NRTI backbone in HIV treatment: will it remain relevant?

Machine learning aided multiscale modelling of the HIV-1 infection in the presence of NRTI therapy

Human Immunodeficiency Virus (HIV) is one of the most common chronic infectious diseases in humans. Extending the expected lifetime of patients depends on the use of optimal antiretroviral therapies. Emergence of the drug-resistant strains can reduce the effectiveness of treatments and lead to Acquired Immunodeficiency Syndrome (AIDS), even with antiretroviral therapy. Investigating the genotype-phenotype relationship is a crucial process for optimizing the therapy protocols of the patients. Here, a mathematical modelling framework is proposed to address the impact of existing mutations, timing of initiation, and adherence levels of nucleotide reverse transcriptase inhibitors (NRTIs) on the evolutionary dynamics of the virus strains. For the first time, the existing Stanford HIV drug resistance data have been combined with a multi-strain within-host ordinary differential equation (ODE) model to track the dynamics of the most common NRTI-resistant strains. Overall, the D4T-3TC, D4T-AZT and TDF-D4T drug combinations have been shown to provide higher success rates in preventing treatment failure and further drug resistance. The results are in line with the genotype-phenotype data and pharmacokinetic parameters of the NRTI inhibitors. Moreover, we show that the undetectable mutant strains at the diagnosis have a significant effect on the success/failure rates of the NRTI treatments. Predictions on undetectable strains through our multi-strain within-host model yielded the possible role of viral evolution on the treatment outcomes. It has been recognized that the improvement of multi-scale models can contribute to the understanding of the evolutionary dynamics, and treatment options, and potentially increase the reliability of genotype-phenotype models.

Repositioning HIV protease inhibitors and nucleos(t)ide RNA polymerase inhibitors for the treatment of SARS-CoV-2 infection and COVID-19

AIMS

SARS-CoV-2 is a single-stranded RNA virus which is part of the ß-coronavirus family (like SARS 2002 and MERS 2012). The high prevalence of hospitalization and mortality, in addition to the lack of vaccines and therapeutics, forces scientists and clinicians around the world to evaluate new therapeutic options. One strategy is the repositioning of already known drugs, which were approved drugs for other indications.

SUBJECT AND METHOD

SARS-CoV-2 entry inhibitors, RNA polymerase inhibitors, and protease inhibitors seem to be valuable targets of research. At the beginning of the pandemic, the ClinicalTrials.gov webpage listed n=479 clinical trials related to the antiviral treatment of SARS-CoV-2 (01.04.2020, "SARS-CoV-2," "COVID-19," "antivirals," "therapy"), of which n=376 are still accessible online in January 2021 (10.01.2021). Taking into account further studies not listed in the CTG webpage, this narrative review appraises HIV protease inhibitors and nucleos(t)ide RNA polymerase inhibitors as promising candidates for the treatment of COVID-19.

RESULTS

Lopinavir/ritonavir, darunavir/cobicistat, remdesivir, tenofovir-disoproxilfumarate, favipriravir, and sofosbuvir are evaluated in clinical studies worldwide. Study designs show a high variability and results often are contradictory. Remdesivir is the drug, which is deployed in nearly 70% of the reviewed clinical trials, followed by lopinavir/ritonavir, favipiravir, ribavirine, and sofosbuvir.

DISCUSSION

This review discusses the pharmacological/clinical background and questions the rationale and study design of clinical trials with already approved HIV protease inhibitors and nucleos(t)ide RNA polymerase inhibitors which are repositioned during the SARS-CoV-2 pandemic worldwide. Proposals are made for future study design and drug repositioning of approved antiretroviral compounds.

Incidence of diabetes in HIV-infected patients treated with first-line integrase strand transfer inhibitors: a French multicentre retrospective study

BACKGROUND

Integrase strand transfer inhibitors (INSTIs) are increasingly used in patients living with HIV due to their safety, effectiveness and high genetic barrier. However, an association with weight gain has recently been suggested and several cases of diabetes mellitus have been reported with raltegravir and dolutegravir. The long-time metabolic impact of these recent molecules remains unclear.

OBJECTIVES

To assess if an INSTI as a third agent is statistically associated with new-onset diabetes mellitus compared with an NNRTI or a PI.

PATIENTS AND METHODS

Patients undergoing first-line combined ART (cART) without diabetes at baseline were retrospectively included from the Dat'AIDS French cohort study (ClinicalTrials.gov NCT02898987). Incident diabetes mellitus was defined as a notification of new diabetes in the medical history, a glycated haemoglobin (HbA1c) level superior to 7.5% or the start of a diabetes therapy following the initiation of ART.

