Beware of resistance to 2nd-generation integrase inhibitors: A systematic meta-analysis of HIV-1 integrase inhibitors resistance and drug resistance mutations

OBJECTIVE

Assessing the prevalence of resistance and drug resistance mutations (DRMs) in HIV/AIDS patients towards integrase strand transfer inhibitors (INSTIs), particularly the 2nd-generation INSTIs, provides evidence for rational clinical drug use.

METHODS

A systematic search was conducted on five databases to identify relevant literature reporting original data on INSTIs resistance. Meta-analyses, cumulative meta-analyses, subgroup analyses and meta-regression analyses were performed using selected models based on the results of heterogeneity tests.

RESULTS

A total of 81 studies were included in this analysis. The prevalence of pre-treatment drug resistance (PDR) to 1st-generation INSTIs and 2nd-generation INSTIs were 0.41% (95% CI: 0.19%-0.70%) and 0.04% (95% CI: 0.00%-0.13%), respectively; and the prevalence of acquired drug resistance (ADR) were 7.60% (95% CI: 3.54%-12.92%) and 4.93% (95% CI: 1.78%-9.36%), respectively, and ADR showed an increasing and then decreasing time trend. The results of subgroup analyses showed differences in ADR to 2nd-generation INSTIs between regions and economic levels, with the highest ADR of 12.83% (95% CI: 3.24%-27.17%) in the European region. DRMs varied among HIV patients and reduced drug sensitivity to varying degrees.

CONCLUSION

The prevalence of PDR and DRMs in 2nd-generation INSTIs is currently low, but as the use of DTG-based ART expands, population-level drug resistance monitoring and individual-level genetic testing should be strengthened in order to maximise treatment efficacy. Additionally, attention should be paid to ADR to INSTIs to provide personalised treatments for HIV-infected patients.

Pharmacokinetic drug interactions of integrase strand transfer inhibitors

The integrase strand transfer inhibitor (INSTI)-containing regimens are currently considered as the first-line treatment of human immunodeficiency virus (HIV) infection. Although possessing a common mechanism of action to inhibit HIV integrase irreversibly to stop HIV replication cycle, the INSTIs, including raltegravir, elvitegravir, dolutegravir, and bictegravir, differ in pharmacokinetic characteristics. While raltegravir undergoes biotransformation by the UDP-glucuronosyltransferases (UGTs), elvitegravir is primarily metabolized by cytochrome P450 (CYP) 3A4 and co-formulated with cobicistat to increase its plasma exposure. The metabolism pathways of dolutegravir and bictegravir are similar, both including CYP3A and UGT1A1, and both agents are substrates to different drug transporters. Because of their differences in metabolism, INSTIs interact with other medications differently through CYP enzymes and transporters as inducers or inhibitors. These drug interactions may become an important consideration in the long-term clinical use because the life expectancy of people with HIV (PWH) approaches to that of the general population. Also, common geriatric challenges such as multimorbidity and polypharmacy have been increasingly recognized in PWH. This review provides a summary of pharmacokinetic interactions with INSTIs and future perspectives in implications of INSTI drug interactions.

Combined cART including Tenofovir Disoproxil, Emtricitabine, and Dolutegravir has potent therapeutic effects in HIV-1 infected humanized mice

HIV-1 reservoirs persist in the presence of combined antiretroviral therapy (cART). However, cART has transformed HIV-1 infection into a chronic disease marked by control of HIV-1 viral load and mortality reduction. Major challenges remain, including viral resistance upon termination of cART and persistence and identification of tissue distribution of HIV-1 reservoirs. Thus, appropriate animal models that best mimic HIV-1 pathogenesis are important, and the current study complements our previously published validation of the CD34+ hematopoietic humanized mouse model for this purpose. Here we analyze viral suppression using the recently developed combination of antiretrovirals that include Tenofovir Disoproxil (TDF), Emtricitabine (FTC), and Dolutegravir (DTG), a choice based on recent clinical outcomes showing its improved antiretroviral potency, CD4+ T cell preservation, tolerability, and prevention of viral drug resistance compared to that of previous regimens. We used quantitative Airyscan-based super resolution confocal microscopy of selected mouse tissues. Our data allowed us to identify specific solid tissue reservoirs of human T cells expressing the HIV-1 core protein p24. In particular, lymph node, brain, spleen, and liver were visualized as reservoirs for residual infected cells. Marked reduction of viral replication was evident. Considering that detection and visualization of cryptic sites of HIV-1 infection in tissues are clearly crucial steps towards HIV-1 eradication, appropriate animal models with pseudo-human immune systems are needed. In fact, current studies with humans and non-human primates have limited sample availability at multiple stages of infection and cannot easily analyze the effects of differently administered combined antiretroviral treatments on multiple tissues. That is easier to manage when working with humanized mouse models, although we realize the limitations due to low human cell recovery and thus the number of cells available for thorough and comprehensive analyses. Nonetheless, our data further confirm that the CD34+ humanized mouse model is a potentially useful pre-clinical model to study and improve current anti-HIV-1 therapies.

Past HIV-1 Medications and the Current Status of Combined Antiretroviral Therapy Options for HIV-1 Patients

Combined antiretroviral therapy (cART) is treatment with a combination of several antiretroviral drugs that block multiple stages in the virus replication cycle. An estimated 60% of the 38 million HIV-1 patients globally receive some form of cART. The benefits of cART for controlling HIV-1 replication, transmission, and infection rates have led to its universal recommendation. Implementation has caused a substantial reduction in morbidity and mortality of persons living with HIV-1/AIDS (PLWHA). More specifically, standard cART has provided controlled, undetectable levels of viremia, high treatment efficacy, reduction in pill burden, and an improved lifestyle in HIV-1 patients overall. However, HIV-1 patients living with AIDS (HPLA) generally show high viral loads upon cART interruption. Latently infected resting CD4+ T cells remain a major barrier to curing infected patients on long-term cART. There is a critical need for more effective compounds and therapies that not only potently reactivate latently infected cells, but also lead to the death of these reactivated cells. Efforts are ongoing to better control ongoing viral propagation, including the identification of appropriate animal models that best mimic HIV-1 pathogenesis, before proceeding with clinical trials. Limited toxicity profiles, improved drug penetration to certain tissues, and extended-release formulations are needed to cover gaps in existing HIV-1 treatment options. This review will cover past, current, and new cART strategies recently approved or in ongoing development.

