Clinical Utility of Current NNRTIs and Perspectives of New Agents in This Class under Development

HIV transmission dynamics and population-wide drug resistance in rural South Africa

Despite expanded antiretroviral therapy (ART) in South Africa, HIV-1 transmission persists. Integrase strand transfer inhibitors (INSTI) and long-acting injectables offer potential for superior viral suppression, but pre-existing drug resistance could threaten their effectiveness. In a community-based study in rural KwaZulu-Natal, prior to widespread INSTI usage, we enroled 18,025 individuals to characterise HIV-1 drug resistance and transmission networks to inform public health strategies. HIV testing and reflex viral load quantification were performed, with deep sequencing (20% variant threshold) used to detect resistance mutations. Phylogenetic and geospatial analyses characterised transmission clusters. One-third of participants were HIV-positive, with 21.7% having detectable viral loads; 62.1% of those with detectable viral loads were ART-naïve. Resistance to older reverse transcriptase (RT)-targeting drugs was found, but INSTI resistance remained low (<1%). Non-nucleoside reverse transcriptase inhibitor (NNRTI) resistance, particularly to rilpivirine (RPV) even in ART-naïve individuals, was concerning. Twenty percent of sequenced individuals belonged to transmission clusters, with geographic analysis highlighting higher clustering in peripheral and rural areas. Our findings suggest promise for INSTI-based strategies in this setting but underscore the need for RPV resistance screening before implementing long-acting cabotegravir (CAB) + RPV. The significant clustering emphasises the importance of geographically targeted interventions to effectively curb HIV-1 transmission.

HIV transmission dynamics and population-wide drug resistance in rural South Africa

Despite the scale-up of antiretroviral therapy (ART) in South Africa, HIV-1 incidence remains high. The anticipated use of potent integrase strand transfer inhibitors and long-acting injectables aims to enhance viral suppression at the population level and diminish transmission. Nevertheless, pre-existing drug resistance could impede the efficacy of long-acting injectable ART combinations, such as rilpivirine (an NNRTI) and cabotegravir (an INSTI). Consequently, a thorough understanding of transmission networks and geospatial distributions is vital for tailored interventions, including pre-exposure prophylaxis with long-acting injectables. However, empirical data on background resistance and transmission networks remain limited. In a community-based study in rural KwaZulu-Natal (2018-2019), prior to the widespread use of integrase inhibitor-based first-line ART, we performed HIV testing with reflex HIV-1 RNA viral load quantification on 18,025 participants. From this cohort, 6,096 (33.9%) tested positive for HIV via ELISA, with 1,323 (21.7%) exhibiting detectable viral loads (> 40 copies/mL). Of those with detectable viral loads, 62.1% were ART-naïve, and the majority of the treated were on an efavirenz + cytosine analogue + tenofovir regimen. Deep sequencing analysis, with a variant abundance threshold of 20%, revealed NRTI resistance mutations such as M184V in 2% of ART-naïve and 32% of treated individuals. Tenofovir resistance mutations K65R and K70E were found in 12% and 5% of ART-experienced individuals, respectively, and in less than 1% of ART-naïve individuals. Integrase inhibitor resistance mutations were notably infrequent (< 1%). Prevalence of pre-treatment drug resistance to NNRTIs was 10%, predominantly consisting of the K103N mutation. Among those with viraemic ART, NNRTI resistance was 50%, with rilpivirine-associated mutations observed in 9% of treated and 6% of untreated individuals. Cluster analysis revealed that 20% (205/1,050) of those sequenced were part of a cluster. We identified 171 groups with at least two linked participants; three quarters of clusters had only two individuals, and a quarter had 3-6 individuals. Integrating phylogenetic with geospatial analyses, we revealed a complex transmission network with significant clustering in specific regions, notably peripheral and rural areas. These findings derived from population scale genomic analyses are encouraging in terms of the limited resistance to DTG, but indicate that transitioning to long-acting cabotegravir + rilpivirine for transmission reduction should be accompanied by prior screening for rilpivirine resistance. Whole HIV-1 genome sequencing allowed identification of significant proportions of clusters with multiple individuals, and geospatial analyses suggesting decentralised networks can inform targeting public health interventions to effectively curb HIV-1 transmission.

Using Molecular Transmission Networks to Reveal the Epidemic of Pretreatment HIV-1 Drug Resistance in Guangxi, China

Introduction

Pretreatment drug resistance (PDR) is becoming an obstacle to the success of ART. This study investigated the prevalence of PDR and the transmission clusters (TCs) of drug resistance mutations (DRMs) in two cities where drug abuse used to be high to describe the local HIV-1 transmission dynamics.

Methods

Plasma samples were obtained from 1,027 ART-naïve patients in Guangxi. Viral subtypes and DRMs were identified. Transmission network and related factors were also determined.

