Gilead Sciences announced 24-week data from a Phase 3 clinical trial, SPIRIT (Switching boosted PI to Rilpivirine In Combination with Truvada as a Single Tablet Regimen), which evaluated virologically suppressed treatment-experienced HIV patients switching from a multi-pill regimen containing a ritonavir (Norvir; Abbott Laboratories)-boosted protease inhibitor to the once-daily single tablet regimen Complera (emtricitabine/rilpivirine/tenofovir disoproxil fumarate). The study met its 24-week primary endpoint, which found that switching to Complera was non-inferior to remaining on a ritonavir-boosted protease inhibitor regimen.
SPIRIT (Study 106) was a randomized (2:1), open-label Phase 3 study of switching virologically suppressed HIV patients from a regimen consisting of a ritonavir-boosted protease inhibitor and two nucleoside reverse transcriptase inhibitors (n=159) to Complera (n=317). The primary objective of the study was to evaluate the non-inferiority, at a 12% margin, of Complera compared to a protease-based regimen in maintaining HIV RNA levels <50 copies/mL through 24 weeks of therapy, based on the FDA snapshot algorithm. Secondary endpoints include changes in serum lipid levels, change in CD4 cell count, and safety and tolerability through 48 weeks of therapy. Patients randomized to the protease-based regimens rolled over to Complera after week 24.
At 24 weeks of treatment, 94% of patients (n=297/317) who switched to Complera maintained HIV RNA (viral load) levels <50 copies/mL compared to 90% of patients (n=143/159) who remained on a regimen containing a ritonavir-boosted protease inhibitor-based regimen (FDA snapshot algorithm; 95% CI for the difference: -1.6% to +9.1%; predefined criterion for non-inferiority was the lower bound of a two sided 95% CI of -12%). Fewer patients taking Complera experienced virologic failure compared to those taking a protease-based regimen (0.9% vs. 5%, respectively).
At baseline, patients in the Complera switch arm had mean CD4 cell counts of 576 cells/mm3 compared to 600 cells/mm3 in the protease arm. Changes in CD4 cell counts at 24 weeks of therapy were +20 cells/mm3 for the Complera arm and +32 cells/mm3 for the protease-based regimen (P=0.28).
Complera is a once-daily single tablet approved for treatment-naïve HIV patients. The product combines Gilead’s Truvada (emtricitabine and tenofovir disoproxil fumarate), which itself is a fixed-dose combination of two HIV medicines, with rilpivirine (Edurant; Janssen Therapeutics).
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