Virological response to salvage therapy in HIV-infected persons carrying the reverse transcriptase K65R mutation

Background: The effect of the HIV reverse transcriptase K65R mutation on virological response to salvage therapy has not been clearly defined. Methods: From six Italian clinical centres, all consecutive patients starting salvage antiretroviral therapy after virological failure in the presence of the K65R mutation identified by a genotypic resistance test were selected. Results: Among 145 subjects included over a 197 person-year follow-up, the estimated probability of virological response (VR, defined as reaching HIV RNA 10 copies/ml (interquartile range [IQR] 0.10-2.46): at multivariable regression analysis, salvage regimens containing a TA (β=+0.80; P=0.02) and lamivudine (β=+1.21; P=0.02) as new drug had a positive effect on the reduction of HIV-1 RNA. Conclusions: Development of the K65R mutation does not preclude a high rate of virological response to rescue therapy. Inclusion of a TA in the salvage regimen and the presence of a M184V mutation could have a favourable effect on virological outcome.