Non-Nucleoside Reverse Transcriptase Inhibitors Join Forces with Integrase Inhibitors to Combat HIV

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.

Design and synthesis of Fsp3-enriched spirocyclic-substituted diarylpyrimidine derivatives as novel HIV-1 NNRTIs

In this study, a novel series of diarylpyrimidine derivatives with Fsp3-enriched spirocycles were designed and synthesized to further explore the chemical space of the hydrophobic channel of the NNRTI-binding pocket. The biological evaluation results showed that most of the compounds displayed effective inhibitory potency against the HIV-1 wild-type strain, with EC50 values ranging from micromolar to submicromolar levels. Among them, TT6 turned out to be the most effective inhibitor with an EC50 value of 0.17 μM, demonstrating up to 47 times more active than that of reference drug 3TC (EC50 = 8.01 μM). More encouragingly, TT6 was found to potently inhibit the HIV-1 mutant strain K103N with an EC50 value of 0.69 μM, being about 6-fold more potent than 3TC (EC50 = 3.68 μM) and NVP (EC50 = 4.62 μM). Furthermore, TT6 exhibited the most potent inhibitory activity toward HIV-1 reverse transcriptase with an IC50 value of 0.33 μM. Additionally, molecular simulation studies were conducted to investigate the binding modes between TT6 and NNRTI-binding pocket, which may provide valuable clues for the follow-up structural optimizations.

Synthetic approaches and application of clinically approved small-molecule Anti-HIV drugs: An update

Application of chemotherapeutic agents to inhibit the HIV replication process has brought about a significant metamorphosis in the landscape of AIDS. Substantial declines in morbidity and mortality rates have been attained, accompanied by notable decreases in healthcare resource utilization. However, treatment modalities do not uniformly inhibit HIV replication in every patient, while the emergence of drug-resistant viral strains poses a substantial obstacle to subsequent therapeutic interventions. Furthermore, chronic administration of therapy may lead to the manifestation of toxicities. These challenges necessitate the exploration of novel pharmacological agents and innovative therapeutic approaches aimed at effectively managing the persistent viral replication characteristic of chronic infection. This review examines the role of clinically approved small-molecule drugs in the treatment of HIV/AIDS, which provides an in-depth analysis of the major classes of small-molecule drugs, including nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs), integrase inhibitors, entry inhibitors, and pharmacokinetic enhancers. The review mainly discusses the application, synthetic routes, and mechanisms of action of small-molecule drugs employed in the treatment of HIV, as well as their use in combination with antiretroviral therapy, presenting viewpoints on forthcoming avenues in the development of novel anti-HIV drugs.

Consideration of Nevirapine Analogs To Reduce Metabolically Linked Hepatotoxicity: A Cautionary Tale of the Deuteration Approach

Idiosyncratic drug reactions (IDRs) in their most deleterious form can lead to serious medical complications and potentially fatal events. Nevirapine (NVP), still widely used in developing countries for combinatorial antiretroviral and prophylactic therapies against HIV infection, represents a prototypical example of IDRs causing severe skin rashes and hepatotoxicity. Complex metabolic pathways accompanied by production of multiple reactive metabolites often complicate our understanding of IDR's origin. While assessment of NVP analogs has helped characterize the pathways involved in IDRs for NVP, which are largely driven by metabolism at the 12-methyl position, it has yet to be investigated if some of these analogs could be valuable replacement drugs with reduced reactive metabolite properties and drug-drug interaction (DDI) risks. Here, we evaluated a set of eight NVP analogs, including the deuterated 12-d3-NVP and two NVP metabolites, for their efficacy and inhibitory potencies against HIV reverse transcriptase (HIV-RT). A subset of three analogs, demonstrating >85% inhibition for HIV-RT, was further assessed for their hepatic CYP induction-driven DDI risks. This led to a closer investigation of the inactivation properties of 12-d3-NVP for hepatic CYP3A4 and a comparison of its propensity in generating reactive metabolite species. The metabolic shift triggered with 12-d3-NVP, increasing formation of the 2-hydroxy and glutathione metabolites, emphasized the importance of the dynamic balance between induction and metabolism-dependent inactivation of CYP3A4 and its impact on clearance of NVP during treatment. Unfortunately, the strategy of incorporating deuterium to reduce NVP metabolism and production of the electrophile species elicited opposite results, illustrating the great challenges involved in tackling IDRs through deuteration.

