Tenofovir resistance is higher than expected in adult patients with HIV and treatment failure, according to a global evaluation published online January 28 in Lancet Infectious Disease. The higher-than-expected rates were particularly pronounced in low- to middle-income countries.
The researchers also identified two new risk factors for tenofovir resistance and found that patients with tenofovir resistance commonly have resistance to other antiretrovirals.
“Improvements in the quality of HIV care and viral load monitoring could mitigate the emergence and spread of tenofovir resistance, thereby prolonging the lifetime of tenofovir-containing regimens for both treatment and prophylaxis,” Ravindra K. Gupta, MD, PhD, from University College London, United Kingdom, and other members of the TenoRes Study Group write.
Tenofovir plays a central role in treatment and prophylactic regimens for HIV-1. World Health Organization guidelines recommend tenofovir combined with lamivudine or emtricitabine and efavirenz as first-line therapy in adults with HIV-1.
In addition, the strategy called “treatment as prevention,” aimed at preventing immunological decline and decreasing the spread of HIV-1 by treating with combined antiretroviral therapy at diagnosis, almost always uses tenofovir. Preexposure prophylaxis in uninfected high-risk individuals relies almost entirely on using tenofovir or tenofovir plus emtricitabine, the authors note.
As part of the TenoRes collaboration, the study included data from adult HIV studies looking at HIV drug resistance in Europe, Latin America, North America, sub-Saharan Africa, and Asia. The analysis included 1926 patients from 36 countries who had genotype resistance testing and experienced treatment failure between 1998 and 2015 while receiving regimens containing tenofovir plus a cytosine analogue (lamivudine or emtricitabine) and a non-nucleotide reverse-transcriptase inhibitor (NNRTI; efavirenz or nevirapine).