Raltegravir Research Articles

Changes in plasma levels of oxidized lipoproteins and lipoprotein subfractions with atazanavir-, raltegravir-, darunavir-based initial antiviral therapy and associations with common carotid artery intima-media thickness: ACTG 5260s.

The role of oxidized lipoproteins (high-density [HDLox] and low-density [LDLox]) and total lipoprotein particle (Lp) number and size in HIV-related cardiovascular disease (CVD) is unclear. The goal of this study was to evaluate changes of these biomarkers and their associations with rate of carotid intima media thickness progression over 3 years (ΔCIMT) in chronic HIV infection. Prospective study of 234 HIV-infected antiretroviral treatment-naive participants without CVD who were randomized to receive tenofovir-emtricitabine plus atazanavir/ritonavir, darunavir/ritonavir or raltegravir (RAL) and achieved plasma HIV-1 RNA <50 copies/ml by week 24 and thereafter. Biomarker changes over 24, 48 or 96 weeks from baseline and pairwise treatment group comparisons were examined. Associations of these biomarkers with ΔCIMT were analysed with mixed effects linear regression. HDLp number increased with both protease inhibitors (PIs) over 48 weeks, while LDLp number declined with RAL; Lp size did not change. Over 96 weeks, normalized HDLox declined with both PIs; LDLox increased in all groups. Few treatment group differences were observed across all biomarkers. Associations between ΔCIMT and oxidized lipoproteins at all time points were not apparent (P≥0.10). There was some evidence of slower ΔCIMT for higher HDLp number (P=0.06) and for lower LDLp number (P=0.08) measured at baseline. Unexpectedly, LDLox increased modestly in all treatment groups after ART initiation. Associations of plasma HDLox and LDLox with ΔCIMT were not apparent. While plasma levels of abnormal lipoproteins have been shown to be associated with CVD outcomes, clear associations with sub-clinical atherosclerosis progression were not apparent in our study.

Bidirectional Transfer of Raltegravir in an Ex Vivo Human Cotyledon Perfusion Model.

Placental transfer of the HIV integrase inhibitor raltegravir (RLT) was investigated in term human cotyledons in the maternal-to-fetal (n = 3) and fetal-to-maternal (n = 6) directions. In the maternal-to-fetal direction, the mean ± standard deviation (SD) fetal transfer rate (FTR) was 9.1% ± 1.4%, and the mean ± SD clearance index (IC), i.e., RLT FTR/antipyrine FTR, was 0.28 ± 0.05. In the fetal-to-maternal direction, the mean ± SD CI was 0.31 ± 0.09. Placental transfer of RLT was high in both directions.

Might dolutegravir be part of a functional cure for HIV?

Antiretroviral therapy (ART) has greatly decreased HIV-related morbidity and mortality. However, HIV can establish viral reservoirs that evade both the immune system and ART. Dolutegravir (DTG) is a second-generation integrase strand transfer inhibitor (INSTI) related to the first-generation INSTIs raltegravir (RAL) and elvitegravir (EVG). DTG shows a higher genetic barrier to the development of HIV-1 resistance than RAL and EVG. More interestingly, clinical resistance mutations to DTG in treatment-naïve patients have not been observed to date. This review summarizes recent studies on strategies toward a cure for HIV, explores resistance profiles of DTG, and discusses how DTG might help in finding a functional cure for HIV.

Body Composition Changes After Initiation of Raltegravir or Protease Inhibitors: ACTG A5260s.

