The risks and incidence of K65R and L74V mutations and subsequent virologic responses.

The L74V and K65R mutations confer resistance to several nucleoside analogues, and the impact on subsequent regimens is unclear. The risk of developing L74V or K65R mutation in the era of highly active antiretroviral therapy (HAART) was 4.5 and 2.8 cases per 100 person-years, respectively; concomitant receipt of boosted protease inhibitors protected against K65R. High rates of virologic suppression in the presence of either mutation were observed if the next regimen contained at least 2 active agents. If suboptimal HAART was used, patients with K65R experienced significantly higher rates of virologic suppression than did those with L74V (P = .01).