Three-year Efficacy of Switching to Dolutegravir Plus Lamivudine: A Real-world Study

Background: Dolutegravir (DTG) plus lamivudine (3TC) has proven highly efficacious as a switching strategy in virologically suppressed people with HIV (PWH). As this strategy was introduced relatively recently, real-world, long-term durability studies are lacking.

Methods: We performed a retrospective review of treatment-experienced patients who started DTG + 3TC in a cohort of PWH. HIV-RNA <50 copies/mL was analysed at 144 weeks in an intention-to-treat (ITT) analysis (missing = failure) and a per-protocol (PP) analysis (patients with missing data or changes for reasons other than virological failure were excluded).

Results: The study population comprised 358 PWH (19% women). Median age and time with HIV infection were 51.7 and 13.4 years, respectively. The median number of previous antiretroviral combinations was three. Previous virological failure was reported in 27.1% of patients, and the M184V resistance mutation was detected in 17 patients. At 144 weeks, the percentage of individuals with HIV-RNA <50 copies/mL was 77.4% (277/358) in the ITT analysis and 95.5% (277/290) in the PP analysis. A total of 68 participants were excluded from the PP analysis (data missing, 25, discontinuation due to toxicity, 19; other, 16; death, 8). Two people with virological failure selected resistance-associated mutations (M184V and M184V + R263K). HIV-RNA remained undetectable in 17 patients with a previous history of the M184V mutation.

Conclusion: Our results confirm the real-world, long-term efficacy, tolerability and high genetic barrier of DTG + 3TC in treatment-experienced PWH. Although scarce, mutations causing resistance to nucleosides and integrase can emerge.