Rilpivirine analogs potently inhibit drug-resistant HIV-1 mutants

Deciphering the enigmas of non-nucleoside reverse transcriptase inhibitors (NNRTIs): A medicinal chemistry expedition towards combating HIV drug resistance

The pivotal involvement of reverse transcriptase activity in the pathogenesis of the progressive HIV virus has stimulated gradual advancements in drug discovery initiatives spanning three decades. Consequently, nonnucleoside reverse transcriptase inhibitors (NNRTIs) have emerged as a preeminent category of therapeutic agents for HIV management. Academic institutions and pharmaceutical companies have developed numerous NNRTIs, an essential component of antiretroviral therapy. Six NNRTIs have received Food and Drug Administration approval and are widely used in clinical practice, significantly improving the quality of HIV patients. However, the rapid emergence of drug resistance has limited the effectiveness of these medications, underscoring the necessity for perpetual research and development of novel therapeutic alternatives. To supplement the existing literatures on NNRTIs, a comprehensive review has been compiled to synthesize this extensive dataset into a comprehensible format for the medicinal chemistry community. In this review, a thorough investigation and meticulous analysis were conducted on the progressions achieved in NNRTIs within the past 8 years (2016-2023), and the experiences and insights gained in the development of inhibitors with varying chemical structures were also summarized. The provision of a crucial point of reference for the development of wide-ranging anti-HIV medications is anticipated.

Development and emerging trends of drug resistance mutations in HIV: a bibliometric analysis based on CiteSpace

Background

Antiretroviral therapy has led to AIDS being a chronic disease. Nevertheless, the presence of constantly emerging drug resistance mutations poses a challenge to clinical treatment. A systematic analysis to summarize the advancements and uncharted territory of drug resistance mutations is urgently needed and may provide new clues for solving this problem.

Methods

We gathered 3,694 publications on drug resistance mutations from the Web of Science Core Collection with CiteSpace software and performed an analysis to visualize the results and predict future new directions and emerging trends. Betweenness centrality, count, and burst value were taken as standards.

Results

The number of papers on HIV medication resistance mutations during the last 10 years shows a wave-like trend. In terms of nation, organization, and author, the United States (1449), University of London (193), and Mark A. Wainberg (66) are the most significant contributors. The most frequently cited article is "Drug resistance mutations for surveillance of transmitted HIV-1 drug-resistance: 2009 update." Hot topics in this field include "next-generation sequencing," "tenofovir alafenamide," "children," "regimens," "accumulation," "dolutegravir," "rilpivirine," "sex," "pretreatment drug resistance," and "open label." Research on drug resistance in teenagers, novel mutation detection techniques, and drug development is ongoing, and numerous publications have indicated the presence of mutations related to current medications. Therefore, testing must be performed regularly for patients who have used medications for a long period. Additionally, by choosing medications with a longer half-life, patients can take fewer doses of their prescription, increasing patient compliance.

Conclusion

This study involved a bibliometric visualization analysis of the literature on drug resistance mutations, providing insight into the field's evolution and emerging patterns and offering academics a resource to better understand HIV drug resistance mutations and contribute to the field's advancement.

Contemporary Medicinal Chemistry Strategies for the Discovery and Development of Novel HIV-1 Non-nucleoside Reverse Transcriptase Inhibitors

Currently, HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) are a major component of the highly active anti-retroviral therapy (HAART) regimen. However, the occurrence of drug-resistant strains and adverse reactions after long-term usage have inevitably compromised the clinical application of NNRTIs. Therefore, the development of novel inhibitors with distinct anti-resistance profiles and better pharmacological properties is still an enormous challenge. Herein, we summarize state-of-the-art medicinal chemistry strategies for the discovery of potent NNRTIs, such as structure-based design strategies, contemporary computer-aided drug design, covalent-binding strategies, and the application of multi-target-directed ligands. The strategies described here will facilitate the identification of promising HIV-1 NNRTIs.

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

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

Structure-based non-nucleoside inhibitor design: Developing inhibitors that are effective against resistant mutants

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) inhibit reverse transcription and block the replication of HIV-1. Currently, NNRTIs are usually used as part of a three-drug combination given to patients as antiretroviral therapy. These combinations involve other classes of anti-HIV-1 drugs, commonly nucleoside reverse transcriptase inhibitors (NRTIs). However, attempts are being made to develop two-drug maintenance therapies, some of which involve an NNRTI and an integrase strand transfer inhibitor. This has led to a renewed interest in developing novel NNRTIs, with a major emphasis on designing compounds that can effectively inhibit the known NNRTI-resistant mutants. We have generated and tested novel rilpivirine (RPV) analogs. The new compounds were designed to exploit a small opening in the upper right periphery of the NNRTI-binding pocket. The best of the new compounds, 12, was a more potent inhibitor of the NNRTI-resistant mutants we tested than either doravirine or efavirenz but was inferior to RPV. We describe the limitations on the modifications that can be appended to the "upper right side" of the RPV core and the effects of substituting other cores for the central pyrimidine core of RPV and make suggestions about how this information can be used in NNRTI design.

