Pharmacological intervention of HIV-1 maturation

The Current Pipeline of Antiretroviral Therapy: Expanding Options and Filling Gaps

Highly effective antiretroviral therapy (ART) has transformed human immunodeficiency virus (HIV) care in the past 3 decades. 30 years ago, how many would have imagined that a single-tablet daily ART regimen containing different drug classes could achieve sustained HIV-1 suppression and halt disease progression to acquired immunodeficiency syndrome (AIDS)? Despite this remarkable achievement, challenges in HIV care remain that require further innovation for ART. In this review, we focus on newly approved antiretroviral agents and those undergoing phase 2/3 clinical trials. These new antiretrovirals hold great promise to expand treatment options and fill gaps in HIV care.

Hydrophobic tagging of small molecules: an overview of the literature and future outlook

INTRODUCTION

Hydrophobic tagging (HyT) technology presents a distinct therapeutic strategy diverging from conventional small molecule drugs, providing an innovative approach to drug design. This review aims to provide an overview of the HyT literature and future outlook to offer guidance for drug design.

AREAS COVERED

In this review, the authors introduce the composition, mechanisms and advantages of HyT technology, as well as summarize the detailed applications of HyT technology in anti-cancer, neurodegenerative diseases (NDs), autoimmune disorders, cardiovascular diseases (CVDs), and other fields. Furthermore, this review discusses key aspects of the future development of HyT molecules.

EXPERT OPINION

HyT emerges as a highly promising targeted protein degradation (TPD) strategy, following the successful development of proteolysis targeting chimeras (PROTAC) and molecular glue. Based on exploring new avenues, modification of the HyT molecule itself potentially enhances the technology. Improved synthetic pathways and emphasis on pharmacokinetic (PK) properties will facilitate the development of HyT. Furthermore, elucidating the biochemical basis by which the compound's hydrophobic moiety recruits the protein homeostasis network will enable the development of more precise assays that can guide the optimization of the linker and hydrophobic moiety.

Evaluating HIV-1 Infectivity and Virion Maturation across Varied Producer Cells with a Novel FRET-Based Detection and Quantification Assay

The maturation of HIV-1 virions is a crucial process in viral replication. Although T-cells are a primary source of virus production, much of our understanding of virion maturation comes from studies using the HEK293T human embryonic kidney cell line. Notably, there is a lack of comparative analyses between T-cells and HEK293T cells in terms of virion maturation efficiency in existing literature. We previously developed an advanced virion visualization system based on the FRET principle, enabling the effective distinction between immature and mature virions via fluorescence microscopy. In this study, we utilized pseudotyped, single-round infectious viruses tagged with FRET labels (HIV-1 Gag-iFRET∆Env) derived from Jurkat (a human T-lymphocyte cell line) and HEK293T cells to evaluate their virion maturation rates. HEK293T-derived virions demonstrated a maturity rate of 81.79%, consistent with other studies and our previous findings. However, virions originating from Jurkat cells demonstrated a significantly reduced maturation rate of 68.67% (p < 0.0001). Correspondingly, viruses produced from Jurkat cells exhibited significantly reduced infectivity compared to those derived from HEK293T cells, with the relative infectivity measured at 65.3%. This finding is consistent with the observed relative maturation rate of viruses produced by Jurkat cells. These findings suggest that initiation of virion maturation directly correlates with viral infectivity. Our observation highlights the dynamic nature of virus-host interactions and their implications for virion production and infectivity.

Evaluating HIV-1 Infectivity and Virion Maturation Across Varied Producer Cells with a Novel FRET-Based Detection and Quantification Assay

The maturation of HIV-1 virions is a crucial process in viral replication. Although T cells are a primary source of virus production, much of our understanding of virion maturation comes from studies using the HEK293T human embryonic kidney cell line. Notably, there is a lack of comparative analyses between T cells and HEK293T cells in terms of virion maturation efficiency in existing literature. We previously developed an advanced virion visualization system based on the FRET principle, enabling the effective distinction between immature and mature virions via fluorescence microscopy. In this study, we utilized pseudotyped, single-round infectious viruses tagged with FRET labels (HIV-1 Gag-iFRETΔEnv) derived from Jurkat (a human T lymphocyte cell line) and HEK293T cells to evaluate their virion maturation rates. HEK293T-derived virions demonstrated a maturity rate of 81.79%, consistent with other studies and our previous findings. However, virions originating from Jurkat cells demonstrated a significantly reduced maturation rate of 68.67% (p < 0.0001). Correspondingly, viruses produced from Jurkat cells exhibited significantly reduced infectivity compared to those derived from HEK293T cells, with the relative infectivity measured at 65.3%. This finding is consistent with the observed relative maturation rate of viruses produced by Jurkat cells. These findings suggest that initiation of virion maturation directly correlates with viral infectivity. Our observation highlights the dynamic nature of virus-host interactions and their implications for virion production and infectivity.

Pharmacokinetics and tolerability of the maturation inhibitor GSK3640254 coadministered with darunavir/ritonavir and/or etravirine in healthy adults

AIMS

This phase I study investigated potential drug-drug interactions of the maturation inhibitor GSK3640254 (GSK'254) with darunavir/ritonavir (DRV/RTV) and/or etravirine (ETR).

METHODS

In this randomized, open-label, single-sequence, multiple-dose study, healthy participants received GSK'254 200 mg once daily alone or coadministered with DRV/RTV 600/100 mg twice daily (BID; n = 19), ETR 200 mg BID (n = 19) or DRV/RTV 600/100 mg + ETR 200 mg BID (n = 16) under fed conditions. Primary endpoints were steady-state area under the plasma concentration-time curve from time 0 to the end of the dosing interval (AUC0-τ ) and maximum observed concentration (Cmax ). Secondary endpoints included trough concentration (Cτ ), safety and tolerability. Pharmacokinetic parameters were calculated using standard noncompartmental analysis, and geometric least-squares mean ratios were derived from linear mixed-effects models.

