Improving the positional adaptability: structure-based design of biphenyl-substituted diaryltriazines as novel non-nucleoside HIV-1 reverse transcriptase inhibitors

In order to improve the positional adaptability of our previously reported naphthyl diaryltriazines (NP-DATAs), synthesis of a series of novel biphenyl-substituted diaryltriazines (BP-DATAs) with a flexible side chain attached at the C-6 position is presented. These compounds exhibited excellent potency against wild-type (WT) HIV-1 with EC₅₀ values ranging from 2.6 to 39 nmol/L and most of them showed low nanomolar anti-viral potency against a panel of HIV-1 mutant strains. Compounds 5j and 6k had the best activity against WT, single and double HIV-1 mutants and reverse transcriptase (RT) enzyme comparable to two reference drugs (EFV and ETR) and our lead compound NP-DATA (1). Molecular modeling disclosed that the side chain at the C-6 position of DATAs occupied the entrance channel of the HIV-1 reverse transcriptase non-nucleoside binding pocket (NNIBP) attributing to the improved activity. The preliminary structure–activity relationship and PK profiles were also discussed.

Synthesis and evaluation of the antitumor activity of highly functionalised pyridin-2-ones and pyrimidin-4-ones

The methods for selective synthesis of two novel types of compounds including pyridin-2-ones 3 and pyrimidin-4-ones 4 were developed. The antitumor bioactivity screening showed that certain compounds had potent antitumor activity.

CD4-mimetic sulfopeptide conjugates display sub-nanomolar anti-HIV-1 activity and protect macaques against a SHIV162P3 vaginal challenge

The CD4 and the cryptic coreceptor binding sites of the HIV-1 envelope glycoprotein are key to viral attachment and entry. We developed new molecules comprising a CD4 mimetic peptide linked to anionic compounds (mCD4.1-HS₁₂ and mCD4.1-PS1), that block the CD4-gp120 interaction and simultaneously induce the exposure of the cryptic coreceptor binding site, rendering it accessible to HS₁₂- or PS1- mediated inhibition. Using a cynomolgus macaque model of vaginal challenge with SHIV162P3, we report that mCD4.1-PS1, formulated into a hydroxyethyl-cellulose gel provides 83% protection (5/6 animals). We next engineered the mCD4 moiety of the compound, giving rise to mCD4.2 and mCD4.3 that, when conjugated to PS1, inhibited cell-free and cell-associated HIV-1 with particularly low IC₅₀, in the nM to pM range, including some viral strains that were resistant to the parent molecule mCD4.1. These chemically defined molecules, which target major sites of vulnerability of gp120, are stable for at least 48 hours in conditions replicating the vaginal milieu (37 °C, pH 4.5). They efficiently mimic several large gp120 ligands, including CD4, coreceptor or neutralizing antibodies, to which their efficacy compares very favorably, despite a molecular mass reduced to 5500 Da. Together, these results support the development of such molecules as potential microbicides.

Will dapivirine redeem the promises of anti-HIV microbicides? Overview of product design and clinical testing

Microbicides are being developed in order to prevent sexual transmission of HIV. Dapivirine, a non-nucleoside reverse transcriptase inhibitor, is one of the leading drug candidates in the field, currently being tested in various dosage forms, namely vaginal rings, gels, and films. In particular, a ring allowing sustained drug release for 1month is in an advanced stage of clinical testing. Two parallel phase III clinical trials are underway in sub-Saharan Africa and results are expected to be released in early 2016. This article overviews the development of dapivirine and its multiple products as potential microbicides, with particular emphasis being placed on clinical evaluation. Also, critical aspects regarding regulatory approval, manufacturing, distribution, and access are discussed.

Development and in Vitro Evaluation of a Microbicide Gel Formulation for a Novel Non-Nucleoside Reverse Transcriptase Inhibitor Belonging to the N-Dihydroalkyloxybenzyloxopyrimidines (N-DABOs) Family

Preventing HIV transmission by the use of a vaginal microbicide is a topic of considerable interest in the fight against AIDS. Both a potent anti-HIV agent and an efficient formulation are required to develop a successful microbicide. In this regard, molecules able to inhibit the HIV replication before the integration of the viral DNA into the genetic material of the host cells, such as entry inhibitors or reverse transcriptase inhibitors (RTIs), are ideal candidates for prevention purpose. Among RTIs, S- and N-dihydroalkyloxybenzyloxopyrimidines (S-DABOs and N-DABOs) are interesting compounds active at nanomolar concentration against wild type of RT and with a very interesting activity against RT mutations. Herein, novel N-DABOs were synthesized and tested as anti-HIV agents. Furthermore, their mode of binding was studied by molecular modeling. At the same time, a vaginal microbicide gel formulation was developed and tested for one of the most promising candidates.

Resistance and cross-resistance profile of the diaryltriazine NNRTI and candidate microbicide UAMC01398

OBJECTIVES

The resistance development, cross-resistance to other NNRTIs and the impact of resistance on viral replicative fitness were studied for the new and potent NNRTI UAMC01398.

METHODS

Resistance was selected by dose escalation and by single high-dose selection against a comprehensive panel of NNRTIs used as therapeutics and NNRTIs under investigation for pre-exposure prophylaxis of sexual HIV transmission. A panel of 27 site-directed mutants with single mutations or combinations of mutations involved in reverse transcriptase (RT) inhibitor-mediated resistance was developed and used to confirm resistance to UAMC01398. Cross-resistance to other NNRTIs was assessed, as well as susceptibility of UAMC01398-resistant HIV to diarylpyrimidine-resistant viruses. Finally, the impact of UAMC01398 resistance on HIV replicative fitness was studied.