RESULTS

From 2009 to 2017, 19 462 patients were included, among which 265 cases of diabetes mellitus occurred. Multivariate and survival analyses did not highlight an increase in new-onset diabetes in patients undergoing cART with an INSTI as a third agent compared with an NNRTI or a PI. BMI >30 kg/m2, age >37 years old (in survival analysis), black race or Hispanic ethnicity, arterial hypertension and AIDS were associated with a higher proportion of incident diabetes.

CONCLUSIONS

INSTIs were not statistically associated with new-onset diabetes. However, clinicians should remain aware of this possible metabolic comorbidity, particularly in patients with a high BMI and older patients.

Raman-based metabonomics unravels metabolic changes related to a first-line tenofovir-based treatment in a small cohort of South African HIV-infected patients

In addition to immunological disorders, human immunodeficiency virus (HIV) also causes metabolic abnormalities. Though successful in viral suppression and immune restoration, continued use of antiretroviral therapy (ART) has also been linked to the development of several metabolic ailments. Currently, the only clinical markers used to manage and monitor the development of HIV-induced metabolic disorders, disease progression as well as observing individual's response to antiviral treatment are CD4 count, viral loads and several other single variable colometric assays. Despite the common use of these clinical markers, these markers remain unreliable and limited in the ability to monitor the development of metabolic disorders as well as monitor treatment response. Given these limitations, it is imperative to discover and develop reliable biological markers for overall HIV disease management. Here, Raman spectroscopy was used to profile metabolic changes in the plasma of 22 HIV⁺ receiving a first-line tenofovir-based combination antiretroviral therapy compared to their 8 HIV⁺ ART^- and 10 HIV^- counterparts. Multivariate statistical analysis was performed in order to classify the samples into their respective groups and to identify significantly altered metabolites between the control and experimental groups. Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) discriminant analysis identified significant differences (p < 0.05) in 9 different metabolites. Alterations were identified in spectral regions associated with glucose (1124 cm^-1), lipids/phospholipids (1116 cm^-1, 1098 cm^-1, 1077 cm^-1), proteins (1120 cm^-1), nucleic acids (1081 cm^-1) and phenylalanine (1103 cm^-1). Pathway analysis also revealed 3 significantly altered pathways. This study presented the reproducible nature of Raman spectroscopy in distinguishing between HIV-infected (treated and untreated) and uninfected blood plasma and allowed for the detection and identification of treatment induced metabolite changes. The results obtained in the study may, therefore, give insights into understanding the metabolic effect of HIV therapy.

"It made me more confident that I have it under control": Patient and provider perspectives on moving to a two-drug ART regimen in the United States and Spain

BACKGROUND

Two-drug regimens (2DR) to treat HIV infection have the potential to reduce long-term toxicity and increase therapeutic options for people living with HIV (PLHIV). Prior phase III trials, SWORD-1 and SWORD-2, as well as GEMINI-1 and GEMINI-2, have demonstrated that a dolutegravir-based 2DR is as effective as three- or four-drug regimens among virologically suppressed patients. Limited information exists, however, on patient and provider experiences with 2DR to inform roll-out and integration into routine clinical care.

METHODS

We conducted 39 in-depth interviews with PLHIV currently on 2DR in the context of routine care and 8 of their clinical care providers in the United States (U.S.) and Spain. Participants included 33 male and 6 female PLHIV and 8 providers. Interview topics explored perceptions of and experiences with 2DR compared to prior anti-retroviral regimens (ARVs), side effects, patient satisfaction, and clinical performance. Interviews were audio-recorded, transcribed and analyzed using thematic content analysis.

RESULTS

Participants viewed 2DR as a significant and positive advance, in terms of its ability to effectively treat HIV with reduced toxicity and essentially no reported side effects. Patients noted the central role providers played in the decision to switch to a 2DR regimen and, among U.S. participants, the importance of insurance coverage making this preferred option feasible. Patients and providers agreed that a 2DR regimen would be appropriate for any PLHIV regardless of whether they were treatment naïve or had significant experience with ARVs.

CONCLUSIONS

Participants' experiences with a 2DR regimen were positive with no participants, reporting side effects and all reporting continued viral suppression. Providers valued the reduced toxicity offered by 2DR and served as the primary gateway to a transition to 2DR for patients in both settings. This study provides a foundation for further research on the transition to 2DR regimens in other populations and contexts including low- and middle-income settings.

