Phenotypic impact of resistance mutations on etravirine susceptibility in HIV patients with prior failure to nonnucleoside analogues.

The phenotypic impact on etravirine susceptibility was examined in plasma specimens from 40 nonnucleoside reverse transcriptase inhibitor-experienced HIV patients with distinct nonnucleoside reverse transcriptase inhibitor resistance-associated mutations. Some etravirine resistance-associated mutations produced larger reductions in fold change than others. Y181C in combination with at least one etravirine resistance-associated mutation caused, on average, a 12.6-fold reduced susceptibility to etravirine. Two novel changes, K101H and E399D, significantly diminished etravirine susceptibility. Thus, the original etravirine resistance-associated mutation list should be updated and weighted for a suitable genotypic resistance interpretation.