Results

A total of 1,025 eligible sequences were obtained from Qinzhou (65.8%) and Baise (34.2%) cities. The predominant HIV-1 genotype was CRF08_BC (45.0%), followed by CRF01_AE (40.9%). The overall prevalence of PDR was 8.3%, and resistance to NNRTI was the most common. Putative links with at least one other sequence were found in 543/1,025 (53.0%) sequences, forming 111 clusters (2–143 individuals). The most prevalent shared DRMs included V106I (45.35%), V179D (15.1%), and V179E (15.1%). Clusters related to shared DRMs were more frequent and larger in CRF08_BC. The prevalence of shared DRMs increased with time, while the proportion of PDR gradually decreased. Age > 50 years was associated with clustering. Subtype CRF08_BC was more likely to have DRMs, PDR propagation, and DRM sharing.

Conclusion

PDR prevalence is moderate in this region. The association between PDR and subtype CRF08_BC suggested that DRMs spreading from injection drug users (IDUs) to heterosexuals (HETs) might be the major source of PDR in this region. Our findings highlight the significance of continuous surveillance of PDR.

Multiple Machine Learning Comparisons of HIV Cell-based and Reverse Transcriptase Data Sets

The human immunodeficiency virus (HIV) causes over a million deaths every year and has a huge economic impact in many countries. The first class of drugs approved were nucleoside reverse transcriptase inhibitors. A newer generation of reverse transcriptase inhibitors have become susceptible to drug resistant strains of HIV, and hence, alternatives are urgently needed. We have recently pioneered the use of Bayesian machine learning to generate models with public data to identify new compounds for testing against different disease targets. The current study has used the NIAID ChemDB HIV, Opportunistic Infection and Tuberculosis Therapeutics Database for machine learning studies. We curated and cleaned data from HIV-1 wild-type cell-based and reverse transcriptase (RT) DNA polymerase inhibition assays. Compounds from this database with ≤1 μM HIV-1 RT DNA polymerase activity inhibition and cell-based HIV-1 inhibition are correlated (Pearson r = 0.44, n = 1137, p < 0.0001). Models were trained using multiple machine learning approaches (Bernoulli Naive Bayes, AdaBoost Decision Tree, Random Forest, support vector classification, k-Nearest Neighbors, and deep neural networks as well as consensus approaches) and then their predictive abilities were compared. Our comparison of different machine learning methods demonstrated that support vector classification, deep learning, and a consensus were generally comparable and not significantly different from each other using 5-fold cross validation and using 24 training and test set combinations. This study demonstrates findings in line with our previous studies for various targets that training and testing with multiple data sets does not demonstrate a significant difference between support vector machine and deep neural networks.

Discovery of a semi-synthesized cyclolignan as a potent HIV-1 non-nucleoside reverse transcriptase inhibitor

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are essential components of highly active antiretroviral therapy (HAART) for human immunodeficiency virus type 1 (HIV-1) infection. In this study, we identified (+)-(7'S,8S,8'S)-3',4,4',5,5'-pentamethoxy-2,7'-cyclolignan (SG-1), a cyclolignan semi-synthesized from Machilus robusta and M. wangchiana extracts, as a potent NNRTI. SG-1 displayed anti-HIV-1 activity with an IC₅₀ of 0.77 μmol/L by inhibiting reverse transcriptase (RT) RNA-dependent DNA polymerase activity through a direct binding. It had synergistic effects when combined with tenofovir/lamivudine or zidovudine/lamivudine. The pharmacodynamics properties of SG-1 render it a valuable lead for the development of novel NNRTIs.

Combining New Non-Nucleoside Reverse Transcriptase Inhibitors (RTIs) with AZT Results in Strong Synergism against Multi-RTI-Resistant HIV-1 Strains

Reverse transcriptase inhibitors (RTIs), including nucleoside RTIs (NRTIs) and non-nucleoside RTIs (NNRTIs), are critical antiretroviral drugs for the treatment of human immunodeficiency virus (HIV) infection. Emergence of multi-RTI resistance calls for the development of more potent therapeutics or regimens against RTI-resistant strains. Here, we demonstrated that combining azidothymidine (AZT) with a new NNRTIs under development, diarylpyridine (DAPA)-2e, diarylanilin (DAAN)-14h, or DAAN-15h, resulted in strong synergism against infection by divergent HIV-1 strains, including those resistant to NRTIs and NNRTIs, suggesting the potential for developing these novel NNRTIs as salvage therapy for HIV/acquired immune deficiency syndrome (AIDS) patients.

Design, synthesis and biological evaluation of substituted (+)-SG-1 derivatives as novel anti-HIV agents

SG-1 was previously identified as a potent Non-nucleoside reverse transcriptase inhibitors (NNRTI) which works through inhibition of reverse transcriptase (RT) RNA-dependent DNA polymerase activity via a direct binding event. To further investigate the relationship between its structure and activity, four series of novel analogues were designed and synthesized with 12 of them inhibiting HIV-1 replication with IC₅₀s in the range 0.09-6.71 μM. Compound 4b, 4c, 4f, 2 and 6b were further tested on two NNRTI-resistant HIV-1 strains and one NNRTI-resistant superbug. The result showed that RT- E138K/M184V mutant virus conferred 4.7-9.1-fold resistance to 4c, 4f, 2 and 6b, but only showed slight resistance to 4b (2-fold) which was better than SG-1.

