The study, conducted in Spain, followed 61 individuals living with HIV (88.5% male and 11.5% female) who were stable on efavirenz/tenofovir/emtricitabine and had a viral load below 37 copies/mL for at least two years before study enrollment. All participants had a CD4 count above 350 at the start of the study, and none had previously documented virologic failure, though a single viral load blip between 50 and 200 copies/mL was allowed for study inclusion, according to lead study author Esteban Martinez, M.D., Ph.D.
Participants also had no evidence of resistance to efavirenz (Sustiva, Stocrin), tenofovir disoproxil fumarate (TDF, Viread) or emtricitabine (FTC, Emtriva).
The volunteers were randomized to either continue taking efavirenz/tenofovir/emtricitabine once a day or reduce their regimen to three days a week (Mondays, Wednesdays and Fridays), about half in each group.
Viral load was measured at baseline, 12 weeks and 24 weeks, but more thoroughly for the three-day group at 1, 2, 4, 6 and 8 weeks.
Most of the study cohort was male (89%); roughly two-thirds were Caucasian, while the rest of the volunteers were Hispanic; and three-quarters of the study participants were men who have sex with men. Mean age was roughly 48 years.
After 24 weeks, there were zero treatment failures in either study arm, and with 333 viral load tests in total, none were above 37 copies/mL, suggesting that taking antiretroviral therapy (at least in this case of efavirenz/tenofovir/emtricitabine) three days a week could be a feasible option to maintain undetectable viral loads.
Adherence was measured by standard questionnaire and pill counting, and the overall adherence rate was fine, according to Martinez. The researchers were worried the three-day group would not be able to adjust to the new schedule, and at times, patients missed one dose, but each of them managed to maintain the new schedule using smartphone calendars or other equivalents, he said.
Due to the outstanding results, the researchers asked the ethics committee to extend the study to three years, Martinez said. When asked about patient satisfaction, Martinez noted that all three-day patients were extremely satisfied and no one wanted to go back to once-daily dosing. In fact, participants in the control arm wanted to switch to three-day arm.
Data on participants' viral reservoirs were not included in the study poster presented at ASM Microbe 2016. However, Martinez noted that the reservoirs were measured using total and integrated DNA, and all patient reservoirs remained stable throughout the study.
When asked how applicable these results would be to current clinical care given the reduced use of efavirenz, Martinez stated that while the use of efavirenz is decreasing in first-world countries, it is still widely used in developing countries. At the very least, this confirms the potential for therapy doses to be farther apart than once a day, Martinez concluded.