HIV-1 genotype and phenotype correlate with virological response to abacavir, amprenavir and efavirenz in treatment-experienced patients

Judith Falloon*, Mounir Ait-Khaled, Deborah A. Thomas, Carol L. Brosgart, Joseph J. Eron, Judith Feinberg, Timothy P. Flanigan, Scott M. Hammer, Peter W. Kraus, Robert Murphy, Ramon Torres, Henry Masur, D. J. Manion, M. Rogers, J. Wolfram, G. E. Amphlett, A. Rakik, M. Tisdale

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Objective: To assess the safety and efficacy of three new drugs in patients with antiretroviral failure and to correlate retrospectively baseline factors with virological response. Design and setting: Open-label, 48-week, single-arm, multi-center phase II trial conducted at nine US university or government clinics and private practices. Patients and interventions: Patients with HIV-1 RNA ≥ 500 copies/ml despite ≥ 20 weeks of treatment with at least one protease inhibitor received abacavir 300 mg twice a day, amprenavir 1200 mg twice a day and efavirenz 600 mg once a day. Other antiretrovirals were prohibited until week 16 except for substitutions for possible abacavir hypersensitivity. Main outcome measures: HIV RNA at weeks 16 and 48. Results: A total of 101 highly treatment-experienced patients enrolled; 60 were naive to non-nucleoside analog reverse transcriptase inhibitors (NNRTI). HIV RNA < 400 copies/ml was attained in 25 out of 101 (25%) patients at 16 weeks (35% of NNRTI-naive and 10% of -experienced patients) and 23 (23%) patients at 48 weeks (33% of naive and 7% of experienced patients). CD4 cells increased by a median of 15 × 106 and 43 × 106 cells/I at weeks 16 and 48, respectively. Drug-related rash occurred in 50 out of 99 (51%) of patients, and 17 out of 99 (17%) permanently discontinued one or more drugs as a result. Lower baseline viral load, fewer NNRTI-related mutations, absence of decreased abacavir (≥ 4-fold) and efavirenz (≥ 10-fold) susceptibility, and greater number of drugs to which virus was susceptible were associated with virological response at week 16. Conclusions: Abacavir, amprenavir and efavirenz durably reduced HIV RNA and increased CD4 cell counts in a subset of treatment-experienced adults. Baseline viral load and some genotypic and phenotypic markers of resistance correlated with HIV RNA response.

Original languageEnglish (US)
Pages (from-to)387-396
Number of pages10
Issue number3
StatePublished - Feb 15 2002


  • Antiretroviral therapy
  • Predictors
  • Rescue regimen
  • Resistance

ASJC Scopus subject areas

  • Infectious Diseases
  • Immunology and Allergy
  • Immunology


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