A computational study for rational HIV-1 non-nucleoside reverse transcriptase inhibitor selection and the discovery of novel allosteric pockets for inhibitor design

HIV drug resistant mutations that render the current Highly Active Anti-Retroviral Therapy (HAART) cocktail drugs ineffective are increasingly reported. To study the mechanisms of these mutations in conferring drug resistance, we computationally analyzed 14 reverse transcriptase (RT) structures of HIV-1 on the following parameters: drug-binding pocket volume, allosteric effects caused by the mutations, and structural thermal stability. We constructed structural correlation-based networks of the mutant RT-drug complexes and the analyses support the use of efavirenz (EFZ) as the first-line drug, given that cross-resistance is least likely to develop from EFZ-resistant mutations. On the other hand, rilpivirine (RPV)-resistant mutations showed the highest cross-resistance to the other non-nucleoside RT inhibitors. With significant drug cross-resistance associated with the known allosteric drug-binding site, there is a need to identify new allosteric druggable sites in the structure of RT. Through computational analyses, we found such a novel druggable pocket on the HIV-1 RT structure that is comparable with the original allosteric drug site, opening the possibility to the design of new inhibitors.

The prevalence of drug resistance among treatment-naïve HIV-1-infected individuals in China during pre- and post- 2004

BACKGROUND

The widespread use of antiretroviral therapies has led to considerable concerns about the prevalence of drug-resistant, as transmission of drug-resistant (TDR) strains poses a challenge for the control of the HIV-1 epidemic.

METHODS

We conducted an epidemiological study enrolling treatment-naïve HIV-1-positive subjects at the Peking Union Medical College Hospital since 1991. Drug resistance was determined by submitting the sequences to the Stanford University Network HIV-1 database.

RESULTS

Of 521 participants, 478 samples were amplified and sequenced successfully. HIV Transmitted drug resistance prevalence in China was determined to be 6.7 %. We did not find significant differences in the TDR rate by demographic characteristics. No significant time trend in the prevalence of overall TDR was observed (p > 0.05).

CONCLUSIONS

We identified an intermediate prevalence of transmitted drug resistance (TDR), exhibiting a stable time trend. These findings enhance our understanding of HIV-1 drug resistance prevalence and time trend, and provide some guidelines for the comprehensive public health strategy of TDR prevention.

Structural optimization of pyridine-type DAPY derivatives to exploit the tolerant regions of the NNRTI binding pocket

Based on the crystallographic studies of diarylpyrimidines (DAPYs), we embarked on incorporating the hydrophilic piperidyl or morpholinyl group into the known DAPY derivatives bearing the pyridine moiety as a core structure, with the double aim to exploit additional interactions with the HIV-1 NNRTI binding pocket (NNIBP), as well as to improve the compound solubility. The antiviral evaluation result show that the most potent compounds I-8b2, I-8b3, I-8b4 and I-8c3 exhibited anti-HIV-1 (IIIB) strain activity ranging from 7.4 nM to 9.4 nM (SI = 168-1283), superior to FDA-approved drugs of nevirapine (NVP), lamivudine (3TC) and delavirdine (DLV), and comparable to etravirine (ETV), zidovudine (AZT) and efavirenz (EFV). Additionally, compounds I-8c2 and I-8c3 showed moderate activity against NNRTI resistant strains baring mutations K103N and Y181C with EC50 values of 6.2 μM and 6.8 μM, respectively. Preliminary structure-activity relationships (SARs), reverse transcriptase inhibition efficacy and molecular modeling of selected compounds are also presented. These outcomes support our design hypothesis and demonstrate that the piperidyl group modified pyridine-typed DAPY derivatives are highly potent NNRTIs with improved water solubility.

Minority resistant HIV-1 variants and the response to first-line NNRTI therapy

BACKGROUND

The presence of low-frequency HIV-1 variants with mutations making them resistant to non-nucleoside reverse-transcriptase inhibitors (NNRTI) could influence the virological response to first-line NNRTI therapy.

OBJECTIVES

This study was designed to describe the proportions and quantities of NRTI and NNRTI-resistant variants in patients with successful first-line NNRTI therapy.

STUDY DESIGN

We evaluated the presence of drug-resistance mutations (DRMs) prior to treatment initiation in 131 naive chronically HIV-1-infected patients initiating NNRTI-based first-line therapy. DRMs were detected by ultradeep pyrosequencing (UDPS) on a GS Junior instrument (Roche).