RESULTS

GSK'254 AUC0-τ (geometric least-squares mean ratio [90% confidence interval], 1.14 [1.00-1.29]), Cmax (1.07 [0.92-1.24]) and Cτ (1.17 [1.01-1.35]) were similar when administered alone and with DRV/RTV. Etravirine coadministration decreased GSK'254 AUC0-τ (0.53 [0.48-0.59]), Cmax (0.60 [0.53-0.68]) and Cτ (0.51 [0.39-0.66]). Similar reductions were not observed with GSK'254 + DRV/RTV + ETR (AUC0-τ , 0.94 [0.82-1.09]; Cmax , 0.89 [0.75-1.07]; Cτ , 1.02 [0.89-1.18]). GSK'254 had no meaningful effect on DRV/RTV or ETR concentrations. All reported adverse events (AEs) were grade 1; 3 led to withdrawal and resolved (rash, asymptomatic electrocardiogram T-wave inversion, periorbital oedema). Most common AEs were diarrhoea (n = 9) and headache (n = 7). No deaths or serious AEs occurred.

CONCLUSION

GSK'254 pharmacokinetics was not meaningfully affected by DRV/RTV or DRV/RTV + ETR, but were reduced with only ETR; no new tolerability concerns were observed.

Effects of the HIV-1 maturation inhibitor GSK3640254 on QT interval in healthy participants

GSK3640254 (GSK'254) is a novel HIV-1 maturation inhibitor with pharmacokinetics supporting once-daily (QD) therapy for HIV-1 treatment. This thorough QT/corrected QT (QTc) study evaluated the effect of GSK'254 on cardiac repolarization. In this two-part, randomized study, healthy participants received GSK'254 or placebo QD for 7 days (part 1) to determine safety and pharmacokinetics of a 500-mg supratherapeutic dose. Four sequential treatment periods composed the main QTc study (part 2): GSK'254 100 mg, GSK'254 500 mg, placebo QD for 7 days, or placebo QD for 6 days with a 400-mg moxifloxacin dose on Day 7 (all with a moderate-fat meal). Concentration-QTc analyses modeled the relationship between GSK'254 plasma concentrations and placebo-adjusted change from baseline in QT interval corrected with Fridericia's formula (ΔΔQTcF). Of 50 participants enrolled, 48 completed the study (part 1, 8/8; part 2, 40/42). Least-squares (LS) mean change from baseline in QTcF for GSK'254 100 mg followed the placebo pattern across time points (maximum LS mean ΔΔQTcF, 1.7 ms); the upper bound of the 90% CI remained <10 ms. Maximum LS mean ΔΔQTcF for GSK'254 500 mg exceeded the 10-ms threshold: 10.6 ms (90% CI 7.75-13.38). Neither GSK'254 dose had clinically relevant effects on heart rate or cardiac conduction. By concentration-QTc analysis, no effect on ΔΔQTcF >10 ms is expected up to GSK'254 concentrations of ~3070 ng mL-1 . No clinically relevant effects on cardiac parameters were seen in healthy participants with GSK'254 at the 100-mg dose.

Open-label, drug-drug interaction study between the HIV-1 maturation inhibitor GSK3640254 and a metabolic probe cocktail in healthy participants

AIMS

GSK3640254 (GSK'254) is an HIV-1 maturation inhibitor with pharmacokinetics (PK) supporting once-daily dosing. GSK'254 will be co-administered with cytochrome P450 enzyme substrates and drug transporters, including other antiretrovirals, in people living with HIV-1 (PLWH).

METHODS

In this open-label study, healthy participants received a single dose of a cocktail of eight cytochrome P450 and transporter probe substrates on Day 1, followed by a 10-day washout before receiving GSK'254 200 mg once daily from Days 11 to 20 and a single dose of cocktail + GSK'254 200 mg on Day 21. Geometric least-squares mean ratios and 90% confidence intervals were obtained using linear mixed-effects models. Adverse events (AEs) were monitored.

RESULTS

Of 20 participants enrolled, 19 completed the study. Plasma concentrations of all cocktail substrates were generally similar with or without GSK'254 co-administration. All 90% confidence intervals around geometric least-squares mean ratios for cocktail substrate PK parameters indicated no to weak interactions. Steady-state plasma GSK'254 concentrations were achieved by Day 17 and maintained through Day 21. Nine participants (45%) reported 17 AEs; most (88%) were grade 1. Two grade 2 treatment-related AEs (maculopapular rash [leading to withdrawal] and papular rash) were reported during GSK'254 administration alone.

CONCLUSIONS

Co-administration of GSK'254 with a metabolic probe cocktail in healthy participants indicated very low risk of clinically relevant effect on PK of any substrates or associated metabolites. No new safety/tolerability concerns were identified. These results support ongoing phase IIb and planned phase III studies of GSK'254 in people living with HIV-1.

Cellular Targets of HIV-1 Protease: Just the Tip of the Iceberg?