Fat gain after antiretroviral therapy (ART) occurs, and its association with protease inhibitors (PIs) is unclear. Peripheral and central fat depots and lean mass were measured using standardized and centrally read abdominal CT scans and whole-body dual-energy absorptiometry scans over a 96-week period in human immunodeficiency virus (HIV)-infected treatment-naive participants. The patients were randomized to tenofovir-emtricitabine (TDF/FTC) plus atazanavir-ritonavir (ATV/r), darunavir-ritonavir (DRV/r), or raltegravir (RAL) in ACTG A5260s, a substudy of A5257. Within arm changes were assessed with signed-rank tests. The 96-week percentage changes in fat and lean mass in the 2 PI arms were not different, thus the PI arms were combined and compared to the RAL arm. Associations between baseline biomarkers and changes in body composition were assessed. All analyses used linear regression models. 328 patients were randomized (90% male, 44% white non-Hispanic). The median age was 36 years, HIV-1 RNA 4.6 log10 copies/mL, and CD4 349 cells/μL. Overall, at week 96, increases in limb fat (13.4%), subcutaneous (19.9%) and visceral abdominal fat (25.8%), trunk fat (18%), and lean mass (1.8%) were apparent (P < .001 for changes within each arm). Changes for all fat and lean outcomes were not different between the PI arms or between the RAL and the combined PI arms. Higher baseline HIV-1 RNA levels were associated with greater gains in peripheral and central fat. In treatment-naive participants initiating ART with TDF/FTC, no differences in lean mass and regional fat were found with RAL when compared with ATV/r or DRV/r over 96 weeks. NCT00811954 and NCT00851799.

Mucosal tissue pharmacokinetics of the integrase inhibitor raltegravir in a humanized mouse model: Implications for HIV pre-exposure prophylaxis

Orally administered anti-retroviral drugs show considerable promise for HIV/AIDS pre-exposure prophylaxis (PrEP). For the success of these strategies, pharmacokinetic (PK) data defining the optimal concentration of the drug needed for protection in relevant mucosal exposure sites is essential. Here we employed a humanized mouse model to derive comprehensive PK data on the HIV integrase inhibitor raltegravir (RAL), a leading PrEP drug candidate. Under steady state conditions following oral dosing, plasma and multiple mucosal tissues were sampled simultaneously. RAL exhibited higher drug exposure in mucosal tissues relative to that in plasma with one log higher exposure in vaginal and rectal tissue and two logs higher exposure in intestinal mucosa reflecting the trends seen in the human studies. These data demonstrate the suitability of RAL for HIV PrEP and validate the utility of humanized mouse models for deriving important preclinical PK–PD data.

Dual therapy based on raltegravir and boosted protease inhibitors - the experience of Polish centers.

IntroductionThe aim of the study was to present the experience of Polish centers regarding dual therapy based on the integrase inhibitor raltegravir (RAL) and ritonavir-boosted protease inhibitors (PI/r) for treating treatment-naïve and -experienced HIV-infected patients.Material and methodsThe paper concerns a retrospective multicenter study. The medical databases of six main Polish HIV centers from January 2009 to December 2014 were analyzed for the use of combined antiretroviral treatment consisting of RAL + PI/r. This study included 126 HIV-infected patients receiving RAL + PI/r therapy, of whom 17 patients were treatment-naive and 109 patients were treatment-experienced.ResultsIn treatment-experienced patients, the most common reasons for the introduction of a RAL + PI/r regimen were virologic failure and impaired renal function (45 of 109 patients). In the treatment-naïve group kidney disease was the cause of the RAL + PI/r regimen in 3 of 17 participants. In treatment-experienced patients, 80% of individuals still were on RAL + PI/r treatment after 12 months, 65% after 24 months and 53% of subjects after 60 months. In both groups, the simplification of the antiretroviral regimen was the most common reason for discontinuation of RAL + PI/r based therapy.ConclusionsIn antiretroviral-experienced patients the dual therapy based on RAL + PI/s is safe and effective. In antiretroviral-naïve patients the RAL + PI/r regimen is rarely used in Poland.

A Pilot Study of Raltegravir Plus Combination Antiretroviral Therapy in Early Human Immunodeficiency Virus Infection: Challenges and Lessons Learned.

