Early virologic response to abacavir/lamivudine and tenofovir/emtricitabine during ACTG A5202

Philip Grant, Camlin Tierney, Chakra Budhathoki, Eric Daar, Paul Sax, Ann Collier, Margaret Fischl, Andrew Zolopa, Maya Balamane, David Katzenstein

Research output: Contribution to journalArticlepeer-review


Background: ACTG A5202 randomized treatment-naïve individuals to tenofovir-emtricitabine (TDF/FTC) or abacavir-lamivudine (ABC/3TC) combined with efavirenz (EFV) or atazanavir/ritonavir (ATV/r). Individuals in the high screening viral load (VL) stratum (≥100,000 copies/mL) had increased rates of virologic failure with ABC/3TC. Objective: To compare regimen-specific early virologic response. Methods: Using Wilcoxon rank-sum tests, we compared regimen-specific VL changes from entry to week 4 in A5202 subjects (N = 1,813) and from entry to week 1, 2, and 4 in substudy subjects (n = 179). We evaluated associations between week 4 VL change and time to virologic failure with Cox proportional hazards models. Results: TDF/FTC and ABC/3TC produced similar week 4 VL declines in the entire study population and in the high VL stratum. EFV produced greater VL declines from baseline at week 4 than ATV/r (median -2.1 vs -1.9 log10 copies/mL; P < .001). In the substudy of subjects with week 1, 2, and 4 VL data, there was no difference in VL decline in individuals randomized to TDF/FTC versus ABC/3TC, but EFV resulted in greater VL decline from entry at each of these timepoints than ATV/r. Smaller week 4 VL decline was associated with increased risk of virologic failure. Conclusions: Within all treatment arms, a less robust week 4 virologic response was associated with higher risk for subsequent virologic failure. However, between-regimen differences in week 4 VL declines did not parallel the previously reported differences in longer term virologic efficacy in A5202, suggesting that between-regimen differences in responses were not due to intrinsic differences in antiviral activity.

Original languageEnglish (US)
Pages (from-to)284-291
Number of pages8
JournalHIV Clinical Trials
Issue number6
StatePublished - Jan 1 2013
Externally publishedYes


  • HIV infections
  • anti-HIV agents
  • drug therapy
  • treatment outcome
  • virology

ASJC Scopus subject areas

  • Infectious Diseases
  • Pharmacology (medical)


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