Virologic outcomes of switching to dolutegravir functional mono- or dual therapy with a non-cytosine nucleoside analog: a retrospective study of treatment-experienced, patients living with HIV

BACKGROUND: Dolutegravir (DTG) monotherapy results in virologic failure and the development of DTG resistance. Here, we evaluated virologic outcomes of patients switched to DTG functional mono- or dual therapy with a non-cytosine nucleoside analog (NA). METHODS: This retrospective, single center study included treatment-experienced patients switched to regimens containing ≥ 2 antiretrovirals between 8/13/13–11/22/14 who were later found to be on DTG functional mono- or dual therapy with a non-cytosine NA based on historical genotypes. Eligible patients were either suppressed or viremic at baseline and had ≥ 2 HIV-1 RNA measurements at least 4 weeks apart following switch. Demographics, laboratory values and clinical parameters were extracted from the charts of all eligible patients during study treatment until 12/31/2018 and were summarized using descriptive statistics. The primary endpoint was the proportion of patients with HIV-1 RNA < 50 copies/mL following switch. RESULTS: Of 70 patients switched to DTG functional mono- or dual therapy, 39 were eligible; 19 (49%) were on DTG functional monotherapy and 20 (51%) were on DTG functional dual therapy with a non-cytosine NA. Historical genotypes indicated that all had an M184V/I, and 23 (59%) had an M184V/I and ≥ 1 additional NA mutation. The median duration of follow-up on study treatment was 50 weeks (range 12–244). Following switch, 32/39 (82%) patients achieved or maintained an HIV-1 RNA < 50 copies/mL and 7 (18%) had persistent HIV-1 RNA ≥ 50 copies/mL. Five viremic patients were found to be on functional dual therapy with DTG plus a non-cytosine NA and 2 were on DTG functional monotherapy. Five of these patients had post-switch genotypes ordered as a part of routine clinical care and there was no evidence of treatment-emergent resistance. Five were switched to a different DTG-containing regimen and achieved HIV-1 RNA < 50 copies/mL, 1 was switched to a non-DTG containing regimen and achieved HIV-1 RNA < 50 copies/mL and 1 was lost-to-follow up at week 36. CONCLUSIONS: In this real-world cohort, the majority of whom had virus with the M184V/I and ≥ 1 additional NA mutation, switching to DTG functional mono-or dual therapy with a non-cytosine NA resulted in persistent HIV-1 RNA ≥ 50 copies/mL in 18%. None with post-switch genotypes developed treatment-emergent resistance.