Accelerated aging in perinatally HIV-infected children: clinical manifestations and pathogenetic mechanisms

Background: Premature aging and related diseases have been documented in HIV-infected adults. Data are now emerging also regarding accelerated aging process in HIV-infected children.

Methods: A narrative review was performed searching studies on PubMed published in English language in 2004-2017, using appropriate key words, including “aging”, “children”, “HIV”, “AIDS”, “immunosenescence”, “pathogenesis”, “clinical conditions”.

Results: Premature immunosenescence phenotype of B and T cells in HIV-infected children is mediated through immune system activation and chronic inflammation. Ongoing inflammation processes have been documented by increased levels of pathogen-associated molecular patterns (PAMPS), increased mitochondrial damage, higher levels of pro-inflammatory cytokines, and a positive correlation between sCD14 levels and percentages of activated CD8⁺ cells. Other reported features of premature aging include cellular replicative senescence, linked to an accelerated telomeres shortening. Finally, acceleration of age-associated methylation pattern and other epigenetic modifications have been described in HIV-infected children. All these features may favor the clinical manifestations related to premature aging. Lipid and bone metabolism, cancers, cardiovascular, renal, and neurological systems should be carefully monitored, particularly in children with detectable viremia and/or with CD4/CD8 ratio inversion.

Conclusion: Aging processes in children with HIV infection impact their quality and length of life. Further studies regarding the mechanisms involved in premature aging are needed to search for potential targets of treatment.

Semi-solid prodrug nanoparticles for long-acting delivery of water-soluble antiretroviral drugs within combination HIV therapies

The increasing global prevalence of human immunodeficiency virus (HIV) is estimated at 36.7 million people currently infected. Lifelong antiretroviral (ARV) drug combination dosing allows management as a chronic condition by suppressing circulating viral load to allow for a near-normal life; however, the daily burden of oral administration may lead to non-adherence and drug resistance development. Long-acting (LA) depot injections of nanomilled poorly water-soluble ARVs have shown highly promising clinical results with drug exposure largely maintained over months after a single injection. ARV oral combinations rely on water-soluble backbone drugs which are not compatible with nanomilling. Here, we evaluate a unique prodrug/nanoparticle formation strategy to facilitate semi-solid prodrug nanoparticles (SSPNs) of the highly water-soluble nucleoside reverse transcriptase inhibitor (NRTI) emtricitabine (FTC), and injectable aqueous nanodispersions; in vitro to in vivo extrapolation (IVIVE) modelling predicts sustained prodrug release, with activation in relevant biological environments, representing a first step towards complete injectable LA regimens containing NRTIs.

Non-adherence to daily drug regimens is responsible for many negative clinical effects including drug resistance in life-long treatments for HIV. Here, the authors report on a HIV prodrug nanoparticle platform for long-acting sustained release of water-soluble drug compounds following injection.

Synthesis and Antiviral Evaluation of Carbocyclic Nucleoside Analogs of Nucleoside Reverse Transcriptase Translocation Inhibitor MK-8591 (4'-Ethynyl-2-fluoro-2'-deoxyadenosine)

MK-8591 (4'-ethynyl-2-fluoro-2'-deoxyadenosine) is a novel nucleoside analog that displays a differentiated mechanism of action as a nucleoside reverse transcriptase translocation inhibitor (NRTTI) compared to approved NRTIs. Herein, we describe our recent efforts to explore the impact of structural changes to the properties of MK-8591 through the synthesis and antiviral evaluation of carbocyclic derivatives. Synthesized analogs were evaluated for their antiviral activity, and the corresponding triphosphates were synthesized and evaluated in a biochemical assay. 4'-Ethynyl-G derivative (±)-29 displayed a promising IC₅₀ of 33 nM in a hPBMC cell-based antiviral assay, and its triphosphate (TP), (±)-29-TP, displayed an IC₅₀ of 324 nM in a biochemical RT-polymerase assay. Improved TP anabolite delivery resulting in improved in vitro potency was achieved by preparing the corresponding phosphoramidate prodrug of single enantiomer 29b, with 6-ethoxy G derivative 34b displaying a significantly improved IC₅₀ of 3.0 nM, paving the way for new directions for this novel class of nucleoside analogs.

Cumulative exposure of TDF is associated with kidney tubulopathy whether it is currently used or discontinued

OBJECTIVE

Tenofovir disoproxil fumarate (TDF) increases the risk of kidney tubular dysfunction (KTD). This study was conducted to elucidate whether KTD persists after discontinuation of TDF.

DESIGN

A prospective cross-sectional study which enrolled 941 HIV-1-infected patients.