RESULTS

The mean HIV RNA concentration was 4.78 ± 0.74 log copies/mL and the mean CD4 cell count was 368 ± 184 CD4 cells/mm(3). Patients were mainly infected with subtype B (68%) and 96% were treated with efavirenz. The sensitivity threshold for each mutation was 0.13-1.05% for 2000 reads. Major NRTI-resistant or NNRTI-resistant mutations were detected in 40 patients (33.6%). The median frequency of major NRTI-resistant mutations was 1.37% [IQR: 0.39-84.1], i.e.: a median of 556 copies/mL [IQR: 123-37,553]. The median frequency of major NNRTI-resistant DRMs was 0.78% [IQR: 0.67-7.06], i.e.: a median of 715 copies/mL [IQR: 391-3452]. The genotypic susceptibility score (GSS) of 9 (7.3%) patients with mutations to given treatment detected by UDPS was 1.5 or 2.

CONCLUSIONS

First-line NNRTI-based treatment can produce virological success in naïve HIV-1-infected patients harboring low-frequency DRMs representing <1% of the viral quasispecies. Further studies are needed to determine the clinical cut-off of low-frequency resistant variants associated to virological failure.

Comparing adherence to two different HIV antiretroviral regimens: an instrumental variable analysis

The objective of this observational cohort study was to compare adherence to protease inhibitor (PI)-based regimens or non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimens. HIV-seropositive, antiretroviral-naïve patients initiating therapy between 1998 and 2006 were identified using Veterans Health Administration databases. First-year adherence ratios were calculated as proportion of days covered (PDC). Multivariable regressions were run with an indicator for PDC >95, 90, 85, and 80 % as the dependent variable and an indicator for a PI-based regimen as the key independent variable. We controlled for residual unmeasured confounding by indication using an instrumental variable technique, using the physician's prescribing preference as the instrument. Out of 929 veterans on PI-based and 747 on NNRTI-based regimens, only 19.7 % of PI patients had PDC >80 %, compared to 35.1 % of NNRTI patients. In multivariable analysis, starting a PI regimen was significantly associated with poor adherence for all 4 adherence thresholds using conventional regressions and instrumental variable methods.

Minority variants associated with resistance to HIV-1 nonnucleoside reverse transcriptase inhibitors during primary infection

BACKGROUND

Recent data suggest that subjects harbouring low-frequency variants of HIV that are resistant to non-nucleoside reverse-transcriptase inhibitors (NNRTI) could suffer virological failure when treated with NNRTI-based therapy. Rilpivirine, a second-generation NNRTI, will be used in first-line regimen therapy, but the prevalence of minority variants that are resistant to rilpivirine is unknown.

OBJECTIVES

We evaluated the presence of low-frequency NNRTI resistance associated mutations (RAMs) in 27 patients with a primary HIV-1 infection.

STUDY DESIGN

We performed genotypic resistance test at baseline and used ultradeep pyrosequencing (UDPS) to detect minority RAMs.

RESULTS

Bulk genotyping identified NNRTI-resistant RAMs in 3/27 (11%) patients while UDPS identified NNRTI-resistant RAMs in 10/27 (37%) patients. The 11 RAMs not detected by bulk sequencing were A98G (n=2), L100I (n=3), K101E (n=2), V106I (n=3) and E138G (n=1). The prevalence of these minority variants was 0.34-18.26%. The absolute copy numbers of minority resistant variants were 3.21-5.53 log copies/mL. CRF02 harboured more minority resistant variants than subtypes B (P<0.05). Four samples (15%) had a major rilpivirine resistant mutation (E138G, K101E and E138A), 3 of which were detected by UDPS.

CONCLUSION

In these primary HIV infected patients, as regards to the detection of RAMs at the cut-off level>15-25% of the virus population, the concordance between bulk genotypic and UDPS was perfect. UDPS detected additional major NNRTI-resistant mutations, including rilpivirine resistant variants. Further studies are needed to assess the impact of these minority variants on treatment efficacy.

Synthesis, structure-activity relationships, and docking studies of N-phenylarylformamide derivatives (PAFAs) as non-nucleoside HIV reverse transcriptase inhibitors

A series of N-phenylarylformamide derivatives (PAFAs) with anti-wild-type HIV-1 activity (EC(50) values) ranging from 0.3 nM to 5.1 nM and therapeutic index (TI) ranging from 10 616 to 271 000 were identified as novel non-nucleoside reverse transcriptase inhibitors. Among them, compound 13g (EC(50) = 0.30 nM, TI = 184 578), 13l (EC(50) = 0.37 nM, TI = 212 819), 13m (EC(50) = 0.32 nM, TI = 260 617) and 13r (EC(50) = 0.27 nM, TI = 271 000) displayed the highest activity against this type virus nearly as potent as lead compound GW678248. Moreover, all of them were also active to inhibit the double mutant strain A(17) (K103N + Y181C) with EC(50) values of 0.29 μM, 0.14 μM, 0.10 μM and 0.27 μM, respectively. In particular, compound 13m, which showed broad-spectrum anti-HIV activity, was also effective to inhibit the HIV-2 ROD replication within 4.37 μM concentration.