Impact of genotypic diversity on selection of subtype-specific drug resistance profiles during raltegravir-based therapy in individuals infected with B and BF recombinant HIV-1 strains

BACKGROUND

Current knowledge on HIV-1 resistance to integrase inhibitors (INIs) is based mostly on subtype B strains. This contrasts with the increasing use of INIs in low- and middle-income countries, where non-B subtypes predominate.

MATERIALS AND METHODS

HIV-1 drug resistance genotyping was performed in 30 HIV-1-infected individuals undergoing virological failure to raltegravir. Drug resistance mutations (DRMs) and HIV-1 subtype were characterized using Stanford HIVdb and phylogenetic analyses.

RESULTS

Of the 30 integrase (IN) sequences, 14 were characterized as subtype F (47%), 8 as subtype B (27%), 7 as BF recombinants (23%) and 1 as a putative CRF05_DF (3%). In 25 cases (83%), protease and reverse transcriptase (PR-RT) sequences from the same individuals confirmed the presence of different BF recombinants. Stanford HIVdb genotyping was concordant with phylogenetic inference in 70% of IN and 60% of PR-RT sequences. INI DRMs differed between B and F IN subtypes, with Q148K/R/H, G140S and E138K/A being more prevalent in subtype B (63% versus 0%, P = 0.0021; 50% versus 0%, P = 0.0096; and 50% versus 0%, P = 0.0096, respectively). These differences were independent of the time on raltegravir therapy or viral load at the time of genotyping. INI DRMs in subtype F IN genomes predicted a lower level of resistance to raltegravir and no cross-resistance to second-generation INIs.

CONCLUSIONS

Alternative resistance pathways to raltegravir develop in subtypes B and F IN genomes, with implications for clinical practice. Evaluating the role of HIV-1 subtype in development and persistence of mutations that confer resistance to INIs will be important to improve algorithms for resistance testing and optimize the use of INIs.

Safety and efficacy of elvitegravir, dolutegravir, and raltegravir in a real-world cohort of treatment-naïve and -experienced patients

The aim of this retrospective cohort study was to compare safety, efficacy and rates and reasons of discontinuation of the 3 currently approved integrase strand transfer inhibitors (INSTIs) elvitegravir (EVG), dolutegravir (DTG), and raltegravir (RAL) in HIV-infected treatment-naïve and -experienced patients in a real-world cohort. One hundred four treatment-naïve patients were prescribed an INSTI-based combined antiretroviral therapy (cART)-regimen (first-line group) and 219 patients were switched to an INSTI-based cART-regimen from another treatment regimen (switch group) at our institution between May 2007 and December 2014. Twelve months after initiation of treatment, 92% of patients in the first-line group (EVG: 96%, n = 22/23; DTG: 92%, n = 34/37; RAL: 90%, n = 28/31) and 88% of patients in the switch group (EVG: 94%, n = 32/34; DTG: 90%, n = 69/77; RAL: 85%, n = 67/79) showed full virological suppression (viral load <50 copies/mL). Side effects of any kind occurred in 12% (n = 12/104) of patients in the first-line group, and 10% (n = 21/219) of patients in the switch group. In the switch group neuropsychiatric side effects (depression, vertigo, and sleep disturbances) occurred more frequently in patients treated with DTG (11%, n = 10) compared to the 2 other INSTI-based cART-regimen (EVG: 2%, n = 1; RAL: 1%, n = 1). Side effects only rarely led to discontinuation of treatment (first-line-group: 2%, n = 2/104; switch-group: 1%, n = 3/219). In this real-world setting, INSTI-based ART-regimens were highly efficacious with no significant differences between any of the 3 INSTIs. Overall, side effects were only rarely observed and generally mild in all subgroups. In light of a slightly higher incidence of vertigo and sleep disturbances in patients switched to DTG, awareness of the potential onset of psychiatric symptoms is warranted during follow-up in those patients.

Novel Protease Inhibitors Containing C-5-Modified bis-Tetrahydrofuranylurethane and Aminobenzothiazole as P2 and P2' Ligands That Exert Potent Antiviral Activity against Highly Multidrug-Resistant HIV-1 with a High Genetic Barrier against the Emergence of Drug Resistance

Combination antiretroviral therapy has achieved dramatic reductions in the mortality and morbidity in people with HIV-1 infection. Darunavir (DRV) represents a most efficacious and well-tolerated protease inhibitor (PI) with a high genetic barrier to the emergence of drug-resistant HIV-1. However, highly DRV-resistant variants have been reported in patients receiving long-term DRV-containing regimens. Here, we report three novel HIV-1 PIs (GRL-057-14, GRL-058-14, and GRL-059-14), all of which contain a P2-amino-substituted-bis-tetrahydrofuranylurethane (bis-THF) and a P2'-cyclopropyl-amino-benzothiazole (Cp-Abt). These PIs not only potently inhibit the replication of wild-type HIV-1 (50% effective concentration [EC₅₀], 0.22 nM to 10.4 nM) but also inhibit multi-PI-resistant HIV-1 variants, including highly DRV-resistant HIV_DRV ^R _P51 (EC₅₀, 1.6 nM to 30.7 nM). The emergence of HIV-1 variants resistant to the three compounds was much delayed in selection experiments compared to resistance to DRV, using a mixture of 11 highly multi-PI-resistant HIV-1 isolates as a starting HIV-1 population. GRL-057-14 showed the most potent anti-HIV-1 activity and greatest thermal stability with wild-type protease, and potently inhibited HIV-1 protease's proteolytic activity (K_i value, 0.10 nM) among the three PIs. Structural models indicate that the C-5-isopropylamino-bis-THF moiety of GRL-057-14 forms additional polar interactions with the active site of HIV-1 protease. Moreover, GRL-057-14's P1-bis-fluoro-methylbenzene forms strong hydrogen bonding and effective van der Waals interactions. The present data suggest that the combination of C-5-aminoalkyl-bis-THF, P1-bis-fluoro-methylbenzene, and P2'-Cp-Abt confers highly potent activity against wild-type and multi-PI-resistant HIV strains and warrant further development of the three PIs, in particular, that of GRL-057-14, as potential therapeutic for HIV-1 infection and AIDS.

