The potential role of bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) single‐tablet regimen in the expanding spectrum of fixed‐dose combination therapy for HIV

Single‐tablet regimens (STRs) of highly safe and effective combination antiretroviral therapy (cART) have had a significant beneficial impact on the clinical outcomes and lives of people living with HIV (PLHIV). As a consequence, healthcare professionals caring for PLHIV in high‐income countries have increasingly focused on issues beyond those related to HIV itself, i.e. HIV‐related neurological disease, or associated opportunistic infections, which include co‐infections, and primarily age‐ and lifestyle‐related comorbidities such as cardiovascular disease, diabetes mellitus, renal impairment, osteoporosis and frailty. This review considers drug side effects and comorbidities seen in PLHIV and evaluates the role of a recently licensed STR – bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) – in mitigating some of those challenges. Factors that need to be evaluated for initial cART regimens include: pretreatment CD4 cell count; plasma HIV RNA; HIV drug resistance; hepatitis B co‐infection; HLA‐B*5701 status; drug‐drug interactions; pregnancy and pregnancy potential; psychiatric and physical comorbidities such as renal or bone disease, as well as simplicity and adherence‐friendliness, all of which need to be considered in all lines of therapy. BIC/FTC/TAF constitutes a new STR that includes an unboosted integrase strand transfer inhibitor with a high barrier against resistance with TAF and FTC. Its virological efficacy was non‐inferior to dolutegravir‐based regimens previously recommended by most guidelines for treatment initiation in large double‐blind, randomised clinical trials in treatment‐naïve or switch patients over 96 weeks. Tolerability and pharmacological properties of the regimen make it a useful tool to address several of the clinical management issues raised above.     

Bictegravir/emtricitabine/tenofovir alafenamide in older individuals with HIV: Results of a 96-week,phase 3b,open-label,switch trial in virologically suppressed people ≥65 years of age

Objectives

Bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) is an effective treatment for HIV-1 infection; however, clinical trial data in older people living with HIV (PLWH) are lacking. The primary 24-week and secondary 48-week analyses of study GS-US-380-4449 (NCT03405935), which assessed the efficacy and safety of switching to B/F/TAF in older PLWH, have been published. Here we report the results of the final 96-week analyses from the study.

Methods

In this 96-week, phase 3b, open-label, single-arm trial, virologically suppressed PLWH aged ≥65 years switched from elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide or a tenofovir disoproxil fumarate-based regimen to B/F/TAF. Viral suppression, resistance, immune response, safety, tolerability and adherence were evaluated through week 96.

Results

Of 90 participants screened, 86 were enrolled and switched to B/F/TAF. No participants had HIV-1 RNA ≥50 copies/ml (by FDA Snapshot algorithm) at weeks 72 or 96; virologic suppression rates were 94.2% (81/86; 95% CI 87.0–98.1) and 74.4% (64/86; 95% CI 63.9–83.2), respectively. No treatment-emergent resistance was observed, and CD4 counts remained stable. There were no study drug-related serious adverse events. Three participants experienced drug-related treatment-emergent adverse events that led to premature drug discontinuation. There were no clinically relevant changes from baseline to week 96 in fasting lipid parameters, and the median change in body weight at week 96 was 0.0 kg (IQR −2.3, 2.0). Median self-reported adherence was 100% (IQR 100–100%).

Conclusions

Switching to B/F/TAF is an effective long-term option for virologically suppressed adults ≥65 years of age, with favourable safety and tolerability profiles in this population.     

Randomized comparison of metabolic and renal effects of saquinavir/r or atazanavir/r plus tenofovir/emtricitabine in treatment-naïve HIV-1-infected patients

Objectives

The aim of the study was to compare the effects on lipids, body composition and renal function of once‐daily ritonavir‐boosted saquinavir (SQV/r) or atazanavir (ATV/r) in combination with tenofovir/emtricitabine (TDF/FTC) over 48 weeks.

Methods

An investigator‐initiated, randomized, open‐label, multinational trial comparing SQV/r 2000/100 mg and ATV/r 300/100 mg once daily, both in combination with TDF/FTC, in 123 treatment‐naïve HIV‐1‐infected adults was carried out. The primary endpoint was to demonstrate noninferiority of SQV/r compared with ATV/r with respect to the change in fasting cholesterol after 24 weeks. Secondary outcome measures were changes in metabolic abnormalities, body composition, renal function, and virological and immunological efficacy over 48 weeks. Patients who had used at least one dose of trial drug were included in the analysis.