Human immunodeficiency virus 1 (HIV-1) viral protease (PR) is one of the most studied viral enzymes and a crucial antiviral target. Despite its well-characterized role in virion maturation, an increasing body of research is starting to focus on its ability to cleave host cell proteins. Such findings are apparently in contrast with the dogma of HIV-1 PR activity being restricted to the interior of nascent virions and suggest catalytic activity within the host cell environment. Given the limited amount of PR present in the virion at the time of infection, such events mainly occur during late viral gene expression, mediated by newly synthesized Gag-Pol polyprotein precursors, rather than before proviral integration. HIV-1 PR mainly targets proteins involved in three different processes: those involved in translation, those controlling cell survival, and restriction factors responsible for innate/intrinsic antiviral responses. Indeed, by cleaving host cell translation initiation factors, HIV-1 PR can impair cap-dependent translation, thus promoting IRES-mediated translation of late viral transcripts and viral production. By targeting several apoptotic factors, it modulates cell survival, thus promoting immune evasion and viral dissemination. Additionally, HIV-1 PR counteracts restriction factors incorporated in the virion that would otherwise interfere with nascent virus vitality. Thus, HIV-1 PR appears to modulate host cell function at different times and locations during its life cycle, thereby ensuring efficient viral persistency and propagation. However, we are far from having a complete picture of PR-mediated host cell modulation, which is emerging as a field that needs further investigation.

Strategies to overcome HIV drug resistance-current and future perspectives

The availability of combined antiretroviral therapy (cART) has revolutionized the course of HIV infection, suppressing HIV viremia, restoring the immune system, and improving the quality of life of HIV infected patients. However, the emergence of drug resistant and multidrug resistant strains remains an important contributor to cART failure, associated with a higher risk of HIV-disease progression and mortality. According to the latest WHO HIV Drug Resistance Report, the prevalence of acquired and transmitted HIV drug resistance in ART naive individuals has exponentially increased in the recent years, being an important obstacle in ending HIV-1 epidemic as a public health threat by 2030. The prevalence of three and four-class resistance is estimated to range from 5 to 10% in Europe and less than 3% in North America. The new drug development strategies are focused on improved safety and resistance profile within the existing antiretroviral classes, discovery of drugs with novel mechanisms of action (e.g., attachment/post-attachment inhibitors, capsid inhibitors, maturation inhibitors, nucleoside reverse transcriptase translocation inhibitors), combination therapies with improved adherence, and treatment simplification with infrequent dosing. This review highlight the current progress in the management of salvage therapy for patients with multidrug-resistant HIV-1 infection, discussing the recently approved and under development antiretroviral agents, as well as the new drug targets that are providing a new avenue for the development of therapeutic interventions in HIV infection.

Synthesis, Structure-Activity Relationships, and In Vivo Evaluation of Novel C-17 Amine Derivatives Based on GSK3640254 as HIV-1 Maturation Inhibitors with Broad Spectrum Activity

An investigation of the structure-activity relationships of a series of HIV-1 maturation inhibitors (MIs) based on GSK3640254 (4) was conducted by incorporating novel C-17 amine substituents to reduce the overall basicity of the resultant analogues. We found that replacement of the distal amine on the C-17 sidechain present in 4 with a tertiary alcohol in combination with either a heterocyclic ring system or a cyclohexyl ring substituted with polar groups provided potent wild-type HIV-1 MIs that also retained excellent potency against a T332S/V362I/prR41G variant, a laboratory strain that served as a surrogate to assess HIV-1 polymorphic virus coverage. Compound 26 exhibited broad-spectrum HIV-1 activity against an expanded panel of clinically relevant Gag polymorphic viruses and had the most desirable overall profile in this series of compounds. In pharmacokinetic studies, 26 had low clearance and exhibited 24 and 31% oral bioavailability in rats and dogs, respectively.

Relative Bioavailability and Food Effect of GSK3640254 Tablet and Capsule Formulations in Healthy Participants

GSK3640254 is a next‐generation maturation inhibitor with demonstrated potency across HIV‐1 subtypes and a high barrier to emergent resistance. This phase I, 2‐part, randomized, open‐label study (ClinicalTrials.gov identifier, NCT04263142) in healthy participants assessed the relative bioavailability of a single dose of GSK3640254 200 mg in tablet and capsule formulations (part 1) and the effect of food on the pharmacokinetic profile of the tablet formulation (part 2). Overall, 39 participants were randomized to treatment (part 1, n = 18; part 2, n = 21). All participants in part 1 completed the study; 2 participants in part 2 withdrew before study completion (adverse event, n = 1; physician decision, n = 1). In part 1, plasma exposures of the GSK3640254 tablet formulation were not meaningfully different from those of the capsule formulation when administered in the presence of a moderate‐fat meal. In part 2, GSK3640254 plasma exposures increased by ≈3‐ to 4‐fold under high‐ and moderate‐fat conditions, respectively, compared with fasted conditions. No major safety or tolerability findings were observed. The highest incidence of adverse events (24%) was reported under high‐fat conditions. Taken together, these data support the use of the tablet formulation coadministered with food in the clinical development of GSK3640254 for treatment of HIV‐1.

Phase IIa Proof-of-Concept Evaluation of the Antiviral Efficacy, Safety, Tolerability, and Pharmacokinetics of the Next-Generation Maturation Inhibitor GSK3640254

Background

GSK3640254 (GSK’254) is a next-generation human immunodeficiency virus type 1 (HIV-1) maturation inhibitor with pharmacokinetics (PK) supporting once-daily therapy.

Methods

This phase IIa double-blind (sponsor-unblinded), randomized, placebo-controlled, adaptive study evaluated antiviral effect, safety, tolerability, and PK of once-daily GSK’254 monotherapy administered with food (moderate-fat meal) in HIV-1–positive, treatment-naive adults. In part 1, participants received GSK’254 10 or 200 mg for 10 days. In part 2, participants received GSK’254 40, 80, or 140 mg for 7 days, modified from 10 days by a protocol amendment to decrease potential for resistance-associated mutations (RAMs). The primary endpoint was maximum change from baseline in HIV-1 RNA.