Evaluation of HIV-1 integrase resistance emergence and evolution in patients treated with integrase inhibitors

OBJECTIVES

This study evaluated the emergence of mutations associated with integrase strand transfer inhibitors (INSTI) resistance (INSTI-RMs) and the integrase evolution in human immunodeficiency virus type 1 (HIV-1) infected patients treated with this drug class.

METHODS

The emergence of INSTI-RMs and integrase evolution (estimated as genetic distance between integrase sequences under INSTI treatment and before INSTI treatment) were evaluated in 107 INSTI-naïve patients (19 drug-naïve and 88 drug-experienced) with two plasma genotypic resistance tests: one before INSTI treatment and one under INSTI treatment. A logistic regression analysis was performed to evaluate factors associated with the integrase evolution under INSTI treatment.

RESULTS

The patients were mainly infected by B subtype (72.0%). Eighty-seven patients were treated with raltegravir, 13 with dolutegravir and seven with elvitegravir. Before INSTI treatment one patient harboured the major INSTI-RM R263K and three patients the accessory INSTI-RMs T97A. Under INSTI treatment the emergence of ≥1 INSTI-RM was found in 39 (36.4%) patients. The major INSTI-RMs that more frequently emerged were: N155H (17.8%), G140S (8.4%), Y143R (7.5%), Q148H (6.5%), and Y143C (4.7%). Concerning integrase evolution, a higher genetic distance was found in patients with ≥1 INSTI-RM compared with those without emergence of resistance (0.024 [0.012-0.036] vs. 0.015 [0.009-0.024], P=0.018). This higher integrase evolution was significantly associated with a longer duration of HIV-1 infection, a higher number of past regimens and non-B subtypes.

CONCLUSIONS

These findings confirm that major INSTI-RMs very rarely occur in INSTI-naïve patients. Under INSTI treatment, selection of drug-resistance follows the typical drug-resistance pathways; a higher evolution characterises integrase sequences developing drug-resistance compared with those without any resistance.

HIV-1 Integrase Resistance among Highly Antiretroviral Experienced Patients from Morocco

BACKGROUND

We aimed to analyze for the first time in Morocco the integrase (IN) sequence variability among highly experienced HIV-1-infected patients with no prior IN strand transfer inhibitor (INSTI) exposure who failed on reverse transcriptase inhibitors and protease inhibitors.

METHODS

The HIV-1 IN region was sequenced from plasma samples of all 78 recruited patients. The amino acid IN sequences were HIV-1 subtyped and screened for the presence of polymorphisms against the HxB2 clade B consensus sequence by the geno2pheno subtyping tool and interpreted for drug resistance according to the Stanford algorithm.

RESULTS

The viral subtypes were subtype B (88.4%), CRF02_AG (8.9%), CRF01_AE (1.28%), and subtype C (1.28%). The major INSTI resistance mutations at positions 66, 92, 118, 138, 140, 143, 147, 148, 155, and 263 were absent, while two accessory mutations, L74M/I, known to have no clinical impact to INSTIs in the absence of the major resistance mutations, were detected in three samples (3.84%; two CRF02_AG and one CRF01_AE). Others specific substitutions with an uncertain role on the HIV-1 susceptibility to INSTIs at positions 72, 101, 119, 124, 156, 165, 193, 201, 203, 206, 230, 232, and 249 were found to be relatively common.

CONCLUSION

This study demonstrated that INSTIs should be an excellent alternative for salvage therapy in highly experienced patients with multidrug resistant viruses in Morocco.

Clinical benefits of using inulin clearance and cystatin C for determining glomerular filtration rate in HIV-1-infected individuals treated with dolutegravir

INTRODUCTION

Dolutegravir may inhibit creatinine transporters in renal tubules and elevate serum creatinine levels. We investigated the usefulness of glomerular filtration rate (GFR) measured using inulin clearance (Cin), creatinine clearance (Ccr), and estimated GFR based on both serum creatinine (eGFRcre) and serum cystatin C (eGFRcys).

PATIENTS & METHODS

HIV-1-infected Japanese patients with suppressed viremia and whose antiretroviral drug was switched to dolutegravir from other drugs were included (n = 108, Study 1). We compared eGFRcre and eGFRcys at the start and after 48 weeks of dolutegravir administration. For the patients providing consent, we measured Cin and Ccr (n = 15, Study 2). We assessed biases and accuracy and compared Cin with eGFRcre, eGFRcys, and Ccr.

RESULTS

There were no differences in serum cystatin C and eGFRcys between baseline and at 48 weeks. Moreover, eGFRcre was significantly less accurate (within 30% of measured GFR) than both eGFRcys and Ccr (40% accuracy compared to 93% and 93%, respectively). eGFRcys was significantly less biased than eGFRcre and Ccr (p < 0.0001, p = 0.00036, respectively). No significant difference between Cin and eGFRcys was observed. eGFRcys was significantly correlated with Cin (γ = 0.85, p < 0.0001).

