Transmitted drug resistance to NRTIs and risk of virological failure in naïve patients treated with integrase inhibitors.

OBJECTIVES Nucleoside reverse transcriptase inhibitor (NRTI) transmitted drug resistance mutations (TDRMs) could increase the risk of virological failure (VF) of first-line integrase strand transfer inhibitor (InSTI)-based regimens. METHODS Patients starting two NRTIs (lamivudine/emtricitabine plus abacavir/tenofovir) plus raltegravir or dolutegravir were selected from the EuResist cohort. The role of NRTI genotypic susceptibility score and of specific TDRMs in VF (i.e. two consecutive viral loads > 50 HIV-1 RNA copies/mL or a single viral load ≥ 200 copies/mL after 3 months from antiretroviral therapy start) was evaluated in the overall population and according to the InSTI employed. RESULTS From 2008 to 2017, 1095 patients were eligible for the analysis (55.5% men, median age 39 years). In all, 207 VFs occurred over 1023 patient-years of follow-up. The genotypic susceptibility score (GSS) had no effect on the risk of VF in the overall population. However, the presence of M184V/I independently predicted VF of raltegravir- but not dolutegravir-based therapy when compared with a fully-active backbone [adjusted hazard ratio (aHR) = 3.09, P = 0.035], particularly when associated with other non-thymidine analogue mutations (aHR = 27.62, P = 0.004). Higher-zenith HIV-RNA and lower nadir CD4 counts independently predicted VF. CONCLUSIONS NRTI backbone TDRMs increased the risk of VF with raltegravir-based but not dolutegravir-based regimens.