NRTI-sparing regimens yield higher rates of drug resistance than NRTI-based regimens for HIV-1 treatment

J Glob Antimicrob Resist. 2014 Jun;2(2):103-106. doi: 10.1016/j.jgar.2013.12.001. Epub 2013 Dec 26.

Abstract

To treat human immunodeficiency virus (HIV)-infected patients, international guidelines recommend the combination of two nucleos(t)ide reverse transcriptase inhibitors [N(t)RTIs] and a third agent [non-NRTI (NNRTI), boosted protease inhibitor (r/PI) or integrase inhibitor (INI)] for initial treatment. The objective of this study was to compare the selection of resistance to antiretrovirals (ARVs) for regimens containing or lacking N(t)RTIs in patients experiencing their first virological failure. Eligible patients had a first virological failure, defined as the occurrence of two consecutive HIV plasma viral loads ≥50copies/mL. Genotypic resistance testing was performed at the time of virological failure (on the second sample with detectable viral load ≥50copies/mL) in patients failing regimens of N(t)RTIs+r/PI or NNRTI or INI, r/PI+NNRTI or INI, and INI+NNRTI. Among 434 virological failures analysed, resistance testing results were available in 416 cases (95.9%). Higher rates of drug resistance were observed in patients receiving N(t)RTI-sparing regimens. When the combination of N(t)RTIs+r/PI was used, PIs protect themselves and the associated N(t)RTIs from the selection of resistance; however, this was not observed with the NNRTI+r/PI combination. The same phenomenon was observed for raltegravir: when used in combination with N(t)RTIs, INI resistance mutations were less frequently selected compared with its use in combination with PIs or NNRTIs. In conclusion, regimens of the ARV classes combined impact the frequency of resistance development. Lower resistance is observed for N(t)RTI-based regimens, with more therapeutic options for subsequent regimens after failure.

Keywords: HIV-1; NRTI; Resistance.