Selective resistance profiles emerging in patient-derived clinical isolates with cabotegravir, bictegravir, dolutegravir, and elvitegravir

Clearance of archived integrase strand transfer inhibitors resistance mutations in people with virologically suppressed HIV infection

Introduction

We assessed the kinetics of the clearance of integrase strand transfer inhibitors resistance mutations (INSTIs-RMs) and associated factors from people living with HIV (PWH) displaying suppressed viral replication after virological failure (VF) on an INSTI regimen.

Patients and methods

We included PWH with HIV-RNA viral loads ≤20 copies/mL for at least 5 years in whom INSTIs-RM had been identified at least once in a prior RNA resistance genotyping test. HIV DNAs were sequenced by Sanger sequencing (SS) and ultra-deep sequencing (UDS; detection threshold: 5%) every year over the preceding 5 years.

Results

We included 39 PWH in the study. Most (95%) had experienced VF on a raltegravir-containing regimen. The past INSTIs-RMs were not detected in the peripheral blood mononuclear cells of 35 of the 39 (90%) PWH by SS at the end of follow-up. In a longitudinal analysis (2017-21) based on UDS, the previously detected INSTIs-RMs were not detected in 29 of the 35 (83%) PWH. In multivariable analysis, the duration of viral replication and the level of HIV-RNA during prior VF were significantly associated with the persistence of INSTIs-RM, with odds ratios of 1.05 per week of replication (95% CI, 1.00-1.11; P = 0.024) and 8.26 per log10 copies/mL (95% CI, 1.46-46.59; P = 0.017).

Conclusions

We observed a clear trend towards the clearance of archived INSTIs-RM after a long period of virological control leading to changes in the resistance profile in cellular DNA, raising the possibility of studies assessing the recycling of INSTI classes even in the presence of a history of resistance.

Predictive Efficacy of Dual Therapies Combining Integrase Strand Transfer Inhibitors with Second-Generation Non-Nucleoside Reverse Transcriptase Inhibitors Following HIV-1 Treatment Failure in Cameroon: Implications for the Use of a Long-Acting Therapeutic Strategy in Low- and Middle-Income Countries

Dual therapies (DT) combining integrase strand transfer inhibitors (INSTIs) with second-generation non-nucleoside reverse transcriptase inhibitors (2nd-Gen-NNRTIs) offer new possibilities for HIV treatment to improve adherence. However, drug resistance associated mutations (RAMs) to prior antiretrovirals may jeopardize the efficacy of DT. We herein describe the predicted efficacy of DT combining INSTIs + 2nd-Gen-NNRTI following treatment failure among Cameroonian patients. We genotyped the HIV-1 pol gene using Sanger sequencing and assessed acquired RAMs to NNRTIs and INSTIs in patients failing treatment from March 2019 to December 2023. Drug susceptibility was interpreted using Stanford HIVdb v9.5, and statistical analyses were performed using SPSS v22. Of 130 successfully genotyped participants (median age (IQR): 38 (27-46) years; 59.2% female), 92.3% had RAMs to NNRTIs and 1.5% to INSTIs. Prevailing RAMs were Y181C (32.3%) among NNRTIs and R263K (0.7%) among INSTIs. Among 2nd-Gen-NNRTIs, etravirine, doravirine and rilpivirine had 43.85%, 41.54% and 38.46% genotypic sensitivity, respectively. Among INSTIs, we found 97.69% efficacy for dolutegravir/bictegravir, 96.15% for cabotegravir and 92.31% for elvitegravir/raltegravir. The overall predictive efficacy of DT was lower among participants who failed 1st-Gen-NNRTI (p < 0.001); with etravirine + dolutegravir/bictegravir combination showing the highest score (43.8%). Conclusively, DT combining INSTIs + 2nd-Gen-NNRTIs might be suboptimal in the context of previous ART failure, especially with NNRTI-based treatment in low- and middle-income countries. The general data clearly indicate that without resistance testing, it is nearly impossible to use long-acting dual therapies in previously failing patients.

Low prevalence of archived integrase strand transfer inhibitors resistance associated mutations in Botswana before the roll out of dolutegravir based first line antiretroviral therapy

Background

We evaluated the prevalence of archived proviral drug resistance mutations (DRMs) associated with resistance to integrase strand transfer inhibitors (INSTIs) shortly before Botswana transitioned in 2016 to using dolutegravir (DTG)-based antiretroviral treatment in first-line regimens.

Methods

We used the Stanford University HIV drug resistance database to analyze INSTI-resistance associated mutations (RAMs) in a large representative population-based cohort of adults recruited in 30 geographically dispersed communities as part of the Botswana Combination Prevention Project (BCPP) cohort from 2013 to 2018. A total of 5,144 HIV-1 proviral DNA sequences were included in our analysis; 1,281 sequences were from antiretroviral therapy (ART)-naïve individuals and 3,863 sequences were from non-nucleoside reverse transcriptase inhibitor (NNRTI) ART-experienced individuals. None of the sequences were from DTG-ART experienced participants.

Results

The overall prevalence of major INSTIs DRMs was 1.11% (95% CI 0.82-1.39%). The prevalence of INSTI DRMs in ART-naïve individuals was 1.64% (21/1,281) and 0.93% (36/3,863) in ART-experienced individuals. Major INSTI-RAMs detected in ART-naïve individuals were E138K (2/1,281; 0.16%), G140R (8/1,281;0.62%), E92G (2/1,281;0.16%), R263K (5/1,281; 0.4%), N155H (1/1,281; 0.08%), P145S (1/1,281;0.008%). Among the ART-experienced individuals, major INSTI RAMs detected were E138K (4/3,863; 0.10%), G140R (25/3,863;0.65%), G118R (2/3,863, 0.05%), R263K (4/3,863, 0.10%), T66I (1/3,863;0.03%), E138K + G140R (1/3,863, 0.03%|), G140R + R263K (1/3,863, 0.03%). High-level resistance to cabotegravir (CAB), elvitegravir (EVG), and raltegravir (RAL) was detected in 0.70, 0.16 and 0.06% of the individuals, respectively. Notably, bictegravir (BIC) and dolutegravir (DTG) showed no high-level resistance.

Conclusion

The overall prevalence of archived INSTI RAMs in Botswana was low prior to transitioning to first-line DTG-based ART regimens, and did not differ between ART-naïve and ART-experienced individuals. Ongoing surveillance of INSTI DRMs in Botswana will allow for re-assessment of INSTI resistance risk following nationwide DTG rollout.

Comprehensive database of HIV mutations selected during antiretroviral in vitro passage experiments

BACKGROUND

In vitro passage experiments are crucial to the development of antiretroviral (ARV) drugs.

METHODS

We created an online database containing data from 102 published studies in which HIV-1 or HIV-2 was cultured with increasing concentrations of the FDA-approved nucleoside RT inhibitors (NRTIs), nonnucleoside RT inhibitors (NNRTIs), integrase strand transfer inhibitors (INSTIs), protease inhibitors (PIs), capsid inhibitor (CAI) lenacapavir, and nucleoside RT translocation inhibitor (NRTTI) islatravir. We summarized the mutations selected in the subset of passage experiments with NRTIs lamivudine (3TC), emtricitabine (FTC), abacavir (ABC), tenofovir (TFV), and zidovudine (AZT), NNRTIs doravirine (DOR), efavirenz (EFV), and rilpivirine (RPV), INSTIs bictegravir (BIC), cabotegravir (CAB), and dolutegravir (DTG), and PIs atazanavir (ATV), darunavir (DRV), and lopinavir (LPV). Mutations selected in vitro were compared with those selected in persons receiving the same ARV.

RESULTS

Twenty-seven studies described 89 experiments of wildtype isolates passaged with 3TC, FTC, ABC, TFV, or AZT; sixteen studies described 89 experiments passaged with EFV, RPV, or DOR; eleven studies described 76 experiments passaged with the INSTIs BIC, CAB, or DTG; six studies described 33 experiments passaged with ATV, LPV, or DRV. With several exceptions, mutations selected in two or more experiments were among the most common mutations selected in persons receiving the same ARV.

CONCLUSIONS

We created a database of published ARV in vitro selection experiments. Mutations emerging from these experiments generally predict those observed in persons receiving the same ARV. However, there are notable differences in mutation frequencies between in vitro and in vivo settings.

The Management of Hematopoietic Stem Cell Transplant in People with HIV

Hematopoietic stem cell transplant (HSCT) is now recognized as a standard treatment option for people with HIV (PWH) who develop high-risk hematologic malignancies. However, the involved polypharmacy can lead to complications from drug interactions and toxicities, affecting the efficacy and safety of chemotherapy and antiretroviral therapy (ART). Managing these patients requires a personalized approach, including the careful selection of ART based on previous therapies and potential interactions, alongside risk assessment for infections. This discussion will address the history of HSCT in PWH and management considerations for this group.

Decoupling HIV-1 antiretroviral drug inhibition from plasma antibody activity to evaluate broadly neutralizing antibody therapeutics and vaccines

The development of broadly neutralizing antibody (bnAb)-based therapeutic HIV-1 vaccines and cure concepts depends on monitoring bnAb plasma activity in people with HIV (PWH) on suppressive antiretroviral therapy (ART). To enable this, analytical strategies must be defined to reliably distinguish antibody-based neutralization from drug inhibition. Here, we explore strategies that either utilize drug-resistant viruses or remove drugs from plasma. We develop ART-DEX (ART dissociation and size exclusion), an approach which quantitatively separates drugs from plasma proteins following pH-triggered release allowing accurate definition of antibody-based neutralization. We demonstrate that ART-DEX, alone or combined with ART-resistant viruses, provides a highly effective and scalable means of assessing antibody neutralization during ART. Implementation of ART-DEX in standard neutralization protocols should be considered to enhance the analytical capabilities of studies evaluating bnAb therapeutics and therapeutic vaccines, furthering the development of advanced ART and HIV-1 cure strategies.