METHODS

KTD was predefined as the presence of at least two abnormalities among the five tubular markers (fractional excretion of phosphate, fractional excretion of uric acid, β2 microglobulinuria, N-acetyl-β-D-glucosaminidase, nondiabetic glycosuria). Logistic regression model was used to examine the association between KTD and cumulative TDF use, as well as current status of TDF use.

RESULTS

In total, 94% of study patients were men (median age 45, estimated glomerular filtration rate 75 ml/min per 1.73 m, CD4 575 cells/μl. About 98% were on antiretroviral therapy. In total, 64% of the patients ever used TDF and 39% currently used TDF. Twenty-nine percent used TDF for more than 5 years. KTD was diagnosed in 116 (12%) patients. In multivariate model, more than 5 years of TDF exposure and current TDF use [odds ratio (OR) 4.2, 95% confidence interval (CI) 2.37-7.56], more than 5 years and past TDF use (OR 2.4, 95% CI 1.09-5.33), less than 5 years and current TDF (OR 2.4, 95% CI 1.24-4.85), and less than 5 years and past TDF (OR 2.4, 95% CI 1.22-4.64) were all significantly associated with KTD, with never TDF use as reference. The results were the same using 4 and 3 years of exposure as the cutoff. However, with 2 years exposure, both less than 2 years and current TDF (OR 2.3, 95% CI 0.84-6.20) and less than 2 years and past TDF (OR 1.9, 95% CI 0.73-4.93) were not associated with KTD, whereas both more than 2 years and current TDF and more than 2 years and past TDF were associated.

CONCLUSION

The association between cumulative TDF use and KTD was strong and robust. The results of the study suggested that TDF-related KTD might persist after discontinuation of TDF if patients used TDF for more than 2 years.

Efficacy of Antiviral Drugs against Feline Immunodeficiency Virus

Feline immunodeficiency virus (FIV) is one of the most common infectious agents affecting cats worldwide .FIV and human immunodeficiency virus (HIV) share many properties: both are lifelong persistent lentiviruses that are similar genetically and morphologically and both viruses propagate in T-lymphocytes, macrophages, and neural cells. Experimentally infected cats have measurable immune suppression, which sometimes progresses to an acquired immunodeficiency syndrome. A transient initial state of infection is followed by a long latent stage with low virus replication and absence of clinical signs. In the terminal stage, both viruses can cause severe immunosuppression. Thus, FIV infection in cats has become an important natural model for studying HIV infection in humans, especially for evaluation of antiviral compounds. Of particular importance for chemotherapeutic studies is the close similarity between the reverse transcriptase (RT) of FIV and HIV, which results in high in vitro susceptibility of FIV to many RT-targeted antiviral compounds used in the treatment of HIV-infected patients. Thus, the aim of this article is to provide an up-to-date review of studies on antiviral treatment of FIV, focusing on commercially available compounds for human or animal use.

Efficacy of antiviral chemotherapy for retrovirus-infected cats: What does the current literature tell us?

GLOBAL IMPORTANCE

The two feline retroviruses, feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV), are global and widespread, but differ in their potential to cause disease.

VIRAL INFECTION - FIV

FIV, a lentivirus that shares many properties with human immunodeficiency virus (HIV), can cause an acquired immune deficiency syndrome, which predisposes cats to other infections, stomatitis, neurological disorders and tumours. Although secondary infections are common, specific opportunistic infections or acquired immunodeficiency virus-defining infections, such as those that occur with HIV, are not commonly reported in FIV-infected cats. In most naturally infected cats, FIV does not cause a severe clinical syndrome; with appropriate care, FIV-infected cats can live many years before succumbing to conditions unrelated to their FIV infection. Thus, overall survival time is not necessarily shorter than in uninfected cats, and quality of life is usually high over many years or lifelong.

VIRAL INFECTION - FELV

FeLV, an oncornavirus, is more pathogenic than FIV. Historically, it was considered to account for more disease-related deaths and clinical syndromes in cats than any other infectious agent. Recently, the prevalence and importance of FeLV have been decreasing, mainly because of testing and eradication programmes and the use of FeLV vaccines. Progressive FeLV infection can cause tumours, bone marrow suppression and immunosuppression, as well as neurological and other disorders, and leads to a decrease in life expectancy. However, with appropriate care, many FeLV-infected cats can also live several years with a good quality of life.

PRACTICAL RELEVANCE

A decision regarding treatment or euthanasia should never be based solely on the presence or absence of a retrovirus infection. Antiviral chemotherapy is of increasing interest in veterinary medicine, but is still not used commonly.