CONCLUSIONS

eGFRcys provided the most precise estimate and most closely approximate Cin in HIV-1-infected Japanese patients with suppressed viremia treated with dolutegravir. We demonstrated clinical benefits of inulin clearance and eGFRcys. This is the first study performing inulin clearance for HIV-1-infected individuals and to show data for eGFRcys from a large cohort following a switch to dolutegravir from other antiretroviral agents.

Antiviral Activity of Bictegravir (GS-9883), a Novel Potent HIV-1 Integrase Strand Transfer Inhibitor with an Improved Resistance Profile

Bictegravir (BIC; GS-9883), a novel, potent, once-daily, unboosted inhibitor of HIV-1 integrase (IN), specifically targets IN strand transfer activity (50% inhibitory concentration [IC₅₀] of 7.5 ± 0.3 nM) and HIV-1 integration in cells. BIC exhibits potent and selective in vitro antiretroviral activity in both T-cell lines and primary human T lymphocytes, with 50% effective concentrations ranging from 1.5 to 2.4 nM and selectivity indices up to 8,700 relative to cytotoxicity. BIC exhibits synergistic in vitro antiviral effects in pairwise combinations with tenofovir alafenamide, emtricitabine, or darunavir and maintains potent antiviral activity against HIV-1 variants resistant to other classes of antiretrovirals. BIC displayed an in vitro resistance profile that was markedly improved compared to the integrase strand transfer inhibitors (INSTIs) raltegravir (RAL) and elvitegravir (EVG), and comparable to that of dolutegravir (DTG), against nine INSTI-resistant site-directed HIV-1 mutants. BIC displayed statistically improved antiviral activity relative to EVG, RAL, and DTG against a panel of 47 patient-derived HIV-1 isolates with high-level INSTI resistance; 13 of 47 tested isolates exhibited >2-fold lower resistance to BIC than DTG. In dose-escalation experiments conducted in vitro, BIC and DTG exhibited higher barriers to resistance than EVG, selecting for HIV-1 variants with reduced phenotypic susceptibility at days 71, 87, and 20, respectively. A recombinant virus with the BIC-selected M50I/R263K dual mutations in IN exhibited only 2.8-fold reduced susceptibility to BIC compared to wild-type virus. All BIC-selected variants exhibited low to intermediate levels of cross-resistance to RAL, DTG, and EVG (<8-fold) but remained susceptible to other classes of antiretrovirals. A high barrier to in vitro resistance emergence for both BIC and DTG was also observed in viral breakthrough studies in the presence of constant clinically relevant drug concentrations. The overall virologic profile of BIC supports its ongoing clinical investigation in combination with other antiretroviral agents for both treatment-naive and -experienced HIV-infected patients.

HealthMap: a cluster randomised trial of interactive health plans and self-management support to prevent coronary heart disease in people with HIV

BACKGROUND

The leading causes of morbidity and mortality for people in high-income countries living with HIV are now non-AIDS malignancies, cardiovascular disease and other non-communicable diseases associated with ageing. This protocol describes the trial of HealthMap, a model of care for people with HIV (PWHIV) that includes use of an interactive shared health record and self-management support. The aims of the HealthMap trial are to evaluate engagement of PWHIV and healthcare providers with the model, and its effectiveness for reducing coronary heart disease risk, enhancing self-management, and improving mental health and quality of life of PWHIV.

METHODS/DESIGN

The study is a two-arm cluster randomised trial involving HIV clinical sites in several states in Australia. Doctors will be randomised to the HealthMap model (immediate arm) or to proceed with usual care (deferred arm). People with HIV whose doctors are randomised to the immediate arm receive 1) new opportunities to discuss their health status and goals with their HIV doctor using a HealthMap shared health record; 2) access to their own health record from home; 3) access to health coaching delivered by telephone and online; and 4) access to a peer moderated online group chat programme. Data will be collected from participating PWHIV (n = 710) at baseline, 6 months, and 12 months and from participating doctors (n = 60) at baseline and 12 months. The control arm will be offered the HealthMap intervention at the end of the trial. The primary study outcomes, measured at 12 months, are 1) 10-year risk of non-fatal acute myocardial infarction or coronary heart disease death as estimated by a Framingham Heart Study risk equation; and 2) Positive and Active Engagement in Life Scale from the Health Education Impact Questionnaire (heiQ).

DISCUSSION

The study will determine the viability and utility of a novel technology-supported model of care for maintaining the health and wellbeing of people with HIV. If shown to be effective, the HealthMap model may provide a generalisable, scalable and sustainable system for supporting the care needs of people with HIV, addressing issues of equity of access.

TRIAL REGISTRATION

Universal Trial Number (UTN) U111111506489; ClinicalTrial.gov Id NCT02178930 submitted 29 June 2014.

Combination dolutegravir-abacavir-lamivudine in the management of HIV/AIDS: clinical utility and patient considerations