Availability of integrase strand transfer inhibitors created interest in determining whether their use would decrease persistently infected cell numbers. This study hypothesized that adding raltegravir (RAL) to standard antiretroviral therapy (ART) would decrease human immunodeficiency virus (HIV)-infected CD4+ T cells more than standard combination ART. This was a pilot, randomized study comparing open-label standard triple ART to standard triple ART plus RAL over 96 weeks in ART-naive adults with early HIV infection. The primary objective was to compare quantity and trajectory of HIV DNA. Eighty-two persons were referred. A diverse set of reasons precluded the enrollment of all but 10. Those who enrolled and completed the study had an estimated median duration of HIV infection of 74 days at ART start. The groups had similar baseline characteristics. The RAL group had more rapid first phase plasma HIV RNA decay (0.67 log10 copies/mL/day) than with combination ART (0.34 log10copies/mL/day), p = 0.037. Second phase HIV RNA decay, residual viremia, cell-associated RNA, HIV DNA, CD4+ T-cells with replication-competent virus, and 2LTR circle levels did not differ between groups. Among those with entry plasma HIV RNA levels above the median, 2LTR circles were significantly lower over time than in those with lower entry HIV RNA levels (p = 0.02). Our results suggest homogeneity of responses in cell-associated RNA, HIV DNA, CD4+ T-cells with replication-competent virus, and 2LTR circles with early HIV in both ART groups. The kinetics of 2LTR DNA did not reflect the kinetics of plasma HIV RNA decline following ART initiation.

RTG-loaded nanomicelles (CS–VES–NAC) for oral anti-HIV drug delivery

An acetylcysteine–chitosan–vitamin E succinate copolymer (CVN) was synthesized from chitosan (CS), vitamin E succinate (VES) and N-acetyl-l-cysteine (NAC) as self-assembled nanomicelles for multifunctional delivery of anti-HIV drug Raltegravir (RTG).

Cost-Effectiveness of Dolutegravir in HIV-1 Treatment-Experienced (TE) Patients in France

ObjectivesTo evaluate the cost-effectiveness of a new generation integrase inhibitor (INI), dolutegravir (DTG), in France, in treatment-experienced (TE) and INI-naïve HIV-infected adults with at least two classes resistance compared to raltegravir (RAL), by adapting previously published Anti-Retroviral Analysis by Monte Carlo Individual Simulation (ARAMIS) model.MethodsARAMIS is a microsimulation Markov model with a lifetime time horizon and a monthly cycle length. Health states are defined as with or without opportunistic infection and death. In the initial cohort, efficacy and safety data were derived from a phase III study comparing DTG to RAL. Antiretroviral treatment algorithms, accounting for patient history, were based on French guidelines and experts opinion. Costs are mainly including treatment costs, routine HIV and opportunistic infection care, and death. Utilities depend on CD4+ cell count and the occurrence of opportunistic infections.ResultsThe ARAMIS model indicates in the TE population that DTG compared to RAL over a life time is associated with 0.35 additional quality-adjusted life years (QALY; 10.75 versus 10.41) and additional costs of €7,266 (€390,001 versus €382,735). DTG increased costs are mainly related to a 9.1-month increase in life expectancy for DTG compared with RAL, and consequently a longer time spent on ART. The incremental cost-effectiveness ratio (ICER) for DTG compared with RAL is €21,048 per QALY gained. About 83% and 14% of total lifetime costs are associated with antiretroviral therapy and routine HIV care respectively. Univariate deterministic sensitivity analyses demonstrate the robustness of the model.ConclusionDTG is cost-effective in the management of TE INI naive patients in France, from a collective perspective. These results could be explained by the superior efficacy of DTG in this population and its higher genetic barrier to resistance compared to RAL. These data need to be confirmed with longer-term real life data.

Nanoparticle-Based ARV Drug Combinations for Synergistic Inhibition of Cell-Free and Cell-Cell HIV Transmission.