Results

Maximum changes in HIV-1 RNA of −0.4, −1.2, −1.0, −1.5, and −2.0 log₁₀ occurred with GSK’254 10, 40, 80, 140, and 200 mg, respectively. Regardless of dosing duration, doses ≥40 mg resulted in ≥1-log₁₀ declines in HIV-1 RNA. Plasma PK was generally dose proportional to 140 mg but non-proportional between 140 and 200 mg. Four participants in the 200-mg group developed RAMs on day 11 in part 1, 1 with phenotypic resistance. No RAMs occurred in part 2. Adverse events (AEs) were reported by 22 (65%) participants; headache was the most common (n = 4). Two non–drug-related serious AEs occurred. All AEs were of mild-to-moderate intensity, except for 2 grade 3 non–drug-related AEs in 1 participant.

Conclusions

This monotherapy study established a dose–antiviral response relationship for GSK’254. No safety or tolerability concerns were noted. These results supported dose selection for the ongoing phase IIb study (ClinicalTrials.gov: NCT04493216).

Clinical Trials Registration

NCT03784079.

Betulinic Acid Decorated with Polar Groups and Blue Emitting BODIPY Dye: Synthesis, Cytotoxicity, Cell-Cycle Analysis and Anti-HIV Profiling

Betulinic acid (BA) is a potent triterpene, which has shown promising potential in cancer and HIV-1 treatment. Here, we report a synthesis and biological evaluation of 17 new compounds, including BODIPY labelled analogues derived from BA. The analogues terminated by amino moiety showed increased cytotoxicity (e.g., BA had on CCRF-CEM IC₅₀ > 50 μM, amine 3 IC₅₀ 0.21 and amine 14 IC₅₀ 0.29). The cell-cycle arrest was evaluated and did not show general features for all the tested compounds. A fluorescence microscopy study of six derivatives revealed that only 4 and 6 were detected in living cells. These compounds were colocalized with the endoplasmic reticulum and mitochondria, indicating possible targets in these organelles. The study of anti-HIV-1 activity showed that 8, 10, 16, 17 and 18 have had IC_50i > 10 μM. Only completely processed p24 CA was identified in the viruses formed in the presence of compounds 4 and 12. In the cases of 2, 8, 9, 10, 16, 17 and 18, we identified not fully processed p24 CA and p25 CA-SP1 protein. This observation suggests a similar mechanism of inhibition as described for bevirimat.

Lack of pharmacokinetic interaction between the HIV-1 maturation inhibitor GSK3640254 and combination oral contraceptives in healthy women

Aims

GSK3640254 is a next‐generation maturation inhibitor likely to be coadministered with combined oral contraceptives in HIV‐positive women.

Methods

This phase I, open‐label, 1‐way study assessed pharmacokinetic and pharmacodynamic interactions of GSK3640254 200 mg and ethinyl oestradiol 0.03 mg/levonorgestrel 0.15 mg once daily in healthy female participants who received ethinyl oestradiol/levonorgestrel for 10 days with a moderate‐fat meal after which GSK3640254 was added from Days 11 to 21. Primary endpoints were area under the plasma concentration–time curve to the end of the dosing interval (AUC_0‐t), maximum observed concentration (C_max) and plasma concentration at the end of the dosing interval (C_τ) for ethinyl oestradiol and levonorgestrel. Serum follicle‐stimulating hormone, luteinizing hormone and progesterone concentrations were determined. Adverse events were monitored.

Results

Among 23 enrolled participants, 17 completed the study. Geometric least squares mean ratios (with vs. without GSK3640254) of AUC_0‐t, C_max and C_τ were 0.974, 0.970 and 1.050 for ethinyl oestradiol and 1.069, 1.032 and 1.083 for levonorgestrel, respectively. Three participants had elevated progesterone levels, which occurred before GSK3640254 administration in 2 participants. No participants had elevated follicle‐stimulating hormone or luteinizing hormone values. Fourteen participants (61%) reported adverse events. Four participants reported asymptomatic elevated transaminase levels meeting liver‐stopping criteria; of these, 3 events occurred before GSK3640254 administration and led to study withdrawal.

Conclusion

Ethinyl oestradiol/levonorgestrel plus GSK3640254 coadministration did not affect steady‐state pharmacokinetics or pharmacodynamics of ethinyl oestradiol and levonorgestrel in healthy female participants. No major tolerability findings were reported. Elevated liver transaminase levels were probably due to ethinyl oestradiol/levonorgestrel.

Acankoreagenin and acankoreosides, a family of lupane triterpenoids with anti-inflammatory properties: an overview

Acankoreagenin (ACK, also known as acankoreanogenin and HLEDA) and impressic acid are two lupane-type triterpenes that can be isolated from various Acanthopanax and Schefflera species. They efficiently block activation of the NF-κB signaling pathway and the release of proinflammatory cytokines and/or the action of inflammation mediators (HMGB1, iNOS, and NO). These effects are the basis for the antiviral and anticancer activities reported with these pentacyclic compounds or their various glycoside derivatives. More than 15 acankoreosides (Ack-A to -O, and -R) and a few other mono- and bidesmosidic saponins (acantrifoside A and acangraciliside S) derive from the ACK aglycone. Compounds like Ack-A and -B are remarkable anti-inflammatory agents, inhibiting cytokine release from activated macrophages. Despite their effectiveness, ACK and impressic acid are far much less known and studied than the structurally related compounds betulinic acid and 23-hydroxybetulinic acid (anemosapogenin). The structural differences (notably the R/S stereoisomerism of the 3-hydroxyl group) and functional similarities of these compounds are discussed. The complete series of acankoreosides is presented for the first time. These natural products deserve further attention as anti-inflammatory agents, and ACK is recommended as a template for the design of new anticancer and antiviral drugs.