Results

Data for 118 patients were analysed (57 patients on SQV/r and 61 on ATV/r). At week 24, changes in lipids were modest, without increases in triglycerides, including a significant rise in high‐density lipoprotein (HDL) cholesterol and a nonsignificant decrease in the total:HDL cholesterol ratio in both arms with no significant difference between arms. Lipid changes at week 48 were similar to the changes observed up to week 24, with no significant change in the homeostasis model assessment (HOMA) index. Adipose tissue increased regardless of the regimen, particularly in the peripheral compartment and to a lesser extent in the central abdominal compartment, with an increase in adipose tissue reaching statistical significance in the ATV/r arm. A slight decline in the estimated glomerular filtration rate (eGFR) was observed in both arms during the first 24 weeks, with no progression thereafter. The immunological and virological responses were similar over the 48 weeks.

Conclusions

Combined with TDF/FTC, both SQV/r 2000/100 mg and ATV/r 300/100 mg had comparable modest effects on lipids, had little effect on glucose metabolism, conserved adipose tissue, and similarly reduced eGFR. The virological efficacy was similar.     

Tenofovir disoproxil fumarate (TDF), emtricitabine/TDF, and entecavir in patients with decompensated chronic hepatitis B liver disease

Data are limited on the safety and effectiveness of oral antivirals other than lamivudine and adefovir dipivoxil for treatment of chronic hepatitis B (CHB) in patients with decompensated liver disease. This Phase 2, double-blind study randomized 112 patients with CHB and decompensated liver disease to receive either tenofovir disoproxil fumarate (TDF; n = 45), emtricitabine (FTC)/TDF (fixed-dose combination; n = 45), or entecavir (ETV; n = 22). The primary endpoint was safety; more specifically, tolerability failure (adverse events resulting in permanent treatment discontinuation) and confirmed serum creatinine increase ≥ 0.5 mg/dL from baseline or confirmed serum phosphorus <2 mg/dL. Patients with insufficient viral suppression (e.g., confirmed HBV DNA ≥ 400 copies/mL at week 8 or 24) could begin open-label FTC/TDF but were considered failures in this interim week 48 analysis for efficacy endpoints. Tolerability failure was infrequent across arms: 6.7% TDF, 4.4% FTC/TDF, and 9.1% ETV (P = 0.622) as were confirmed renal parameters meeting threshold 8.9%, 6.7%, and 4.5% (P = 1.000), respectively. Six patients died (none considered related to study drug) and six received liver transplants (none had HBV recurrence). The adverse event and laboratory profiles were consistent with advanced liver disease and complications, with no unexpected safety signals. At week 48, HBV DNA was <400 copies/mL (69 IU/mL) in 70.5% (TDF), 87.8% (FTC/TDF), and 72.7% (ETV) of patients. Proportions with normal alanine aminotransferase were: 57% (TDF), 76% (FTC/TDF), and 55% (ETV). Hepatitis B e antigen (HBeAg) loss/seroconversion occurred in 21%/21% (TDF), 27%/13% (FTC/TDF), and 0%/0% (ETV). Child-Turcotte-Pugh and Modification for End-stage Liver Disease scores improved in all groups. CONCLUSION: All treatments were well tolerated in patients with decompensated liver disease due to CHB with improvement in virologic, biochemical, and clinical parameters.     

Pharmacokinetics of emtricitabine, didanosine and efavirenz administered once-daily for the treatment of HIV-infected adults (pharmacokinetic substudy of the ANRS 091 trial)

Objective This study was conducted to investigate the pharmacokinetics of emtricitabine (FTC), didanosine (ddI), and efavirenz (EFV) when administered in a once‐daily combination. Methods Nine antiretroviral‐naïve HIV‐infected adults who received FTC [200 mg once a day (qd)], ddI (400 mg qd if ≥60 kg; 250 mg qd if <60 kg) and EFV (600 mg qd) were studied. The following pharmacokinetic (PK) parameters were determined over 24 h at steady‐state after 4 weeks of treatment: area under the plasma concentration vs. time curve (AUC_{0–24 h}), maximum (C_max) and minimum (C_min) plasma concentrations, time to reach C_max (T_max), and the elimination half‐life (t_1/2). EFV plasma concentrations were also measured during follow‐up. Results Median PK parameters for FTC, ddI and EFV, respectively, were as follows. AUC_{0–24 h}: 7.2, 7.0 and 36.4 h×mg/L; C_max: 1.8, 2.6 and 2.5 mg/L; C_min: 0.04, < 0.01 and 1.0 mg/L; T_max: 1.8, 1.1 and 2.5 h; t_1/2: 7.4, 2.3, and 23.7 h. EFV plasma concentrations measured 10–13 h postdosing were higher during follow‐up than during the PK study (2.57 vs. 1.19 mg/L, P<0.01). Conclusion The simultaneous administration of FTC, ddI and EFV did not affect the PK parameters of FTC when compared to historical controls. EFV C_max and C_min were lower than expected, but the data may have been slightly underestimated in this study. High ddI AUC and C_max were measured in these patients, and further studies are warranted to confirm this finding.     