EVIDENCE BASE

This article reviews the current literature on antiviral chemotherapy in retrovirus-infected cats, focusing on drugs that are currently available on the market and, thus, could potentially be used in cats.

Nucleoside-sparing antiretroviral regimens

Nucleoside reverse transcriptase inhibitors (NRTIs) were the first drugs approved for use as antiretroviral therapy in patients infected with HIV. Despite the introduction of other classes of antiretroviral drugs, they remain an important component of combination regimens as recommended by many treatment guidelines. They also continue to be used in prevention of disease from mother to child, postexposure prophylaxis, and more recently for preexposure prophylaxis. Unfortunately, the toxicities associated with this class of drugs can limit their use. Although NRTI-sparing regimens are not currently recommended for first-line therapy there is an increasing amount of data supporting their use in both treatment-naive and in treatment-experienced patients.

Switching tenofovir/emtricitabine plus lopinavir/r to raltegravir plus Darunavir/r in patients with suppressed viral load did not result in improvement of renal function but could sustain viral suppression: a randomized multicenter trial

Background

Whether tenofovir nephrotoxicity is reversible after its withdrawal is unknown. Furthermore, there are no data on the viral efficacy of raltegravir (RAL) plus ritonavir-boosted Darunavir (DRV/r) in patients with suppressed viral load.

Methods

This multicenter, randomized trial compared renal function and viral efficacy in patients with suppressed viral load treated with RAL+DRV/r and ritonavir-boosted lopinavir (LPV/r) plus tenofovir/emtricitabine (TVD), who had been previously on LPV/r+TVD. The primary endpoint was the proportion of patients with >10% improvement in estimated glomerular filtration rate (eGFR) at 48 weeks calculated with Cockcroft-Gault equation.

Results

58 randomized and treatment-exposed patients were analyzed (28 on RAL+DRV/r and 30 on LPV/r+TVD). Greater than 10% improvement in eGFR was noted in 6 (25%) out of 24 with RAL+DRV/r and 3 (11%) of 28 with LPV/r+TVD, and the difference was not statistically significant (p=0.272, 95% CI -0.067 to 0.354). Sensitivity analyses using three other equations for eGFR showed the same results. Urinary β2 microglobulin, a sensitive marker of tenofovir tubulopathy, significantly improved with RAL+DRV/r than with LPV/r+TVD (-271 versus -64 µg/gCr, p=0.026). Per protocol analysis showed that the HIV-RNA was <50 copies/mL at week 48 in all patients of both arms (24 in RAL+DRV and 29 in LPV/r+TVD).

Conclusions

Switching LPV/r+TVD to RAL+DRV/r did not significantly increase the proportion of patients who showed >10% improvement in renal function among those with relatively preserved eGFR. However, the switch improved urinary β2 microglobulin, suggesting that discontinuation of TDF might be beneficial in the long-term. RAL+DRV/r showed favorable viral efficacy in patients with suppressed viral load.

Trial Registration

ClinicalTrials.gov NCT01294761 http://clinicaltrials.gov/ct2/show/NCT01294761?term=SPARE&rank=2, Umin Clinical Trials Registry UMIN000005116 http://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000006083&language=J)

Identification of potent and orally bioavailable nucleotide competing reverse transcriptase inhibitors: in vitro and in vivo optimization of a series of benzofurano[3,2-d]pyrimidin-2-one derived inhibitors

Recently, a new class of HIV reverse transcriptase (HIV-RT) inhibitors has been reported. The novel mechanism of inhibition by this class involves competitive binding to the active site of the RT enzyme and has been termed Nucleotide-Competing Reverse Transcriptase Inhibitors (NcRTIs). In this publication we describe the optimization of a novel benzofurano[3,2-d]pyrimidin-2-one series of NcRTIs. The starting point for the current study was inhibitor 2, which had high biochemical and antiviral potency but only moderate permeability in a Caco-2 assay and high B-to-A efflux, resulting in moderate rat bioavailability and low Cmax. We present herein the results and strategies we employed to optimize both the potency as well as the permeability, metabolic stability and pharmacokinetic profile of this series. One of the key observations of the present study was the importance of shielding polar functionality, at least in the context of the current chemotype, to enhance permeability. These studies led to the identification of inhibitors 39 and 45, which display sub-nanomolar antiviral potency in a p24 ELISA assay with significantly reduced efflux ratios (ratios <1.5). These inhibitors also display excellent rat pharmacokinetic profiles with high bioavailabilities and low clearance.