PIBIK: Switching to B/F/TAF maintains HIV suppression through 48 weeks

Viral suppression is maintained through 48 weeks in adults with HIV-1 harbouring drug resistance mutations, who switched to bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) fixed-dose combination pill from a boosted protease inhibitor (bPI) therapy, according to recent data from the phase IV open-label PIBIK trial.

Already, B/F/TAF proved better than bPI at week 24, as previously reported. The proportion of participants with a pure virologic response (PVR), defined as HIV-1 RNA <50 c/mL, was 100 percent among those who switched to B/F/TAF therapy vs 97.4 percent among those who remained on bPI (difference, 2.6 percent, 95 percent confidence interval [CI], –2.4 to 7.5). [HIV Glasgow 2022, abstract 089]

The 48-week data presented at EACS 023 showed that B/F/TAF maintained its efficacy at week 48 in the presence of limited nucleoside reverse transcriptase inhibitor (NRTI) resistance, the investigators said.

PVR rates at week 48 were identical to those recorded at week 24 (100 percent with B/F/TAF and 97.4 percent with bPI; difference, 2.6 percent, 95 percent CI, –2.4 to 7.5). [Iwuji C, et al, EACS 2023]

PIBIK included 72 adults with HIV-1 who were on a bPI-based antiretroviral therapy (ART) regimen with a documented viral load of <50 copies/mL for at least 6 months on the current regimen and at baseline. Of these participants, 34 had one NRTI mutation and 38 had at least two. The types of drug resistance mutations were M184V/I only (with or without any NRTI-associated mutation), up to two thymidine analogue mutations (TAMs) with or without M184V/I, M184V/I with any NRTI-associated mutation, and K70E/G.

Thirty-three participants were randomly assigned to the group who were switched immediately to B/F/TAF (immediate switch; mean age 53.1 years, 88 percent men, 70 percent White), while 39 were assigned to the group who were initially maintained on bPI for 24 weeks and then switched to B/F/TAF for the next 24 weeks (delayed switch; mean age 55.6 years, 90 percent men, 76 percent White).

In terms of safety, the three-drug combination pill was well tolerated, the investigators said.

By week 48, drug-related adverse events (AEs) had occurred in 9.1 percent of participants in the immediate switch group and in 35.9 percent of those in the delayed switch group. In the immediate switch group, two participants had weight gain, and another two had nondiabetic hyperglycaemia. In the delayed switch group, the AEs included headache (n=4), tiredness/fatigue (n=3), low mood (n=2), anxiety (n=2), insomnia (n=2), and weight gain (n=2).

The investigators noted that despite the increase in HbA_1c, BMI, and weight, the switch to B/F/TAF led to improvements in lipid values.

Overall, the findings suggest that the fixed-dose B/F/TAF regimen may be effective in maintaining virologic suppression in patients with drug-resistance mutations.