HIV-1 transmitted drug resistance in newly diagnosed individuals in Italy over the period 2015-21

BACKGROUND

Transmitted drug resistance (TDR) is still a critical aspect for the management of individuals living with HIV-1. Thus, its evaluation is crucial to optimize HIV care.

METHODS

Overall, 2386 HIV-1 protease/reverse transcriptase and 1831 integrase sequences from drug-naïve individuals diagnosed in north and central Italy between 2015 and 2021 were analysed. TDR was evaluated over time. Phylogeny was generated by maximum likelihood. Factors associated with TDR were evaluated by logistic regression.

RESULTS

Individuals were mainly male (79.1%) and Italian (56.2%), with a median (IQR) age of 38 (30-48). Non-B infected individuals accounted for 44.6% (N = 1065) of the overall population and increased over time (2015-2021, from 42.1% to 51.0%, P = 0.002). TDR prevalence to any class was 8.0% (B subtype 9.5% versus non-B subtypes 6.1%, P = 0.002) and remained almost constant over time. Overall, 300 transmission clusters (TCs) involving 1155 (48.4%) individuals were identified, with a similar proportion in B and non-infected individuals (49.7% versus 46.8%, P = 0.148). A similar prevalence of TDR among individuals in TCs and those out of TCs was found (8.2% versus 7.8%, P = 0.707).By multivariable analysis, subtypes A, F, and CFR02_AG were negatively associated with TDR. No other factors, including being part of TCs, were significantly associated with TDR.

CONCLUSIONS

Between 2015 and 2021, TDR prevalence in Italy was 8% and remained almost stable over time. Resistant strains were found circulating regardless of being in TCs, but less likely in non-B subtypes. These results highlight the importance of a continuous surveillance of newly diagnosed individuals for evidence of TDR to inform clinical practice.

N-Substituted Bicyclic Carbamoyl Pyridones: Integrase Strand Transfer Inhibitors that Potently Inhibit Drug-Resistant HIV-1 Integrase Mutants

HIV-1 integrase (IN) is an important molecular target for the development of anti-AIDS drugs. A recently FDA-approved second-generation integrase strand transfer inhibitor (INSTI) cabotegravir (CAB, 2021) is being marketed for use in long-duration antiviral formulations. However, missed doses during extended therapy can potentially result in persistent low levels of CAB that could select for resistant mutant forms of IN, leading to virological failure. We report a series of N-substituted bicyclic carbamoyl pyridones (BiCAPs) that are simplified analogs of CAB. Several of these potently inhibit wild-type HIV-1 in single-round infection assays in cultured cells and retain high inhibitory potencies against a panel of viral constructs carrying resistant mutant forms of IN. Our lead compound, 7c, proved to be more potent than CAB against the therapeutically important resistant double mutants E138K/Q148K (>12-fold relative to CAB) and G140S/Q148R (>36-fold relative to CAB). A significant number of the BiCAPs also potently inhibit the drug-resistant IN mutant R263K, which has proven to be problematic for the FDA-approved second-generation INSTIs.

Preliminary report of transmitted drug resistance to integrase strand chain transfer inhibitors in treatment-naïve HIV infected patients

Transmitted Resistance exists in a newly diagnosed person who has not yet started their treatment. Our objective was to obtain a profile of HIV-1 resistance to integrase inhibitors in newly diagnosed treatment-naïve patients. Fifty people newly diagnosed with HIV-1 infection who had never received antiretroviral treatment were recruited. The complete integrase gene was amplified by nested RTPCR and the sequences obtained were analyzed with the ReCall and HIVdb v9.0. The overall prevalence transmitted due to mutations with some impact on integrase strand transfer inhibitors (INSTI) activity during the study period was 8%. The major E138K mutation was detected in only 1 patient and the secondary G163R mutation was detected in the other 3. The transmitted resistance for the first generation INSTI was 8% and for the second generation it was 0%. In Chile the resistance transmitted to INSTI is low and it is in according values detect in other part of the world.

Clair M, Polli JW, Vanveggel S, Vandermeulen K, D’Amico R, Garges HP, Zolopa A, Spreen WR, van Wyk J, Cutrell AG. Expanded Multivariable Models to Assist Patient Selection for Long-Acting Cabotegravir + Rilpivirine Treatment: Clinical Utility of a Combination of Patient, Drug Concentration, and Viral Factors Associated With Virologic Failure

BACKGROUND

Previously reported post hoc multivariable analyses exploring predictors of confirmed virologic failure (CVF) with cabotegravir + rilpivirine long-acting (CAB + RPV LA) were expanded to include data beyond week 48, additional covariates, and additional participants.

METHODS

Pooled data from 1651 participants were used to explore dosing regimen (every 4 or every 8 weeks), demographic, viral, and pharmacokinetic covariates as potential predictors of CVF. Prior dosing regimen experience was accounted for using 2 populations. Two models were conducted in each population-baseline factor analyses exploring factors known at baseline and multivariable analyses exploring baseline factors plus postbaseline model-predicted CAB/RPV trough concentrations (4 and 44 weeks postinjection). Retained factors were evaluated to understand their contribution to CVF (alone or in combination).

RESULTS

Overall, 1.4% (n = 23/1651) of participants had CVF through 152 weeks. The presence of RPV resistance-associated mutations, human immunodeficiency virus-1 subtype A6/A1, and body mass index ≥30 kg/m2 were associated with an increased risk of CVF (P < .05 adjusted incidence rate ratio), with participants with ≥2 of these baseline factors having a higher risk of CVF. Lower model-predicted CAB/RPV troughs were additional factors retained for multivariable analyses.

CONCLUSIONS

The presence of ≥2 baseline factors (RPV resistance-associated mutations, A6/A1 subtype, and/or body mass index ≥30 kg/m2) was associated with increased CVF risk, consistent with prior analyses. Inclusion of initial model-predicted CAB/RPV trough concentrations (≤first quartile) did not improve the prediction of CVF beyond the presence of a combination of ≥2 baseline factors, reinforcing the clinical utility of the baseline factors in the appropriate use of CAB + RPV LA.

Treatment-emergent reverse transcriptase resistance during antiretroviral therapy with bictegravir, tenofovir alafenamide, and emtricitabine: A case series

OBJECTIVES

Bictegravir/tenofovir alafenamide/emtricitabine (BIC/TAF/FTC) is a complete regimen for the treatment of HIV with a high barrier to resistance and few reported cases of treatment failure. We present three cases of treatment-emergent resistance to nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) in patients with suboptimal treatment adherence and assess whether the resistance-associated mutations were present before BIC/TAF/FTC initiation or emerged during therapy.

METHODS

We used genotypic drug resistance testing by Sanger sequencing to identify emergent resistance mutations in plasma viral load specimens collected after combination antiretroviral therapy initiation in all participants. Additionally, we performed ultra-deep sequencing by Illumina MiSeq on the earliest available plasma HIV-1 viral load specimen and on any available specimens closest in time to the initiation of BIC/TAF/FTC therapy to identify low-abundance resistance mutations present in the viral quasispecies.

RESULTS

All three participants developed NRTI resistance after prolonged exposure and incomplete adherence to BIC/TAF/FTC. The T69N, K70E, M184I, and/or T215I mutations identified in clinical samples at the time of virological failure were not present on deep sequencing of either baseline samples or samples collected before BIC/TAF/FTC initiation.

CONCLUSIONS

Despite a generally high genetic barrier to resistance, NRTI resistance-associated mutations may emerge during therapy with BIC/TAF/FTC in the setting of suboptimal adherence.

A National HIV Provider Survey of Antiretroviral Therapy Preferences for Management of Treatment-Naive and Experienced Individuals With Drug Resistance

Background

HIV clinical practice guidelines outline broad treatment principles but offer less explicit recommendations by permutations of encountered viral resistance. We hypothesize that there is variability in antiretroviral (ARV) regimen decision making among providers when considering HIV drug resistance (HIVDR).

Methods

US HIV providers provided ARV regimen recommendations for case vignettes in a series of electronic surveys encompassing variations of HIVDR. Responses were characterized by drugs and classes selected and anticipated activity based on genotypic susceptibility. Heterogeneity was defined as the proportion of unique ARV regimens from total responses.

Results

An overall 119 providers from the United States participated. Among case vignettes with isolated M184V and viremia, 85.9% selected a regimen with 2 nucleoside reverse transcriptase inhibitors (NRTIs) + integrase strand transfer inhibitor (INSTI); 9.9% selected regimens with >3 ARVs. Alternatively, in scenarios of viremia with moderate to high-level NRTI resistance, >50% of providers selected an NRTI-sparing regimen, while a minority recommended 2 NRTIs + INSTI (21/123, 17%). In moderate to high-level INSTI resistance, there was response heterogeneity, with no common unifying approach to management (127 unique regimens/181 responses, 70% heterogeneity). Providers used cabotegravir/rilpivirine for treatment simplification in suppressed cases, despite a history of treatment failure (37/205, 36%).