The current standard of care for human immunodeficiency virus (HIV) treatment is a three-drug regimen containing a nonnucleoside reverse transcriptase inhibitor, a protease inhibitor, or an integrase strand transfer inhibitor (INSTI) plus two nucleoside/tide reverse transcriptase inhibitors. Given their potency, safety, and distinctive mechanism of action, INSTIs represent an important advance in HIV type 1 (HIV-1) therapy. Dolutegravir (DTG) is a new-generation INSTI recently approved for the treatment of HIV-1-infected adult patients, with distinct advantages compared with other available antiretroviral agents. In well-designed, large clinical trials, DTG-containing regimens have demonstrated either noninferiority or superiority to current first-line agents such as raltegravir-, darunavir/ritonavir-, and efavirenz-containing regimens. The favorable safety profile, low potential for drug interactions, minimal impact on lipids, good tolerability, and high resistance barrier of DTG makes this compound one of the preferred choices for HIV therapy in multiple clinical scenarios, including treatment-naïve and treatment-experienced patients. DTG is the only antiretroviral drug not yet associated with de novo emergence of resistance mutations in treatment-naïve individuals. However, data from in vitro studies and clinical trial suggest the possibility of cross-resistance between first- and second-generation INSTIs. Even though these profiles are infrequent at the moment, they need to be monitored in all current patients treated with INSTIs. With its potent activity, good tolerability, simplicity of dosing, and minimal drug interaction profile, DTG will likely play a major role in the management of patients with HIV-1 infection. On the basis of clinical trial data, current guidelines endorse DTG in combination with nucleoside/tide reverse transcriptase inhibitors as one of the recommended regimens in antiretroviral therapy-naïve patients. Most of the favorable clinical experiences from clinical trials are based on the combination of DTG with abacavir/lamivudine, and DTG is planned to be coformulated with abacavir/lamivudine. This will provide a further advantage, given that single tablet regimens are associated with higher adherence rates as well as improvement in quality of life and enhanced patient preference.

Dolutegravir: a new option for HIV treatment

ABSTRACT: 

The need for new strategies for treating HIV-1 infection has led to the development of a number of new drugs. The aim of this article is to review the latest results of clinical trials of dolutegravir, an integrase inhibitor whose efficacy, tolerability and safety have been confirmed in treatment-naive and treatment-experienced patients. The findings, together with its high genetic barrier and limited interactions with other drugs, indicate that dolutegravir will play an important role in the future treatment of HIV infection.

Dolutegravir: first global approval

Dolutegravir, an orally administered HIV-1 integrase strand transfer inhibitor (INSTI), is under development by ViiV Healthcare. Like other drugs belonging in the INSTI class of antiretroviral agents, dolutegravir binds to the integrase site of HIV-1 and blocks the strand transfer integration step, thereby preventing the replication of HIV-1. Dolutegravir is being developed as an unboosted once-daily therapy for use in combination with other antiretroviral agents for the treatment of both treatment-naïve and treatment-experienced patients with HIV-1 infection. Dolutegravir has been approved in the USA for the treatment of HIV-1 infection in combination with other antiretroviral agents and has been filed for approval in the EU and Canada. Phase III development is underway in North America, Europe, South Africa, South America, Australia and Taiwan. This article summarizes the milestones in the development of dolutegravir leading to this first approval for the treatment of HIV-1 infection in both therapy-naïve and -experienced patients.

Minimal sequence variability of the region of HIV-1 integrase targeted by the Abbott RealTime HIV-1 viral load assay in clinical specimens with reduced susceptibility to raltegravir

The Abbott RealTime (ART) HIV-1 assay targets the integrase region and is designed to tolerate mismatches. Variability in integrase sequences comprising the assay target regions from >1000 clinical specimens submitted for phenotypic and genotypic raltegravir resistance testing were analyzed. In this large collection of sequences from clinical specimens, the number and location of raltegravir resistance associated mutations did not differ from those tested previously and shown not to result in under-estimation of viral loads.

Dolutegravir in antiretroviral-naive adults with HIV-1: 96-week results from a randomized dose-ranging study

Objective:

To evaluate the efficacy and safety/tolerability of dolutegravir (DTG, S/GSK1349572), a potent inhibitor of HIV integrase, through the full 96 weeks of the SPRING-1 study.

Design:

ING112276 (SPRING-1) was a 96-week, randomized, partially blinded, phase IIb dose-ranging study.

Methods:

Treatment-naive adults with HIV received DTG 10, 25, or 50 mg once daily or efavirenz (EFV) 600 mg once daily (control arm) combined with investigator-selected dual nucleos(t)ide reverse transcriptase inhibitor backbone regimen (tenofovir/emtricitabine or abacavir/lamivudine). The primary endpoint of the study was the proportion of participants with plasma HIV-1 RNA less than 50 copies/ml, based on time to loss of virologic response at 16 weeks (conducted for the purpose of phase III dose selection), with a planned analysis at 96 weeks. Safety and tolerability were also assessed.

Results:

Of 208 participants randomized to treatment, 205 received study drug. At week 96, the proportion of participants achieving plasma HIV-1 RNA less than 50 copies/ml was 79, 78, and 88% for DTG 10, 25, and 50 mg, respectively, compared with 72% for EFV. The median increase from baseline in CD4⁺ cells was 338 cells/μl with DTG (all treatment groups combined) compared with 301 cells/μl with EFV (P = 0.155). No clinically significant dose-related trends in adverse events were observed, and fewer participants who received DTG withdrew because of adverse events (3%) compared with EFV (10%).

Conclusion:

Throughout the 96 weeks of the SPRING-1 study, DTG demonstrated sustained efficacy and favorable safety/tolerability in treatment-naive individuals with HIV-1.

Microbicides: topical prevention against HIV

Microbicides represent a potential intervention strategy for preventing HIV transmission. Vaginal microbicides would meet the need for a discreet method that women could use to protect themselves against HIV. Although early-generation microbicides failed to demonstrate efficacy, newer candidates are based on more potent antiretroviral (ARV) products. Positive data from the CAPRISA 004 trial of tenofovir gel support use in women and represent a turning point for the field. This article reviews current progress in development of ARV-based microbicides. We discuss the consensus on selection criteria, the potential for drug resistance, rationale for drug combinations, and the use of pharmacokinetic (PK)/pharmacodynamic (PD) assessment in product development. The urgent need for continued progress in development of formulations for sustained delivery is emphasized. Finally, as the boundaries between different prevention technologies become increasingly blurred, consideration is given to the potential synergy of diverse approaches across the prevention landscape.

