Bictegravir Combo Single-Dose Regimen Comparable to SBR in Select HIV-1 Positive Adults

Week 24 safety and efficacy data on women who switched from a baseline regimen (SBR) to B/F/TAF were presented at CROI 2018.

Recently approved by the US Food and Drug Administration (FDA), Biktarvy (Gilead), a once-daily tablet HIV drug regimen that combines bictegravir, emtricitabine, and tenofovir alafenamide (B/F/TAF), has shown high rates of viral suppression and no resistance in ongoing phase 3 studies. The regimen is indicated for the treatment of adults with HIV-1 who have no history of antiretroviral therapy (ART), or to replace a current ART regimen in those who have achieved virologic suppression. It is the smallest INSTI-based triple-therapy single tablet regimen available.

In an oral abstract presentation at the 25th Conference on Retroviruses and Opportunistic Infections (CROI), Cissy Kityo, MD, MSc, from the Joint Clinical Research Centre, reported week 24 safety and efficacy data from an international randomized, open-label, multicenter phase 3 trial which enrolled HIV-1 positive women who had achieved virologic suppression from either a protease inhibitor or a boosted regimen containing elvitegravir.

The women were randomly assigned to 2 arms: those who would switch to the B/F/TAF regimen, and those who would remain on the baseline regimen (SBR) of “[elvitegravir (E)/cobicistat (C)/F/TAF, E/C/F/tenofovir disoproxil fumarate (TDR), or atazanavir (ATV)+ritonavir (RTV+F/TDF)].”

“The primary efficacy endpoint was the proportion of women with HIV-1 RNA >50 copies (c)/mL at week 48 with 4% noninferiority margin (FDA snapshot),” the study authors wrote. The results for the secondary efficacy endpoint of HIV-1 RNA <50 c/mL at week 24, as well as adverse events and laboratory abnormalities for the same time period, were presented at CROI.

A total of 470 women were randomized and treated in the study; 234 were switched to the B/F/TAF regimen, while 236 stayed on the SBR regimen. Of those who stayed on the SBR regimen, 125 were on E/C/F/TAF, 98 were on E/C/F/TDF, and 13 were on the ATV+RTV+FTC/TDF regimen.

Demographic and baseline characteristics were well-balanced across all participants: 37% black, 28.3% white, and 21.7% Asian, with a median age of 39 years.

At week 24, the investigators found that the safety and efficacy of the B/F/TAF regimen were comparable to that of the SBR regimen. A total of 98.7% of participants in the B/F/TAF arm achieved HIV-1 RNA <50 c/mL at week 24 compared with 99.2% of participants in the SBR arm.

Two participants—1 from each arm of the study—had resistance to testing; however, neither developed resistance to any of the drugs involved in the study. Furthermore, none of the participants stopped treatment due to adverse events. No notable difference between arms was noted in terms of grade 3 or 4 treatment-emergent adverse events; 17% of participants taking the B/F/TAF regimen experienced grade 3 or 4 laboratory abnormalities compared with 18% of those on an SBR regimen.

The B/F/TAF regimen was found to be safe and well-tolerated and those women who “switched to B/F/TAF maintained high levels of virologic suppression at week 24 with comparable efficacy to those who remained on a baseline regimen,” according to the study authors. “This analysis supports the efficacy and safety of B/F/TAF in women observed in other B/F/TAF phase 2 and 3 studies.”