Conclusions

Our national survey of US HIV providers revealed a consensus to management of HIV resistance with potential alternative options in cases with low heterogeneity. Providers selected cabotegravir/rilpivirine as a viable treatment simplification strategy in suppressed cases with a history of treatment failure. The responses to the case vignettes could be used an education tool for ARV decision making in HIVDR.

The New Era of Long-Acting Antiretroviral Therapy: When and Why to Make the Switch

PURPOSE OF REVIEW

Despite the availability of safe and effective oral combination antiretroviral therapy, barriers to maintaining viral suppression remain a challenge to ending the HIV epidemic. Long-acting injectable antiretroviral therapy was developed as an alternative to daily oral therapy. This review summarizes the current literature on the efficacy of long-acting cabotegravir plus rilpivirine for the treatment of HIV-1, reasons to switch to injectable therapy, and barriers to switching.

RECENT FINDINGS

Long-acting cabotegravir plus rilpivirine is safe and effective in maintaining HIV-1 virologic suppression. Ideal candidates for switching to long-acting cabotegravir plus rilpivirine are virologically suppressed on oral regimens with good adherence and no history of virologic failure or baseline resistance. Indications to switch to injectable therapy include patient preference, the potential for improved adherence, and avoidance of adverse effects. Implementation research is needed to assess and overcome system barriers. Long-acting cabotegravir plus rilpivirine is a novel alternative to oral antiretrovirals, with the potential to improve adherence and quality of life in people with HIV.

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.

Doravirine responses to HIV-1 viruses bearing mutations to NRTIs and NNRTIs under in vitro selective drug pressure

OBJECTIVES

The NNRTI doravirine has been recently approved for the first-line treatment of HIV-infected patients, eliciting favourable responses against viruses bearing the K103N, Y181C and G190A mutations. This study used in vitro drug selections to elaborate the breadth of doravirine responses against viruses bearing NNRTI and NRTI resistance-associated mutations (RAMs).

METHODS

WT clinical isolates (n = 6) and viruses harbouring common NRTI and NNRTI RAMs (n = 6) were serially passaged in escalating concentrations of doravirine, doravirine/islatravir, doravirine/lamivudine and rilpivirine over 24 weeks. Genotypic analysis ascertained the appearance and accumulation of NNRTI RAMs. Phenotypic drug susceptibility assays assessed resistance conferred by acquired NNRTI RAMs.

RESULTS

For WT viruses, doravirine pressure led to the appearance of V108I or V106A/I/M RAMs after 8 weeks, conferring low-level (∼2-fold) resistance. After 24 weeks, the accumulation of three to six secondary RAMs, including F227L, M230L, L234I and/or Y318, resulted in high-level (>100-fold) resistance to doravirine. Notably, viruses with these doravirine RAMs remained susceptible to rilpivirine and efavirenz. This contrasted with rilpivirine where acquisition of E138K, L100I and/or K101E resulted in >50-fold cross-resistance to all NNRTIs. Doravirine selection of viruses bearing common NRTI and NNRTI RAMs showed delayed acquisition of RAMs compared with WT virus. Pairing doravirine with islatravir or lamivudine attenuated the development of NNRTI RAMs.

CONCLUSIONS

Doravirine showed favourable resistance profiles against viruses harbouring NRTI and NNRTI RAMs. The high barrier to resistance to doravirine coupled with the long intracellular half-life of islatravir may provide the opportunity for long-acting treatment options.

The G118R plus R263K Combination of Integrase Mutations Associated with Dolutegravir-Based Treatment Failure Reduces HIV-1 Replicative Capacity and Integration

Human immunodeficiency virus (HIV) treatment with antiretroviral regimens containing integrase strand transfer inhibitors such as dolutegravir (DTG) and bictegravir (BIC) offers high levels of protection against the development of drug resistance mutations. Despite this, resistance to DTG and BIC can occur through the development of the R263K integrase substitution. Failure with DTG has also been associated with the emergence of the G118R substitution. G118R and R263K are usually found separately but have been reported together in highly treatment-experienced persons who experienced treatment failure with DTG. We used cell-free strand transfer and DNA binding assays and cell-based infectivity, replicative capacity, and resistance assays to characterize the G118R plus R263K combination of integrase mutations. R263K reduced DTG and BIC susceptibility ~2-fold, in agreement with our previous work. Single-cycle infectivity assays showed that G118R and G118R plus R263K conferred ~10-fold resistance to DTG. G118R alone conferred low levels of resistance to BIC (3.9-fold). However, the G118R plus R263K combination conferred high levels of resistance to BIC (33.7-fold), likely precluding the use of BIC after DTG failure with the G118R plus R263K combination. DNA binding, viral infectivity, and replicative capacity of the double mutant were further impaired, compared to single mutants. We propose that impaired fitness helps to explain the scarcity of the G118R plus R263K combination of integrase substitutions in clinical settings and that immunodeficiency likely contributes to its development.

Dose-Ranging Plasma and Genital Tissue Pharmacokinetics and Biodegradation of Ultra-Long-Acting Cabotegravir In Situ Forming Implant

HIV continues to affect millions of men and women worldwide. The development of long-acting injectables for HIV prevention can overcome adherence challenges with daily oral prevention regimens by reducing dosing frequency and stigma. We previously developed an ultra-long-acting injectable, biodegradable, and removeable in situ forming implant (ISFI) with cabotegravir (CAB) that demonstrated protection after multiple rectal SHIV challenges in female macaques. Here, we sought to further characterize CAB ISFI pharmacokinetics (PK) in mice by assessing the effect of dose and number of injections on CAB PK, time to completion of CAB release and polymer degradation, long-term genital tissue PK, and CAB PK tail after implant removal. CAB concentrations in plasma were above the benchmark for protection for 11-12 months with proportionality between dose and drug exposure. CAB ISFI exhibited high concentrations in vaginal, cervical, and rectal tissues for up to 180 days. Furthermore, depots were easily retrievable up to 180 days post-administration with up to 34% residual CAB and near complete (85%) polymer degradation quantified in depots ex vivo. After depot removal, results demonstrated a median 11-fold decline in CAB plasma concentrations across all doses. Ultimately, this study provided critical PK information for the CAB ISFI formulation that could aid in its future translation to clinical studies.

A computational overview of integrase strand transfer inhibitors (INSTIs) against emerging and evolving drug-resistant HIV-1 integrase mutants

AIDS (Acquired immunodeficiency syndrome) is one of the chronic and potentially life-threatening epidemics across the world. Hitherto, the non-existence of definitive drugs that could completely cure the Human immunodeficiency virus (HIV) implies an urgent necessity for the discovery of novel anti-HIV agents. Since integration is the most crucial stage in retroviral replication, hindering it can inhibit overall viral transmission. The 5 FDA-approved integrase inhibitors were computationally investigated, especially owing to the rising multiple mutations against their susceptibility. This comparative study will open new possibilities to guide the rational design of novel lead compounds for antiretroviral therapies (ARTs), more specifically the structure-based design of novel Integrase strand transfer inhibitors (INSTIs) that may possess a better resistance profile than present drugs. Further, we have discussed potent anti-HIV natural compounds and their interactions as an alternative approach, recommending the urgent need to tap into the rich vein of indigenous knowledge for reverse pharmacology. Moreover, herein, we discuss existing evidence that might change in the near future.

Ultra-long-acting in-situ forming implants with cabotegravir protect female macaques against rectal SHIV infection

Ultra-long-acting delivery platforms for HIV pre-exposure prophylaxis (PrEP) may increase adherence and maximize public health benefit. We report on an injectable, biodegradable, and removable in-situ forming implant (ISFI) that is administered subcutaneously and can release the integrase inhibitor cabotegravir (CAB) above protective benchmarks for more than 6 months. CAB ISFIs are well-tolerated in female mice and female macaques showing no signs of toxicity or chronic inflammation. In macaques, median plasma CAB concentrations exceed established PrEP protection benchmarks within 3 weeks and confer complete protection against repeated rectal SHIV challenges. Implant removal via a small incision in 2 macaques at week 12 results in a 7- to 48-fold decrease in plasma CAB levels within 72 hours. Modeling to translate CAB ISFI dosing suggests that a 3 mL injection would exceed protective benchmarks in humans for over 5 months post administration. Our results support the clinical advancement of CAB ISFIs for ultra-long-acting PrEP in humans.

Investigational drugs for HIV: trends, opportunities and key players

INTRODUCTION

Since the first antiretroviral drug was described, the field of HIV treatment and prevention has undergone two drug-based revolutions: the first one, enabled by the virtually concomitant discovery of non-nucleoside reverse transcriptase and protease inhibitors, was the inception of combined antiretroviral therapy. The second followed the creation of integrase strand-transfer inhibitors with improved safety, potency, and resistance profiles. Long-acting antiretroviral drugs, including broadly neutralizing antibodies, now offer the opportunity for a third transformational change in HIV management.

AREAS COVERED

Our review focused on HIV treatment and prevention with investigational drugs that offer the potential for infrequent dosing, including drugs not yet approved for clinical use. We also discussed approved drugs for which administration modalities or formulations are being optimized. We performed a literature search in published manuscripts, conference communications, and registered clinical trials.

EXPERT OPINION

While the field focuses on extending dosing intervals, we identify drug tissue penetration as an understudied opportunity to improve HIV care. We repeat that self-administration remains an essential milestone to reach the full potential of long-acting drugs. Treatments and prevention strategies based on broadly neutralizing antibodies require a deeper understanding of their antiretroviral properties.

