Hyaluronidase impacts exposures of long-acting injectable paliperidone palmitate in rodent models

A significant challenge in the development of long-acting injectable drug formulations, especially for anti-infective agents, is delivering an efficacious dose within a tolerable injection volume. Co-administration of the extracellular matrix-degrading enzyme hyaluronidase can increase maximum tolerable injection volumes but is untested for this benefit with long-acting injectable formulations. One concern is that hyaluronidase could potentially alter the tissue response surrounding an injection depot, a response known to be important for drug release kinetics of long-acting injectable formulations. The objective of this pilot study was to evaluate the impact of co-administration of hyaluronidase on the drug release kinetics, pharmacokinetic profiles, and injection site histopathology of the long-acting injectable paliperidone palmitate for up to four weeks following intramuscular injection in mouse and rat models. In both species, co-administration of hyaluronidase increased paliperidone plasma exposures the first week after injection but did not negate the overall long-acting release nature of the formulation. Hyaluronidase-associated modification of the injection site depot was observed in mice but not in rats. These findings suggest that further investigation of hyaluronidase with long-acting injectable agents is warranted.

Polymer-prodrug conjugates as candidates for degradable, long-acting implants, releasing the water-soluble nucleoside reverse-transcriptase inhibitor emtricitabine

Circulating, soluble polymer-drug conjugates have been utilised for many years to aid the delivery of sensitive, poorly-soluble or cytotoxic drugs, prolong circulation times or minimise side effects. Long-acting therapeutics are increasing in their healthcare importance, with intramuscular and subcutaneous administration of liquid formulations being most common. Degradable implants also offer opportunities and the use of polymer-prodrug conjugates as implant materials has not been widely reported in this context. Here, the potential for polymer-prodrug conjugates of the water soluble nucleoside reverse transciption inhibitor emtricitabine (FTC) is studied. A novel diol monomer scaffold, allowing variation of prodrug substitution, has been used to form polyesters and polycarbonates by step-growth polymerisation. Materials have been screened for physical properties that enable implant formation, studied for drug release to provide mechanistic insights, and tunable prolonged release of FTC has been demonstrated over a period of at least two weeks under relevant physiological conditions.

Physiologically Based Pharmacokinetic Modelling of Cabotegravir Microarray Patches in Rats and Humans

Microarray patches (MAPs) are currently under investigation as a self-administered, pain-free alternative used to achieve long-acting (LA) drug delivery. Cabotegravir is a potent antiretroviral that has demonstrated superior results over current pre-exposure prophylaxis (PrEP) regimens. This study aimed to apply physiologically based pharmacokinetic (PBPK) modelling to describe the pharmacokinetics of the dissolving bilayer MAP platform and predict the optimal dosing strategies for a once-weekly cabotegravir MAP. A mathematical description of a MAP was implemented into a PBPK model, and empirical models were utilised for parameter estimation. The intradermal PBPK model was verified against previously published in vivo rat data for intramuscular (IM) and MAP administration, and in vivo human data for the IM administration of LA cabotegravir. The verified model was utilised for the prediction of 300 mg, 150 mg and 75 mg once-weekly MAP administration in humans. Cabotegravir plasma concentrations >4 × protein-adjusted 90% inhibitory concentration (PA-IC90) (0.664 µg/mL) and >8 × PA-IC90 (1.33 µg/mL) were set as targets. The 75 mg, 150 mg and 300 mg once-weekly cabotegravir MAP regimens were predicted to sustain plasma concentrations >4 × PA-IC90, while the 300 mg and 150 mg regimens achieved plasma concentrations >8 × PA-IC90. These data demonstrate the potential for a once-weekly cabotegravir MAP using practical patch sizes for humans and inform the further development of cabotegravir MAPs for HIV PrEP.

