Evidence of multidrug resistance is emerging among those failing first-line, tenofovir-based HIV regimens in sub-Saharan Africa. A significant proportion of this group who had resistance to an older class of antiretrovirals (ARVs) were also resistant to newer treatments.

Publishing their findings in The Lancet Infectious Diseases, researchers analyzed 712 participants in 20 studies within the TenoRes collaboration who had failed a first-line treatment for HIV containing Viread (tenofovir disoproxil fumarate, or TDF) plus a cytosine analogue antiretroviral (ARV)—Epivir (lamivudine) or Emtriva (emtricitabine)—and a non-nucleoside reverse transcriptase inhibitor (NNRTI), including Viramune (nevirapine) or Sustiva (efavirenz).

The participants had their fist study visits between 2005 and 2013.

Sixteen percent (115 of 712) of the cohort had at least one thymide analogue mutation (TAM). The two older ARVs Retrovir (zidovudine, or AZT) and Zerit (stavudine, or d4T) belong to a subclass of nucleoside reverse transcriptase inhibitors (NRTIs).

Those who had TAMs had lower CD4s when they started treatment than those who did not have TAMs (60.5 cells vs. 95 cells) and had a higher rate of resistance to Viread (81 percent vs. 59 percent), NNRTI resistance (93 percent vs. 77 percent) and cytosine analogue resistance (87 percent vs. 63 percent).

Those with TAMs were 29 percent more likely to have resistance to Viread than those without TAMs.

To read a press release about the study, click here. 

To read the study, click here.