First Efficacy Trials on Switch to RPV/FTC/TAF for HIV Yield Positive Results

For treating HIV infection, switching to a single pill containing rilpivirine (RPV), emtricitabine (FTC) and tenofovir alafenamide (TAF) from either of 2 pills with different components of the same drug classes was found to be effective with less adverse effects, according to a new study.

In a statement released when the RPV/FTC/TAF product (Odefsey, Gilead) was approved by the US Food and Drug Administration (FDA) in 2016, the manufacturer characterized it as "the smallest pill of any single tablet regimen for the treatment of HIV".

A single daily tablet containing 1 nonnucleoside reverse transcriptase inhibitor (NNRTI) such as efavirenz (EFV) or rilpivirine (RPV) with 2 nucleos(t)ide reverse transcriptase inhibitors (NRTIs) such as emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF) is among the most commonly prescribed, complete treatment regimens for HIV-1 infection, according to investigators who evaluated a switch to RPV/FTC/TAF from 2 other products which have been associated with problematic adverse effects.

Debbie Hagins, MD, from the Georgia Department of Public Health, Chatham Care Center in Savannah, Georgia, and colleagues pointed out that regimens with TAF have demonstrated improved bone and renal safety compared with TDF-containing regimens, with comparable efficacy, and are now preferred as the initial antiretroviral treatment in patients with DC4 cell counts more than 200 cells/µL and HIV RNA of less than 100,000 HIV-1 RNA copies/mL.

"Whether to switch from an effective regimen remains of clinical interest," the investigators indicated.

To address that question, 2 switch trials were conducted, both randomizing virologically suppressed participants 1:1 to continue their current regimen, or switch to the RPV/FTC/TAF study drug. The primary assessment of efficacy was maintaining baseline HIV-1 RNA of less than 50 copies/ml to study completion at 96 weeks.

"The RPV/FTC/TAF was FDA approved based upon bioequivalency, and so these are the first efficacy studies [performed] with this new drug," Hagins told MD Magazine®.

In trial number 1216, a total of 630 participants received either the study drug or continued to take RPV/FTC/TDF (Complera, Gilead). In trial number 1160, a total of 875 participants were randomized to the study drug or to continue EFV/FTC/TDF (Atripla, Gilead). Both trials were double-blinded, with tablets in both groups manufactured to identical appearance.

The investigators reported that in both trials, the efficacy of switching to RPV/FTC/TAF was noninferior at week 96 to that of continuing baseline therapy. In study 1216, a total of 89.2% of participants who switched to the study drug maintained HIV RNA of less than 50 copies/ml compared with 88.5% of those continuing their previous regimen. In study 1160, a total of 85.2% of participants who switched to the study drug met that criteria at 96 weeks, compared with 85.1% on the continued regimen. No participant receiving the study drug developed treatment-emergent resistance, while 2 participants showed resistance with EFV/FTC/TDF and 1 showed resistance with RPV/FTC/TDF.

In addition, the investigators note that significant improvements in bone mineral density and renal tubular markers were found in the group switched to the study drug compared with those continuing baseline therapy, and that these improvements continued through the 96-week study period.

"Until there is a cure [for HIV], we have effective treatments," Hagins commented. "We will continue to develop treatments that are safe, effective, and easy to take or administer."

The report, “Switching to coformulated rilpivirine (RPV), emtricitabine (FTC) and tenofovir alafenamide from either RPV, FTC and tenofovir disoproxil fumarate (TDF) or efavirenz, FTC and TDF: 96-week results from two randomized clinical trials,” was published in HIV Medicine.