Nevirapine once daily: pharmacology, metabolic profile and efficacy data of the new extended-release formulation

INTRODUCTION

Nevirapine (NVP), a non-nucleoside reverse transcriptase inhibitor, has been an important component of HIV infection treatment for many years. Currently, twice-a-day dosing is required for the successful application of NVP immediate release (IR), but there is potential for a more convenient once-a-day antiretroviral combination.

AREAS COVERED

The purpose of this article is to review the recent data on once-daily NVP extended release (XR) looking at all the important pharmacologic, pharmacokinetic and clinical data on NVP IR/XR through a systematic MEDLINE database search as well as a review of abstracts presented at international HIV meetings on NVP XR studies up to December 2010. The article provides the reader with an overview of all the pharmacodynamic and pharmacokinetic aspects of NVP IR/XR, as well as its preclinical and clinical efficacy and its safety.

EXPERT OPINION

NVP XR is as effective as NVP IR among HIV-infected patients with a similar safety profile. NVP XR requires careful monitoring during initiation, but its favorable lipid profile may be of clinical benefit in reducing the risk for coronary artery disease in HIV-infected patients who are receiving long-term antiretroviral therapy. Further research is needed to predict short-term toxicity.

Highly suppressing wild-type HIV-1 and Y181C mutant HIV-1 strains by 10-chloromethyl-11-demethyl-12-oxo-calanolide A with druggable profile

We herein report a new compound: 10-chloromethyl-11-demethyl-12-oxo-calanolide A (20, EC(50) = 7.4 nM, SI = 1417), which demonstrates a druggable profile with 32.7% oral bioavailability in rat, tolerated oral single dose toxicity in mice, and especially the feature of highly efficient suppression of the wild-type HIV-1 and Y181C mutant HIV-1 at an EC(50) = 7.4 nM and EC(50) = 0.46 nM, respectively.

Novel 1,3-dihydro-benzimidazol-2-ones and their analogues as potent non-nucleoside HIV-1 reverse transcriptase inhibitors

A series of novel benzimidazolones and their analogues, characterized by the presence of one or more methyl groups or other bioisosteric moieties at different positions of the phenyl ring at N-1, were synthesized and evaluated as inhibitors of human immunodeficiency virus type-1 (HIV-1). Most of the new compounds proved to be highly effective in inhibiting both HIV-1 replication in MT4 cells with minimal cytotoxicity and RT enzyme at nanomolar concentrations. Some derivatives were also tested against RTs containing single amino acid mutations responsible for resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs). The different potencies displayed by the new compounds were studied using molecular modeling.

TMC278, a next-generation nonnucleoside reverse transcriptase inhibitor (NNRTI), active against wild-type and NNRTI-resistant HIV-1

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) have proven efficacy against human immunodeficiency virus type 1 (HIV-1). However, in the setting of incomplete viral suppression, efavirenz and nevirapine select for resistant viruses. The diarylpyrimidine etravirine has demonstrated durable efficacy for patients infected with NNRTI-resistant HIV-1. A screening strategy used to test NNRTI candidates from the same series as etravirine identified TMC278 (rilpivirine). TMC278 is an NNRTI showing subnanomolar 50% effective concentrations (EC50 values) against wild-type HIV-1 group M isolates (0.07 to 1.01 nM) and nanomolar EC50 values against group O isolates (2.88 to 8.45 nM). Sensitivity to TMC278 was not affected by the presence of most single NNRTI resistance-associated mutations (RAMs), including those at positions 100, 103, 106, 138, 179, 188, 190, 221, 230, and 236. The HIV-1 site-directed mutant with Y181C was sensitive to TMC278, whereas that with K101P or Y181I/V was resistant. In vitro, considerable cross-resistance between TMC278 and etravirine was observed. Sensitivity to TMC278 was observed for 62% of efavirenz- and/or nevirapine-resistant HIV-1 recombinant clinical isolates. TMC278 inhibited viral replication at concentrations at which first-generation NNRTIs could not suppress replication. The rates of selection of TMC278-resistant strains were comparable among HIV-1 group M subtypes. NNRTI RAMs emerging in HIV-1 under selective pressure from TMC278 included combinations of V90I, L100I, K101E, V106A/I, V108I, E138G/K/Q/R, V179F/I, Y181C/I, V189I, G190E, H221Y, F227C, and M230I/L. E138R was identified as a new NNRTI RAM. These in vitro analyses demonstrate that TMC278 is a potent next-generation NNRTI, with a high genetic barrier to resistance development.

