NIH Halts Trizivir-Only Arm of HIV Treatment Study; Combination Drug Alone Inferior To Two Other Regimens Containing Sustiva
When taken alone, Trizivir, a three-drug combination pill manufactured by GlaxoSmithKline, is inferior to similar drug regimens that contain Bristol Myers-Squibb's Sustiva in treating HIV-positive patients who have never taken antiretroviral drugs, researchers from the Division of AIDS at NIH's National Institute of Allergy and Infectious Diseases wrote in a letter sent on Monday to HIV/AIDS health care providers. Trizivir contains the antiretroviral drugs abacavir, lamivudine and zidovudine. Based on interim data from a double-blind, placebo-matched clinical trial, researchers stopped one arm of the study because patients taking Trizivir experienced virologic failure -- defined as having a viral load level above 200 copies/ml at least four months after beginning the treatment -- sooner and more often than patients in the other two arms of the study. The other two treatment regimens being evaluated include a combination of lamivudine and zidovudine -- Glaxo's Combivir -- plus Sustiva, or a combination of Trizivir and Sustiva. After an average of 32 weeks in the study, 167 of the 1,147 study participants experienced virologic failure; 21% of the patients in the Trizivir-only group experienced failure, compared with 10% in the other two groups. These data met pre-determined criteria for stopping the one arm of the study. The researchers noted in the letter that there were no concerns regarding the drug's toxicity. Study participants who were taking Trizivir were told what they were taking and were offered "several alternatives" to Trizivir alone. However, they have been asked to continue to participate in the study. Volunteers in the other two groups were told that they are taking a combination that contains Sustiva, but they do not know the other drugs in their combination. The trial will continue through approximately September 2004 and will compare the remaining two drug combinations (Letter text, 3/10). According to Reuters, Glaxo's 2002 sales of Trizivir totaled $473 million (Reuters, 3/11).This is part of the KHN Morning Briefing, a summary of health policy coverage from major news organizations. Sign up for an email subscription.