Rapid reduction in HIV viral load in late pregnancy with raltegravir: a case report

The use of raltegravir (RAL) is not preferred to prevent perinatal transmission in pregnancy due to lack of safety and pharmacokinetic data in this population. Data have been limited to few case reports of patients who present for treatment late in pregnancy, have multidrug resistance, or have poor adherence, requiring an additional class such as an integrase inhibitor to further lower viral load. This case report describes and supports the initiation of RAL in very late pregnancy (week 33) to rapidly decrease viral load and successfully prevent perinatal transmission. By increasing the efficacy and safety data of RAL use in pregnancy, we believe this report can help provide some guidance on the management of complex cases.

Once-daily dolutegravir versus raltegravir in antiretroviral-naive adults with HIV-1 infection: 48 week results from the randomised, double-blind, non-inferiority SPRING-2 study

BACKGROUND

Dolutegravir (S/GSK1349572) is a once-daily HIV integrase inhibitor with potent antiviral activity and a favourable safety profile. We compared dolutegravir with HIV integrase inhibitor raltegravir, as initial treatment for adults with HIV-1.

METHODS

SPRING-2 is a 96 week, phase 3, randomised, double-blind, active-controlled, non-inferiority study that began on Oct 19, 2010, at 100 sites in Canada, USA, Australia, and Europe. Treatment-naive adults (aged ≥ 18 years) with HIV-1 infection and HIV-1 RNA concentrations of 1000 copies per mL or greater were randomly assigned (1:1) via a computer-generated randomisation sequence to receive either dolutegravir (50 mg once daily) or raltegravir (400 mg twice daily). Study drugs were given with coformulated tenofovir/emtricitabine or abacavir/lamivudine. Randomisation was stratified by screening HIV-1 RNA (≤ 100,000 copies per mL or >100,000 copies per mL) and nucleoside reverse transcriptase inhibitor backbone. Investigators were not masked to HIV-1 RNA results before randomisation. The primary endpoint was the proportion of participants with HIV-1 RNA less than 50 copies per mL at 48 weeks, with a 10% non-inferiority margin. Main secondary endpoints were changes from baseline in CD4 cell counts, incidence and severity of adverse events, changes in laboratory parameters, and genotypic or phenotypic evidence of resistance. Our primary analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01227824.

FINDINGS

411 patients were randomly allocated to receive dolutegravir and 411 to receive raltegravir and received at least one dose of study drug. At 48 weeks, 361 (88%) patients in the dolutegravir group achieved an HIV-1 RNA value of less than 50 copies per mL compared with 351 (85%) in the raltegravir group (adjusted difference 2·5%; 95% CI -2·2 to 7·1). Adverse events were similar between treatment groups. The most common events were nausea (59 [14%] patients in the dolutegravir group vs 53 [13%] in the raltegravir group), headache (51 [12%] vs 48 [12%]), nasopharyngitis (46 [11%] vs 48 [12%]), and diarrhoea (47 [11%] in each group). Few patients had drug-related serious adverse events (three [<1%] vs five [1%]), and few had adverse events leading to discontinuation (ten [2%] vs seven [2%] in each group). CD4 cell counts increased from baseline to week 48 in both treatment groups by a median of 230 cells per μL. Rates of graded laboratory toxic effects were similar. We noted no evidence of treatment-emergent resistance in patients with virological failure on dolutegravir, whereas of the patients with virologic failure who received raltegravir, one (6%) had integrase treatment-emergent resistance and four (21%) had nucleoside reverse transcriptase inhibitors treatment-emergent resistance.

INTERPRETATION

The non-inferior efficacy and similar safety profile of dolutegravir compared with raltegravir means that if approved, combination treatment with once-daily dolutegravir and fixed-dose nucleoside reverse transcriptase inhibitors would be an effective new option for treatment of HIV-1 in treatment-naive patients.

FUNDING

ViiV Healthcare.

Prevalent polymorphisms in wild-type HIV-1 integrase are unlikely to engender drug resistance to dolutegravir (S/GSK1349572)

The majority of HIV-1 integrase amino acid sites are highly conserved, suggesting that most are necessary to carry out the critical structural and functional roles of integrase. We analyzed the 34 most variable sites in integrase (>10% variability) and showed that prevalent polymorphic amino acids at these positions did not affect susceptibility to the integrase inhibitor dolutegravir (S/GSK1349572), as demonstrated both in vitro (in site-directed mutagenesis studies) and in vivo (in a phase IIa study of dolutegravir monotherapy in HIV-infected individuals). Ongoing clinical trials will provide additional data on the virologic activity of dolutegravir across subject viruses with and without prevalent polymorphic substitutions.

HIV-1 integrase resistance among antiretroviral treatment naive and experienced patients from Northwestern Poland

Background

HIV integrase inhibitor use is limited by low genetic barrier to resistance and possible cross-resistance among representatives of this class of antiretrovirals. The aim of this study was to analyse integrase sequence variability among antiretroviral treatment naive and experienced patients with no prior integrase inhibitor (InI) exposure and investigate development of the InI drug resistance mutations following the virologic failure of the raltegravir containing regimen.

Methods

Sequencing of HIV-1 integrase region from plasma samples of 80 integrase treatment naive patients and serial samples from 12 patients with observed virologic failure on raltegravir containing treatment whenever plasma vireamia exceeded >50 copies/ml was performed. Drug resistance mutations were called with Stanford DB database and grouped into major and minor variants. For subtyping bootstrapped phylogenetic analysis was used; Bayesian Monte Carlo Marcov Chain (MCMC) model was implemented to infer on the phylogenetic relationships between the serial sequences from patients failing on raltegravir.