Safety and efficacy of long-acting intramuscular cabotegravir and rilpivirine in adults with HIV-1 infection: a systematic review and meta-analysis protocol

BACKGROUND

Current antiretroviral regimens have, for the most part, achieved optimal antiretroviral efficacy and tolerability, transforming HIV infection from a deadly disease into a manageable chronic condition. However, adherence to daily oral drug intake remains an issue, as it is the most important determinant for sustained viral suppression and prevention of the emergence of drug-resistant viral strains. The long-acting injection antiretroviral cabotegravir and rilpivirine combination, a novel drug delivery approach, is about to revolutionise the therapy for people living with HIV. In this protocol, we aim to generate a clinically useful summary of the interventions based on their efficacy.

METHODS AND ANALYSIS

We searched the literature for eligible studies published from inception up to 16 August 2022 through PubMed, EMBASE, Cochrane Library, Scopus and ClinicalTrials.gov. Two methodologically trained researchers will select the qualified studies for data extraction independently. Cochrane Risk of Bias tool will be used to assess the risk of bias in included studies. Statistical heterogeneity will be computed by Cochrane X² and I² tests. Sensitivity analysis will be conducted to evaluate the stability of the results. Publication biases will be evaluated by Begg's and Egger's tests. The quality of evidence will be assessed by the Grading of Recommendations Assessment, Development and Evaluation system. The RevMan V.5.3 and Stata V.14.0 software will be applied for statistical analyses.

ETHICS AND DISSEMINATION

Ethical approval will not be required for this systematic review because the data used are not linked to the individual patient. The results of this review will be disseminated by being published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42022310414.

Relative cost-effectiveness of long-acting injectable cabotegravir versus oral pre-exposure prophylaxis in South Africa based on the HPTN 083 and HPTN 084 trials: a modelled economic evaluation and threshold analysis

BACKGROUND

Long-acting injectable cabotegravir, a drug taken every 2 months, has been shown to be more effective at preventing HIV infection than daily oral tenofovir disoproxil fumarate and emtricitabine, but its cost-effectiveness in a high-prevalence setting is not known. We aimed to estimate the incremental cost-effectiveness of long-acting injectable cabotegravir compared with tenofovir disoproxil fumarate and emtricitabine in South Africa, using methods standard to government planning, and to determine the threshold price at which long-acting injectable cabotegravir is as cost-effective as tenofovir disoproxil fumarate and emtricitabine.

METHODS

In this modelled economic evaluation and threshold analysis, we updated a deterministic model of the South African HIV epidemic with data from the HPTN 083 and HPTN 084 trials to evaluate the effect of tenofovir disoproxil fumarate and emtricitabine and long-acting injectable cabotegravir provision to heterosexual adolescents and young women and men aged 15-24 years, female sex workers, and men who have sex with men. We estimated the average intervention cost, in 2021 US$, using ingredients-based costing, and modelled the cost-effectiveness of two coverage scenarios (medium or high, assuming higher uptake of long-acting injectable cabotegravir than tenofovir disoproxil fumarate and emtricitabine throughout) and, for long-acting injectable cabotegravir, two duration subscenarios (minimum: same pre-exposure prophylaxis duration as for tenofovir disoproxil fumarate and emtricitabine; maximum: longer duration than tenofovir disoproxil fumarate and emtricitabine) over 2022-41.

FINDINGS

Across long-acting injectable cabotegravir scenarios, 15-28% more new HIV infections were averted compared with the baseline scenario (current tenofovir disoproxil fumarate and emtricitabine roll-out). In scenarios with increased coverage with oral tenofovir disoproxil fumarate and emtricitabine, 4-8% more new HIV infections were averted compared with the baseline scenario. If long-acting injectable cabotegravir drug costs were equal to those of tenofovir disoproxil fumarate and emtricitabine for the same 2-month period, the incremental cost of long-acting injectable cabotegravir to the HIV programme was higher than that of tenofovir disoproxil fumarate and emtricitabine (5-10% vs 2-4%) due to higher assumed uptake of long-acting injectable cabotegravir. The cost per infection averted was $6053-6610 (tenofovir disoproxil fumarate and emtricitabine) and $4471-6785 (long-acting injectable cabotegravir). The cost per long-acting cabotegravir injection needed to be less than twice that of a 2-month supply of tenofovir disoproxil fumarate and emtricitabine to remain as cost-effective, with threshold prices ranging between $9·03 per injection (high coverage; maximum duration) and $14·47 per injection (medium coverage; minimum duration).

INTERPRETATION

Long-acting injectable cabotegravir could potentially substantially change HIV prevention. However, for its implementation to be financially feasible across low-income and middle-income countries with high HIV incidence, long-acting injectable cabotegravir must be reasonably priced.

FUNDING

United States Agency for International Development, The Bill & Melinda Gates Foundation.

Genotypic correlates of resistance to the HIV-1 strand transfer integrase inhibitor cabotegravir

Cabotegravir (CAB) is an integrase strand transfer inhibitor (INSTI) formulated as a long-acting injectable drug approved for pre-exposure prophylaxis and use with a long acting rilpivirine formulation for therapy in patients with virological suppression. However, there has been no comprehensive review of the genetic mechanisms of CAB resistance. Studies reporting the selection of drug resistance mutations (DRMs) by CAB and the results of in vitro CAB susceptibility testing were reviewed. The impact of integrase mutations on CAB susceptibility was assessed using regularized regression analysis. The most commonly selected mutations in the 24 persons developing virological failure while receiving CAB included Q148R (n = 15), N155H (n = 7), and E138K (n = 5). T97A, G118R, G140 A/R/S, and R263K each developed in 1-2 persons. With the exception of T97A, G118R, and G140 A/R, these DRMs were also selected in vitro while G140R was selected in the SIV macaque model. Although these DRMs are similar to those occurring in persons receiving the related INSTI dolutegravir, Q148R was more likely to occur with CAB while G118R and R263K were more likely to occur with dolutegravir. Regularized regression analysis identified 14 DRMs significantly associated with reduced CAB susceptibility including six primary DRMs which reduced susceptibility on their own including G118R, Q148 H/K/R, N155H, and R263K, and eight accessory DRMs including M50I, L74 F/M, T97A, E138K, and G140 A/C/S. Isolates with Q148 H/K/R in combination with L74M, E138 A/K, G140 A/S, and N155H often had >10-fold reduced CAB susceptibility. M50I, L74M, and T97A are polymorphic mutations that alone did not appear to increase the risk of virological failure in persons receiving a CAB-containing regimen. Careful patient screening is required to prevent CAB from being used during active virus replication. Close virological monitoring is required to minimize CAB exposure to active replication to prevent the emergence of DRMs associated with cross-resistance to other INSTIs.

Long-Acting Injectable Cabotegravir for HIV Prevention: What Do We Know and Need to Know about the Risks and Consequences of Cabotegravir Resistance?

PURPOSE OF REVIEW

Cabotegravir is a potent integrase strand transfer inhibitor (INSTI) recently approved as a long-acting injectable formulation for HIV prevention (CAB-LA). We summarize what is known about cabotegravir pharmacokinetics, activity, and emergence of resistance from in vitro, macaque and clinical studies, and we evaluate the risk of resistance from CAB-LA with on-time injections and after CAB-LA discontinuation.

RECENT FINDINGS

The accumulation of multiple INSTI mutations is required for high-level cabotegravir resistance, and the same mutation combinations may cause cross-resistance to dolutegravir, which is widely used for first-line antiretroviral therapy in low- and middle-income countries. Though CAB-LA was highly effective in preventing HIV, breakthrough infections did occur in trials of CAB-LA despite on-time injections, resulting in selection of single and combinations of INSTI resistance mutations. As CAB-LA is scaled-up, prompt HIV diagnosis to prevent resistance, and resistance monitoring could help preserve the effectiveness of INSTIs for both HIV treatment and prevention.

HIV-1 subtype F integrase polymorphisms external to the catalytic core domain contribute to severe loss of replication capacity in context of the integrase inhibitor resistance mutation Q148H

BACKGROUND

In prior studies, HIV-1 BF recombinants with subtype F integrases failed to develop resistance to raltegravir through the Q148H mutational pathway. We aimed to determine the role of subtype-specific polymorphisms in integrase on drug susceptibility, viral replication and integration.

METHODS

Integrase sequences were retrieved from the Los Alamos Database or obtained from the Garrahan HIV cohort. HIV-1 infectious molecular clones with or without Q148H (+ G140S) resistance mutations were constructed using integrases of subtype B (NL4-3) or F1(BF) ARMA159 and URTR23. Integrase chimeras were generated by reciprocal exchanges of a 200 bp fragment spanning amino acids 85-150 of the catalytic core domain (CCD) of NL4-3-Q148H and either ARMA159-Q148H or URTR23-Q148H. Viral infections were quantified by p24 ELISA and Alu-gag integration PCR assay.

RESULTS

At least 18 different polymorphisms distinguish subtype B from F1(BF) recombinant integrases. In phenotypic experiments, p24 at Day 15 post-infection was high (105-106 pg/mL) for WT and NL4-3-Q148H; by contrast, it was low (102-104 pg/mL) for both F1(BF)-Q148H + G140S viruses, and undetectable for the Q148H mutants. Compared with WT viruses, integrated DNA was reduced by 5-fold for NL4-3-Q148H (P = 0.05), 9-fold for URTR23-Q148H (P = 0.01) and 16000-fold for ARMA159-Q148H (P = 0.01). Reciprocal exchange between B and F1(BF) of an integrase CCD region failed to rescue the replicative defect of F1(BF) integrase mutants.

