New Data Support Switch to B/F/TAF in Women and Patients With Resistance to Other HIV Therapies

Two phase 3 studies presented at IAS 2019 evaluated a switch to B/F/TAF among individuals virologically suppressed on other HIV treatment regimens.

New data presented at the 10th IAS Conference on HIV Science (IAS 2019) suggest that bictegravir 50 mg/emtricitabine 200 mg/tenofovir alafenamide 25mg tablets (B/F/TAF) could be efficacious treatment for HIV in women and virologically suppressed individuals with known resistance to other therapies.

B/F/TAF (Biktarvy) was approved by the US Food and Drug Administration in February 2018 for the treatment of HIV-1 in individuals weighing at least 25 kilograms who do not have a history of antiretroviral treatment history or individuals who are virally suppressed on an antiretroviral regimen with no history of treatment failure.

The drug, which was developed by Gilead, was recently evaluated in 2 phase 3 trials, for which data were presented at the IAS 2019 meeting in Mexico City, Mexico.

One of the studies, a phase 3, international, randomized, open-label trial, evaluated a switch to B/F/TAF among female study participants. According to 96-week efficacy and safety data presented in an oral abstract presentation at IAS, the study enrolled 470 female patients who were virologically suppressed on a baseline regimen of either elvitegravir/cobicistat/F/TAF; (150/150/200/10 mg), elvitegravir/cobicistat/F/TDF (150/150/200/300 mg) or atazanavir+ritonavir+F/TDF (300+100+200/300 mg) who switched 1 to 1 from these baseline regimens to B/F/TAF.

The primary end point of the research was non-inferiority in virologic suppression, with a low rate of adverse events and no documented resistance at Week 48. This was achieved and previously presented. At Week 48, all participants, including those on baseline regimens, switched to B/F/TAF through Week 96.

The new Week 96 data found that 99.5% of women who received B/F/TAF continuously since the beginning of the study and 98.5% of women who switched to B/F/TAF at Week 48 maintained virologic suppression, with no development of treatment-emergent resistance. Additionally, the regimen was shown to be well-tolerated by the participants with low frequencies of serious adverse events.

In a statement issued by Gilead, Cissy Kityo, MD, executive director of the Joint Clinical Research Center in Uganda, and lead investigator of the study, reflected on the need for more female patients to be enrolled in HIV trials.

“Despite the fact that women account for the majority of new HIV infections globally, they remain largely underrepresented in HIV clinical trials,” she said. “The findings from this study conducted exclusively in women yield important long-term data on the safety, tolerability, and efficacy of Biktarvy in this important patient population.”

The second study evaluated B/F/TAF’s potential for efficacy in a study population of individuals who were virologically suppressed and had documented resistance to nucleo(s)tide or non-nucleo(s)tide reverse transcriptase inhibitors (NRTIs or NNRTIs).

This phase 3, ongoing, randomized, double-blinded study evaluated 565 individuals who were virologically suppressed and switched 1 to 1 from a regimen of dolutegravir (DTG)+F/TAF (50+200/25 mg) or DTG+F/TDF (50+200/300 mg) to DTG+F/TAF or B/F/TAF for 48 weeks. This study stands out from previous research as it included individuals with previously documented resistance to NRTIs, NNRTIs, or protease inhibitors (PIs); only participants with documented integrase inhibitor resistance were excluded, and 24% of participants had resistance to NRTIs.

According to the abstract, the primary end point was the proportion of participants with HIV-1 RNA > 50 c/ml at Week 48. At that point, it was observed that 0.4% (n = 284) of participants on B/F/TAF had HIV-1 RNA >50 c/ml, compared with 1.1% of participants on DTG+F/TAG (n = 281), demonstrating non-inferiority.

Additionally, at Week 49, there was no detection of treatment-emergent resistance, and it is reported that none of the patients with pre-existing NRTI resistance mutations had HIV RNA > 50 c/mL.

“The single-tablet regimen B/F/TAF is an effective option for people virologically suppressed on DTG+F/TDF or F/TAF, with or without NRTI resistance mutations including M184V, K65R, and TAMs,” Paul E. Sax, MD, a member of Contagion®’s Editorial Advisory Board, and colleagues wrote in the conclusion of their abstract.

The presentations “Longer-term (96-week) efficacy and safety of switching to bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) in women,” and “Switching to a single-tablet regimen bictegravir, emtricitabine, and tenofovir alafenamide (B/F/TAF) from dolutegravir (DTG) plus emtricitabine and either tenofovir alafenamide or tenofovir disoproxil fumarate (F/TAF or F/TDF)” were presented in oral abstract sessions on Monday, July 22, 2019, at IAS 2019 in Mexico City, Mexico.