Structural basis for strand-transfer inhibitor binding to HIV intasomes

The HIV intasome is a large nucleoprotein assembly that mediates the integration of a DNA copy of the viral genome into host chromatin. Intasomes are targeted by the latest generation of antiretroviral drugs, integrase strand-transfer inhibitors (INSTIs). Challenges associated with lentiviral intasome biochemistry have hindered high-resolution structural studies of how INSTIs bind to their native drug target. Here, we present high-resolution cryo-electron microscopy structures of HIV intasomes bound to the latest generation of INSTIs. These structures highlight how small changes in the integrase active site can have notable implications for drug binding and design and provide mechanistic insights into why a leading INSTI retains efficacy against a broad spectrum of drug-resistant variants. The data have implications for expanding effective treatments available for HIV-infected individuals.

Two Coselected Distal Mutations in HIV-1 Reverse Transcriptase (RT) Alter Susceptibility to Nonnucleoside RT Inhibitors and Nucleoside Analogs

Although antiretroviral therapy (ART) is highly successful, drug-resistant variants can arise that blunt the efficacy of ART. New inhibitors that are broadly effective against known drug-resistant variants are needed, although such compounds might select for novel resistance mutations that affect the sensitivity of the virus to other compounds. Compound 13 selects for resistance mutations that differ from traditional NNRTI resistance mutations. These mutations cause increased sensitivity to NRTIs, such as AZT.

Two mutations, G112D and M230I, were selected in the reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) by a novel nonnucleoside reverse transcriptase inhibitor (NNRTI). G112D is located near the HIV-1 polymerase active site; M230I is located near the hydrophobic region where NNRTIs bind. Thus, M230I could directly interfere with NNRTI binding but G112D could not. Biochemical and virological assays were performed to analyze the effects of these mutations individually and in combination. M230I alone caused a reduction in susceptibility to NNRTIs, while G112D alone did not. The G112D/M230I double mutant was less susceptible to NNRTIs than was M230I alone. In contrast, both mutations affected the ability of RT to incorporate nucleoside analogs. We suggest that the mutations interact with each other via the bound nucleic acid substrate; the nucleic acid forms part of the polymerase active site, which is near G112D. The positioning of the nucleic acid is influenced by its interactions with the “primer grip” region and could be influenced by the M230I mutation.

IMPORTANCE Although antiretroviral therapy (ART) is highly successful, drug-resistant variants can arise that blunt the efficacy of ART. New inhibitors that are broadly effective against known drug-resistant variants are needed, although such compounds might select for novel resistance mutations that affect the sensitivity of the virus to other compounds. Compound 13 selects for resistance mutations that differ from traditional NNRTI resistance mutations. These mutations cause increased sensitivity to NRTIs, such as AZT.

Efficacies of Cabotegravir and Bictegravir against drug-resistant HIV-1 integrase mutants

Background

Integrase strand transfer inhibitors (INSTIs) are the class of antiretroviral (ARV) drugs most recently approved by the FDA for the treatment of HIV-1 infections. INSTIs block the strand transfer reaction catalyzed by HIV-1 integrase (IN) and have been shown to potently inhibit infection by wild-type HIV-1. Of the three current FDA-approved INSTIs, Dolutegravir (DTG), has been the most effective, in part because treatment does not readily select for resistant mutants. However, recent studies showed that when INSTI-experienced patients are put on a DTG-salvage therapy, they have reduced response rates. Two new INSTIs, Cabotegravir (CAB) and Bictegravir (BIC), are currently in late-stage clinical trials.

Results

Both CAB and BIC had much broader antiviral profiles than RAL and EVG against the INSTI-resistant single, double, and triple HIV-1 mutants used in this study. BIC was more effective than DTG against several INSTI-resistant mutants. Overall, in terms of their ability to inhibit a broad range of INSTI-resistant IN mutants, BIC was superior to DTG, and DTG was superior to CAB. Modeling the binding of CAB, BIC, and DTG within the active site of IN suggested that the “left side” of the INSTI pharmacophore (the side away from the viral DNA) was important in determining the ability of the compound to inhibit the IN mutants we tested.