CONCLUSIONS

The functional impairment of Q148H in the context of subtype F integrases from BF recombinants explains the lack of selection of this pathway in vivo. Non-B polymorphisms external to the integrase CCD may influence the pathway to integrase strand transfer inhibitor resistance.

Allosteric Integrase Inhibitor Influences on HIV-1 Integration and Roles of LEDGF/p75 and HDGFL2 Host Factors

Allosteric integrase (IN) inhibitors (ALLINIs), which are promising preclinical compounds that engage the lens epithelium-derived growth factor (LEDGF)/p75 binding site on IN, can inhibit different aspects of human immunodeficiency virus 1 (HIV-1) replication. During the late phase of replication, ALLINIs induce aberrant IN hyper-multimerization, the consequences of which disrupt IN binding to genomic RNA and virus particle morphogenesis. During the early phase of infection, ALLINIs can suppress HIV-1 integration into host genes, which is also observed in LEDGF/p75-depelted cells. Despite this similarity, the roles of LEDGF/p75 and its paralog hepatoma-derived growth factor like 2 (HDGFL2) in ALLINI-mediated integration retargeting are untested. Herein, we mapped integration sites in cells knocked out for LEDGF/p75, HDGFL2, or both factors, which revealed that these two proteins in large part account for ALLINI-mediated integration retargeting during the early phase of infection. We also determined that ALLINI-treated viruses are defective during the subsequent round of infection for integration into genes associated with speckle-associated domains, which are naturally highly targeted for HIV-1 integration. Class II IN mutant viruses with alterations distal from the LEDGF/p75 binding site moreover shared this integration retargeting phenotype. Altogether, our findings help to inform the molecular bases and consequences of ALLINI action.

Viro-Immunological, Clinical Outcomes and Costs of Switching to BIC/TAF/FTC in a Cohort of People Living with HIV: A 48-Week Prospective Analysis

To date, therapeutic switches are performed to reduce and prevent toxicity, improve adherence, promote virological control, and save costs. Drug switches are a daily challenge in the management of people living with HIV (PLWH), especially in those with multiple comorbidities and on polypharmacy. The objectives of this prospective analysis were: (I) to evaluate the viro-immunological efficacy of BIC/FTC/TAF in a cohort of PLWH who switched to this regimen from any other previous, at the Infectious and Tropical Diseases Unit of the Padua University Hospital; (II) to assess the impact on body weight, lipids, and renal function parameters at week 48; and (III) to evaluate daily costs changes, adherence, and the rate and causes of discontinuation of the regimen. We included all adult PLWH who switched to BIC/FTC/TAF from 1 February 2020 to 31 October 2021. We collected demographic, clinical, and laboratory data at baseline and week 48 after the switch. In addition, the estimated cART-related cost changes over the follow-up period were calculated. Over the study period, 290 individuals who switched to BIC/FTC/TAF, 76.9% were males, with a median age of 52 years, and 94.8% had an undetectable baseline HIV viremia. After a median time of 35 days (IQR: 1–55), 41 (14.1%) individuals discontinued the regimen. Factors significantly associated with discontinuation were switching from dual regimens, and neurological disorders. At week 48, we detected a significant increase in body weight, BMI, CD4 T-cell count, and CD4/CD8 ratio, and a significant reduction in triglycerides and costs; all patients had undetectable HIV RNA. Our results showed that switching to BIC/FTC/TAF may favor slightly immunological recovery and cost saving (−4.2 EUR/day from baseline to week 48, equivalent to a mean saving of 1533 EUR/year/person). The reduction in triglycerides does not appear to be clinically relevant, even if statistically significant, nor do both the increase in body weight and BMI (+1 kg and +0.29 BMI, respectively) and the increase in CD4 T-cell count (+45 cells/mmc). Further studies are needed to confirm our results.

First report of computational protein-ligand docking to evaluate susceptibility to HIV integrase inhibitors in HIV-infected Iranian patients

Background

Iran has recently included integrase (INT) inhibitors (INTIs) in the first-line treatment regimen in human immunodeficiency virus (HIV)-infected patients. However, there is no bioinformatics data to elaborate the impact of resistance-associated mutations (RAMs) and naturally occurring polymorphisms (NOPs) on INTIs treatment outcome in Iranian patients.

Method

In this cross-sectional survey, 850 HIV-1-infected patients enrolled; of them, 78 samples had successful sequencing results for INT gene. Several analyses were performed including docking screening, genotypic resistance, secondary/tertiary structures, post-translational modification (PTM), immune epitopes, etc.

Result

The average docking energy (E value) of different samples with elvitegravir (EVG) and raltegravir (RAL) was more than other INTIs. Phylogenetic tree analysis and Stanford HIV Subtyping program revealed HIV-1 CRF35-AD was the predominant subtype (94.9%) in our cases; in any event, online subtyping tools confirmed A1 as the most frequent subtype. For the first time, CRF-01B and BF were identified as new subtypes in Iran. Decreased CD4 count was associated with several factors: poor or unstable adherence, naïve treatment, and drug user status.

Conclusion

As the first bioinformatic report on HIV-integrase from Iran, this study indicates that EVG and RAL are the optimal INTIs in first-line antiretroviral therapy (ART) in Iranian patients. Some conserved motifs and specific amino acids in INT-protein binding sites have characterized that mutation(s) in them may disrupt INT-drugs interaction and cause a significant loss in susceptibility to INTIs. Good adherence, treatment of naïve patients, and monitoring injection drug users are fundamental factors to control HIV infection in Iran effectively.

Drug-drug interactions of Integrase Strand Transfer Inhibitors among older people living with HIV: Interazioni farmacologiche degli inibitori delle integrase tra le persone anziane che vivono con HIV

The advancement of Human Immunodeficiency Virus (HIV) treatment improves the life expectancy of HIV-positive individuals. People living with HIV have more polypharmacy and drug-drug interactions than those without HIV. Integrase strand transfer inhibitors (INSTIs) are the newest class commonly used for HIV treatment. There are five INSTIs currently approved by the Food and Drug Administration, including raltegravir, elvitegravir, dolutegravir, bictegravir, and cabotegravir. INSTIs class contributes to better safety and efficacy profile, making them the preferred or recommended antiretroviral regimens in HIV treatment guidelines worldwide. Despite the shared mechanism of action, INSTIs differ in pharmacokinetics, contributing to different drug-drug interactions. This review summarized the potential drug interactions of INSTIs and the management of the drug interactions in clinical practice.

Forgiveness of INSTI-Containing Regimens at Drug Concentrations Simulating Variable Adherence In Vitro

The integrase strand transfer inhibitor (INSTI)-based regimens bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF), dolutegravir (DTG)+FTC/TAF, DTG/lamivudine (3TC), and DTG/rilpivirine (RPV) are all approved for treatment of HIV-infected patients, with various limitations. Here, time to in vitro viral breakthrough (VB) and resistance barrier using simulated human drug exposures at either full or suboptimal treatment adherence to each regimen were compared. At drug concentrations corresponding to full adherence and 1 missed dose (Cmin and Cmin-1), no VB occurred with any regimen. At Cmin-2, VB occurred only with DTG+3TC, with emergent resistance to both drugs. At Cmin-3, VB occurred with all regimens: 100% of DTG+3TC cultures had VB by day 12, and <15% of BIC+FTC+TAF, DTG+FTC+TAF, and DTG+RPV cultures had VB. Emergent reverse transcriptase (RT) or integrase (IN) resistance was seen with DTG+RPV and DTG+3TC but not with BIC+FTC+TAF or DTG+FTC+TAF. At Cmin-4, 100% VB occurred with DTG+3TC and DTG+FTC+TAF by day 12, while 94% VB occurred with DTG+RPV by day 25 and only 50% VB occurred with BIC+FTC+TAF by day 35. Emergent Cmin-4 drug resistance was seen with all regimens but at differing frequencies; DTG+RPV had the most cultures with resistance. Emergent resistance was consistent with clinical observations. Overall, under high adherence conditions, no in vitro VB or resistance development occurred with these INSTI-based regimens. However, when multiple missed doses were simulated in vitro, BIC+FTC+TAF had the highest forgiveness and barrier to resistance of all tested regimens. Compared to DTG+3TC and DTG+FTC+TAF, DTG+RPV had higher forgiveness but lower resistance barrier after several simulated missed doses.

Pre-Treatment Integrase Inhibitor Resistance and Natural Polymorphisms among HIV-1 Subtype C Infected Patients in Ethiopia

Dolutegravir-based antiretroviral therapy (ART) has been scaled up in many developing countries, including Ethiopia. However, subtype-dependent polymorphic differences might influence the occurrence of HIV-drug-resistance mutations (HIVDRMs). We analyzed the prevalence of pre-treatment integrase strand transfer inhibitor (INSTI) HIVDRMs and naturally occurring polymorphisms (NOPs) of the integrase gene, using plasma samples collected as part of the national HIVDR survey in Ethiopia in 2017. We included a total of 460 HIV-1 integrase gene sequences from INSTI-naïve (n = 373 ART-naïve and n = 87 ART-experienced) patients. No dolutegravir-associated HIVDRMs were detected, regardless of previous exposure to ART. However, we found E92G in one ART-naïve patient specimen and accessory mutations in 20/460 (4.3%) of the specimens. Moreover, among the 288 integrase amino acid positions of the subtype C, 187/288 (64.9%) were conserved (<1.0% variability). Analysis of the genetic barrier showed that the Q148H/K/R dolutegravir resistance pathway was less selected in subtype C. Docking analysis of the dolutegravir showed that protease- and reverse-transcriptase-associated HIVDRMs did not affect the native structure of the HIV-1 integrase. Our results support the implementation of a wide scale-up of dolutegravir-based regimes. However, the detection of polymorphisms contributing to INSTI warrants the continuous surveillance of INSTI resistance.

