Evolution of L74V or K65R Mutations in VIremic Subjects on Tenofovir Disoproxil Fumarate (TDF) or Abacavir (ABC) (EVITA)

This is a multicenter, open-label, non-randomized, dual-arm pilot study to investigate the prevalence of the reverse transcriptase (RT) resistance mutations, K65R/x or L74V/x, in HIV-1 plasma from subjects experiencing confirmed first-time incomplete virologic suppression during treatment with an initial antiretroviral (ARV) regimen consisting of at least 12 weeks of TDF or ABC + emtricitabine (FTC) or lamivudine (3TC) + non-nucleoside reverse transcriptase inhibitor (NNRTI) or protease inhibitor (PI). Subjects will be followed until a substantial loss of virologic or immunologic control requires a treatment switch. Confirmed first-time incomplete virologic suppression is defined as an initial plasma HIV-1 RNA response \< 400 copies/mL, and subsequent virologic rebound \> 400 copies/mL measured at two consecutive times. Subjects will have a screening genotype to establish adherence to their non-suppressive TDF- or ABC-containing regimen by the presence of M184V (or other treatment-related primary) mutation and to demonstrate that the evolution of treatment-emergent RT mutations can be characterized. Twenty subjects (a maximum of 10 per arm) will be enrolled at 10-20 United States (U.S.) sites. If fewer than 20 subjects can be enrolled, the study may be discontinued early by the sponsor. Equal numbers of subjects on Arm A versus Arm B will be a goal.