Efficacy and resistance of recently developed non-nucleoside reverse transcriptase inhibitors for HIV-1

Since the introduction of the HAART, non-nucleoside reverse transcriptase inhibitors (NNRTIs) have played an essential role in treating HIV: their strong antiviral potency, good metabolic profile and low pill burden make them an ideal option in the design of an optimized triple drug regimen. Nonetheless, the currently approved NNRTIs (efavirenz and nevirapine) are weighed by peculiar toxicities, while a low genetic barrier and the development of cross-resistance significantly limits their use in cases of suboptimal adherence. Many drugs are in development and they are all designed with the aim to overcome resistance problems. In this review we present data on virological efficacy and resistance profiles of some of the most promising new molecules: some (such as rilpivirine) are close to being marketed, others are in Phase II trials (IDX899 and RDEA806), others again have just completed preclinical studies and are having their first clinical evaluations (RO-5028, UK-453061 and BILR-355 BS); etravirine is already approved by the US FDA, but it is still not licensed in Europe. Other new molecules (Merck MK-4965, GlaxoSmithKline GW678284 and a pyridazinone derivative by Roche), which are currently in early-development phases, are also briefly described.

Prevalence of antiretroviral drug resistance in treated HIV-1 infected patients: under the initiative of access to the NNRTI-based regimen in Thailand

To determine the prevalence of antiretroviral resistance in treatment-failure HIV-1 infected individuals, under the initiative of the non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimen in Thailand, plasma samples were collected from 1,376 HIV-1 infected patients, who were failing in their current HAART therapy during 2000-2004. They were stratified into 2 intervals: group one (1), 558 HIV-1 infected patients (2000-2002; before the initiative of access to HAART), and group two (2), 818 HIV-1 infected patients (2003-2004; after the initiative of access to HAART). Genotypic resistance testing was performed. The frequency of antiretroviral drug resistance in treatment-failure HIV-1 infected patients has significantly increased over time from 68.5% (382/558) during 2000-2002 to 74.9% (613/818) during 2003-2004 (P<0.01). Resistance to NNRTI during 2003-2004 (59.2%) was much higher than that during 2000-2002 (36.9%; P<0.001). However, the frequency of nucleoside reverse transcriptase inhibitor (NRTI) drug resistance was not significantly higher (P=0.153). We showed that this correlated with an increase in the NNRTI-based regimen prescribed during 2003-2004, especially the Thai-produced combination pill, GPO-VIR. Our finding also showed that a high level of genotypic drug resistance is associated with GPO-VIR (40.8% lamivudine, 40.6% stavudine, 43.8% nevirapine). In order to avoid the rapid emergence of resistant viruses in a resource-poor setting, a close surveillance of antiretroviral drug resistance is feasible and should be considered.

Synthesis and antiviral activity of new dimeric inhibitors against HIV-1

This paper describes the synthesis and the antiviral activities of dimeric compounds derived from homo and asymmetric combinations of N-1 propynyloxymethyl analogues 1a,b of MKC-442, an N-1 4-iodobenzyloxymethyl analogue of TNK-651 5, potent contraceptive norgestrel and AZT. They were obtained by Sonogashira reaction, 'click' chemistry or Pd-catalyzed oxidative coupling. The iodo precursor 5 turned out as a potent compound against wild type and mutated HIV-1 virus. All dimeric compounds showed lower activity against HIV-1 than MKC-442, except the asymmetric dimer of AZT and 1a which showed an activity comparable to MKC-442.

Determinants of nevirapine hypersensitivity and its effect on the association between hepatitis C status and mortality in antiretroviral drug-naive HIV-positive patients

OBJECTIVE

To assess risks factors and outcomes associated with nevirapine hypersensitivity reactions, and to determine the effect of hypersensitivity as a modifier of the association between hepatitis C virus (HCV) infection and mortality among antiretroviral drug-naive patients.

METHODS

The primary endpoint was hypersensitivity reactions in a population-based cohort of antiretroviral therapy-naive HIV-individuals, 18 years or older in British Columbia, Canada, who started triple antiretroviral therapy with nevirapine between May 1997 and June 2003. Univariate and multivariate analyses were performed to identify predictors of nonaccidental mortality in the subgroup of patients with known HCV serostatus.

RESULTS

A total of 66 (9.6%) of 685 patients met the definition for hypersensitivity reactions. In the univariate logistic regression analysis, no variables were identified as risk factors. In multivariate survival analyses conducted to identify characteristics associated with nonaccidental mortality, patients with both HCV coinfection and hypersensitivity reactions had a higher risk of death (hazard ratio, 7.12; 95% confidence interval, 2.73-18.53; P < 0.001) compared with those who did not have HCV coinfection or hypersensitivity reaction.

CONCLUSION

Results of this study suggest that the hypersensitivity reaction behaves as an effect modifier of the association between HCV infection and mortality in this cohort of antiretroviral drug-naive HIV-positive patients. These results support the current recommendation against the use of nevirapine in HIV/HCV-coinfected patients.

Efficacy and safety of TMC125 (etravirine) in treatment-experienced HIV-1-infected patients in DUET-2: 24-week results from a randomised, double-blind, placebo-controlled trial

BACKGROUND

TMC125 (etravirine) is a non-nucleoside reverse-transcriptase inhibitor (NNRTI) with activity against NNRTI-resistant HIV-1 in phase IIb trials. The aim of DUET-2 is to examine the efficacy, tolerability, and safety of TMC125 in treatment-experienced patients.

