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Conference
"Emerging Data from Switch Studies" Dr. Daniel Podzamczer (biography) English - 2002-04-20 - 18 minutes
(35 slides)
Summary : Due to the important limitations of current protease inhibitors (PI)-containing regimens, the strategy of " simplification " therapy i.e. switching from a PI-based regimen to one containing a non-nucleoside reserve transcriptase inhibitor (NNRTI) (nevirapine or efavirenz) or abacavir is being widely used, particularly in Europe. The theoretical advantages of this strategy include: to offer a more comfortable and simpler regimen, without food restrictions, to avoid metabolic complications and possibly lipodystrophy, and to improve adherence and quality of life. It is not easy to evaluate data emerging from current studies because many of them are not randomized; have relatively small sample sizes; and/or a short follow-up.
Abacavir has been shown to maintain virological suppression in most cases, with an improvement in some metabolic parameters (reduction in cholesterol and triglyceride plasma levels). However, the failure rate increases in patients who were previously treated with sub-optimal nucleoside analogue regimens. By contrast, nevirapine and efavirenz seem to maintain virological control even in these patients. While metabolic improvements have been clearly demonstrated in patients who have switched to nevirapine (reduction in total cholesterol and triglyceride plasma levels and elevation of HLD cholesterol plasma levels). The metabolic results have been more variable in efavirenz-treated patients.
The NEFA trial is the first study to compare the three PI-sparing options in patients with undetectable plasma viral loads while taking PI-containing regimens. This Spanish multicenter, randomized, open trial studied 460 patients. No differences in the overall efficacy rates were found between the treatment arms in the intent-to-treat (ITT) analysis performed at 12 months. Although there was a higher virological failure rate in the abacavir arm (10.7% vs. 5.1% (NVP) vs. 3.2% (EFV), p=0.019), better tolerance of abacavir led to a lower proportion of patients discontinuing therapy due to adverse effects in this arm, compared to nevirapine- or efavirenz- treated patients (6.0% vs. 16.7% and 16.6%, respectively, p=0.006). Of note, approximately 50% of this cohort had previously received mono/dual nucleoside analogue therapy: 20.2% of these patients failed in the abacavir arm vs. 6.4% (nevirapine arm) and 4.4% (efavirenz arm).
Preliminary six-month data from a metabolic substudy showed metabolic improvements in the overall cohort, especially in patients without lipodystrophy. Nevirapine use was associated with a better performance in terms of the proportion of patients with changes in HDL cholesterol and triglyceride plasma levels, as well as in the proportion of patients wih changes in HDL cholesterol and triglyceride plasma levels, as well as in the proportion of patients with any improvements in lipid alterations.
In summary, reported data from PI switch studies suggest that, while virological suppression may be maintained and metabolic alterations improved by the three PI-sparing regimens, there may be some differences between them, both in terms of efficacy as well as in metabolic benefits, Longer follow-up is needed to ascertain if these differences are maintained over time.
Learning objectives : To compare the virological response when switching from protease inhibitors (PI) to either nevirapine, efavirenz or abacavir in HIV-infected adults having suppressed viral load while on two NRTIs and at least one PI.
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