Abacavir-lamivudine versus tenofovir-emtricitabine for initial HIV-1 therapy

N Engl J Med. 2009 Dec 3;361(23):2230-40. doi: 10.1056/NEJMoa0906768. Epub 2009 Dec 1.


Background: The use of fixed-dose combination nucleoside reverse-transcriptase inhibitors (NRTIs) with a nonnucleoside reverse-transcriptase inhibitor or a ritonavir-boosted protease inhibitor is recommended as initial therapy in patients with human immunodeficiency virus type 1 (HIV-1) infection, but which NRTI combination has greater efficacy and safety is not known.

Methods: In a randomized, blinded equivalence study involving 1858 eligible patients, we compared four once-daily antiretroviral regimens as initial therapy for HIV-1 infection: abacavir-lamivudine or tenofovir disoproxil fumarate (DF)-emtricitabine plus efavirenz or ritonavir-boosted atazanavir. The primary efficacy end point was the time from randomization to virologic failure (defined as a confirmed HIV-1 RNA level > or = 1000 copies per milliliter at or after 16 weeks and before 24 weeks, or > or = 200 copies per milliliter at or after 24 weeks).

Results: A scheduled interim review by an independent data and safety monitoring board showed significant differences in virologic efficacy, according to the NRTI combination, among patients with screening HIV-1 RNA levels of 100,000 copies per milliliter or more. At a median follow-up of 60 weeks, among the 797 patients with screening HIV-1 RNA levels of 100,000 copies per milliliter or more, the time to virologic failure was significantly shorter in the abacavir-lamivudine group than in the tenofovir DF-emtricitabine group (hazard ratio, 2.33; 95% confidence interval, 1.46 to 3.72; P<0.001), with 57 virologic failures (14%) in the abacavir-lamivudine group versus 26 (7%) in the tenofovir DF-emtricitabine group. The time to the first adverse event was also shorter in the abacavir-lamivudine group (P<0.001). There was no significant difference between the study groups in the change from the baseline CD4 cell count at week 48.

Conclusions: In patients with screening HIV-1 RNA levels of 100,000 copies per milliliter or more, the times to virologic failure and the first adverse event were both significantly shorter in patients randomly assigned to abacavir-lamivudine than in those assigned to tenofovir DF-emtricitabine. (ClinicalTrials.gov number, NCT00118898.)

Publication types

  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenine / adverse effects
  • Adenine / analogs & derivatives*
  • Adenine / therapeutic use
  • Adolescent
  • Adult
  • Analysis of Variance
  • Anti-HIV Agents / adverse effects
  • Anti-HIV Agents / therapeutic use*
  • CD4 Lymphocyte Count
  • Deoxycytidine / adverse effects
  • Deoxycytidine / analogs & derivatives*
  • Deoxycytidine / therapeutic use
  • Dideoxynucleosides
  • Double-Blind Method
  • Drug Combinations
  • Drug Resistance, Viral
  • Emtricitabine
  • Female
  • Fractures, Bone / chemically induced
  • HIV Infections / drug therapy*
  • HIV Infections / immunology
  • HIV-1* / genetics
  • HIV-1* / isolation & purification
  • Humans
  • Lamivudine / adverse effects
  • Lamivudine / therapeutic use*
  • Male
  • Middle Aged
  • Organophosphonates / adverse effects
  • Organophosphonates / therapeutic use*
  • RNA, Viral / blood
  • Tenofovir
  • Therapeutic Equivalency
  • Time Factors
  • Treatment Failure
  • Viral Load
  • Young Adult


  • Anti-HIV Agents
  • Dideoxynucleosides
  • Drug Combinations
  • Organophosphonates
  • RNA, Viral
  • abacavir, lamivudine drug combination
  • Deoxycytidine
  • Lamivudine
  • Tenofovir
  • Emtricitabine
  • Adenine

Associated data

  • ClinicalTrials.gov/NCT00118898

Grant support