Substitution of raltegravir for ritonavir-boosted protease inhibitors in HIV-infected patients: The SPIRAL study

BACKGROUND: Switching to raltegravir in selected patients treated with ritonavir-boosted protease inhibitors may result in similar efficacy and lower plasma lipids. Methods: SPIRAL is a 48-week multicentre, open-label trial in which HIV-infected adults with less than 50 copies/ml of plasma HIV RNA for at least the previous 6 months on ritonavir-boosted protease inhibitor-based therapy were randomized (1: 1) to switch from the ritonavir-boosted protease inhibitor to raltegravir or to continue on ritonavir-boosted protease inhibitor-based therapy. Primary endpoint was the proportion of patients free of treatment failure (noncompleter = failure) at 48 weeks. SPIRAL study was powered to show noninferior efficacy of raltegravir-based therapy with a margin of-12.5%. Results: Two hundred and seventy-three patients assigned to switch to raltegravir (n = 139) or to continue ritonavir-boosted protease inhibitor (n = 134) were included in the efficacy analysis. At 48 weeks, 89.2% (raltegravir-based therapy) and 86.6% (ritonavir-boosted protease inhibitor-based therapy) of the patients remained free of treatment failure [difference 2.6%; 95% confidence interval (CI)-5.2 to 10.6]. A total of 96.9% (raltegravir-based therapy) and 95.1% (ritonavir-boosted protease inhibitor-based therapy) of the patients remained free of virological failure (difference 1.8%; 95% CI-3.5 to 7.5). Switching to raltegravir was associated with significant decreases in plasma lipids and total-to-HDL cholesterol ratio relative to continuing ritonavir-boosted protease inhibitor. Severe adverse events and study drug discontinuations due to any adverse event occurred in 4 and 2% of the patients in each group. Conclusion: In patients with sustained virological suppression on ritonavir-boosted protease inhibitor-based therapy, switching from ritonavir-boosted protease inhibitor to raltegravir demonstrated noninferior efficacy and resulted in a better lipid profile at 48 weeks than continuing ritonavir-boosted protease inhibitor.