Unboosted atazanavir as maintenance treatment in naïve patients

HIV Treat Bull - 2009 Jan-Feb;10(1/2): 03

Simon Collins, HIV i-Base

JF Delfraissy presented results from a 48-week study that randomised 252 treatment-naïve patients after a 26-30 week induction phase of boosted atazanaivr/r 300/100mg plus 2 RTIs, to either continue or switch to once-daily unboosted atazanavir (400mg) plus continued RTIs. Only patients suppressed to <50 copies/mL were randomised to switch. Tenofovir was not allowed as an RTI because of the negative drug interaction with atazanavir.

Of 252 patients at baseline (median CD4 245 cells/mm³; median HIV-RNA 4.95 logs), 30 discontinued (nine for side effects) and 50 failed to reach undetectable viral load and continued on boosted ATV/r. This left 172 patients who were randomised 1:1 to either ATV or ATV/r.

At week 48, the ATV arm demonstrated similar (non-inferior, margin 15%) efficacy with 78% and 86% of patients suppressed to < 50 and <400 copies/mL respectively, compared to 75% and 81% of patients who remained on boosted ATV.

CD4 responses were similar. Although there were more discontinuations prior to week 48 with boosted atazanavir (14% vs 8%), fewer patients on ATV/r experienced virological rebound (7 vs 11). None had emergence of PI resistance.

As expected, side effects favoured unboosted ATV: grade 3–4 total bilirubin in 47% vs 14% and mean percent triglyceride change from the switch to week 48 was +9.8 vs. -27.0, both for ATV/r & ATV, respectively.

Comment

The balance between maintaining suppression and improved tolerability may make maintenance treatment without ritonavir an option for some naîve patients who have tolerability difficulties, but this will also reduce the safety buffer zone for adherence times.

Confirming individual drug levels using therapeutic drug monitoring (TDM) would be a safer approach.

Reference

Delfraissy JF et al. Efficacy and safety of 48-week maintenance with QD ATV vs ATV/r (both + 2NRTIs) in patients with VL <50 copies/mL after induction with ATV/r + 2NRTIs: study AI424136. J Int AIDS Soc 2008, 11(Suppl 1):O42 doi:10.1186/1758-2652-11-S1-O42.

2009-02-10
IB2009-01-03

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