Nanocarrier-based drug delivery systems are playing an emerging role in human immunodeficiency virus (HIV) chemoprophylaxis and treatment due to their ability to alter the pharmacokinetics and improve the therapeutic index of various antiretroviral (ARV) drug compounds used alone and in combination. Although several nanocarriers have been described for combination delivery of ARV drugs, measurement of drug-drug activities facilitated by the use of these nanotechnology platforms has not been fully investigated for topical prevention. Here, we show that physicochemically diverse ARV drugs can be encapsulated within polymeric nanoparticles to deliver multidrug combinations that provide potent HIV chemoprophylaxis in relevant models of cell-free, cell-cell, and mucosal tissue infection. In contrast to existing approaches that coformulate ARV drug combinations together in a single nanocarrier, we prepared single-drug-loaded nanoparticles that were subsequently combined upon administration. ARV drug-nanoparticles were prepared using emulsion-solvent evaporation techniques to incorporate maraviroc (MVC), etravirine (ETR), and raltegravir (RAL) into poly(lactic-co-glycolic acid) (PLGA) nanoparticles. We compared the antiviral potency of the free and formulated drug combinations for all pairwise and triple drug combinations against both cell-free and cell-associated HIV-1 infection in vitro. The efficacy of ARV-drug nanoparticle combinations was also assessed in a macaque cervicovaginal explant model using a chimeric simian-human immunodeficiency virus (SHIV) containing the reverse transcriptase (RT) of HIV-1. We observed that our ARV-NPs maintained potent HIV inhibition and were more effective when used in combinations. In particular, ARV-NP combinations involving ETR-NP exhibited significantly higher antiviral potency and dose-reduction against both cell-free and cell-associated HIV-1 BaL infection in vitro. Furthermore, ARV-NP combinations that showed large dose-reduction were identified to be synergistic, whereas the equivalent free-drug combinations were observed to be strictly additive. Higher intracellular drug concentration was measured for cells dosed with the triple ARV-NP combination compared to the equivalent unformulated drugs. Finally, as a first step toward evaluating challenge studies in animal models, we also show that our ARV-NP combinations inhibit RT-SHIV virus propagation in macaque cervicovaginal tissue and block virus transmission by migratory cells emigrating from the tissue. Our results demonstrate that ARV-NP combinations control HIV-1 transmission more efficiently than free-drug combinations. These studies provide a rationale to better understand the role of nanocarrier systems in facilitating multidrug effects in relevant cells and tissues associated with HIV infection.

Adherence to Post-Exposure Prophylaxis (PEP) and Incidence of HIV Seroconversion in a Major North American Cohort

BackgroundThere is limited evidence on the efficacy of post-exposure prophylaxis (PEP) for sexual exposures. We sought to determine the factors associated with adherence to treatment and describe the incidence of PEP failures in a Montreal clinic.MethodsWe prospectively assessed all patients consulting for PEP following sexual exposures from October 2000 to July 2014. Patients were followed at 4 and 16 weeks after starting PEP. Treatment adherence was determined by self-report at week 4. Multivariable logistic regression was used to estimate the factors predicting adherence to treatment.Results3547 PEP consults were included. Patients were mainly male (92%), MSM (83%) and sought PEP for anal intercourse (72%). Seventy-eight percent (n = 2772) of patients received a prescription for PEP, consisting of Tenofovir/Emtracitabine (TVD) + Lopinavir/Ritonavir (LPV) in 74% of cases, followed by Zidovudine/Lamivudine (CBV) + LPV (10%) and TVD + Raltegravir (RAL) (8%). Seventy percent of patients were adherent to treatment. Compared to TVD+LPV, patients taking CBV+LPV were less likely to adhere to treatment (OR 0.58, 95% CI 0.44–0.75), while no difference was observed for patients taking TVD+RAL (OR 1.15, 95% CI 0.83–1.59). First-time PEP consults, older and male patients were also more adherent to treatment. Ten treated patients seroconverted (0.37%) during the study period, yet only 1 case can be attributed to PEP failure (failure rate = 0.04%).ConclusionPEP regimen was associated with treatment adherence. Patients were more likely to be adherent to TVD-based regimens. Ten patients seroconverted after taking PEP; however, only 1 case was a PEP failure as the remaining patients continued to engage in high-risk behavior during follow-up. One month PEP is an effective preventive measure to avoid HIV infection.

Identification of minority resistance mutations in the HIV-1 integrase coding region using next generation sequencing

