title: Early virologic response to abacavir/lamivudine and tenofovir/emtricitabine during ACTG A5202.
abstract: 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.
authors: Division of Infectious Diseases, Stanford University, Palo Alto, California.
authors: Philip M
authors: PM
authors: Grant
authors: Center for Biostatistics in AIDS Research, Harvard School of Public Health, Boston, Massachusetts.
authors: Camlin
authors: C
authors: Tierney
authors: Center for Biostatistics in AIDS Research, Harvard School of Public Health, Boston, Massachusetts.
authors: Chakra
authors: C
authors: Budhathoki
authors: Division of HIV Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California.
authors: Eric S
authors: ES
authors: Daar
authors: Division of Infectious Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts.
authors: Paul E
authors: PE
authors: Sax
authors: Division of Infectious Diseases, University of Washington, Seattle, Washington.
authors: Ann C
authors: AC
authors: Collier
authors: Division of Infectious Diseases, University of Miami, Miami, Florida.
authors: Margaret A
authors: MA
authors: Fischl
authors: Division of Infectious Diseases, Stanford University, Palo Alto, California.
authors: Andrew R
authors: AR
authors: Zolopa
authors: Division of Infectious Diseases, Stanford University, Palo Alto, California.
authors: Maya
authors: M
authors: Balamane
authors: Division of Infectious Diseases, Stanford University, Palo Alto, California.
authors: David
authors: D
authors: Katzenstein
mesh_terms: D000225:Adenine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000328:Adult; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D018791:CD4 Lymphocyte Count; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D015224:Dideoxynucleosides / Q000627:therapeutic use*; D004338:Drug Combinations; D004359:Drug Therapy, Combination; D000068679:Emtricitabine; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D019259:Lamivudine / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D063065:Organophosphonates / Q000008:administration & dosage / Q000627:therapeutic use*; D000068698:Tenofovir; D019562:Viral Load; D000099227:Abacavir
chemical_list: D000225:Adenine; D019380:Anti-HIV Agents; D003841:Deoxycytidine; D015224:Dideoxynucleosides; D004338:Drug Combinations; D000068679:Emtricitabine; D019259:Lamivudine; D063065:Organophosphonates; D000068698:Tenofovir; C492871:abacavir, lamivudine drug combination; D000099227:Abacavir
keywords: HIV infections; anti-HIV agents; drug therapy; treatment outcome; virology