For HIV-infected individuals starting antiretroviral therapy (ART), it has been unclear which of two commonly used drug combinations is safer and more effective: abacavir plus lamivudine or tenofovir plus emtricitabine.
Now, the first published results of a study known as A5202 indicate that the tenofovir + emtricitabine combination works better in a subgroup of treatment-naïve individuals. The AIDS Clinical Trials Group conducted this study with funding from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.
In the study, nearly 2,000 HIV-infected men and women starting ART were assigned at random to one of four daily regimens containing either abacavir + lamivudine or tenofovir + emtricitabine together with either efavirenz or ritonavir-boosted atazanavir. Neither the participants nor the study team knew who was taking which drug regimen.
Both abacavir + lamivudine and tenofovir + emtricitabine reduced the amount of HIV in most study participants. However, among individuals who had high viral loads (100,000 copies or more of HIV RNA per milliliter of blood) at entry into the study, the treatment regimens containing abacavir + lamivudine were significantly less effective at controlling HIV than the regimens containing tenofovir + emtricitabine. In addition, among participants with high initial viral loads, those who received abacavir + lamivudine experienced their first serious side effect sooner than those who received tenofovir + emtricitabine.
First announced in February 2008, these findings were taken into account in the formulation of the U.S. Department of Health and Human Services Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents. There, the tenofovir + emtricitabine combination (in addition to one or more other antiretroviral drugs) is listed as a preferred option for treating HIV-infected individuals who are starting antiretroviral therapy.
PE Sax et al. Abacavir-lamivudine versus tenofovir-emtricitabine for initial HIV-1 therapy. New England Journal of Medicine. DOI 10.1056/NEJMoa0906768 (2009).
Catherine Godfrey, M.D., the NIAID medical officer who oversaw this study, is available for interviews.
To schedule interviews, please contact Laura Sivitz, 301-402-1663, firstname.lastname@example.org.