BackgroundThe current widely applied standard method to screen for HIV-1 genotypic resistance is based on Sanger population sequencing (Sseq), which does not allow for the identification of minority variants (MVs) below the limit of detection for the Sseq-method in patients receiving integrase strand-transfer inhibitors (INSTI). Next generation sequencing (NGS) has facilitated the detection of MVs at a much deeper level than Sseq. ObjectivesHere, we compared Illumina MiSeq and Sseq approaches to evaluate the detection of MVs involved in resistance to the three commonly used INSTI: raltegravir (RAL), elvitegravir (EVG) and dolutegravir (DTG). Study designNGS and Sseq were used to analyze RT-PCR products of the HIV-1 integrase coding region from six patients and in serial samples from two patients. NGS sequences were assembled and analyzed using the low frequency variant detection (LFVDT) tool in CLC genomic workbench. ResultsSseq detected INSTI resistance and accessory mutations in three of the patients (called INSTI Res+), while no resistance or accessory mutations were detected in the remaining three patients (called INSTI Res-). Additional INSTI resistance and/or accessory mutations were detected by NGS analysis of integrase sequences from all three INSTI Res+ and one INSTI Res- patient. ConclusionOur observations suggested that NGS demonstrated a higher sensitivity than sSEQ in the identification of INSTI relevant MVs both in patients at treatment baseline and in patients receiving INSTI therapy. Thus NGS can be a valuable tool in monitoring of antiretroviral minority resistance in patients receiving INSTI therapy.

Testing anti-HIV activity of antiretroviral agents in vitro using flow cytometry analysis of CEM-GFP cells infected with transfection-derived HIV-1 NL4-3.

An assay, specifically optimized to evaluate the anti-HIV activity of antiretrovirals by flow cytometry analysis, is described. As widely used anti-HIV agents, zidovudine (AZT), abacavir (ABC), 2',3'-dideoxyinosine (DDI), lamivudine (3TC), nevirapine (NVP), and efavirenz (EFV), and as drugs of recent approval raltegravir (RAL), etravirine (ETR), and rilpivirine (RPV), were utilized as reference drugs. HIV-1 NL4-3 virus was prepared by transfection of HEK293T cells with purified plasmid DNA and quantified by p24 antigen-capture assay. For infection, CEM-GFP cells were exposed to vehicle or to several concentrations of the drugs for 2 hr at 37 °C before HIV-1 NL4-3 was added to each sample. The adsorption was prolonged for 3 hr at 37 °C. After 72 hr of incubation, HIV-induced GFP expression in infected CEM-GFP cells was assessed by flow cytometry analysis and expressed as % positive cells. For comparison, p24 production in supernatants was assessed by a commercial ELISA kit. On the basis of IC50 values, the anti-HIV activity, as assayed by this method, was EFV > 3TC > AZT > NVP > DDI > ABC and ETR > RPV > RAL. The comparison between the IC50 values calculated through flow cytometry and p24 production revealed overlapping results, showing that the optimized protocol of CEM-GFP infection with HIV NL4-3 is a suitable method to perform quantitative, rapid and low-expensive screening tests to evaluate the in vitro effect of new candidate anti-HIV drugs.

The dolutegravir R263K resistance mutation in HIV-1 integrase is incompatible with the emergence of resistance against raltegravir.

Although the integrase inhibitor dolutegravir (DTG) has demonstrated greater resilience than other antiretroviral drugs at withstanding the emergence of HIV-1 resistance mutations, such substitutions can develop, albeit rarely, in treatment-experienced integrase inhibitor-naïve individuals. The most common substitution in integrase under those circumstances is R263K whereas another substitution that was selected against DTG in tissue culture was G118R. The objective of this study was to determine the effects of these DTG-specific resistance substitutions on the ability of HIV-1 to become resistant against either of two other integrase inhibitors, raltegravir (RAL) and elvitegravir (EVG). We performed tissue culture selection experiments using DTG-resistant viruses containing integrase substitutions at positions R263K, H51Y/R263K, E138K/R263K, G118R and H51Y/G118R in the presence of increasing concentrations of either RAL or EVG. Changes in integrase sequences were monitored by genotyping. The presence of the R263K substitution delayed the emergence of resistance against RAL whereas the simultaneous presence of either the H51Y or E138K secondary substitutions in combination with R263K somewhat mitigated this inhibitory effect. In contrast, resistance against EVG appeared earlier than in wild-type virus in viruses containing the R263K and E138K/R263K DTG-associated resistance substitutions. The DTG-resistant R263K substitution antagonized the development of HIV-1 resistance against RAL while partially facilitating the occurrence of resistance against EVG.

Characterization of the Drug Resistance Profiles of Integrase Strand Transfer Inhibitors in Simian Immunodeficiency Virus SIVmac239.

