Durable Efficacy of Switching From a 3- or 4-Drug Tenofovir Alafenamide–Based Regimen to the 2-Drug Regimen Dolutegravir/Lamivudine in the TANGO Study Through Week 196

Background: Switching to the 2-drug regimen dolutegravir (DTG)/lamivudine (3TC) demonstrated durable noninferior efficacy vs continuing 3- or 4-drug tenofovir alafenamide–based regimens for maintaining virologic suppression in people with HIV-1 through week 144 in TANGO. Setting: One hundred thirty-four centers, 10 countries. Methods: Adults with HIV-1 RNA <50 copies/mL for >6 months and no history of virologic failure were randomized to switch from stable tenofovir alafenamide–based regimens to DTG/3TC on day 1 [early-switch (ES) group] for 196 weeks. Those randomized to continue tenofovir alafenamide–based regimens on day 1 who maintained virologic suppression at week 144 switched to DTG/3TC at week 148 [late-switch (LS) group]. Efficacy, safety, and tolerability (including weight and biomarker changes) of DTG/3TC in ES and LS groups were assessed through week 196. Results: Overall, 369 participants switched to DTG/3TC on day 1 (ES) and 298 switched at week 148 (LS). In the ES group, 83% (306/369) maintained virologic suppression through year 4, and 3% (11/369) reported new adverse events between weeks 144 and 196. The LS group at week 196 and the ES group at week 48 had comparable proportions with virologic suppression (93% each) and similar safety profiles. No LS participants and 1 ES participant met confirmed virologic withdrawal criteria through week 196, with no resistance-associated mutations observed. Treatment continued to be well tolerated long term. Conclusions: Switching from tenofovir alafenamide–based regimens to DTG/3TC showed durable efficacy, high barrier to resistance, and good tolerability through 4 years. These results support DTG/3TC as a robust treatment for maintaining virologic suppression.