A Phase I Evaluation of the Pharmacokinetics and Tolerability of the HIV-1 Maturation Inhibitor GSK3640254 and Tenofovir Alafenamide/Emtricitabine in Healthy Participants

GSK3640254 is a next-generation maturation inhibitor that would likely be combined with standard antiretroviral agents to form a regimen of ≥2 fully active classes. This phase I, open-label, 2-period, 1-way study assessed potential pharmacokinetic (PK) interactions between GSK3640254 and tenofovir alafenamide/emtricitabine (TAF/FTC; including the metabolite tenofovir [TFV]) in healthy volunteers. Eligible participants received TAF/FTC 25/200 mg once daily (QD) on days 1 through 21 with a moderate-fat meal; GSK3640254 200 mg QD was added on days 15 through 21. Geometric least-squares mean ratios (GMRs) and 90% confidence intervals (CIs) were derived using linear mixed-effect models. Adverse events (AEs) and laboratory, electrocardiogram, and vital sign parameters were monitored. Sixteen participants, all male, received treatment; one withdrew because of treatment-related grade 1 urticaria. After TAF/FTC + GSK3640254 coadministration, TAF steady-state area under the plasma concentration-time curve from time zero to the end of the dosing interval and maximum observed concentration were 11% and 13% lower than when TAF/FTC was administered alone, with GMRs (90% CI) of 0.886 (0.75 to 1.04) and 0.874 (0.68 to 1.12), respectively. Steady-state PK of TFV and FTC was similar when TAF/FTC was administered alone or with GSK3640254. No clinically significant trends in tolerability or safety were observed. GSK3640254 200 mg QD did not meaningfully affect the steady-state PK of TAF, TFV, or FTC in healthy participants under fed conditions and was not associated with major tolerability or safety findings. These data support the further investigation of GSK3640254 for coadministration with TAF/FTC for the treatment of HIV. (This study has been registered at ClinicalTrials.gov under identifier NCT03836729.)

Phase I evaluation of pharmacokinetics and tolerability of the HIV-1 maturation inhibitor GSK3640254 and dolutegravir in healthy adults

Aims

GSK3640254, a novel, next‐generation maturation inhibitor effective against a range of HIV polymorphisms with no cross‐resistance to current antiretroviral therapy, could potentially be coadministered with dolutegravir as a 2‐drug regimen. In this phase I study, pharmacokinetics and tolerability of GSK3640254 plus dolutegravir were assessed.

Methods

Healthy participants received dolutegravir 50 mg once daily (QD) on Days 1–5 in period 1, GSK3640254 200 mg QD on Days 1–7 in period 2, and dolutegravir 50 mg plus GSK3640254 200 mg QD on Days 1–7 in period 3. All treatments were administered with a moderate‐fat meal 30 minutes prior to dosing. Pharmacokinetics parameters were derived by noncompartmental methods, and geometric mean ratios (GMRs) and 90% confidence intervals (CIs) were derived using linear mixed effects models. Adverse events, laboratory measurements, electrocardiography and vital signs were monitored.

Results

Sixteen participants completed the study. GMRs (90% CIs) for dolutegravir area under the plasma concentration–time curve from time 0 to the end of the dosing interval at steady state, maximum observed concentration and plasma concentration at the end of the dosing interval were 1.17 (1.118–1.233), 1.09 (1.044–1.138) and 1.24 (1.160–1.315), respectively. The GMRs (90% CIs) for GSK3640254 were 1.04 (0.992–1.094), 0.99 (0.923–1.065) and 0.10 (0.939–1.056), respectively. Dolutegravir plus GSK3640254 coadministration did not meaningfully alter steady‐state exposure to dolutegravir or GSK3640254. No clinically significant trends in tolerability or safety were observed.

Conclusion

Coadministration of GSK3640254 with dolutegravir did not result in clinically significant drug interaction and was well tolerated.

Mechanisms underlying of antiretroviral drugs in different cellular reservoirs with a focus on macrophages

Ongoing with current combinations of antiretroviral drugs for the treatment of Human Immunodeficiency Virus (HIV) infection can successfully maintain long-term suppression of HIV-1 replication in plasma. Still, none of these therapies is capable of extinguishing the virus from the long-lived cellular reservoir, including monocyte-derived macrophages (MDM), that means the principal obstacle to HIV cure. MDM are widely distributed in all tissues and organs, including central system nervous (CNS) where they represent the most frequent HIV-infected cells that means the principal obstacle to HIV cure. Current FDA-approved antiretroviral drugs target viral reverse transcriptase, protease, integrase, and entry processes (coreceptor or fusion blockade). It is desirable to continue to develop new antiretrovirals directed against alternative targets in the virus lifecycle in order to further optimize therapeutic options, overcome resistance to existing medications, and potentially contribute to the elimination of viral reservoirs.This review provides a comprehensive overview of the activity of antiretroviral drugs (classical and upcoming) in monocytes-derived macrophages (MDM). Defining the antiviral activity of these drugs in this important cellular HIV-1 reservoir provides crucial hints about their efficacy in HIV-1 infected patients.