We previously showed that the simian immunodeficiency virus SIVmac239 is susceptible to human immunodeficiency virus (HIV) integrase (IN) strand transfer inhibitors (INSTIs) and that the same IN drug resistance mutations result in similar phenotypes in both viruses. Now we wished to determine whether tissue culture drug selection studies with SIV would yield the same resistance mutations as in HIV. Tissue culture selection experiments were performed using rhesus macaque peripheral blood mononuclear cells (PBMCs) infected with SIVmac239 viruses in the presence of increasing concentrations of dolutegravir (DTG), elvitegravir (EVG), and raltegravir (RAL). We now show that 22 weeks of selection pressure with DTG yielded a mutation at position R263K in SIV, similar to what has been observed in HIV, and that selections with EVG led to emergence of the E92Q substitution, which is a primary INSTI resistance mutation in HIV associated with EVG treatment failure. To study this at a biochemical level, purified recombinant SIVmac239 wild-type (WT) and E92Q, T97A, G118R, Y143R, Q148R, N155H, R263K, E92Q T97A, E92Q Y143R, R263K H51Y, and G140S Q148R recombinant substitution-containing IN enzymes were produced, and each of the characteristics strand transfer, 3'-processing activity, and INSTI inhibitory constants was assessed in cell-free assays. The results show that the G118R and G140S Q148R substitutions decreased Km' and Vmax'/Km' for strand transfer compared to those of the WT. RAL and EVG showed reduced activity against both viruses and against enzymes containing Q148R, E92Q Y143R, and G140S Q148R. Both viruses and enzymes containing Q148R and G140S Q148R showed moderate levels of resistance against DTG. This study further confirms that the same mutations associated with drug resistance in HIV display similar profiles in SIV. Our goal was to definitively establish whether HIV and simian immunodeficiency virus (SIV) share similar resistance pathways under tissue culture drug selection pressure with integrase strand transfer inhibitors and to test the effect of HIV-1 integrase resistance-associated mutations on SIV integrase catalytic activity and resistance to integrase strand transfer inhibitors. Clinically relevant HIV integrase resistance-associated mutations were selected in SIV in our tissue culture experiments. Not only do we report on the characterization of SIV recombinant integrase enzyme catalytic activities, we also provide the first research anywhere on the effect of mutations within recombinant integrase SIV enzymes on drug resistance.

An Unexpected Effect of Atazanavir on Carotid Wall Thickness

HIV-infected patients are at increased risk for cardiovascular disease (CVD). Some antiretroviral agents have been associated with CVD in observational studies, but randomized, prospective data are lacking. Now, investigators have analyzed changes in carotid intima-media thickness (IMT), a marker for future CVD, in a subset of participants in ACTG A5257. This randomized trial compared ritonavir-boosted atazanavir, ritonavir-boosted darunavir, and raltegravir, each combined with tenofovir/FTC, for initial HIV …

HIV-1 Group O Resistance Against Integrase Inhibitors

HIV-1 group O (HIV-O) is a rare variant that is characterized by a high number of natural polymorphisms in the integrase coding region that may impact on susceptibility to integrase strand transfer inhibitors (INSTIs) and on the emergence of resistance substitutions. We previously reported that HIV-O is more susceptible to RAL than HIV-1 group M (HIV-M). The aim of this study was to assess pathways of resistance to INSTIs in group 0 variants. Accordingly, we selected for resistance to each of raltegravir (RAL), elvitegravir (EVG), and dolutegravir (DTG) in cord blood mononuclear cells using HIV group O subtypes A and B, an HIV-O divergent isolate, and HIV-1 group M (subtype B, which served as a reference). Site-directed mutagenesis was performed on the pCOM2.5 HIV group 0 infectious clone to ascertain the impact of INSTI resistance substitutions at positions Q148R, N155H, and R263K within integrase on susceptibility to INSTIs and infectiousness. Cell culture selections of group O variants yielded similar patterns of resistance to RAL, EVG, and DTG as observed for subtype B. In the DTG selections, subtype B yielded S153Y, whereas a natural S153A polymorphism sometimes led to A153V in group O. The pCMO2.5/Q148R and pCMO2.5/N155H variants displayed far higher levels of resistance to DTG (>1000 FC) than was seen for group M viruses. HIV-O harboring Q148R and N155H shows higher resistance to DTG compared with HIV-M subtype B.