RESULTS

We showed that UAMC01398 has potent activity against dapivirine-resistant HIV, that at least four mutations in the RT are required in concert for resistance and that the resistance profile is similar to rilpivirine, both genotypically and phenotypically. Resistance development to UAMC01398 is associated with a severe fitness cost.

CONCLUSIONS

These data, together with the enhanced safety profile and good solubility in aqueous gels, make UAMC01398 an excellent candidate for HIV topical prevention.

Anti-HIV Drug Discovery and Development: Current Innovations and Future Trends

The early effectiveness of combinatorial antiretroviral therapy (cART) in the treatment of HIV infection has been compromised to some extent by rapid development of multidrug-resistant HIV strains, poor bioavailability, and cumulative toxicities, and so there is a need for alternative strategies of antiretroviral drug discovery and additional therapeutic agents with novel action modes or targets. From this perspective, we first review current strategies of antiretroviral drug discovery and optimization, with the aid of selected examples from the recent literature. We highlight the development of phosphate ester-based prodrugs as a means to improve the aqueous solubility of HIV inhibitors, and the introduction of the substrate envelope hypothesis as a new approach for overcoming HIV drug resistance. Finally, we discuss future directions for research, including opportunities for exploitation of novel antiretroviral targets, and the strategy of activation of latent HIV reservoirs as a means to eradicate the virus.

Investigational reverse transcriptase inhibitors for the treatment of HIV

INTRODUCTION

While considerable advances have been made in the development of antiretroviral agents, there is still work to be done. Reverse transcriptase inhibitors are important drugs for the treatment of HIV, and considerable research is currently ongoing to develop new agents and to modify currently existing agents.

AREAS COVERED

Herein, the authors discuss both investigational nucleoside reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs), including agents that are in various stages of development. They also discuss novel formulations that are being investigated for currently available drugs, and discuss the advantages that these new formulations may provide.

EXPERT OPINION

New formulations and co-formulations of currently existing antiretrovirals will represent an important area of development, as a means to improve adherence for HIV-positive individuals. New formulations will continue to be developed, with a focus on allowing for less-frequent administration, as well increasing drug concentrations at local sites such as vaginal tissue, rectal tissue and sites in the immune system.

Cross-Sectional Analysis of Selected Genital Tract Immunological Markers and Molecular Vaginal Microbiota in Sub-Saharan African Women, with Relevance to HIV Risk and Prevention

Data on immune mediators in the genital tract and the factors that modulate them in sub-Saharan women are limited. Cervicovaginal lavage (CVL) samples from 430 sexually active women from Kenya, South Africa, and Rwanda were analyzed for 12 soluble immune mediators using Bio-Plex and Meso Scale Discovery multiplex platforms, as well as single enzyme-linked immunosorbent assays. Ten bacterial species were quantified in vaginal swab samples. Bacterial vaginosis (BV) was defined by Nugent scoring. CVL samples from HIV-infected women showed a clear-cut proinflammatory profile. Pregnant women, adolescents, and women engaging in traditional vaginal practices differed in specific soluble markers compared to reference groups of adult HIV-negative women. Cervical mucus, cervical ectopy, abnormal vaginal discharge, and having multiple sex partners were each associated with an increase in inflammatory mediators. The levels of interleukin-1α (IL-1α), IL-1β, IL-6, IL-12(p70), and IL-8 were elevated, whereas the IL-1RA/IL-1(α+β) ratio decreased in women with BV. The level of gamma interferon-induced protein 10 was lower in BV-positive than in BV-negative women, suggesting its suppression as a potential immune evasion mechanism by BV-associated bacteria. Lactobacillus crispatus and Lactobacillus vaginalis were associated with decreased proinflammatory cytokines and each BV-associated species with increased proinflammatory cytokines. Remarkably, the in vitro anti-HIV activity of CVL samples from BV-positive women was stronger than that of BV-negative women. In conclusion, we found significant associations of factors, including vaginal microbiota, which can influence immune mediators in the vaginal environment in sexually active women. These factors need to be considered when establishing normative levels or pathogenic cutoffs of biomarkers of inflammation and associated risks in African women.

Development and characterization of a solid dispersion film for the vaginal application of the anti-HIV microbicide UAMC01398

The purpose of this work was to design and evaluate a vaginal film delivery system for UAMC01398, a novel non-nucleoside reverse transcriptase inhibitor currently under investigation for use as an anti-HIV microbicide. UAMC01398 (1mg) films consisting of hydroxypropylmethylcellulose (HPMC) and polyethylene glycol 400 (PEG400) in different ratios were prepared by solvent evaporation. Based on its flexibility, softness and translucent appearance, the 30% PEG400 and 70% HPMC containing film was selected for further assessment. The vaginal film formulation was fast-dissolving (<10 min in 1 mL of vaginal fluid simulant), stable up to at least one month and safe toward epithelial cells and lactobacilli. Furthermore, formulating UAMC01398 into the film dosage form did not influence its antiviral activity. Powder X-ray diffraction revealed the amorphous nature of the UAMC01398 film, resulting in enhanced compound permeation across the epithelial HEC-1A cell layer, presumably owing to the induction of supersaturation. The in vivo vaginal tissue uptake of UAMC01398 in rabbits, as measured by systemic concentrations, was increased compared to the previously established non-solubilizing gel (significant difference) and sulfobutyl ether-β-cyclodextrin (5%) containing gel. To conclude, we identified a film formulation suitable for the vaginal delivery of UAMC01398.