Evaluation of hypophosphataemia in tenofovir disoproxil fumarate (TDF)-exposed and TDF-unexposed HIV-infected out-patients receiving highly active antiretroviral therapy

OBJECTIVES: Cases of hypophosphataemia (often coincident with renal dysfunction) have been reported in HIV-infected patients taking tenofovir disoproxil fumarate (TDF), but randomized placebo-controlled trials of HIV-infected persons with normal baseline renal function have found a comparable incidence of hypophosphataemia in the TDF and placebo groups. We assessed the incidence of grade 2 and higher hypophosphataemia in the HIV Outpatient Study (HOPS). METHODS: We analysed a prospective cohort of patients who initiated either a TDF-containing highly active antiretroviral therapy (HAART) regimen [TDF-exposed (TDF+) group; n = 165] or a TDF-sparing HAART regimen [TDF-unexposed (TDF-) group; n = 90], and who had normal baseline phosphate and creatinine values. RESULTS: The TDF+ and TDF- groups had comparable median follow-up times (10.9 vs 8.8 months, respectively; P = 0.18) and number of phosphate measurements (median = 3 for both) and were similar on most clinical and demographic factors. During follow up, 12.7% of TDF+vs 6.7% of TDF-patients developed grade 2 hypophosphataemia (2.0-2.4 mg/dL), and 2.4% of TDF+ patients vs 0% of TDF-patients developed grade 3 hypophosphataemia (1.0-1.9 mg/dL); none developed grade 4 hypophosphataemia (<1.0 mg/dL). The incidence of grade 2 or higher hypophosphataemia was 16.7 per 100 person-years among TDF+ patients vs 8.0 per 100 person-years among TDF-patients (P = 0.11). CONCLUSIONS: The incidence of hypophosphataemia was somewhat elevated in HOPS patients who took TDF-containing HAART compared with those who took TDF-sparing HAART during the first 1 to 2 years of observation, but the difference was not statistically significant. Longer follow-up of a larger population is needed to determine if this trend towards an association achieves statistical significance and to evaluate the clinical consequences of hypophosphataemia.     

Five‐year on‐treatment efficacy of lamivudine‐, tenofovir‐ and tenofovir + emtricitabine‐based HAART in HBV–HIV‐coinfected patients

Summary. Data on the efficacy of lamivudine (LAM)‐, tenofovir (TDF)‐ and emtricitabine (FTC)‐based antiretroviral therapy (HAART) in HBV–HIV coinfection are limited. We completed a retrospective analysis of HBV–HIV‐coinfected patients treated at the Medical University of Vienna. One‐hundred and ten coinfected patients were included, with 57% being initially HBV e‐Antigen (HBeAg) positive. Baseline HBV load was significantly higher in HBeAg+ than in HBeAg? patients (5962 ± 3663 vs 20 ± 19 × 10⁶ IU/mL; P < 0.0001). Over a median observation period of 83 month (range: 26–183), 87% received HAART and 91% showed a suppression of HBV replication. After 5 years of continuous treatment, HBeAg seroconversion was achieved in 21% of LAM‐, 50% of TDF‐ (P = 0.042 vs LAM) and in 57% of TDF + FTC (P = 0.008 vs LAM)‐treated patients, respectively. HBsAg loss after 5 years was found in 8% (LAM), 25% (TDF; P = 0.085 vs LAM) and 29% (TDF + FTC; P = 0.037 vs LAM) of HBeAg+ patients. In HBeAg? patients, HBsAg loss was achieved in 11% (LAM), 27% (TDF; P = 0.263 vs LAM) and 36% (TDF + FTC; P = 0.05 vs LAM), respectively. Pretreatment CD4+ counts did not influence rates of HBeAg seroconversion and of HBsAg loss. Patients with HBsAg loss had lower baseline HBV‐DNA levels and higher AST/ALT levels than patients without HBsAg loss. Transient HAART‐related hepatotoxicity was found in 32% (Grade I: 21%; II:7%; III:2%; IV:0%). Most HBV–HIV‐coinfected patients achieve complete suppression of HBV replication despite high baseline viremia. TDF‐based HAART leads to high rates of HBeAg seroconversion and HBsAg loss after 5 years of continuous exposure. One‐third of HBV–HIV‐coinfected patients may experience transient HAART‐related hepatotoxicity.