Abstract
In the SAILING study, dolutegravir demonstrated superior virologic efficacy compared with raltegravir in treatment-experienced, integrase strand transfer inhibitor (INSTI)-naive patients with HIV-1 who harbored resistance to ≥2 antiretroviral drug classes. Significantly fewer dolutegravir-treated patients demonstrated virologic failure with treatment-emergent resistance than raltegravir-treated patients through 48 weeks. Investigator-selected background therapy (ISBT) included at least one fully active agent, selected on the basis of resistance analysis. Genotypic and phenotypic resistance testing were performed on baseline and time-of-failure samples from patients with protocol-defined virologic failure (PDVF). A post hoc analysis of SAILING (N = 715; 354 dolutegravir, 361 raltegravir) assessed efficacy in subpopulations defined by ISBT activity, resistance profiles, and treatment history. When ISBT contained only nucleoside reverse transcriptase inhibitors (NRTIs), PDVF occurred in 0% (0/32) of dolutegravir-treated patients and 21.9% (7/32) of raltegravir-treated patients (p = .005). In patients harboring M184 V whose ISBT contained lamivudine or emtricitabine plus a second NRTI, 0% (0/13) of dolutegravir- and 33.3% (4/12) of raltegravir-treated patients (p = .026) experienced PDVF. Among patients receiving protease inhibitor (PI)-containing ISBT, 6.0% (18/300) of dolutegravir-treated patients versus 11.8% (36/305) of raltegravir-treated patients (p = .012) experienced PDVF. Darunavir/ritonavir was part of ISBT in 130 dolutegravir-treated patients and 145 raltegravir-treated patients; 6 (4.6%) and 12 (8.3%), respectively, experienced PDVF (difference -3.7%; 95% confidence interval: -10.1% to 2.5%; p = .256). There was no or less virologic failure in treatment-experienced, INSTI-naive subjects receiving dolutegravir versus raltegravir, even when the ISBT was suboptimal or NRTI resistance was present at baseline. These findings are not explained by the use of PI/ritonavir-containing ISBT.