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Efficacy and safety by baseline HIV-RNA and CD4 count in treatment-naive patients treated With atazanavir/r and lopinavir/r in the CASTLE study

Purpose of the study

In the CASTLE study, lower response rates were observed in patients with baseline HIV-RNA ≥100,000 copies/mL in both arms and were associated with lower baseline CD4 cell count for LPV/r but not ATV/r.

Methods

Randomized, open-label, prospective study comparing once-daily ATV/r with twice-daily LPV/r, both with fixed-dose TDF/FTC in 883 treatment-naive patients. Treatment outcomes of HIV-RNA <50 c/mL at week 48 using confirmed virologic response (CVR) and grade 2–4 treatment-related AEs through week 48 are presented by pre-specified baseline HIV-RNA and CD4 cell count strata.

Summary of results

The proportion of responders (CVR HIV-RNA <50 c/mL, ITT) at week 48 by baseline HIV RNA strata (<100,000, 100,000–<500,000, and ≥500,000) were 83%, 76%, and 64% for ATV/r and 80%, 74%, and 61% for LPV/r (Table 1).

Table 1 CVR Treatment Outcomes of HIV RNA <50 c/mL at Week 48 by Baseline CD4 Cell Count, n (%).

In patients with both baseline CD4 <100 and HIV-RNA ≥100,000, 60/83 (72%) on ATV/r and 40/64 (63%) on LPV/r achieved HIV RNA <50 c/mL (CVR, ITT). Incidence of grades 2–4 treatment-related AEs through week 48 by baseline HIV-RNA strata (<100,000, 100,000–<500,000, and ≥500,000) were 29%, 26%, and 15% for ATV/r; and 31%, 27%, and 30% for LPV/r. (Table 2.)

Table 2 Grade 2–4 Treatment-Related AEs through Week 48 by Baseline CD4 Cell Count (cells/mm3), n (%).

Conclusion

Lower response rates at higher baseline HIV-RNA were seen for both ATV/r and LPV/r. The trend for lower response rates at lower baseline CD4 cell counts for LPV/r observed in the ITT analysis did not appear to be present in the on-treatment analysis. ATV/r and LPV/r had consistent adverse event (AE) profiles within each arm by baseline HIV-RNA. More AEs, most commonly diarrhea and nausea, were observed with LPV/r at low baseline CD4 cell counts.

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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Uy, J., Yang, R., Thiry, A. et al. Efficacy and safety by baseline HIV-RNA and CD4 count in treatment-naive patients treated With atazanavir/r and lopinavir/r in the CASTLE study. JIAS 11, P8 (2008). https://doi.org/10.1186/1758-2652-11-S1-P8

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  • DOI: https://doi.org/10.1186/1758-2652-11-S1-P8

Keywords

  • Virologic Response
  • Lower Response Rate
  • Count Stratum
  • Castle Study