Complex of HIV-1 Integrase with Cellular Ku Protein: Interaction Interface and Search for Inhibitors

The interaction of HIV-1 integrase and the cellular Ku70 protein is necessary for HIV replication due to its positive effect on post-integration DNA repair. We have previously described in detail the Ku70 binding site within integrase. However, the integrase binding site in Ku70 remained poorly characterized. Here, using a peptide fishing assay and site-directed mutagenesis, we have identified residues I72, S73, and I76 of Ku70 as key for integrase binding. The molecular dynamics studies have revealed a possible way for IN to bind to Ku70, which is consistent with experimental data. According to this model, residues I72 and I76 of Ku70 form a "leucine zipper" with integrase residues, and, therefore, their concealment by low-molecular-weight compounds should impede the Ku70 interaction with integrase. We have identified such compounds by molecular docking and have confirmed their capacity to inhibit the formation of the integrase complex with Ku70. Our data demonstrate that the site of IN binding within Ku70 identified in the present work may be used for further search for inhibitors of the integrase binding to Ku70.

Integrase Inhibitor Resistance Mechanisms and Structural Characteristics in Antiretroviral Therapy-Experienced, Integrase Inhibitor-Naive Adults with HIV-1 Infection Treated with Dolutegravir plus Two Nucleoside Reverse Transcriptase Inhibitors in the DAWNING Study

At week 48 in the phase IIIb DAWNING study, the integrase strand transfer inhibitor (INSTI) dolutegravir plus 2 nucleoside reverse transcriptase inhibitors demonstrated superiority to ritonavir-boosted lopinavir in achieving virologic suppression in adults with HIV-1 who failed first-line therapy. Here, we report emergent HIV-1 drug resistance and mechanistic underpinnings among dolutegravir-treated adults in DAWNING. Population viral genotyping, phenotyping, and clonal analyses were performed on participants meeting confirmed virologic withdrawal (CVW) criteria on dolutegravir-containing regimens. Dolutegravir binding to and structural changes in HIV-1 integrase-DNA complexes with INSTI resistance-associated substitutions were evaluated. Of participants who received dolutegravir through week 48 plus an additional 110 weeks for this assessment, 6 met CVW criteria with treatment-emergent INSTI resistance-associated substitutions and 1 had R263R/K at baseline but not at CVW. All 7 achieved HIV-1 RNA levels of <400 copies/mL (5 achieved <50 copies/mL) before CVW. Treatment-emergent G118R was detected in 5 participants, occurring with ≥2 other integrase substitutions, including R263R/K, in 3 participants and without other integrase substitutions in 2 participants. G118R or R263K increased the rate of dolutegravir dissociation from integrase-DNA complexes versus wild-type but retained prolonged binding. Overall, among treatment-experienced adults who received dolutegravir in DAWNING, 6 of 314 participants developed treatment-emergent INSTI resistance-associated substitutions, with a change in in vitro dolutegravir resistance of >10-fold and reduced viral replication capacity versus baseline levels. This study demonstrates that the pathway to dolutegravir resistance is a challenging balance between HIV-1 phenotypic change and associated loss of viral fitness. (This study has been registered at ClinicalTrials.gov under identifier NCT02227238.).

Adherence, resistance, and viral suppression on dolutegravir in sub-Saharan Africa: implications for the TLD era

Dolutegravir (DTG) is now a component of preferred first-line antiretroviral therapy (ART) worldwide. ADVANCE and NAMSAL were two landmark clinical trials conducted exclusively in sub-Saharan Africa, which studied the effectiveness of DTG-based first-line regimens for ART-naive individuals. In this review, we examine the data from these studies to consider the contributions of adherence and HIV drug resistance to treatment failure on DTG-based ART, as compared with efavirenz (EFV)-based ART, which has a lower genetic barrier to resistance. We also discuss the implications of virologic failure on DTG and consolidate currently available data to conclude with recommendations for virologic monitoring on DTG-based ART.

INSTIs and NNRTIs Potently Inhibit HIV-1 Polypurine Tract Mutants in a Single Round Infection Assay

Integrase strand transfer inhibitors (INSTIs) are a class of antiretroviral compounds that prevent the insertion of a DNA copy of the viral genome into the host genome by targeting the viral enzyme integrase (IN). Dolutegravir (DTG) is a leading INSTI that is given, usually in combination with nucleoside reverse transcriptase inhibitors (NRTIs), to treat HIV-1 infections. The emergence of resistance to DTG and other leading INSTIs is rare. However, there are recent reports suggesting that drug resistance mutations can occur at positions outside the integrase gene either in the HIV-1 polypurine tract (PPT) or in the envelope gene (env). Here, we used single round infectivity assays to measure the antiviral potencies of several FDA-approved INSTIs and non-nucleoside reverse transcriptase inhibitors (NNRTIs) against a panel of HIV-1 PPT mutants. We also tested several of our promising INSTIs and NNRTIs in these assays. No measurable loss in potency was observed for either INSTIs or NNRTIs against the HIV-1 PPT mutants. This suggests that HIV-1 PPT mutants are not able, by themselves, to confer resistance to INSTIs or NNRTIs.

Outcomes After Switching to BIC/FTC/TAF in Patients with Virological Failure to Protease Inhibitors or Non-Nucleoside Reverse Transcriptase Inhibitors: A Real-World Cohort Study

Purpose

This study evaluated the real-world tolerability and treatment effectiveness of BIC/FTC/TAF in treatment-experienced patients living with HIV-1 in Taiwan, especially in those with viremia at switch.

Patients and Methods

This was a retrospective cohort study of adult patients in Taiwan with HIV-1 who received BIC/FTC/TAF from between November 2019 and November 2020. The primary endpoint was the rate of viral suppression (plasma HIV RNA load <50 copies/mL) while on BIC/FTC/TAF. The secondary endpoints included durability of treatment, incidence of and reasons for discontinuation of BIC/FTC/TAF, and changes in weight and lipid profiles.

Results

A total of 175 patients were switched to BIC/FTC/TAF. Among them, 74 patients (42%) were using INSTI based regimen, 34 patients (19%) NNRTI based regimen and 65 patients (37%) with PI based regimen before switching. Before starting BIC/FTC/TAF, 84.6% of the patients were virologically suppressed, of whom 97.3% maintained suppression while on BIC/FTC/TAF. Overall, 15.4% of the patients (n=27) had a detectable viral load before BIC/FTC/TAF, of whom 81.5% achieved and maintained virologic suppression on BIC/FTC/TAF during follow-up. Only two patients discontinued BIC/FTC/TAF due to adverse events, with rash being the predominant cause. By month 12, the median changes in weight was +4 kg (IQR, −1.8 to 8.2). There were no significant differences from baseline to the end of follow-up in triglycerides (p = 0.07), total cholesterol (p = 0.92), LDL-C (p = 0.12), and HDL-C (p = 0.053).

Conclusion

The results of this real-world cohort study suggest that switching to BIC/FTC/TAF may be an option to achieve and maintain virological suppression, even in patients with residual viremia at baseline. Our results also demonstrated a low discontinuation rate, a moderate gain in weight, and no significant increases in lipid levels with BIC/FTC/TAF. However, studies with larger sample sizes are warranted to evaluate the clinical implications of our findings.

High-level resistance to bictegravir and cabotegravir in subtype A- and D-infected HIV-1 patients failing raltegravir with multiple resistance mutations

OBJECTIVES

The second-generation integrase strand transfer inhibitor (INSTI) bictegravir is becoming accessible in low- and middle-income countries (LMICs), and another INSTI, cabotegravir, has recently been approved as a long-acting injectable. Data on bictegravir and cabotegravir susceptibility in raltegravir-experienced HIV-1 subtype A- and D-infected patients carrying drug resistance mutations (DRMs) remain very scarce in LMICs.

PATIENTS AND METHODS

HIV-1 integrase (IN)-recombinant viruses from eight patients failing raltegravir-based third-line therapy in Uganda were genotypically and phenotypically tested for susceptibility to bictegravir and cabotegravir. Ability of these viruses to integrate into human genomes was assessed in MT-4 cells.

RESULTS

HIV-1 IN-recombinant viruses harbouring single primary mutations (N155H or Y143R/S) or in combination with secondary INSTI mutations (T97A, M50I, L74IM, E157Q, G163R or V151I) were susceptible to both bictegravir and cabotegravir. However, combinations of primary INSTI-resistance mutations such as E138A/G140A/G163R/Q148R or E138K/G140A/S147G/Q148K led to decreased susceptibility to both cabotegravir (fold change in EC50 values from 429 to 1000×) and bictegravir (60 to 100×), exhibiting a high degree of cross-resistance. However, these same IN-recombinant viruses showed impaired integration capacity (14% to 48%) relative to the WT HIV-1 NL4-3 strain in the absence of drug.

CONCLUSIONS

Though not currently widely accessible in most LMICs, bictegravir and cabotegravir offer a valid alternative to HIV-infected individuals harbouring subtype A and D HIV-1 variants with reduced susceptibility to first-generation INSTIs but previous exposure to raltegravir may reduce efficacy, more so with cabotegravir.