Fluorine in anti-HIV drugs approved by FDA from 1981 to 2023

Human immunodeficiency virus (HIV) is the etiological agent of acquired immunodeficiency syndrome (AIDS). Nowadays, FDA has approved over thirty antiretroviral drugs grouped in six categories. Interestingly, one-third of these drugs contain different number of fluorine atoms. The introduction of fluorine to obtain drug-like compounds is a well-accepted strategy in medicinal chemistry. In this review, we summarized 11 fluorine-containing anti-HIV drugs, focusing on their efficacy, resistance, safety, and specific roles of fluorine in the development of each drug. These examples may be of help for the discovery of new drug candidates bearing fluorine in their structures.

Fragment Hopping-Based Design of Novel Biphenyl-DAPY Derivatives as Potent Non-Nucleoside Reverse Transcriptase Inhibitors Featuring Significantly Improved Anti-Resistance Efficacy

To enhance the anti-resistance efficacy of our previously reported non-nucleoside reverse transcriptase inhibitor (NNRTI) 4, a series of novel biphenyl-DAPY derivatives were developed using the fragment-hopping strategy. Most of the compounds 8a-v exhibited remarkably improved anti-HIV-1 potency. The most active compound 8r proved to be exceptionally potent against the wild-type HIV-1 (EC₅₀ = 2.3 nM) and five mutant strains, such as K103N (EC₅₀ = 8 nM) and E138K (EC₅₀ = 6 nM), significantly better than 4. The new DAPY analogue was 8-fold less cytotoxic and had a 17-fold higher selectivity index (CC₅₀ = 40.77 μM, SI > 17391) than etravirine and rilpivirine. Also, it displayed favorable pharmacokinetic properties with an oral bioavailability of 31.19% and weak sensitivity toward both CYP and hERG. No apparent acute toxicity (2 g/kg) and tissue damage occurred. These findings will further expand the possibility of successfully identifying biphenyl-DAPY analogues as highly potent, safe, and orally active NNRTIs for HIV treatment.

Identification of Novel Diarylpyrimidines as Potent HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitors by Exploring the Primer Grip Region

HIV-1 reverse transcriptase (RT) plays a crucial role in the viral replication cycle, and RT inhibitors can represent a promising pathway in treating AIDS. To explore the primer grip region of HIV-1 RT, using -CH2O- as a linker, substituted benzene or pyridine rings were introduced into the left wing of diarylpyrimidines (DAPYs). A total of 17 compounds with new structures were synthesized. It showed that all compounds exhibited anti-HIV-1 (wild-type) activity values ranging from 7.6−199.0 nM. Among them, TF2 (EC50 = 7.6 nM) showed the most potent activity, which was better than that of NVP (EC50 = 122.6 nM). Notably, compared with RPV (CC50 = 3.98 μM), TF2 (CC50 > 279,329.6 nM) showed low cytotoxicity. For HIV-1 mutant strains K103N and E138K, most compounds showed effective activities. Especially for K103N, TF2 (EC50 = 28.1 nM), TF12 (EC50 = 34.7 nM) and TF13 (EC50 = 28.0 nM) exhibited outstanding activity, being superior to that of NVP (EC50 = 7495.1 nM) and EFV (EC50 = 95.1 nM). Additionally, TF2 also showed the most potent activity against E138K (EC50 = 44.0 nM) and Y181C mutant strains (EC50 = 139.3 nM). In addition, all the compounds showed strong enzyme inhibition (IC50 = 0.036−0.483 μM), which demonstrated that their target was HIV-1 RT. Moreover, molecular dynamics simulation studies were implemented to predict the binding mode of TF2 in the binding pocket of wild-type and K103N HIV-1 RT.

