Week 48 Resistance Analyses of the Once-Daily, Single-Tablet Regimen Darunavir/Cobicistat/Emtricitabine/Tenofovir Alafenamide (D/C/F/TAF) in Adults Living with HIV-1 from the Phase III Randomized AMBER and EMERALD Trials

HIV drug resistance in the era of contemporary antiretroviral therapy: A clinical perspective

Contemporary antiretroviral therapy (ART) regimens have high barriers to the development of drug resistance. However, resistance to earlier antiretrovirals and uncommon cases of resistance to contemporary ART illustrate the continued need for good clinical management of HIV drug resistance. Here, we describe HIV drug-resistance mechanisms, the interaction of HIV drug-resistant mutations and the patterns of drug resistance to contemporary ART. We then provide guidance on the management of HIV drug resistance, including how to limit the development of resistance and manage virologic failure that is complicated by resistance. To complement this, links to resources and treatment guidelines are provided that can assist with the interpretation of HIV drug resistance test results and optimal ART selection in the clinic.

A four-drug combination oral tablet of darunavir, cobicistat, emtricitabine, and tenofovir alafenamide for the treatment of HIV-1 infection in adults

INTRODUCTION

Darunavir (DRV)/cobicistat (COBI)/emtricitabine (FTC)/tenofovir alafenamide (TAF) is the only protease inhibitor-based single-tablet regimen (STR) approved for the treatment of HIV infection of adults and pediatric patients weighing at least 40 kg. DRV/COBI/FTC/TAF has demonstrated to be an effective regimen, to have a high genetic barrier to resistance, and to be well tolerated.

AREAS COVERED

The authors summarize the chemistry and pharmacology of DRV, COBI, FTC, and TAF and discuss trials conducted on antiretroviral therapy (ART)-naïve and -experienced people living with HIV designed to evaluate safety, tolerability, and efficacy of the STR. This work also reports studies comparing DRV/COBI/FTC/TAF with competitive agents in real-world settings.

EXPERT OPINION

Despite the availability of newer antiretroviral drugs and strategies in the management of HIV infection, including long-acting therapies, DRV/COBI/FTC/TAF is still considered an alternative regimen for the treatment of ART-naïve adults. DRV/COBI/FTC/TAF is an effective, well-tolerated, and safe antiretroviral regimen and represents a valid option for people who need to switch therapy due to tolerability issues, such as the onset of neuropsychiatric effects related to integrase strand transfer inhibitors, or virological failure.

Assessing the Virologic Impact of Archived Resistance in the Dolutegravir/Lamivudine 2-Drug Regimen HIV-1 Switch Study TANGO through Week 144

The TANGO study (ClinicalTrials.gov, NCT03446573) demonstrated that switching to dolutegravir/lamivudine (DTG/3TC) was non-inferior to continuing tenofovir alafenamide-based regimens (TBR) through week 144. Retrospective baseline proviral DNA genotypes were performed for 734 participants (post-hoc analysis) to assess the impact of archived, pre-existing drug resistance on 144-week virologic outcomes by last on-treatment viral load (VL) and Snapshot. A total of 320 (86%) participants on DTG/3TC and 318 (85%) on TBR had both proviral genotype data and ≥1 on-treatment post-baseline VL results and were defined as the proviral DNA resistance analysis population. Archived International AIDS Society-USA major nucleoside reverse transcriptase inhibitor, non-nucleoside reverse transcriptase inhibitor, protease inhibitor, and integrase strand transfer inhibitor resistance-associated mutations (RAMs) were observed in 42 (7%), 90 (14%), 42 (7%), and 11 (2%) participants, respectively, across both groups; 469 (74%) had no major RAMs at baseline. M184V/I (1%), K65N/R (<1%), and thymidine analogue mutations (2%) were infrequent. Through week 144, >99% of participants on DTG/3TC and 99% on TBR were virologically suppressed (last on-treatment VL <50 copies/mL) regardless of the presence of major RAMs. Results from the sensitivity analysis by Snapshot were consistent with the last available on-treatment VL. In TANGO, archived, pre-existing major RAMs did not impact virologic outcomes through week 144.

High efficacy of switching to bictegravir/emtricitabine/tenofovir alafenamide in people with suppressed HIV and preexisting M184V/I

OBJECTIVE

We investigated the prevalence of preexisting M184V/I and associated risk factors among clinical trial participants with suppressed HIV and evaluated the impact of M184V/I on virologic response after switching to bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF).

DESIGN

Participant data were pooled from six clinical trials investigating the safety and efficacy of switching to B/F/TAF in virologically suppressed people with HIV.

METHODS

Preexisting drug resistance was assessed by historical genotypes and/or baseline proviral DNA genotyping. Virologic outcomes were determined by last available on-treatment HIV-1 RNA. Stepwise selection identified potential risk factors for M184V/I in a multivariate logistic regression model.

