Long-term outcome of lamivudine/dolutegravir dual therapy in HIV-infected, virologically suppressed patients

Background: The use of DTG-containing two-drug regimens is one of the most promising solutions to the need to ease the management of HIV treatment without harming its efficacy and safety. We report long- term results in patients switched, while virologically suppressed, to the combination of dolutegravir (DTG) plus lamivudine (3TC).

Methods: This is a prospective, clinical, uncontrolled cohort enrolling ART-experienced people living with HIV (PLWH) with HIV-RNA < 50 copies/ml for 6 months or longer, negative hepatitis B virus surface antigen, and without known M184V/I mutations. Kaplan-Meiers curves are used to describe persistency of virological suppression on therapy and a Cox regression model to evaluate baseline characteristics and the risk of stopping therapy.

Results: 218 individuals switched their regimen since 2015. The mean estimated follow-up was of 64.3 months (95% CI 61.3-67.3) for approximately 1000 patient/years. After 5 years of follow-up, 77.1% were still on the DTG-3TC combination. No virologic failure was detected throughout the whole study period, and only 15 subjects presented single isolated viral blips above 50 copies/ml. Most patients stopped therapy because of reasons unrelated to study drugs (lost to follow-up; patients' decision; moved to other Centers), but due to the unselected nature of the casuistry; 11 subjects died in the 5 years of follow-up mostly because of pre-existing co-morbidities (6 neoplastic diseases and 2 end-stage liver disease). The median baseline CD4 count was 669 cells/mcl (IQR 483-927). After 5 years it raised to 899 cells/mcl (IQR 646-1160) (P < 0.001) without a significant change of CD8 counts that lowered from 767 cells/mcl (IQR 532-1034) to 683 cells/mcl (IQR 538-988). Consequently, the CD4/CD8 ratio varied from 0.93 (IQR 0.60-1.30) to 1.15 (IQR 0.77-1.45) (P < 0.0001). A non-significant (P = 0.320) increment of mean creatinine, 0.06 mg/dl in magnitude, was observed over the whole follow-up.

Conclusion: These long-term results over 5 years reinforce the durability and good tolerability of DTG-3TC. Our results continue to support the recommended switch use of this 2DR as a well-accepted treatment option for ART-experienced PLWH.