Modern Human Immunodeficiency Virus Therapy: Progress and Prospects

A Review of FDA-Approved Anti-HIV-1 Drugs, Anti-Gag Compounds, and Potential Strategies for HIV-1 Eradication

Acquired immunodeficiency syndrome (AIDS) is an enormous global health threat stemming from human immunodeficiency virus (HIV-1) infection. Up to now, the tremendous advances in combination antiretroviral therapy (cART) have shifted HIV-1 infection from a fatal illness into a manageable chronic disorder. However, the presence of latent reservoirs, the multifaceted nature of HIV-1, drug resistance, severe off-target effects, poor adherence, and high cost restrict the efficacy of current cART targeting the distinct stages of the virus life cycle. Therefore, there is an unmet need for the discovery of new therapeutics that not only bypass the limitations of the current therapy but also protect the body's health at the same time. The main goal for complete HIV-1 eradication is purging latently infected cells from patients' bodies. A potential strategy called "lock-in and apoptosis" targets the budding phase of the life cycle of the virus and leads to susceptibility to apoptosis of HIV-1 infected cells for the elimination of HIV-1 reservoirs and, ultimately, for complete eradication. The current work intends to present the main advantages and disadvantages of United States Food and Drug Administration (FDA)-approved anti-HIV-1 drugs as well as plausible strategies for the design and development of more anti-HIV-1 compounds with better potency, favorable pharmacokinetic profiles, and improved safety issues.

We should not stop considering HIV drug resistance testing at failure of first-line antiretroviral therapy

HIV drug resistance is a major global hurdle to successful and sustained antiretroviral therapy. Global guidelines recommend testing for antiretroviral drug resistance and results are used to inform treatment regimen design for patients at different stages of therapy. Several clinical trials investigated optimal regimens after failure of first-line antiretroviral therapy, yielding data that advanced knowledge and informed care. However, further interpretation of data from these studies questioned the benefit of antiretroviral drug resistance testing for cases in which first-line treatment is not effective and, furthermore, that relying on the results of antiretroviral drug resistance testing could be misleading and unnecessary. In this Viewpoint, which is largely focused on high-income settings, we review these data, reflect on the potential problems with their interpretation, and call for caution in their extrapolation. Without negating the importance of the data, and recognising the varied circumstances related to HIV drug resistance testing in different global settings, we advise caution before changing current practice and recommendations. We believe that we should not universally stop considering HIV drug resistance testing at failure of first-line antiretroviral therapy.

Antiviral compounds modulate elasticity, strength and material fatigue of a virus capsid framework

This study investigates whether the biochemical and antiviral effects of organic compounds that bind different sites in the mature human immunodeficiency virus capsid may be related to the modulation of different mechanical properties of the protein lattice from which the capsid is built. Mechanical force was used as a probe to quantify, in atomic force microscopy experiments at physiological pH and ionic strength, ligand-mediated changes in capsid lattice elasticity, breathing, strength against local dislocation by mechanical stress, and resistance to material fatigue. The results indicate that the effects of the tested compounds on assembly or biochemical stability can be linked, from a physics-based perspective, to their interference with the mechanical behavior of the viral capsid framework. The antivirals CAP-1 and CAI-55 increased the intrinsic elasticity and breathing of the capsid protein lattice and may entropically decrease the probability of the capsid protein to assemble into a functionally competent conformation. Antiviral PF74 increased the resistance of the capsid protein lattice to disruption by mechanical stress and material fatigue and may enthalpically strengthen the basal capsid lattice against breakage and disintegration. This study provides proof of concept that the interrogation of the mechanical properties of the nanostructured protein material that makes a virus capsid may provide fundamental insights into the biophysical action of capsid-binding antiviral agents. The implications for drug design by specifically targeting the biomechanics of viruses are discussed.

Considerations and challenges in developing novel long-acting antiretrovirals modalities for treatment and prevention of HIV-1 infection: a regulatory perspective

PURPOSE OF REVIEW

Outline some regulatory considerations and scientific challenges related to the development of long-acting antiretrovirals (ARVs) for the treatment and prevention of HIV-1 infection.

RECENT FINDINGS

Poor adherence to oral ARV regimens continues to pose challenges for effective treatment and prevention of HIV-1 infection. The development of long-acting ARV modalities for treatment and prevention of HIV-1 infection is emerging as a promising alternative to the current treatment and prevention paradigm and has gained considerable interest.

SUMMARY

The development of long-acting ARVs can present some unique drug development challenges. Advance planning and prioritization of studies early in development can facilitate the development of long-acting ARVs for the prevention and treatment of HIV-1 infection for all populations, including pediatric patients and pregnant women.

Lopinavir/Ritonavir: A Review of Analytical Methodologies for the Drug Substances, Pharmaceutical Formulations and Biological Matrices

Lopinavir/ritonavir is a potent coformulation of protease inhibitors used against HIV infection. Lopinavir is the main responsible for viral load suppression, whereas ritonavir is a pharmacokinetic enhancer. Both of them have recently gained relevance as candidate drugs against severe coronavirus disease (COVID-19). However, significant beneficial effects were not observed in randomized clinical trials. This review summarizes the main physical-chemical, pharmacodynamic, and pharmacokinetic properties of ritonavir and lopinavir, along with the analytical methodologies applied for biological matrices, pharmaceutical formulations, and stability studies. The work also aimed to provide a comprehensive impurity profile for the combined formulation. Several analytical methods in four different pharmacopeias and 37 articles in literature were evaluated and summarized. Chromatographic methods for these drugs frequently use C8 or C18 stationary phases with acetonitrile and phosphate buffer (with ultraviolet detection) or acetate buffer (with tandem mass spectrometry detection) as the mobile phase. Official compendia methods show disadvantages as extended total run time and complex mobile phases. HPLC tandem-mass spectrometry provided high sensitivity in methodologies applied for human plasma and serum samples, supporting the therapeutic drug monitoring in HIV patients. Ritonavir and lopinavir major degradation products arise in alkaline and acidic environments, respectively. Other non-chromatographic methods were also summarized. Establishing the impurity profile for the combined formulation is challenging due to a large number of impurities reported. Easier and faster analytical methods for impurity assessment are still needed.