Phase I evaluation of the safety, tolerability, and pharmacokinetics of GSK3640254, a next-generation HIV-1 maturation inhibitor

Despite advances in HIV-1 management with antiretroviral therapy, drug resistance and toxicities with multidrug regimens can result in treatment failure. Hence, there is a continuing demand for antiretroviral agents (ARVs) with novel mechanisms of action. Maturation inhibitors inhibit HIV-1 replication via a unique mechanism of action and can be combined with other ARVs. Two phase I randomized clinical trials were conducted for a maturation inhibitor, GSK3640254, to determine safety, pharmacokinetics (NCT03231943), and relative bioavailability (NCT03575962) in healthy adults. The first trial was conducted in two parts. Part 1 was conducted in a two-cohort, interlocking, eight-period fashion in 20 participants with single ascending doses of GSK3640254 (1-700 mg) or placebo. In Part 2, 58 participants were randomized to receive GSK3640254 (n = 44) or placebo (n = 14). Four participants reported adverse events (AEs) leading to study discontinuation, with one adverse drug reaction (maculopapular rash). There was no relationship between frequency or severity of AEs and dose. Pharmacokinetic assessments showed that GSK3640254 was slowly absorbed, with time to maximum concentration (tmax) occurring between 3.5 and 4 hours and half-life of ~24 hours. In the relative bioavailability study of GSK3640254 mesylate salt vs bis-hydrochloride salt capsules in 14 healthy adults, the mesylate salt performed slightly better than the bis-hydrochloride formulation (12%-16% increase in area under the concentration-time curve and maximum concentration); tmax (5 hours) was similar between the formulations. Initial pharmacokinetic and safety data from these healthy-participant studies informed further development of GSK3640254 for once-daily dosing for the treatment of HIV-1 infection.

Phosphate Derivatives of 3-Carboxyacylbetulin: SynThesis, In Vitro Anti-HIV and Molecular Docking Study

Lupane-type pentacyclic triterpenes such as betulin and betulinic acid play an important role in the search for new therapies that would be effective in controlling viral infections. The aim of this study was the synthesis and evaluation of in vitro anti-HIV-1 activity for phosphate derivatives of 3-carboxyacylbetulin 3-5 as well as an in silico study of new compounds as potential ligands of the C-terminal domain of the HIV-1 capsid-spacer peptide 1 (CA-CTD-SP1) as a molecular target of HIV-1 maturation inhibitors. In vitro studies showed that 28-diethoxyphosphoryl-3-O-(3',3'-dimethylsuccinyl)betulin (compound 3), the phosphate analog of bevirimat (betulinic acid derivative, HIV-1 maturation inhibitor), has IC50 (half maximal inhibitory concentration) equal to 0.02 μM. Compound 3 inhibits viral replication at a level comparable to bevirimat and is also more selective (selectivity indices = 1250 and 967, respectively). Molecular docking was used to examine the probable interaction between the phosphate derivatives of 3-carboxyacylbetulin and C-terminal domain (CTD) of the HIV-1 capsid (CA)-spacer peptide 1 (SP1) fragment of Gag protein, designated as CTD-SP1. Compared with interactions between bevirimat (BVM) and the protein, an increased number of strong interactions between ligand 3 and the protein, generated by the phosphate group, were observed. These compounds might have the potential to also inhibit SARS-CoV2 proteins, in as far as the intrinsically imprecise docking scores suggest.

Recent Advances in HIV-1 Gag Inhibitor Design and Development

Acquired Immune Deficiency Syndrome (AIDS) treatment with combination antiretroviral therapy (cART) has improved the life quality of many patients since its implementation. However, resistance mutations and the accumulation of severe side effects associated with cART remain enormous challenges that need to be addressed with the continual design and redesign of anti-HIV drugs. In this review, we focus on the importance of the HIV-1 Gag polyprotein as the master coordinator of HIV-1 assembly and maturation and as an emerging drug target. Due to its multiple roles in the HIV-1 life cycle, the individual Gag domains are attractive but also challenging targets for inhibitor design. However, recent encouraging developments in targeting the Gag domains such as the capsid protein with highly potent and potentially long-acting inhibitors, as well as the exploration and successful targeting of challenging HIV-1 proteins such as the matrix protein, have demonstrated the therapeutic viability of this important protein. Such Gag-directed inhibitors have great potential for combating the AIDS pandemic and to be useful tools to dissect HIV-1 biology.

New Phosphorus Analogs of Bevirimat: Synthesis, Evaluation of Anti-HIV-1 Activity and Molecular Docking Study

Since the beginning of the human immunodeficiency virus (HIV) epidemic, many groups of drugs characterized by diverse mechanisms of action have been developed, which can suppress HIV viremia. 3-O-(3′,3′-Dimethylsuccinyl) betulinic acid, known as bevirimat (BVM), was the first compound in the class of HIV maturation inhibitors. In the present work, phosphate and phosphonate derivatives of 3-carboxyacylbetulinic acid were synthesized and evaluated for anti-HIV-1 activity. In vitro studies showed that 30-diethylphosphonate analog of BVM (compound 14a) has comparable effects to BVM (half maximal inhibitory concentrations (IC₅₀) equal to 0.02 μM and 0.03 μM, respectively) and is also more selective (selectivity indices: 3450 and 967, respectively). To investigate the possible mechanism of antiviral effect of 14a, molecular docking was carried out on the C-terminal domain (CTD) of HIV-1 capsid (CA)–spacer peptide 1 (SP1) fragment of Gag protein, designated as CTD-SP1, which was described as a molecular target for maturation inhibitors. Compared with interactions between BVM and the protein, an increased number of strong interactions between ligand 14a and protein, generated by the phosphonate group, was observed.