RESULTS

Altogether, 2034 participants switched treatment regimens to B/F/TAF and had follow-up HIV-1 RNA data, and 1825 of these participants had baseline genotypic data available. Preexisting M184V/I was identified in 182 (10%), mostly by baseline proviral DNA genotype ( n  = 167). Most substitutions were M184V ( n  = 161) or M184V/I mixtures ( n  = 10). Other resistance substitutions were often detected in addition to M184V/I ( n  = 147). At last on-treatment visit, 98% (179/182) with preexisting M184V/I and 99% (2012/2034) of all B/F/TAF-treated participants had HIV-1 RNA less than 50 copies/ml, with no treatment-emergent resistance to B/F/TAF. Among adult participants, factors associated with preexisting M184V/I included other resistance, black race, Hispanic/Latinx ethnicity, lower baseline CD4 + cell count, advanced HIV disease, longer duration of antiretroviral therapy, and greater number of prior third agents.

CONCLUSION

M184V/I was detected in 10% of virologically suppressed clinical trial participants at study baseline. Switching to B/F/TAF demonstrated durable efficacy in maintaining viral suppression, including in those with preexisting M184V/I.

Real-World Adherence to Antiretroviral Therapy Among HIV-1 Patients Across the United States

Introduction

Recent changes in antiretroviral therapies (ARTs) may have affected medication adherence of people living with human immunodeficiency virus-1 (HIV-1). In this study adherence to ART regimens among patients with HIV-1 (PWH) across the US during a recent time period was examined and study findings were stratified by US region and state.

Methods

A retrospective observational study using the Symphony Health Solution Integrated Dataverse database was conducted. Patients ≥ 18 years of age who had a diagnosis of HIV-1 (without an HIV-2 diagnosis) and who were treated with ART between July 2017 and September 2018 (first pharmacy record: index date) were selected from the data source. Both patients who had not been previously treated with ART and those who were treatment experienced were included. Patients were required to have ≥ 1 medical/pharmacy record ≥ 12 months after their index date (follow-up period). Patient characteristics were examined during a 12-month pre-index period. During the follow-up, medication adherence, measured as the proportion of days covered (PDC), was examined for all patients and stratified by US region and state.

Results

Among 206,474 adult PWH treated with ART, mean age was 47.9 years, 73.4% were male, and 30.0% were Caucasian. The most prevalent comorbid conditions were hyperlipidemia (25.1%), depressive disorders (14.8%), and type 2 diabetes (12.1%). During the follow-up period, mean (standard deviation) PDC was 74.1% (25.9%) among PWH across the US [Midwest: 74.4% (25.5%); Northeast: 74.3% (26.1%); South: 73.2% (26.3%); West: 76.4% (24.8%)]. Across all US regions, > 60% of PWH had adherence < 90% and > 40% had adherence < 80%; the West had the highest adherent population.

Conclusions

Among PWH treated with ART across the US, a majority had suboptimal adherence. Implementation of strategies to improve ART adherence, including clinical consideration of ARTs with high genetic barriers to resistance, is needed in the US.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01883-8.

Week 96 resistance analyses of the once-daily, single-tablet regimen (STR) darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) in adults living with HIV-1 from the phase 3 randomized AMBER and EMERALD trials

In AMBER and EMERALD, darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) 800/150/200/10 mg demonstrated high virological response and low virological failure (VF) through week 96. Week 96 resistance analyses are presented. Post-baseline samples for genotyping/phenotyping were analyzed from protocol-defined-VFs with viral load (VL) ≥ 400 copies/ml at failure/later time points. Post-hoc analyses were deep sequencing (AMBER) and HIV-1 proviral DNA sequencing from baseline samples (VL < 50 copies/ml) (EMERALD). Through week 96 across studies, no darunavir, primary protease inhibitor (PI), or tenofovir resistance-associated-mutations (RAMs) occurred in patients continuing (N = 1125) or switching to D/C/F/TAF (N = 715). M184I/V (emtricitabine RAM) was detected in one patient in each arm of AMBER. In EMERALD D/C/F/TAF patients with prior VF and baseline genoarchive data (N = 98), 4% had darunavir RAMs, 36% emtricitabine RAMs, mainly at position 184 (32%), 4% tenofovir RAMs, and 19% ≥3 thymidine-analogue-associated-mutations at screening. The predicted phenotype showed 0% had reduced susceptibility to darunavir, 37% to emtricitabine, and 22% to tenofovir. All achieved VL < 50 copies/ml at week 96/prior discontinuation, with no VF. D/C/F/TAF has a high barrier to resistance; no darunavir, primary PI, or tenofovir RAMs occurred through 96 weeks in AMBER and EMERALD. In EMERALD, baseline archived darunavir, emtricitabine, and tenofovir RAMs in patients with prior VF did not preclude virologic response.