Chloroquine, an Anti-Malaria Drug as Effective Prevention for Hantavirus Infections

We investigated whether chloroquine can prevent hantavirus infection and disease in vitro and in vivo, using the Hantaan virus newborn C57BL/6 mice model and the Syrian hamster model for Andes virus. In vitro antiviral experiments were performed using Vero E6 cells, and Old World and New World hantavirus species. Hantavirus RNA was detected using quantitative RT-PCR. For all hantavirus species tested, results indicate that the IC₅₀ of chloroquine (mean 10.2 ± 1.43 μM) is significantly lower than the CC₅₀ (mean 260 ± 2.52 μM) yielding an overall selectivity index of 25.5. We also investigated the potential of chloroquine to prevent death in newborn mice after Hantaan virus infection and its antiviral effect in the hantavirus Syrian hamster model. For this purpose, C57Bl/6 mother mice were treated subcutaneously with daily doses of chloroquine. Subsequently, 1-day-old suckling mice were inoculated intracerebrally with 5 x 10² Hantaan virus particles. In litters of untreated mothers, none of the pups survived challenge. The highest survival rate (72.7% of pups) was found when mother mice were administered a concentration of 10 mg/kg chloroquine. Survival rates declined in a dose-dependent manner, with 47.6% survival when treated with 5 mg/kg chloroquine, and 4.2% when treated with 1 mg/kg chloroquine. Assessing the antiviral therapeutic and prophylactic effect of chloroquine in the Syrian hamster model was done using two different administration routes (intraperitoneally and subcutaneously using an osmotic pump system). Evaluating the prophylactic effect, a delay in onset of disease was noted and for the osmotic pump, 60% survival was observed. Our results show that chloroquine can be highly effective against Hantaan virus infection in newborn mice and against Andes virus in Syrian hamsters.

Design strategies for long-acting anti-HIV pharmaceuticals

Current combination antiretroviral therapy (cART) for human immunodeficiency virus (HIV) is limited by the frequent dosing and unfavorable adherence, and the rapid appearance of resistant mutants. Thus, there is a continuous need to improve and optimize the present therapies. The clinical phase III trials of FLAIR and ATLAS, showed two-drug injectable cabotegravir (CAB) and rilpivirine (RPV) formulation is potent, safe, and tolerable in HIV-infected patients. The recent approval of cabenuva (CAB+RPV) by Health Canada is a milestone in the development of long-term therapies for HIV infection. Broadly neutralizing antibodies (bNAbs) with excellent breath and efficiency against HIV have been investigated as LA antiviral weapons. Several modern modalities capable of sustained drug release for long-term treatment and prevention of HIV infection are also in development, such as implants, vaginal rings, and nanotherapies.

Mechanistic Assessment of Extrahepatic Contributions to Glucuronidation of Integrase Strand Transfer Inhibitors

Integrase strand transfer inhibitor (INSTI)-based regimens dominate initial human immunodeficiency virus treatment. Most INSTIs are metabolized predominantly via UDP-glucuronosyltransferases (UGTs). For drugs predominantly metabolized by UGTs, including INSTIs, in vitro data recovered from human liver microsomes (HLMs) alone often underpredict human oral clearance. While several factors may contribute, extrahepatic glucuronidation may contribute to this underprediction. Thus, we comprehensively characterized the kinetics for the glucuronidation of INSTIs (cabotegravir, dolutegravir, and raltegravir) using pooled human microsomal preparations from liver (HLMs), intestine (HIMs), and kidney (HKMs) tissues; human embryonic kidney 293 cells expressing individual UGTs; and recombinant UGTs. In vitro glucuronidation of cabotegravir (HLMs≈HKMs>>>HIMs), dolutegravir (HLMs>HIMs>>HKMs), and raltegravir (HLMs>HKMs>> HIMs) occurred in hepatic and extrahepatic tissues. The kinetic data from expression systems suggested the major enzymes in each tissue: hepatic UGT1A9 > UGT1A1 (dolutegravir and raltegravir) and UGT1A1 (cabotegravir), intestinal UGT1A3 > UGT1A8 > UGT1A1 (dolutegravir) and UGT1A8 > UGT1A1 (raltegravir), and renal UGT1A9 (dolutegravir and raltegravir). Enzymes catalyzing cabotegravir glucuronidation in the kidney and intestine could not be identified unequivocally. Using data from dolutegravir glucuronidation as a prototype, a "bottom-up" physiologically based pharmacokinetic model was developed in a stepwise approach and predicted dolutegravir oral clearance within 4.5-fold (hepatic data only), 2-fold (hepatic and intestinal data), and 32% (hepatic, intestinal, and renal data). These results suggest clinically meaningful glucuronidation of dolutegravir in tissues other than the liver. Incorporation of additional novel mechanistic and physiologic underpinnings of dolutegravir metabolism along with in silico approaches appears to be a powerful tool to accurately predict the clearance of dolutegravir from in vitro data.