An Overview of Human Immunodeficiency Virus-1 Antiretroviral Drugs: General Principles and Current Status

Treatment with highly active antiretroviral therapy (HAART) can prolong a patient's life-span by disrupting pivotal steps in the replication cycle of the human immunodeficiency virus-1 (HIV-1). However, drug resistance is emerging as a major problem worldwide due to the prolonged period of treatment undergone by HIV-1 patients. Since the approval of zidovudine in 1987, over thirty antiretroviral drugs have been categorized into the following six distinct classes based on their biological function and resistance profiles: (1) nucleoside analog reverse-transcriptase inhibitors; (2) non–nucleoside reverse transcriptase inhibitors; (3) integrase strand transferase inhibitors; (4) protease inhibitors; (5) fusion inhibitors; and (6) co-receptor antagonists. Additionally, several antiretroviral drugs have been developed recently, such as a long active drug, humanized antibody and pro-drug metabolized into an active form in the patient's body. Although plenty of antiretroviral drugs are beneficially used to treat patients with HIV-1, the ongoing efforts to develop antiretroviral drugs have overcome the drug resistances, adverse effects, and limited adherence of drugs observed in previous drugs to some extent. Furthermore, studies focused on agents targeting latent HIV-1 reservoirs should be strengthened, as that may lead to eradication of HIV-1.

Limited HIV-1 Subtype C nef 3'PPT Variation in Combination Antiretroviral Therapy Naïve and Experienced People Living with HIV in Botswana

Dolutegravir (DTG) is a potent anti-HIV drug that is used to treat HIV globally. There have been reports of mutations in the HIV-1 3'-polypurine tract (3'PPT) of the nef gene, contributing to DTG failure; however, there are limited 'real-world' data on this. In addition, there is a knowledge gap on the variability of 3'PPT residues in patients receiving combination antiretroviral therapy (cART) with and without viral load (VL) suppression. HIV-1 subtype C (HIV-1C) whole-genome sequences from cART naïve and experienced individuals were generated using next-generation sequencing. The nef gene sequences were trimmed from the generated whole-genome sequences using standard bioinformatics tools. In addition, we generated separate integrase and nef gene sequences by Sanger sequencing of plasma samples from individuals with virologic failure (VF) while on a DTG/raltegravir (RAL)-based cART. Analysis of 3'PPT residues was performed, and comparison of proportions computed using Pearson's chi-square test with p-values < 0.05 was considered statistically significant. A total of 6009 HIV-1C full genome sequences were generated and had a median log10 HIV-1 VL (Q1, Q3) copies/mL of 1.60 (1.60, 2.60). A total of 12 matching integrase and nef gene sequences from therapy-experienced participants failing DTG/ RAL-based cART were generated. HIV-1C 3'PPT nef gene sequences from therapy-experienced patients failing DTG cART (n = 12), cART naïve individuals (n = 1263), and individuals on cART with and without virological suppression (n = 4696) all had a highly conserved 3'PPT motif with no statistically significant differences identified. Our study confirms the high conservation of the HIV-1 nef gene 3'PPT motif in 'real-world' patients and showed no differences in the motif according to VL suppression or INSTI-based cART failure. Future studies should explore other HIV-1 regions outside of the pol gene for associations with DTG failure.

Cell culture selections reveal favourable drug resistance profiles for doravirine and islatravir

BACKGROUND

The newer generation NNRTIs, including doravirine and rilpivirine, were designed to show high potency and overcome K103N, Y181C and G190A resistance.

OBJECTIVES

To assess emergent resistance to doravirine and rilpivirine, alone and paired with lamivudine or islatravir through in vitro drug selections.

METHODS

Subtype B (n = 3), non-B subtype (n = 3), and pNL4.3 viral isolates were passaged in cord blood mononuclear cells with progressively increasing concentrations of drug(s). Genotypic analysis compared the acquisition and accumulation of drug resistance mutations at weeks 8 and 24 following drug pressure. Cell-based phenotypic assays assessed cross-resistance patterns to NNRTIs by acquired resistance mutations.

RESULTS

Doravirine pressure resulted in the acquisition of V108I (6/7) and V106A/I/M (5/7) mutations at weeks 8, followed by F227L (4/7), Y318F (4/7), M230L (2/7) or L234I (2/7) by weeks 24. In contrast, rilpivirine resulted in E138K (5/7) followed by L100I (3/7), K101E (1/7), or M230L (1/7). Doravirine resistance pathways retained susceptibility to rilpivirine, whereas rilpivirine resistance conferred intermediate resistance (12-152-fold) to doravirine. Dual selections with islatravir or lamivudine delayed and diminished emergent resistance to doravirine, resulting in V108I (9/15) with fewer or no other changes at weeks 24. There was a lesser delay in emergent resistance to rilpivirine when combined with islatravir or lamivudine. The M184V mutation did not arise in dual selections with islatravir or lamivudine.

CONCLUSIONS

Doravirine showed a more robust resistance profile compared with other NNRTIs. The long intracellular half-life of islatravir and delayed acquisition of resistance in dual selections provide an opportunity for long-acting treatment options.

Switching to Bictegravir, Emtricitabine, and Tenofovir Alafenamide in Virologically Suppressed Adults With Human Immunodeficiency Virus

Background

Bictegravir (B)/emtricitabine (F)/tenofovir alafenamide (TAF) is guideline-recommended treatment for human immunodeficiency virus type 1 (HIV-1). We evaluated whether people receiving dolutegravir (DTG) plus F/TAF or F/TDF (tenofovir disoproxil fumarate) with viral suppression can switch to B/F/TAF without compromising safety or efficacy, regardless of preexisting nucleoside reverse transcriptase inhibitor (NRTI) resistance.

Methods

In this multicenter, randomized, double-blinded, active-controlled, noninferiority trial, we enrolled adults who were virologically suppressed for ≥6 months before screening (with documented/suspected NRTI resistance) or ≥3 months before screening (with no documented/suspected NRTI resistance) on DTG plus either F/TDF or F/TAF. We randomly assigned (1:1) participants to switch to B/F/TAF or DTG + F/TAF once daily for 48 weeks, each with matching placebo. The primary endpoint was proportion of participants with plasma HIV-1 RNA ≥50 copies/mL at week 48 (snapshot algorithm); the prespecified noninferiority margin was 4%.

Results

Five hundred sixty-seven adults were randomized; 565 were treated (284 B/F/TAF, 281 DTG + F/TAF). At week 48, B/F/TAF was noninferior to DTG + F/TAF, as 0.4% (1/284) vs 1.1% (3/281) had HIV-1 RNA ≥50 copies/mL (difference, −0.7% [95.001% confidence interval {CI}, −2.8% to 1.0%]). There were no significant differences in efficacy among participants with suspected or confirmed prior NRTI resistance (n = 138). No participant had treatment-emergent drug resistance. Median weight change from baseline at week 48 was +1.3 kg (B/F/TAF) vs +1.1 kg (DTG + F/TAF) (P = .46). Weight change differed by baseline NRTIs (+2.2 kg [F/TDF] and +0.6 kg [F/TAF], P < .001), with no differences between B/F/TAF and DTG + F/TAF.

Conclusions

The single-tablet regimen B/F/TAF is a safe, effective option for people virologically suppressed on DTG plus either F/TDF or F/TAF, including in individuals with preexisting resistance to NRTIs.

Clinical Trials Registration

NCT03110380.

Pharmacokinetics and Drug-Drug Interactions of Long-Acting Intramuscular Cabotegravir and Rilpivirine

Combined antiretroviral treatments have significantly improved the morbidity and mortality related to HIV infection, thus transforming HIV infection into a chronic disease; however, the efficacy of antiretroviral treatments is highly dependent on the ability of infected individuals to adhere to life-long drug combination therapies. A major milestone in HIV treatment is the marketing of the long-acting intramuscular antiretroviral drugs cabotegravir and rilpivirine, allowing for infrequent drug administration, with the potential to improve adherence to therapy and treatment satisfaction. Intramuscular administration of cabotegravir and rilpivirine leads to differences in pharmacokinetics and drug-drug interaction (DDI) profiles compared with oral administration. A notable difference is the long elimination half-life with intramuscular administration, which reaches 5.6-11.5 weeks for cabotegravir and 13-28 weeks for rilpivirine, compared with 41 and 45 h, respectively, with their oral administration. Cabotegravir and rilpivirine have a low potential to cause DDIs, however these drugs can be victims of DDIs. Cabotegravir is mainly metabolized by UGT1A1, and rilpivirine is mainly metabolized by CYP3A4, therefore these agents are susceptible to DDIs with inhibitors, and particularly inducers of drug-metabolizing enzymes. Intramuscular administration of cabotegravir and rilpivirine has the advantage of eliminating DDIs occurring at the gastrointestinal level, however interactions can still occur at the hepatic level. This review provides insight on the intramuscular administration of drugs and summarizes the pharmacology of long-acting cabotegravir and rilpivirine. Particular emphasis is placed on DDI profiles after oral and intramuscular administration of these antiretroviral drugs.

Primary resistance to integrase strand transfer inhibitors in Spain using ultrasensitive HIV-1 genotyping

BACKGROUND

Transmission of resistance mutations to integrase strand transfer inhibitors (INSTIs) in HIV-infected patients may compromise the efficacy of first-line antiretroviral regimens currently recommended worldwide. Continued surveillance of transmitted drug resistance (TDR) is thus warranted.

OBJECTIVES

We evaluated the rates and effects on virological outcomes of TDR in a 96 week prospective multicentre cohort study of ART-naive HIV-1-infected subjects initiating INSTI-based ART in Spain between April 2015 and December 2016.