Results

Majority of the integrase region sequences were classified as subtype B; the remaining ones being subtype D, C, G, as well as CRF01_AE , CRF02_AG and CRF13_cpx recombinants. No major integrase drug resistance mutations have been observed in InI-treatment naive patients. In 30 (38.5%) cases polymorphic variation with predominance of the E157Q mutation was observed. This mutation was more common among subtype B (26 cases, 54.2%) than non-B sequences (5 cases, 16.7%), p=0.00099, OR: 5.91 (95% CI:1.77-22.63)]. Other variants included L68V, L74IL, T97A, E138D, V151I, R263K. Among 12 (26.1%) raltegravir treated patients treatment failure was observed; major InI drug resistance mutations (G140S, Q148H and N155H, V151I, E92EQ, V151I, G163R) were noted in four of these cases (8.3% of the total InI-treated patients). Time to the development of drug resistance ranged from 2.6 to 16.3 months with mean increase of HIV viral load of 4.34 (95% CI:1.86-6.84) log HIV-RNA copies/ml at the time of emergence of the major mutations. Baseline polymorphisms, including E157Q were not associated with the virologic failure on raltegravir.

Conclusions

In InI treatment naive patients polymorphic integrase sequence variation was common, with no major resistance mutants. In the treatment failing patients selection of drug resistance occurred rapidly and followed the typical drug resistance pathways. Preexisting integrase polymorphisms were not associated with the treatment failure.

Safety and efficacy of dolutegravir in treatment-experienced subjects with raltegravir-resistant HIV type 1 infection: 24-week results of the VIKING Study

Background. Dolutegravir (DTG; S/GSK1349572), a human immunodeficiency virus type 1 (HIV-1) integrase inhibitor, has limited cross-resistance to raltegravir (RAL) and elvitegravir in vitro. This phase IIb study assessed the activity of DTG in HIV-1–infected subjects with genotypic evidence of RAL resistance.

Methods. Subjects received DTG 50 mg once daily (cohort I) or 50 mg twice daily (cohort II) while continuing a failing regimen (without RAL) through day 10, after which the background regimen was optimized, when feasible, for cohort I, and at least 1 fully active drug was mandated for cohort II. The primary efficacy end point was the proportion of subjects on day 11 in whom the plasma HIV-1 RNA load decreased by ≥0.7 log₁₀ copies/mL from baseline or was <400 copies/mL.

Results. A rapid antiviral response was observed. More subjects achieved the primary end point in cohort II (23 of 24 [96%]), compared with cohort I (21 of 27 [78%]) at day 11. At week 24, 41% and 75% of subjects had an HIV-1 RNA load of <50 copies/mL in cohorts I and II, respectively. Further integrase genotypic evolution was uncommon. Dolutegravir had a good, similar safety profile with each dosing regimen.

Conclusion. Dolutegravir 50 mg twice daily with an optimized background provided greater and more durable benefit than the once-daily regimen. These data are the first clinical demonstration of the activity of any integrase inhibitor in subjects with HIV-1 resistant to RAL.

3D-QSAR studies of quinoline ring derivatives as HIV-1 integrase inhibitors

In the process of HIV-1 virus replication, integrase plays a quite important role. Integrase inhibitors of quinoline ring derivatives were analysed by the Comparative Molecular Field Analysis (CoMFA), Comparative Molecular Similarity Induces Analysis (CoMSIA) and Topomer CoMFA methods. Firstly, 77 compounds were selected to form the training and test sets. Secondly, predictive models were constructed with the CoMFA, CoMSIA and Topomer CoMFA methods. The CoMFA model yielded the best model with q (2) of 0.76 and [Formula: see text] of 0.99, the CoMSIA model has q (2 )= 0.70 and [Formula: see text] of 0.99, while the Topomer CoMFA model has q (2) of 0.66 and [Formula: see text] of 0.97. These results provide a helpful contribution to the design of novel highly active HIV-1 integrase inhibitors.

Uncommon pathways of immune escape attenuate HIV-1 integrase replication capacity

An attenuation of the HIV-1 replication capacity (RC) has been observed for immune-mediated escape mutations in Gag restricted by protective HLA alleles. However, the extent to which escape mutations affect other viral proteins during natural infection is not well understood. We generated recombinant viruses encoding plasma HIV-1 RNA integrase sequences from antiretroviral-naïve individuals with early (n = 88) and chronic (n = 304) infections and measured the in vitro RC of each. In contrast to data from previous studies of Gag, we observed little evidence that host HLA allele expression was associated with integrase RC. A modest negative correlation was observed between the number of HLA-B-associated integrase polymorphisms and RC in chronic infection (R = -0.2; P = 0.003); however, this effect was not driven by mutations restricted by protective HLA alleles. Notably, the integrase variants S119R, G163E, and I220L, which represent uncommon polymorphisms associated with HLA-C*05, -A*33, and -B*52, respectively, correlated with lower RC (all q < 0.2). We identified a novel C*05-restricted epitope (HTDNGSNF(114-121)) that likely contributes to the selection of the S119R variant, the polymorphism most significantly associated with lower RC in patient sequences. An NL4-3 mutant encoding the S119R polymorphism displayed a ~35%-reduced function that was rescued by a single compensatory mutation of A91E. Together, these data indicate that substantial HLA-driven attenuation of integrase is not a general phenomenon during HIV-1 adaptation to host immunity. However, uncommon polymorphisms selected by HLA alleles that are not conventionally regarded to be protective may be associated with impaired protein function. Vulnerable epitopes in integrase might therefore be considered for future vaccine strategies.

Population pharmacokinetic analysis and pharmacogenetics of raltegravir in HIV-positive and healthy individuals

The objectives of this study were to characterize raltegravir (RAL) population pharmacokinetics in HIV-positive (HIV(+)) and healthy individuals, identify influential factors, and search for new candidate genes involved in UDP glucuronosyltransferase (UGT)-mediated glucuronidation. The pharmacokinetic analysis was performed with NONMEM. Genetic association analysis was performed with PLINK using the relative bioavailability as the phenotype. Simulations were performed to compare once- and twice-daily regimens. A 2-compartment model with first-order absorption adequately described the data. Atazanavir, gender, and bilirubin levels influenced RAL relative bioavailability, which was 30% lower in HIV(+) than in healthy individuals. UGT1A9*3 was the only genetic variant possibly influencing RAL pharmacokinetics. The majority of RAL pharmacokinetic variability remains unexplained by genetic and nongenetic factors. Owing to the very large variability, trough drug levels might be very low under the standard dosing regimen, raising the question of a potential relevance of therapeutic drug monitoring of RAL in some situations.