METHODS

In this continuing randomised, double-blind, placebo-controlled, phase III trial, HIV-1-infected patients on failing antiretroviral therapy with evidence of resistance to currently available NNRTIs and at least three primary protease inhibitor mutations were eligible for enrolment if on stable (8 weeks unchanged) antiretroviral therapy with plasma HIV-1 RNA greater than 5000 copies per mL. Patients were randomly assigned to receive either TMC125 (200 mg) or placebo, each given twice daily with darunavir-ritonavir, investigator-selected nucleoside/nucleotide reverse transcriptase inhibitors, and optional enfuvirtide. The primary endpoint was the proportion of patients with confirmed viral load below 50 copies per mL at week 24 (FDA time-to-loss of virological response algorithm). Analyses were by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00255099.

FINDINGS

591 patients were randomised and treated (295 patients in the TMC125 group and 296 in the placebo group). By week 24, 51 (17%) patients in the TMC125 group and 73 (25%) in the placebo group had discontinued, mainly because of virological failure. 183 (62%) patients in the TMC125 group and 129 (44%) in the placebo group achieved confirmed viral load below 50 copies per mL at week 24 (difference 18%, 95% CI 11-26; p=0.0003). The type and frequency of adverse events were much the same in the two groups.

INTERPRETATION

In treatment-experienced patients, treatment with TMC125 led to better virological suppression at week 24 than did placebo. The safety and tolerability profile of TMC125 was generally comparable with placebo.

Efficacy and safety of etravirine (TMC125) in patients with highly resistant HIV-1: primary 24-week analysis

OBJECTIVE

TMC125-C223 is an open-label, partially blinded, randomized clinical trial to evaluate the efficacy and safety of two dosages of etravirine (TMC125), a non-nucleoside reverse transcriptase inhibitor (NNRTI) with activity against wild-type and NNRTI-resistant HIV-1.

DESIGN

A total of 199 patients were randomly assigned 2: 2: 1 to twice-daily etravirine 400 mg, 800 mg and control groups, respectively. The primary endpoint was a change in viral load from baseline at week 24 in the intention-to-treat population.

METHODS

Patients had HIV-1 with genotypic resistance to approved NNRTIs and at least three primary protease inhibitor (PI) mutations. Etravirine groups received an optimized background of at least two approved antiretroviral agents [nucleoside reverse transcriptase inhibitors (NRTI) and/or lopinavir/ritonavir and/or enfuvirtide]. Control patients received optimized regimens of at least three antiretroviral agents (NRTIs or PIs and/or enfuvirtide).

RESULTS

The mean change from baseline in HIV-1 RNA at week 24 was -1.04, -1.18 and -0.19 log10 copies/ml for etravirine 400 mg twice a day, 800 mg twice a day and the control group, respectively (P < 0.05 for both etravirine groups versus control). Etravirine showed no dose-related effects on safety and tolerability. No consistent pattern of neuropsychiatric symptoms was observed. There were few hepatic adverse events, and rashes were predominantly early onset and mild to moderate in severity.

CONCLUSION

Etravirine plus an optimized background significantly reduced HIV-1-RNA levels from baseline after 24 weeks in patients with substantial NNRTI and PI resistance, and demonstrated a favorable safety profile compared with control.

Novel nonnucleoside inhibitors that select nucleoside inhibitor resistance mutations in human immunodeficiency virus type 1 reverse transcriptase

Mutations in and around the catalytic site of the reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) are associated with resistance to nucleoside RT inhibitors (NRTIs), whereas changes in the hydrophobic pocket of the RT are attributed to nonnucleoside RT inhibitor (NNRTI) resistance. In this study, we report a novel series of nonnucleoside inhibitors of HIV-1, exemplified by VRX-329747 and VRX-413638, which inhibit both NNRTI- and NRTI-resistant HIV-1 isolates. Enzymatic studies indicated that these compounds are HIV-1 RT inhibitors. Surprisingly, however, following prolonged (6 months) tissue culture selection, this series of nonnucleoside inhibitors did not select NNRTI-resistant mutations in HIV-1 RT. Rather, four mutations (M41L, A62T/V, V118I, and M184V) known to cause resistance to NRTIs and two additional novel mutations (S68N and G112S) adjacent to the catalytic site of the enzyme were selected. Although the M184V mutation appears to be the initial mutation to establish resistance, this mutation alone confers only a two- to fourfold decrease in susceptibility to VRX-329747 and VRX-413638. At least two additional mutations must accumulate for significant resistance. Moreover, while VRX-329747-selected viruses are resistant to lamivudine and emtricitabine due to the M184V mutation, they remain susceptible to zidovudine, stavudine, dideoxyinosine, abacavir, tenofovir, and efavirenz. These results directly demonstrate that VRX-329747 and VRX-413638 are novel nonnucleoside inhibitors of HIV-1 RT with the potential to augment current therapies.

