The single-tablet antiretroviral regimen of bictegravir, emtricitabine, and tenofovir alafenamide (B/F/TAF) was assessed as being noninferior to two dolutegravir (DTG)-containing regimens among adults aged 50 and over living with HIV, according to a new study.
The study pooled data from two phase 3, randomized, double-blind B/F/TAF studies comparing that regimen with DTG-containing regimens for adults living with HIV who were treatment naive. Anthony Mills, MD, a physician in private practice in West Hollywood, Calif., and his associates reported results at the 144-week mark for the two studies in a poster that was presented as part of the Conference on Retroviruses & Opportunistic Infections, which was presented online this year. CROI organizers chose to hold a virtual meeting because of concerns about the spread of COVID-19.
In the two trials, the B/F/TAF regimen was compared with a DTG and abacavir/lamivudine (DTG + ABC/3TC) regimen, as well as with DTG plus emtricitabine/tenofovir alafenamide (DTG + F/TAF). A total of 629 patients were enrolled in the first study, and 645 in the second. Of these, a total of 196 patients were aged 50 years or older. Across all study arms, most participants (73%-92%) were male, and 20%-37% were black or of African descent. Participants identifying as Hispanic or being of Latino ancestry made up 11%-27% of participants.
About 80%-90% of patients had asymptomatic HIV infection at the time of enrollment, with median CD4 counts ranging from 405-534 cells/mcL across study arms. Patients had a median 4.27-4.53 log (base 10) copies/mL at baseline. In both studies, patients had to have at least 500 HIV-1 RNA copies per mL, and couldn’t have known resistance to any of the study drugs.
At week 144, there were no statistically significant differences in virologic outcomes across study arms in the younger or older age subgroups: 81% of the B/F/TAF patients older than 50 years had fewer than 50 copies/mL of HIV-1 RNA, compared with 83% and 88% of the younger DTG/ABC/3TC and DTG + F/TAF groups meeting this mark, respectively.
Results were similar for the patients aged younger than 50 years, with 82%, 84%, and 83% of the B/F/TAF, DTG/ABC/3TC, and DTG + F/TAF groups having fewer than 50 copies/mL of HIV-1 RNA, respectively.
No patients in either age group showed resistance to any components of the treatment regimens. No treatment-emergent resistance was seen in any study participants, and few adverse events occurred. Those that were seen didn’t occur more frequently in older patients, compared with younger patients, and no patients discontinued their treatment because of renal issues.
Bone mineral density (BMD) was only measured in the study that compared B/F/TAF with DTG/ABC/3TC. Hip BMD decreased slightly in both groups, but the changes were comparable between older and younger participants. For both age groups, differences weren’t significant between the B/F/TAF group and those taking DTG/ABC/3TC. Spine density actually increased slightly in older patients taking B/F/TAF, but the difference between this measure and the slight decrease in older patients taking DTG/ABC/3TC was not significant.
Weight increased over time for all groups, ranging from a gain of 3.4 kg at 144 weeks for older patients taking DTG + F/TAF to 5.3 kg for the same regimen in younger patients, but none of the between-group differences were significant.
All fasting lipids rose for each study arm in both older and younger patients. Some of the between-group differences were statistically significant, but “there were no clinically significant differences in median changes from baseline in fasting lipids” among those aged 50 years or older, noted Dr. Mills and associates.
In terms of safety, no study drug-related discontinuations for renal adverse events occurred in either the B/F/TAF or the DTG + F/TAF groups, and the investigators saw no proximal renal tubulopathy.
The estimated glomerular filtration rate (eGFR) was calculated using the Cockroft-Gault equation. All three antiviral regimens were associated with early drops in eGFR, “consistent with inhibition of tubular creatinine secretion via organic cation transporter 2,” noted Dr. Mills and associates.
Other adverse events were rare in all groups in both older and younger patients, without significant differences between therapies.
The study was supported by Gilead Sciences, which also provided support to Dr. Mills. One coauthor is a Gilead employee.
SOURCE: Mills A et al. CROI 2020, .