Localization of ASV integrase-DNA contacts by site-directed crosslinking and their structural analysis

Background

We applied crosslinking techniques as a first step in preparation of stable avian sarcoma virus (ASV) integrase (IN)-DNA complexes for crystallographic investigations. These results were then compared with the crystal structures of the prototype foamy virus (PFV) intasome and with published data for other retroviral IN proteins.

Methodology/Results

Photoaffinity crosslinking and site-directed chemical crosslinking were used to localize the sites of contacts with DNA substrates on the surface of ASV IN. Sulfhydryl groups of cysteines engineered into ASV IN and amino-modified nucleotides in DNA substrates were used for attachment of photocrosslinkers. Analysis of photocrosslinking data revealed several specific DNA-protein contacts. To confirm contact sites, thiol-modified nucleotides were introduced into oligo-DNA substrates at suggested points of contact and chemically crosslinked to the cysteines via formation of disulfide bridges. Cysteines incorporated in positions 124 and 146 in the ASV IN core domain were shown to interact directly with host and viral portions of the Y-mer DNA substrate, respectively. Crosslinking of an R244C ASV IN derivative identified contacts at positions 11 and 12 on both strands of viral DNA. The most efficient disulfide crosslinking was observed for complexes of the ASV IN E157C and D64C derivatives with linear viral DNA substrate carrying a thiol-modified scissile phosphate.

Conclusion

Analysis of our crosslinking results as well as published results of retroviral IN protein from other laboratories shows good agreement with the structure of PFV IN and derived ASV, HIV, and MuLV models for the core domain, but only partial agreement for the N- and C-terminal domains. These differences might be explained by structural variations and evolutionary selection for residues at alternate positions to perform analogous functions, and by methodological differences: i.e., a static picture of a particular assembly from crystallography vs. a variety of interactions that might occur during formation of functional IN complexes in solution.

Role of raltegravir in the management of HIV-1 infection

The development of multiple agents with potent antiretroviral activity against HIV has ushered in a new age of optimism in the management of patients infected with the virus. However, the viruses' dynamic ability to develop resistance against these agents necessitates the investigation of novel targets for viral suppression. Raltegravir represents a first-in-class agent targeting the HIV integrase enzyme, which is responsible for integration of virally encoded DNA into the host genome. Over the last 5 years, clinical trials data has demonstrated an increasing role for raltegravir in the management of both treatment-experienced and treatment-naïve HIV-1-infected patients. This review focuses on the evidence supporting raltegravir's efficacy in an array of clinical settings. Other HIV-1 integrase inhibitors in development are also briefly discussed.

Pharmacophore modelling and atom-based 3D-QSAR studies on N-methyl pyrimidones as HIV-1 integrase inhibitors

Pharmacophore modelling and atom-based 3D-QSAR studies were carried out for a series of compounds belonging to N-methyl pyrimidones as HIV-1 integrase inhibitors. Based on the ligand-based pharmacophore model, we got 5-point pharmacophore model AADDR, with two hydrogen bond acceptors (A), two hydrogen bond donors (D) and one aromatic ring (R). The generated pharmacophore-based alignment was used to derive a predictive atom-based 3D-QSAR model for the training set (r(2) = 0.92, SD = 0.16, F = 84.8, N = 40) and for test set (Q(2) = 0.71, RMSE = 0.06, Pearson R = 0.90, N = 10). From these results, AADDR pharmacophore feature was selected as best common pharmacophore hypothesis, and atom-based 3D-QSAR results also support the outcome by means of favourable and unfavourable regions of hydrophobic and electron-withdrawing groups for the most potent compound 30. These results can be useful for further design of new and potent HIV-1 IN inhibitors.

Patterns of resistance development with integrase inhibitors in HIV

Raltegravir, the only integrase (IN) inhibitor approved for use in HIV therapy, has recently been licensed. Raltegravir inhibits HIV-1 replication by blocking the IN strand transfer reaction. More than 30 mutations have been associated with resistance to raltegravir and other IN strand transfer inhibitors (INSTIs). The majority of the mutations are located in the vicinity of the IN active site within the catalytic core domain which is also the binding pocket for INSTIs. High-level resistance to INSTIs primarily involves three independent mutations at residues Q148, N155, and Y143. The mutations significantly affect replication capacity of the virus and are often accompanied by other mutations that either improve replication fitness and/or increase resistance to the inhibitors. The pattern of development of INSTI resistance mutations has been extensively studied in vitro and in vivo. This has been augmented by cell-based phenotypic studies and investigation of the mechanisms of resistance using biochemical assays. The recent elucidation of the structure of the prototype foamy virus IN, which is closely related to HIV-1, in complex with INSTIs has greatly enhanced our understanding of the evolution and mechanisms of IN drug resistance.

Performance of the Abbott RealTime HIV-1 viral load assay is not impacted by integrase inhibitor resistance-associated mutations

The Abbott RealTime HIV-1 viral load assay uses primers and probes targeted to integrase, which is also the target of integrase inhibitors such as raltegravir. Viral loads of 42 raltegravir-susceptible and 40 raltegravir-resistant specimens were determined using RealTime HIV-1 and Roche Monitor (v1.5). The differences in viral load measurements between assays were comparable in the two groups, demonstrating that the RealTime HIV-1 assay can tolerate raltegravir-selected mutations.