WEPDB0103 - Poster Discussion Session
Virological efficacy of the four tenofovir-containing WHO-recommended regimens for initial antiretroviral therapy
Presented by Michele Tang (United States).
M. Tang1, P. Kanki2, R. Shafer1
1Stanford University School of Medicine, Infectious Diseases, Stanford, United States, 2Harvard School of Public Health, Department of Immunology and Infectious Diseases, Boston, United States
Background: The 2010 WHO Antiretroviral (ARV) Treatment Guidelines have added four
new ARV regimens for first-line therapy: tenofovir (TDF) plus lamivudine (3TC)
plus nevirapine (NVP), TDF plus emtricitabine (FTC) plus NVP, TDF plus 3TC plus
efavirenz (EFV), and TDF plus FTC plus EFV. It is not known, however, whether
each of these new regimens are equally efficacious or even as efficacious as
the older non-TDF-containing dual NRTI / NNRTI regimens.
Methods: We systematically reviewed published studies and abstracts of the virological efficacy
of the four TDF-containing regimens for initial ARV therapy.
Results: Thirty prospective and retrospective studies assessed
the efficacy of one or more of the four TDF-containing regimens: TDF/3TC/NVP (3
studies), TDF/FTC/NVP (9 studies), TDF/3TC/EFV (7 studies), and TDF/FTC/EFV (13
studies). Two of the studies included more than one TDF-containing regimen of interest. In most studies, TDF/FTC/NVP, TDF/3TC/EFV, and TDF/FTC/EFV were equivalent
or superior to their respective comparator arms. In contrast, TDF/3TC/NVP was
inferior to AZT/3TC/NVP in two of three studies: in one of these two studies
and in a third open-label study, high rates of virological failure and drug
resistance led to premature study discontinuation. Virological failure and the
multi-nucleoside resistance mutation K65R occurred commonly among those
receiving TDF/3TC/NVP, occasionally among those receiving TDF/3TC/EFV or
TDF/FTC/NVP, and rarely among those receiving TDF/FTC/EFV.
Conclusion: TDF/3TC/NVP is the least well-studied and appears to
be the least efficacious of the four WHO-recommended TDF-containing regimens. The
apparent inferiority of TDF/3TC/NVP compared with AZT/3TC/NVP despite the greater
antiviral activity of TDF compared with AZT underscores that ARV regimens are
more than the sum of their parts. Further study of the TDF/3TC/NVP regimen is
urgently required before this regimen is widely deployed for initial ARV
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