BICSTaR suggests efficacy of start/switch to bictegravir/emtricitabine/TAF in PLHIV

Initiation or switch to the single-tablet regimen of bictegravir/emtricitabine/tenofovir alafenamide (TAF) led to low HIV-1 RNA viral load in people living with HIV (PLHIV), according to the BICSTaR study presented at HIV Glasgow 2020.

The findings were based on analysis of 513 PLHIV (91 percent male, 89 percent White) from Europe and Canada who had completed 12-month follow-up in the ongoing BICSTaR study. Most patients were treatment experienced (ie, prior exposure to antiretroviral therapy [ART]; n=429, median age 49 years), while the remaining 84 patients (median age 38 years) were treatment naïve.

In the treatment-experienced cohort, 71, 18, and 13 percent switched from INSTI-, NNRTI-, and PI-*based regimens, respectively, with 26 percent having prior exposure to tenofovir disoproxil fumarate (TDF). Eight percent had previously experienced virological failure.

At 12 months, all treatment-naïve patients who initiated bictegravir/emtricitabine/TAF (n=74) achieved a viral load of <50 copies/mL, as did 96 percent of treatment-experienced patients (n=357) who switched to the regimen. [HIV Glasgow 2020, abstract P046]

Effectiveness was consistent regardless of age (≥50 or <50 years) in both treatment-naïve (100 percent for both age categories) and treatment-experienced patients (93 percent [≥50 years] and 98 percent [<50 years]), or sex (100 percent of both male and female treatment-naïve patients and 96 and 97 percent of male and female treatment-experienced patients, respectively).

Fourteen and 15 percent of treatment-naïve and treatment-experienced patients experienced drug-related adverse events (DRAEs), the most frequent being gastrointestinal and neuropsychiatric AEs (5 and 4 percent, respectively). Ninety percent of participants remained on treatment; DRAE-related discontinuations occurred in 3.6 and 7.2 percent of treatment-naïve and treatment-experienced patients, respectively.

The only two serious DRAEs were in treatment-experienced patients (two cases of depression). At 12 months, treatment-naïve (n=48) and treatment-experienced (n=269) patients experienced a median weight change of +2.5 and +0.9 kg, respectively, while BMI changes were +0.8 and +0.3 kg/m², respectively. Nineteen and 5 percent of treatment-naïve and treatment-experienced patients, respectively, experienced a weight gain of >10 percent.

There were no major resistance substitutions to the components of the bictegravir/emtricitabine/TAF regimen.

“[The results of the BICSTaR study show that] the use of bictegravir/emtricitabine/TAF in this real-world clinical cohort was associated with a high level of effectiveness and safety through 12 months, inclusive of male, female, and older PLHIV,” said the researchers.

Successful switch from PI-based regimen

Another study also showed sustained virological suppression among most PLHIV who switched from a PI-based regimen to bictegravir/emtricitabine/TAF.

Participants were 577 patients with virologically-suppressed HIV (HIV-1 RNA <50 copies/mL) who were on a boosted PI-based regimen of atazanavir or darunavir plus either emtricitabine/TDF or abacavir/lamivudine for ≥6 months pre-screening. They were randomized 1:1 to either remain on their baseline PI regimen or switch to bictegravir/emtricitabine/TAF.

Following 48 weeks of the randomized treatments, 516 patients (median age 48 years, 17 percent female, 26 percent Black) were enrolled in the open-label extension study and received bictegravir/emtricitabine/TAF, 272 and 244 who were originally randomized to bictegravir/emtricitabine/TAF and the PI regimen, respectively. Patients received bictegravir/emtricitabine/TAF for a median 101 weeks.

Virological suppression (HIV-1 RNA <50 copies/mL) during the open-label phase was maintained in 97–100 percent of patients at all timepoints over 156 weeks. [HIV Glasgow 2020, abstract P036]

There was no documented incidence of resistance to bictegravir/emtricitabine/TAF or discontinuation due to lack of efficacy during the open-label phase.

About 14 percent of patients on bictegravir/emtricitabine/TAF experienced DRAEs which were mostly grade 1, the most common being headache (2 percent). AEs led to discontinuation in six patients; four during the open-label phase.

Body weight changed by a median 2 kg at weeks 48 and 72, and 2.2 kg at week 96. Change in the total:HDL cholesterol ratio was -0.1, -0.2, and -0.2 at weeks 48, 72, and 96, respectively. LDL-cholesterol changed by a median -3, -4, and -7 mg/dL, respectively, and estimated glomerular filtration rate changed by a median -4.2, -6.3, and -3.4 mL/min.

“Long-term follow-up of … switching to bictegravir/emtricitabine/TAF from a boosted PI regimen demonstrates continued high rates of virologic suppression with no emergent resistance and was safe and well tolerated through a maximum of 156 weeks,” noted the researchers.