ViiV Healthcare and Shionogi announced that initial results have been received from the SPRING-2 (ING113086) Phase 3 study of the investigational integrase inhibitor dolutegravir in treatment-naive adults with HIV-1.

SPRING-2 (ING113086) is an ongoing randomized, double-blind, multicenter, parallel group, non-inferiority study designed to compare the efficacy and safety of dolutegravir 50mg administered once-daily versus raltegravir 400mg (Isentress; Merck) administered twice daily over 48-weeks, both with two nucleoside reverse transcriptase inhibitors (NRTIs); 411 treatment-naive study participants were randomized in each arm. Both treatment arms are administered with investigator-selected dual nucleoside reverse transcriptase inhibitor therapy (either abacavir + lamivudine [Epzicom; GlaxoSmithKline Pharmaceuticals] or tenofovir + emtricitabine [Truvada; Gilead Sciences, Inc.]). The primary endpoint of the study was the proportion of study participants with undetectable HIV-1 RNA (<50c/mL) through 48 weeks.  Secondary objectives include the assessment of antiviral activity of dolutegravir compared to raltegravir at 96-weeks, to compare the tolerability, long-term safety and antiviral and immunologic activity of dolutegravir to raltegravir and to evaluate viral resistance in study participants experiencing virological failure.

The study met its primary objective, demonstrating non-inferiority of dolutegravir to raltegravir. Through 48 weeks, 88% of study participants on dolutegravir were virologically suppressed (<50 copies/mL) vs. 85% of participants on raltegravir [with a 95% confidence interval (CI) for the difference, -2.2% to + 7.1%; the lower end of the CI (-2.2%) was above the prespecified -10% non-inferiority limit].

Dolutegravir (S/GSK1349572) is an investigational once-daily, unboosted integrase inhibitor. Integrase inhibitors block HIV replication by preventing the viral DNA from integrating into the genetic material of human immune cells (T-cells). This step is essential in the HIV replication cycle and is also responsible for establishing chronic infection.

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