Dolutegravir/Lamivudine Efficacy and Safety Outcomes in People With HIV-1 With or Without Historical Resistance Results at Screening: 48-Week Pooled Analysis.

Drug resistance testing aids in appropriate antiretroviral therapy selection to improve treatment success but may not be readily available. We evaluated the impact of switching to dolutegravir/lamivudine (DTG/3TC) using pooled data from the TANGO and SALSA trials in adults who were virologically suppressed with or without historical resistance results at screening. Adults who were virologically suppressed (HIV-1 RNA <50 copies/mL for >6 months) with no prior virologic failure were randomized to switch to DTG/3TC (TANGO, n = 369; SALSA, n = 246) or continue their current antiretroviral regimen (CAR; TANGO, n = 372; SALSA, n = 247). Week 48 HIV-1 RNA ≥50 and <50 copies/mL (Snapshot algorithm, Food and Drug Administration; intention-to-treat exposed), CD4+ cell count, and safety were analyzed by availability of historical resistance results. Overall, 294 of 615 (48%) participants in the DTG/3TC group and 277 of 619 (45%) participants in the CAR group had no historical resistance results at screening. At week 48, proportions with Snapshot HIV-1 RNA ≥50 copies/mL were low (≤1.1%) and similar across treatment groups and by historical resistance results availability. High proportions (91%-95%) maintained virologic suppression through week 48, regardless of results availability. Across both subgroups of results availability, greater increases in CD4+ cell count from baseline to week 48 occurred with DTG/3TC vs CAR. No participants taking DTG/3TC had confirmed virologic withdrawal, regardless of historical resistance results availability. One participant undergoing CAR without historical resistance results had confirmed virologic withdrawal; no resistance was detected. Overall, DTG/3TC was well tolerated; few adverse events led to withdrawal. Findings support DTG/3TC as a robust switch option for adults who are virologically suppressed with HIV-1 and no prior virologic failure, regardless of historical resistance results availability. TANGO: NCT03446573, https://clinicaltrials.gov/study/NCT03446573. SALSA: NCT04021290, https://clinicaltrials.gov/study/NCT04021290.