Triphenylphosphonium Analogues of Betulin and Betulinic Acid with Biological Activity: A Comprehensive Review

Naturally occurring pentacyclic lupane triterpenoids such as betulin (1) or betulinic acid (2) and their synthetic derivatives display a broad spectrum of biological activities and, therefore, have been the subject of great interest. However, the use of these compounds as potential therapeutic agents is limited by their low bioavailability, high hydrophobicity, and insufficient intracellular accumulation. In this context, research on modifications of the parent structures that will improve their pharmacokinetic properties is particularly important. In the past few years, methods of synthesis as well as cytotoxic and antiparasitic properties of a series of lupane triterpenoids modified by introducing one or two triphenylphosphonium moieties at the C-2, C-3, C-28, or C-30 positions by carbon-carbon or ester bonds have been described. The presence of triphenylphosphonium groups affects not only physical properties but also the mechanism of action of a potential drug. This review summarizes published findings on synthetic methods and biological properties of the triphenylphosphonium derivatives of betulin and betulinic acid.

Inhibition of HIV Maturation via Selective Unfolding and Cross-Linking of Gag Polyprotein by a Mercaptobenzamide Acetylator

For HIV to become infectious, any new virion produced from an infected cell must undergo a maturation process that involves the assembly of viral polyproteins Gag and Gag-Pol at the membrane surface. The self-assembly of these viral proteins drives formation of a new viral particle as well as the activation of HIV protease, which is needed to cleave the polyproteins so that the final core structure of the virus will properly form. Molecules that interfere with HIV maturation will prevent any new virions from infecting additional cells. In this manuscript, we characterize the unique mechanism by which a mercaptobenzamide thioester small molecule (SAMT-247) interferes with HIV maturation via a series of selective acetylations at highly conserved cysteine and lysine residues in Gag and Gag-Pol polyproteins. The results provide the first insights into how acetylation can be utilized to perturb the process of HIV maturation and reveal a new strategy to limit the infectivity of HIV.

Second Generation Inhibitors of HIV-1 Maturation

The strategy and tactics subtending the discovery and development of the second generation HIV-1 maturation inhibitor GSK-3532795/BMS-955176, a compound that exhibits a broader spectrum of antiviral effect in vitro and in clinical studies than the prototypical maturation inhibitor bevirimat, are described.

Insight into the mechanism of action of EP-39, a bevirimat derivative that inhibits HIV-1 maturation

Maturation of human immunodeficiency virus type 1 (HIV-1) particles is a key step for viral infectivity. This process can be blocked using maturation inhibitors (MIs) that affect the cleavage of the capsid-spacer peptide 1 (CA-SP1) junction. Here, we investigated the mechanisms underlying the activity of EP-39, a bevirimat (BVM) derivative with better hydrosolubility. To this aim, we selected in vitro EP-39- and BVM-resistant mutants. We found that EP-39-resistant viruses have four mutations within the CA domain (CA-A194T, CA-T200N, CA-V230I, and CA-V230A) and one in the first residue of SP1 (SP1-A1V). We also identified six mutations that confer BVM resistance (CA-A194T, CA-L231F, CA-L231M, SP1-A1V, SP1-S5N and SP1-V7A). To characterize the EP-39 and BVM-resistant mutants, we studied EP-39 effects on mutant virus replication and performed a biochemical analysis with both MIs. We observed common and distinct characteristics, suggesting that, although EP-39 and BVM share the same chemical skeleton, they could interact in a different way with the Gag polyprotein precursor (Pr55Gag). Using an in silico approach, we observed that EP-39 and BVM present different predicted positions on the hexameric crystal structure of the CA_CTD-SP1 Gag fragment. To clearly understand the relationship between assembly and maturation, we investigated the impact of all identified mutations on virus assembly by expressing Pr55Gag mutants. Finally, using NMR, we have shown that the interaction of EP-39 with a peptide carrying the SP1-A1V mutation (CA-SP1(A1V)-NC) is almost suppressed in comparison with the wild type peptide. These results suggest that EP-39 and BVM could interact differently with the Pr55Gag lattice and that the mutation of the first SP1 residue induces a loss of interaction between Pr55Gag and EP-39.

Natural product-derived compounds in HIV suppression, remission, and eradication strategies

While combination antiretroviral therapy (cART) has successfully converted HIV to a chronic but manageable infection in many parts of the world, HIV continues to persist within latent cellular reservoirs, which can become reactivated at any time to produce infectious virus. New therapies are therefore needed not only for HIV suppression but also for containing or eliminating HIV reservoirs. Compounds derived from plant, marine, and other natural products have been found to combat HIV infection and/or target HIV reservoirs, and these discoveries have substantially guided current HIV therapy-based studies. Here we summarize the role of natural product-derived compounds in current HIV suppression, remission, and cure strategies.

Recent progress in the antiviral activity and mechanism study of pentacyclic triterpenoids and their derivatives

Viral infections cause many serious human diseases with high mortality rates. New drug‐resistant strains are continually emerging due to the high viral mutation rate, which makes it necessary to develop new antiviral agents. Compounds of plant origin are particularly interesting. The pentacyclic triterpenoids (PTs) are a diverse class of natural products from plants composed of three terpene units. They exhibit antitumor, anti‐inflammatory, and antiviral activities. Oleanolic, betulinic, and ursolic acids are representative PTs widely present in nature with a broad antiviral spectrum. This review focuses on the recent literatures in the antiviral efficacy of this class of phytochemicals and their derivatives. In addition, their modes of action are also summarized.