Nanoparticulate drug carriers for delivery of HIV/AIDS therapy to viral reservoir sites

Providing the optimum treatment of AIDS is a major challenge in the 21st Century. HIV is localised and harboured in certain inaccessible compartments of the body, such as the CNS, the cerebrospinal fluid, the lymphatic system and in the macrophages, where it cannot be reached by the majority of therapeutic agents in adequate concentrations or in which the therapeutic agents cannot reside for the necessary duration. Progression in HIV/AIDS treatment suggests that available therapy can lower the systemic viral load below the detection limit. However, on discontinuation of treatment, there is relapse of the infection from the reservoir sites and a potential for resistance development. This review discusses the aetiology and pathology of HIV, with emphasis on the viral reservoirs, current therapy of AIDS, and the opportunity for nanotechnology-based drug delivery systems to facilitate complete eradication of viral load from the reservoir sites. Literature-cited examples of drug delivery systems that are under investigation for the treatment of AIDS are discussed. The article also focuses on the future outlook and strategies for investigational drug formulations that use nanotherapeutic strategy for HIV/AIDS.

Short-term antiviral activity of TMC278--a novel NNRTI--in treatment-naive HIV-1-infected subjects

OBJECTIVE

To evaluate antiviral activity, pharmacokinetics, tolerability and safety of TMC278, a non-nucleoside reverse transcriptase inhibitor (NNRTI), when given as a 25, 50, 100 or 150 mg once-daily dose for 7 days to antiretroviral-naive HIV-infected subjects.

DESIGN

Randomized, double-blind, placebo-controlled, phase IIa clinical trial.

METHODS

Participants were 47 antiretroviral naive HIV-infected subjects. Primary outcome was the change in plasma HIV-1 RNA viral load from baseline to day 8. Secondary outcomes were evaluation of pharmacokinetics of TMC278, immunologic changes, safety and tolerability, and evolution of viral genotypic and phenotypic patterns.

RESULTS

Patients treated with TMC278 achieved a median decrease in plasma viral load from baseline of 1.199 log10 copies/ml compared with a 0.002 log10 copies/ml gain in the placebo group (P < 0.01). A significantly higher proportion of subjects in the TMC278 groups obtained a viral load decrease of > 1.0 log10 compared with the placebo group (25/36 versus 0/11) (P < 0.01). No significant dose differences were noted in either antiviral effect or safety. No genotypic changes associated with antiretroviral resistance were detected between baseline and the end of the trial. Plasma concentrations of TMC278 were above the target concentration (13.5 ng/ml) at all time points for all TMC278-treated subjects. The most common reported adverse event was headache (TMC278 14%; placebo 18%).

CONCLUSIONS

TMC278 showed antiviral activity when given as monotherapy for 7 days at all doses studied and the drug was safe and well tolerated. Trials of longer treatment duration with TMC278, in combination with other antiretroviral drugs, are underway to assess the long-term durability of antiviral response, safety and tolerability.

Synthesis and biological investigation of S-aryl-S-DABO derivatives as HIV-1 inhibitors

S-Aryl-S-DABO derivatives, a novel subclass of S-DABO anti-HIV-1 agents, were synthesized via Ullmann type reaction starting from the corresponding 2-thiouracils by the aid of microwave irradiation. The results of their evaluation as inhibitors of RT are reported together with their antiviral activity in cellular assays.

Tri-substituted triazoles as potent non-nucleoside inhibitors of the HIV-1 reverse transcriptase

A new series of 1,2,4-triazoles was synthesized and tested against several NNRTI-resistant HIV-1 isolates. Several of these compounds exhibited potent antiviral activities against efavirenz- and nevirapine-resistant viruses, containing K103N and/or Y181C mutations or Y188L mutation. Triazoles were first synthesized from commercially available substituted phenylthiosemicarbazides, then from isothiocyanates, and later by condensing the desired substituted anilines with thiosemicarbazones.

Structure−Activity Relationship Studies of Novel Benzophenones Leading to the Discovery of a Potent, Next Generation HIV Nonnucleoside Reverse Transcriptase Inhibitor

Despite the progress of the past two decades, there is still considerable need for safe, efficacious drugs that target human immunodeficiency virus (HIV). This is particularly true for the growing number of patients infected with virus resistant to currently approved HIV drugs. Our high throughput screening effort identified a benzophenone template as a potential nonnucleoside reverse transcriptase inhibitor (NNRTI). This manuscript describes our extensive exploration of the benzophenone structure-activity relationships, which culminated in the identification of several compounds with very potent inhibition of both wild type and clinically relevant NNRTI-resistant mutant strains of HIV. These potent inhibitors include 70h (GW678248), which has in vitro antiviral assay IC(50) values of 0.5 nM against wild-type HIV, 1 nM against the K103N mutant associated with clinical resistance to efavirenz, and 0.7 nM against the Y181C mutant associated with clinical resistance to nevirapine. Compound 70h has also demonstrated relatively low clearance in intravenous pharmacokinetic studies in three species, and it is the active component of a drug candidate which has progressed to phase 2 clinical studies.