HIV.
Results from this analysis showed that none (0/31) of the patients on the Kaletra regimen and 31 percent (20/64) of patients on the nelfinavir regimen exhibited genotypic resistance.
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