Week 96 subgroup analyses of the phase 3, randomized AMBER and EMERALD trials evaluating the efficacy and safety of the once daily darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) single-tablet regimen in antiretroviral treatment (ART)-naïve and -experienced, virologically-suppressed adults living with HIV-1

BACKGROUND

Darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) 800/150/200/10 mg was investigated in AMBER (treatment-naïve adults; NCT02431247) and EMERALD (treatment-experienced, virologically-suppressed adults; NCT02269917).

OBJECTIVE

To describe a Week 96 pre-planned subgroup analysis of D/C/F/TAF arms by demographic characteristics (age ≤/>50 years, gender, black/non-black race), and baseline clinical characteristics (AMBER: viral load [VL], CD4⁺ count, WHO clinical stage, HIV-1 subtype and antiretroviral resistance; EMERALD: prior virologic failure [VF], antiretroviral experience, screening boosted protease inhibitor [PI], and boosting agent).

METHODS

Patients in D/C/F/TAF and control arms could continue on/switch to D/C/F/TAF in a single-arm, open-label extension phase after Week 48 until Week 96. Efficacy endpoints were percentage cumulative confirmed VL ≥50 copies/mL (virologic rebound; EMERALD), and VL <50 (virologic response), or ≥50 copies/mL (VF) (FDA snapshot; both trials).

RESULTS

D/C/F/TAF demonstrated high Week 96 virologic responses (AMBER: 85% [308/362]; EMERALD: 91% [692/763]) and low VF rates (AMBER: 6% [20/362]; EMERALD: 1% [9/763]). In EMERALD, D/C/F/TAF showed low virologic rebound cumulative through Week 96 (3% [24/763]). Results were consistent across subgroups, including prior antiretroviral experience in EMERALD. No darunavir, primary PI, or tenofovir resistance-associated mutations were observed post-baseline. Study-drug-related serious adverse events (AEs) and AE-related discontinuations were <1% and 2%, respectively (both D/C/F/TAF arms), and similar across subgroups. eGFR_cyst and bone mineral density improved or were stable and lipids increased through Week 96 across demographic subgroups, with small changes in total-cholesterol/HDL-cholesterol ratio.

CONCLUSIONS

D/C/F/TAF was effective with a high barrier to resistance and bone/renal safety benefits, regardless of demographic or clinical characteristics for treatment-naïve and treatment-experienced, virologically-suppressed adults.

Week 96 results of a phase 3 trial of darunavir/cobicistat/emtricitabine/tenofovir alafenamide in treatment-naive HIV-1 patients

BACKGROUND

Darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) 800/150/200/10 mg was investigated through 96 weeks in AMBER (NCT02431247).

METHODS

Treatment-naive, HIV-1-positive adults [screening plasma viral load ≥1000 copies/ml; CD4 cell count >50 cells/μl) were randomized (1 : 1) to D/C/F/TAF (N = 362) or D/C plus emtricitabine/tenofovir-disoproxil-fumarate (F/TDF) (N = 363) over at least 48 weeks. After week 48, patients could continue on or switch to D/C/F/TAF in an open-label extension phase until week 96.

RESULTS

At week 96, D/C/F/TAF exposure was 626 patient-years (D/C/F/TAF arm) and 109 patient-years (control arm post switch), week 96 virologic suppression (viral load <50 copies/ml; FDA-Snapshot, from baseline) was 85.1% (308/362) (D/C/F/TAF) and 83.7% (304/363) (control). Week 96 virologic failure (viral load ≥50 copies/ml; FDA-Snapshot) was 5.5% (20/362) and 4.4% (16/363), respectively. No darunavir, primary protease inhibitor or tenofovir resistance-associated mutations (RAMs) were observed post baseline. In one patient in each arm, an M184I and/or V RAM was detected. Few adverse event-related discontinuations (3% D/C/F/TAF; <1% control post switch) and no deaths occurred on D/C/F/TAF. Improved renal and bone parameters were maintained in the D/C/F/TAF arm and observed in the control arm post switch. Increases in total-cholesterol/high-density-lipoprotein--cholesterol rtio at week 96 were +0.25 versus baseline (D/C/F/TAF) and +0.24 versus switch (control).

CONCLUSION

At week 96, D/C/F/TAF resulted in high virologic response and low virologic failure rates, with no resistance development to darunavir or TAF/TDF. Bone, renal and lipid safety were consistent with known D/C/F/TAF component profiles. Control arm safety post switch was consistent with the D/C/F/TAF arm. AMBER week 96 results confirm the efficacy, high barrier to resistance and bone/renal safety benefits of D/C/F/TAF for treatment-naive patients.