The Combination of the R263K and T66I Resistance Substitutions in HIV-1 Integrase Is Incompatible with High-Level Viral Replication and the Development of High-Level Drug Resistance.

The R263K substitution in integrase has been selected in tissue culture with dolutegravir (DTG) and has been reported for several treatment-experienced individuals receiving DTG as part of salvage therapy. The R263K substitution seems to be incompatible with the presence of common resistance mutations associated with raltegravir (RAL), a different integrase strand transfer inhibitor (INSTI). T66I is a substitution that is common in individuals who have developed resistance against a different INSTI termed elvitegravir (EVG), but it is not known whether these two mutations might be compatible in the context of resistance against DTG or what impact the combination of these substitutions might have on resistance against INSTIs. E138K is a common secondary substitution observed with various primary resistance substitutions in RAL- and EVG-treated individuals. Viral infectivity, replicative capacity, and resistance against INSTIs were measured in cell-based assays. Strand transfer and 3' processing activities were measured biochemically. The combination of the R263K and T66I substitutions decreased HIV-1 infectivity, replicative capacity, and strand transfer activity. The addition of the E138K substitution partially compensated for these deficits and resulted in high levels of resistance against EVG but not against DTG or RAL. These findings suggest that the presence of the T66I substitution will not compromise the activity of DTG and may also help to prevent the additional generation of the R263K mutation. Our observations support the use of DTG in second-line therapy for individuals who experience treatment failure with EVG due to the T66I substitution. The integrase strand transfer inhibitors (INSTIs) elvitegravir and dolutegravir are newly developed inhibitors against human immunodeficiency virus type 1 (HIV-1). HIV drug-resistant mutations in integrase that can arise in individuals treated with elvitegravir commonly include the T66I substitution, whereas R263K is a signature resistance substitution against dolutegravir. In order to determine how different combinations of integrase resistance mutations can influence the outcome of therapy, we report here the effects of the T66I, E138K, and R263K substitutions, alone and in combination, on viral replicative capacity and resistance to integrase inhibitors. Our results show that the addition of R263K to the T66I substitution diminishes viral replicative capacity and strand transfer activity while not compromising susceptibility to dolutegravir. This supports the use of dolutegravir in second-line therapy for patients failing elvitegravir therapy who harbor the T66I resistance substitution.

Sequence-Based Predictive Models of Resistance to HIV-1 Integrase Inhibitors: An n-Grams Approach to Phenotype Assessment.

Amino acid substitutions in HIV-1 proteins critical to the viral replication cycle have the potential to undermine successful inhibition of those targets, with some mutations leading to either reduced susceptibility to certain medications or complete drug resistance. Phenotypic tests are best suited to quantify the effects of complex mutational patterns on drug resistance; however, the relatively high cost and long turnaround time associated with phenotyping has increased the demand for in silico drug-specific models capable of accurately predicting phenotype directly from the target protein sequences. The focus of this study is on the HIV-1 integrase (IN) enzyme, which mediates integration of reversibly transcribed viral DNA into the host cell genome, and the development of predictive statistical learning models of resistance to the IN inhibitors Raltegravir (RAL) and Elvitegravir (EVG). Models were trained using datasets of IN protein sequence variants each having a known phenotype, quantified as the fold change in susceptibility to the respective inhibitor, and obtained using an experimental assay. A sequence-based approach employing n-grams relative frequencies was implemented to uniquely characterize each IN variant as a feature vector of input attributes. Models for classifying IN variants as susceptible or resistant reach cross-validation balanced accuracy rates of 89% with RAL and 85% with EVG. Additionally, regression models achieve Pearson's correlation coefficients, between experimental and predicted log-transformed phenotypic fold change values, as high as r = 0.80 with RAL and r = 0.76 with EVG. Our results suggest that as additional training data are made publicly available, the models may hold promise as supplementary tools for making treatment decisions.

Changes to Initial Postexposure Prophylaxis Regimens Between the Emergency Department and Clinic

Changes to Initial Postexposure Prophylaxis Regimens Between the Emergency Department and Clinic