Conclusions

Of the two INSTIs in late stage clinical trials, BIC appears to be better able to inhibit the replication of a broad range of IN mutants. BIC retained potency against several of the INSTI-resistant mutants that caused a decrease in susceptibility to DTG.

Electronic supplementary material

The online version of this article (10.1186/s12977-018-0420-7) contains supplementary material, which is available to authorized users.

Novel HIV-1 Non-nucleoside Reverse Transcriptase Inhibitors: A Combinatorial Approach

Highly active antiretroviral therapy (HAART) is one of the most effective means for fighting against HIV-infection. HAART primarily targets HIV-1 reverse transcriptase (RT), and 14 of 28 compounds approved by the FDA as anti-HIV drugs act on this enzyme. HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) hold a special place among HIV RT inhibitors owing to their high specificity and unique mode of action. Nonetheless, these drugs show a tendency to decrease their efficacy due to high HIV-1 variability and formation of resistant virus strains tolerant to clinically applied HIV NNRTIs. A combinatorial approach based on varying substituents within various fragments of the parent molecule that results in development of highly potent compounds is one of the approaches aimed at designing novel HIV NNRTIs. Generation of HIV NNRTIs based on pyrimidine derivatives explicitly exemplifies this approach, which is discussed in this review.

Rilpivirine and Doravirine Have Complementary Efficacies Against NNRTI-Resistant HIV-1 Mutants

BACKGROUND

Rilpivirine (RPV) is the latest non-nucleoside reverse transcriptase inhibitor (NNRTI) to be approved by Food and Drug Administration to combat HIV-1 infections. NNRTIs inhibit the chemical step in viral DNA synthesis by binding to an allosteric site located about 10 Å from the polymerase active site of reverse transcriptase (RT). Although NNRTIs potently inhibit the replication of wild-type HIV-1, the binding site is not conserved, and mutations arise in the binding pocket. Doravirine (DOR) is a new NNRTI in phase III clinical trials.

METHODS

Using a single round HIV-1 infection assay, we tested RPV and DOR against a broad panel of NNRTI-resistant mutants to determine their respective activities. We also used molecular modeling to determine if the susceptibility profile of each compound was related to how they bind RT.

RESULTS

Several mutants displayed decreased susceptibility to DOR. However, with the exception of E138K, our data suggest that the mutations that reduce the potency of DOR and RPV are non-overlapping. Thus, these 2 NNRTIs have the potential to be used together in combination therapy. We also show that the location at which DOR and RPV bind with the NNRTI binding pocket of RT correlates with the differences in their respective susceptibility to the panel of NNRTI-resistance mutations.

CONCLUSIONS

This shows that (1) DOR is susceptible to a number of well-known NNRTI resistance mutations and (2) an understanding of the mutational susceptibilities and binding interactions of NNRTIs with RT could be used to develop pairs of compounds with non-overlapping mutational susceptibilities.

Novel diaryltriazines with a picolinonitrile moiety as potent HIV-1 RT inhibitors: a patent evaluation of WO2016059647(A2)

Diaryltriazine derivatives, which are structurally related to diarylpyrimidines, are a representative class of HIV-1 reverse transcriptase inhibitors with remarkable antiviral activities against wild-type and several mutant strains of HIV-1. A series of novel diaryltriazines with a picolinonitrile moiety was reported as potent HIV-1 RT inhibitors in the patent WO2016059647(A2). Two representative compounds 5e (hydrochloride) and 6e (hydrochloride) exhibited outstanding activities against various HIV-1 strains in cell-based assays, which were superior to those of AZT. Moreover, modeling simulation study is performed and discussed in details, providing deep insights and valuable information to explain the excellent antiviral potency of 6e. Finally, several cases to improve anti-drug-resistance profiles by targeting highly conserved residues in HIV-1 RT are herein preliminarily summarized.

Role of phenotypic investigation in the era of routine genotypic HIV-1 drug resistance testing

The emergence of drug resistance can seriously compromise HIV type-1 therapy and decrease therapeutic options. Resistance testing is highly recommended to guide treatment decisions and drug activity can be accurately predicted in the clinical setting through genotypic assays. While phenotypic systems are not suitable for monitoring drug resistance in routine laboratory practice, genotyping can misclassify unusual or complex mutational patterns, particularly with recently approved antivirals. In addition, phenotypic assays remain fundamental for characterizing candidate antiretroviral compounds. This review aims to discuss how phenotypic assays contributed to and still play a role in understanding the mechanisms of resistance of both licensed and investigational HIV type-1 inhibitors.