Insights into the activity of maturation inhibitor PF-46396 on HIV-1 clade C

HIV maturation inhibitors are an emerging class of anti-retroviral compounds that inhibit the viral protease-mediated cleavage of the Gag, CA-SP1 (capsid-spacer peptide 1) peptide to mature CA. The first-in-class maturation inhibitor bevirimat (BVM) displayed potent activity against HIV-1 clade B but was ineffective against other HIV-1 clades including clade C. Another pyridone-based maturation inhibitor, PF-46396 displayed potent activity against HIV-1 clade B. In this study, we aimed at determining the activity of PF-46396 against HIV-1 clade C. We employed various biochemical and virological assays to demonstrate that PF-46396 is effective against HIV-1 clade C. We observed a dose dependent accumulation of CA-SP1 intermediate in presence of the compound. We carried out mutagenesis in the CA- SP1 region of HIV-1 clade C Gag and observed that the mutations conferred resistance against the compound. Many mutations inhibited Gag processing thereby reducing virus release in the absence of the compound. However, presence of PF-46396 rescued these defects and enhanced virus release, replication capacity and infectivity of HIV-1 clade C. These results put together identify PF-46396 as a broadly active maturation inhibitor against HIV-1 clade B and C and help in rational designing of novel analogs with reduced toxicity and increased efficacy for its potential use in clinics.

Reversibly pH-responsive polyurethane membranes for on-demand intravaginal drug delivery

To provide better protection for women against sexually transmitted infections, on-demand intravaginal drug delivery was attempted by synthesizing reversibly pH-sensitive polyether-polyurethane copolymers using poly(ethylene glycol) (PEG) and 1,4-bis(2-hydroxyethyl)piperazine (HEP). Chemical structure and thermo-characteristics of the synthesized polyurethanes were confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), ¹H-nuclear magnetic resonance (¹H-NMR), and melting point testing. Membranes were cast by solvent evaporation method using the prepared pH-sensitive polyurethanes. The impact of varying pH on membrane swelling and surface morphology was evaluated via swelling ratio change and scanning electron microscopy (SEM). The prepared pH-responsive membranes showed two times higher swelling ratio at pH 4 than pH 7 and pH-triggered switchable surface morphology change. The anionic anti-inflammatory drug diclofenac sodium (NaDF) was used as a model compound for release studies. The prepared pH-responsive polyurethane membranes allowed continuous NaDF release for 24h and around 20% release of total NaDF within 3h at pH 7 but little-to-no drug release at pH 4.5. NaDF permeation across the prepared membranes demonstrated a reversible pH-responsiveness. The pH-responsive polyurethane membranes did not show any noticeable negative impact on vaginal epithelial cell viability or induction of pro-inflammatory cytokine production compared to controls. Overall, the non-cytotoxic HEP-based pH-responsive polyurethane demonstrated its potential to be used in membrane-based implants such as intravaginal rings to achieve on-demand "on-and-off" intravaginal drug delivery.

STATEMENT OF SIGNIFICANCE

A reversible and sharp switch between "off" and "on" drug release is achieved for the first time through new pH-sensitive polyurethane membranes, which can serve as window membranes in reservoir-type intravaginal rings for on-demand drug delivery to prevent sexually transmitted infections (STIs). Close to zero drug release occurs at the normal vaginal pH (4.5) for minimal side effects. Drug release is only triggered by elevation of pH to 7 during heterosexual intercourse. The reversibly sharp and fast "on-and-off" switch arises from the creative incorporation of a pH-sensitive monomer in the soft segment of polyurethane. This polyurethane biomaterial holds great potential to better protect women who are generally at higher risk and are more vulnerable to STIs.

Characterization of New Cationic N,N-Dimethyl[70]fulleropyrrolidinium Iodide Derivatives as Potent HIV-1 Maturation Inhibitors

HIV-1 maturation can be impaired by altering protease (PR) activity, the structure of the Gag-Pol substrate, or the molecular interactions of viral structural proteins. Here we report the synthesis and characterization of new cationic N,N-dimethyl[70]fulleropyrrolidinium iodide derivatives that inhibit more than 99% of HIV-1 infectivity at low micromolar concentrations. Analysis of the HIV-1 life cycle indicated that these compounds inhibit viral maturation by impairing Gag and Gag-Pol processing. Importantly, fullerene derivatives 2a-c did not inhibit in vitro PR activity and strongly interacted with HIV immature capsid protein in pull-down experiments. Furthermore, these compounds potently blocked infectivity of viruses harboring mutant PR that are resistant to multiple PR inhibitors or mutant Gag proteins that confer resistance to the maturation inhibitor Bevirimat. Collectively, our studies indicate fullerene derivatives 2a-c as potent and novel HIV-1 maturation inhibitors.

Fullerene Derivatives Strongly Inhibit HIV-1 Replication by Affecting Virus Maturation without Impairing Protease Activity

Three compounds (1, 2, and 3) previously reported to inhibit HIV-1 replication and/or in vitro activity of reverse transcriptase were studied, but only fullerene derivatives 1 and 2 showed strong antiviral activity on the replication of HIV-1 in human CD4(+) T cells. However, these compounds did not inhibit infection by single-round infection vesicular stomatitis virus glycoprotein G (VSV-G)-pseudotyped viruses, indicating no effect on the early steps of the viral life cycle. In contrast, analysis of single-round infection VSV-G-pseudotyped HIV-1 produced in the presence of compound 1 or 2 showed a complete lack of infectivity in human CD4(+) T cells, suggesting that the late stages of the HIV-1 life cycle were affected. Quantification of virion-associated viral RNA and p24 indicates that RNA packaging and viral production were unremarkable in these viruses. However, Gag and Gag-Pol processing was affected, as evidenced by immunoblot analysis with an anti-p24 antibody and the measurement of virion-associated reverse transcriptase activity, ratifying the effect of the fullerene derivatives on virion maturation of the HIV-1 life cycle. Surprisingly, fullerenes 1 and 2 did not inhibit HIV-1 protease in an in vitro assay at the doses that potently blocked viral infectivity, suggesting a protease-independent mechanism of action. Highlighting the potential therapeutic relevance of fullerene derivatives, these compounds block infection by HIV-1 resistant to protease and maturation inhibitors.