METHODS

Pre-ART plasma samples were genotyped for integrase, protease and reverse transcriptase resistance using Sanger population sequencing or MiSeq™ using a ≥ 20% mutant sensitivity cut-off. Those present at 1%-19% of the virus population were considered to be low-frequency variants.

RESULTS

From a total of 214 available samples, 173 (80.8%), 210 (98.1%) and 214 (100.0%) were successfully amplified for integrase, reverse transcriptase and protease genes, respectively. Using a Sanger-like cut-off, the overall prevalence of any TDR, INSTI-, NRTI-, NNRTI- and protease inhibitor (PI)-associated mutations was 13.1%, 1.7%, 3.8%, 7.1% and 0.9%, respectively. Only three (1.7%) subjects had INSTI TDR (R263K, E138K and G163R), while minority variants with integrase TDR were detected in 9.6% of subjects. There were no virological failures during 96 weeks of follow-up in subjects harbouring TDR as majority variants.

CONCLUSIONS

Transmitted INSTI resistance remains rare in Spain and, to date, is not associated with virological failure to first-line INSTI-based regimens.

Long-acting injectable therapy: an emerging paradigm for the treatment of HIV infection

PURPOSE OF REVIEW

Long-acting formulations of antiretrovirals have the potential to reshape the treatment paradigm for HIV infection. Emerging evidence demonstrates efficacy and safety of two drug regimens for the treatment of HIV infection. This review focuses on recent advances with long-acting cabotegravir and rilpivirine administered intramuscularly every 4 weeks for the treatment of HIV infection in virologically suppressed patients.

RECENT FINDINGS

Despite the development of complete, orally administered single tablet regimens with improved efficacy, side effects, tolerability, with an improved drug interaction potential, patients still have challenges adhering to daily oral therapy. Psychological factors including HIV stigma contribute to patient's ability to adhere to treatment. Newer nonoral treatment regimens may improve adherence, patient satisfaction and limit HIV stigma.

SUMMARY

A two-drug intramuscular regimen of cabotegravir and rilpivirine has advanced through phase 3 clinical development. Results from studies assessing safety, virologic, pharmacologic, and drug interactions have been completed. Larger efficacy studies have demonstrated noninferiority of switching virologically suppressed patients from a three drug daily oral regimen to a two-drug intramuscular regimen administered Q4W with long-term data to 160 weeks demonstrating durability of treatment response.

Prevalence of genotypic baseline risk factors for cabotegravir + rilpivirine failure among ARV-naive patients

BACKGROUND

Multivariable baseline factor analysis across cabotegravir + rilpivirine clinical trials showed that HIV-1 subtypes A6/A1 and the presence of rilpivirine resistance-associated mutations (RAMs) were associated with an increased risk of virological failure of this dual therapy. The aim of this study was to describe the prevalence of genotypic baseline risk factors for cabotegravir + rilpivirine failure among ARV-naive patients.

PATIENTS AND METHODS

From 2010 to 2020, 4212 sequences from ARV-naive patients were collected from three large Parisian academic hospital genotypic databases. Cabotegravir and rilpivirine RAMs were defined according to the ANRS algorithm.

RESULTS

Among 4212 ARV-naive patients, 38.6% were infected with subtype B, 32.4% with CRF02_AG (32.4%) and 5.1% with subtype A (85.5% being A6/A1 subtype). Overall, the presence of at least one cabotegravir or rilpivirine RAM was 16.2% and 14.3%, respectively. Considering genotypic resistance interpretation, using the ANRS algorithm, 0.74% (n = 31), 7.3% (n = 306) and 0.09% (n = 4) of sequences were resistant to cabotegravir, rilpivirine or both, respectively. The overall prevalence of L74I in integrase and E138A in RT was 13.0% and 3.2%, respectively, and stable over the decade. Thus, adding 183 subtype A6/A1 sequences to 244 sequences interpreted as resistant to rilpivirine led to 427 (10.1%) sequences combining both baseline virological risk factors for cabotegravir + rilpivirine dual-therapy failure.

CONCLUSIONS

Among large sequence databases, when adding prevalence of rilpivirine-resistant viruses and HIV-1 subtype A6/A1 sequences, 10.1% of patients would not be eligible for cabotegravir + rilpivirine dual therapy. These data re-emphasize the need for a pre-therapeutic genotypic resistance test to detect polymorphisms and transmitted drug resistance and to define HIV-1 subtype.

The potential role of long-acting injectable cabotegravir-rilpivirine in the treatment of HIV in sub-Saharan Africa: a modelling analysis

BACKGROUND

The use of a combination of the integrase inhibitor, cabotegravir, and the non-nucleoside reverse transcriptase inhibitor, rilpivirine, in a long-acting injectable form is being considered as an antiretroviral treatment option for people with HIV in sub-Saharan Africa. We aimed to model the effects of injectable cabotegravir-rilpivirine to help to inform its potential effectiveness and cost-effectiveness under different possible policies for its introduction.

METHODS

We used an existing individual-based model of HIV to predict the effects of introducing monthly injections of cabotegravir-rilpivirine for people with HIV in low-income settings in sub-Saharan Africa. We evaluated policies in the context of 1000 setting scenarios that reflected characteristics of HIV epidemics and programmes in sub-Saharan Africa. We compared three policies for introduction of injectable cabotegravir-rilpivirine with continued use of dolutegravir-based oral regimens for: all individuals on antiretroviral therapy (ART); individuals with a recently measured viral load of more than 1000 copies per mL (signifying poor adherence to oral drugs, and often associated with drug resistance); and individuals with a recently measured viral load of less than 1000 copies per mL (a group with a lower prevalence of pre-existing drug resistance). We also did cost-effectiveness analysis, taking a health system perspective over a 10 year period, with 3% discounting of disability-adjusted life-years (DALYs) and costs. A cost-effectiveness threshold of US$500 per DALY averted was used to establish if a policy was cost-effective.

FINDINGS

In our model, all policies involving the introduction of injectable cabotegravir-rilpivirine were predicted to lead to an increased proportion of people with HIV on ART, increased viral load suppression, and decreased AIDS-related mortality, with lesser benefits in people with a recently measured viral load of less than 1000 copies per mL. Its introduction is also predicted to lead to increases in resistance to integrase inhibitors and non-nucleoside reverse transcriptase inhibitors if introduced in all people with HIV on ART or in those with a recently measured viral load of less than 1000 copies per mL, but to a lesser extent if introduced in people with more than 1000 copies per mL due to concentration of its use in people less adherent to oral therapy. Consistent with the effect on AIDS-related mortality, all approaches to the introduction of injectable cabotegravir-rilpivirine are predicted to avert DALYs. Assuming a cost of $120 per person per year, use of this regimen in people with a recently measured viral load of more than 1000 copies per mL was borderline cost-effective (median cost per DALY averted across setting scenarios $404). The other approaches considered for its use are unlikely to be cost-effective unless the cost per year of injectable cabotegravir-rilpivirine is considerably reduced.

INTERPRETATION

Our modelling suggests that injectable cabotegravir-rilpivirine offers potential benefits; however, to be a cost-effective option, its introduction might need to be carefully targeted to individuals with HIV who might otherwise have suboptimal adherence to ART. As data accumulate from trials and implementation studies, such findings can be incorporated into the model to better inform on the full consequences of policy alternatives.

FUNDING

Bill & Melinda Gates Foundation, including through the HIV Modelling Consortium (OPP1191655).

Dolutegravir Plus Lamivudine Two-Drug Regimen: Safety, Efficacy and Diagnostic Considerations for Its Use in Real-Life Clinical Practice-A Refined Approach in the COVID-19 Era

The diagnostic and therapeutic management of the Coronavirus Disease 2019 (COVID-19) pandemic in the HIV population brought some known criticalities (and opportunities) to the forefront, for both those who are facing their first therapeutic line today, and for those already well viro-suppressed. The clinical, socioeconomic, and psychological impact of the COVID-19 pandemic should not affect the long-term care of people living with HIV, which creates an urgent need to optimize the diagnostic and treatment approach to the first-line or switch regimens. The use of dolutegravir plus a lamivudine two-drug regimen is one of the most promising solutions to ease the management of HIV treatment in this difficult period. In this review, we report the most salient features related to the use of this regimen from real-life cohorts, meta-analyses, randomized clinical trials, and studies presented at international conferences up to March 2021. We focused on the diagnostic and clinical-management implications of its use in real life, and how these comply with the contingent historical situation. The issue of the timing and type of diagnostic procedures and the relevance of classical diagnostic tests (such as genotype for resistance detection) is also discussed. According to the currently available results, dolutegravir plus a lamivudine two-drug regimen represents an outstanding tool, whose expected advantages fulfill the current requirements for optimal daily care of our HIV patients.

Long Dissociation of Bictegravir from HIV-1 Integrase-DNA Complexes

The HIV integrase (IN) strand transfer inhibitor (INSTI) bictegravir (BIC) has a long dissociation half-life (t_1/2) from wild-type IN-DNA complexes: BIC 163 hr > dolutegravir (DTG) 96 hr > raltegravir (RAL) 10 hr > elvitegravir (EVG) 3.3 hr. In cells, BIC had more durable antiviral activity against wild-type HIV after drug washout than RAL or EVG. BIC also had a longer t_1/2 and maintained longer antiviral activity after drug washout than DTG with the clinically relevant resistance IN mutant G140S+Q148H. Structural analyses indicate that BIC makes more contacts with the IN-DNA complex than DTG mainly via its bicyclic ring system which may contribute to more prolonged residence time and resilience against many resistance mutations.