Structure-Based Discovery of Novel NH2-Biphenyl-Diarylpyrimidines as Potent Non-Nucleoside Reverse Transcriptase Inhibitors with Significantly Improved Safety: From NH2-Naphthyl-Diarylpyrimidine to NH2-Biphenyl-Diarylpyrimidine

Results from recently completed studies suggested that the NH₂-naphthyl-diarylpyrimidine JX-7 displayed remarkable inhibitory activity against wild-type HIV-1 (EC₅₀ = 5 nM) and numerous clinically observed variants in MT-4 cells; however, its high cytotoxicity (CC₅₀ = 19 μM) precluded its further development as a clinical candidate. One approach we took to improve the safety involved replacing the naphthyl of JX-7 with biphenyl to provide a series of novel NH₂-biphenyl-DAPYs. Investigation of the structure-activity relationships (SARs) led to the identification of 4ab, a potent NNRTI with significantly reduced cytotoxicity (CC₅₀ = 120 μM), approximately 6-fold lower than JX-7, which maintained remarkable anti-HIV-1 activity against wild-type HIV-1 (EC₅₀ = 1.9 nM) and multiple mutant strains simultaneously. Also, 4ab displayed weak CYP sensitivity, little inhibition of hERG, and no apparent in vivo acute toxicity. These promising results demonstrate that 4ab can be used as a drug candidate for HIV-1 therapy.

Pyrroles as Privileged Scaffolds in the Search for New Potential HIV Inhibitors

Acquired immunodeficiency syndrome (AIDS) is caused by human immunodeficiency virus (HIV) and remains a global health problem four decades after the report of its first case. Despite success in viral load suppression and the increase in patient survival due to combined antiretroviral therapy (cART), the development of new drugs has become imperative due to strains that have become resistant to antiretrovirals. In this context, there has been a continuous search for new anti-HIV agents based on several chemical scaffolds, including nitrogenated heterocyclic pyrrole rings, which have been included in several compounds with antiretroviral activity. Thus, this review aims to describe pyrrole-based compounds with anti-HIV activity as a new potential treatment against AIDS, covering the period between 2015 and 2020. Our research allowed us to conclude that pyrrole derivatives are still worth exploring, as they may provide highly active compounds targeting different steps of the HIV-1 replication cycle and act with an innovative mechanism.

Dolutegravir Plus Lamivudine Two-Drug Regimen: Safety, Efficacy and Diagnostic Considerations for Its Use in Real-Life Clinical Practice-A Refined Approach in the COVID-19 Era

The diagnostic and therapeutic management of the Coronavirus Disease 2019 (COVID-19) pandemic in the HIV population brought some known criticalities (and opportunities) to the forefront, for both those who are facing their first therapeutic line today, and for those already well viro-suppressed. The clinical, socioeconomic, and psychological impact of the COVID-19 pandemic should not affect the long-term care of people living with HIV, which creates an urgent need to optimize the diagnostic and treatment approach to the first-line or switch regimens. The use of dolutegravir plus a lamivudine two-drug regimen is one of the most promising solutions to ease the management of HIV treatment in this difficult period. In this review, we report the most salient features related to the use of this regimen from real-life cohorts, meta-analyses, randomized clinical trials, and studies presented at international conferences up to March 2021. We focused on the diagnostic and clinical-management implications of its use in real life, and how these comply with the contingent historical situation. The issue of the timing and type of diagnostic procedures and the relevance of classical diagnostic tests (such as genotype for resistance detection) is also discussed. According to the currently available results, dolutegravir plus a lamivudine two-drug regimen represents an outstanding tool, whose expected advantages fulfill the current requirements for optimal daily care of our HIV patients.