ROME – The latest World Health Organization guidelines for combination antiretroviral therapy in low- and middle-income countries recommend four triple-drug combinations (all including tenofovir) for first-line HIV treatment.
However, in a July 20 presentation at the International AIDS Society Conference on HIV Pathogenesis and Treatment, Dr. Michele Tang, of Stanford (Calif.) University, offered a meta-analysis showing that one of these combinations – tenofovir, lamivudine, and nevirapine (TDF/3TC/NVP) – appears to control HIV less effectively than do the three others.
Dr. Tang and her colleagues conducted a systematic review that included 29 studies evaluating tenofovir combined with lamivudine plus nevirapine; emtricitabine and nevirapine; emtricitabine and efavirenz; and/or lamivudine and efavirenz.
The TDF/3TC/NVP combination was the least well studied of the four tenofovir-containing regimens, occurring in only three of the studies Dr. Tang’s group looked at, which were an open-label pilot study, a randomized controlled trial, and a 2010 retrospective cohort study. In the open-label pilot study without a comparator, the regimen was associated with a 30% rate of virologic failure. In the two others, it was associated with 25% and 21% rates of failure, whereas the failure rates of the comparator regimens were 3% and 10%, respectively.
The U.S. Department of Health and Human Services guidelines already classify TDF/3TC/NVP as a regimen to be used "with caution," Dr. Tang noted.
Antiretroviral regimens "are more than the sum of their parts," she said.
"3TC and FTC [emtricitabine] are not interchangeable. As clinicians, we tend to think of them as interchangeable, but there are some differences."
Further study is "urgently required before this regimen is widely deployed for initial ARV [antiretroviral] therapy," Dr. Tang said.
She did not offer any financial disclosures.