Constructing Antiretroviral Supramolecular Polymers as Long-Acting Injectables through Rational Design of Drug Amphiphiles with Alternating Antiretroviral-Based and Hydrophobic Residues

One of the main challenges in the development of long-acting injectables for HIV treatment is the limited duration of drug release, which results in the need for frequent dosing and reduced patient adherence. In this context, we leverage the intrinsic reversible features of supramolecular polymers and their unique ability to form a three-dimensional network under physiological conditions to design a class of self-assembling drug amphiphiles (DAs) based upon lamivudine, a water-soluble antiretroviral (ARV) agent and nucleoside reverse transcriptase inhibitor. The designed ARV DAs contain three pairs of alternating hydrophobic valine (V) and hydrophilic lamivudine-modified lysine (K3TC) residues with a varying number of glutamic acids (E) placed on the C-terminus. Upon dissolution in deionized water, all three ARV DAs were found to spontaneously associate into supramolecular filaments of several micrometers in length, with varying levels of lateral stacking. Addition of 1× PBS triggered immediate gelation of the two ARV DAs with 2 or 3 E residues, and upon dilution in an in vitro setting, the dissociation from the supramolecular state to the monomeric state enabled a long-acting linear release of the ARV DAs. In vivo studies further confirmed their injectability, rapid in situ hydrogel formation, enhanced local retention, and long-acting therapeutic release over a month. Importantly, our pharmacokinetic studies suggest that the injected ARV supramolecular polymeric hydrogel was able to maintain a plasma concentration of lamivudine above its IC50 value for more than 40 days in mice and showed minimal systemic immunogenicity. We believe that these results shed important light on the rational design of long-acting injectables using the drug-based molecular assembly strategy, and the reported ARV supramolecular hydrogels hold great promise for improving HIV treatment outcomes.

Interleukin 6 Blockade With Tocilizumab Diminishes Indices of Inflammation That Are Linked to Mortality in Treated Human Immunodeficiency Virus Infection

BACKGROUND

People with human immunodeficiency virus (PWH) are at increased risk for comorbidities, and plasma interleukin 6 (IL-6) levels are among the most robust predictors of these outcomes. Tocilizumab (TCZ) blocks the receptor for IL-6, inhibiting functions of this cytokine.

METHODS

This was a 40-week, placebo-controlled, crossover trial (NCT02049437) where PWH on stable antiretroviral therapy (ART) were randomized to receive 3 monthly doses of TCZ or matching placebo intravenously. Following a 10-week treatment period and a 12-week washout, participants were switched to the opposite treatment. The primary endpoints were safety and posttreatment levels of C-reactive protein (CRP) and CD4+ T-cell cycling. Secondary endpoints included changes in inflammatory indices and lipid levels.

RESULTS

There were 9 treatment-related toxicities of grade 2 or greater during TCZ administration (mostly neutropenia) and 2 during placebo administration. Thirty-one of 34 participants completed the study and were included in a modified intent-to-treat analysis. TCZ reduced levels of CRP (median decrease, 1819.9 ng/mL, P < .0001; effect size, 0.87) and reduced inflammatory markers in PWH, including D-dimer, soluble CD14, and tumor necrosis factor receptors. T-cell cycling tended to decrease in all maturation subsets after TCZ administration, but was only significant among naive CD4 T cells. Lipid levels, including lipid classes that have been related to cardiovascular disease risk, increased during TCZ treatment.

CONCLUSIONS

TCZ is safe and decreases inflammation in PWH; IL-6 is a key driver of the inflammatory environment that predicts morbidity and mortality in ART-treated PWH. The clinical significance of lipid elevations during TCZ treatment requires further study. Clinical Trials Registration. NCT02049437.

Preclinical Evaluation of Long-Acting Emtricitabine Semi-Solid Prodrug Nanoparticle Formulations

Long-acting injectable (LAI) formulations promise to deliver patient benefits by overcoming issues associated with non-adherence. A preclinical assessment of semi-solid prodrug nanoparticle (SSPN) LAI formulations of emtricitabine (FTC) is reported here. Pharmacokinetics over 28 days were assessed in Wistar rats, New Zealand white rabbits, and Balb/C mice following intramuscular injection. Two lead formulations were assessed for the prevention of an HIV infection in NSG-cmah^-/- humanised mice to ensure antiviral activities were as anticipated according to the pharmacokinetics. Cmax was reached by 12, 48, and 24 h in rats, rabbits, and mice, respectively. Plasma concentrations were below the limit of detection (2 ng/mL) by 21 days in rats and rabbits, and 28 days in mice. Mice treated with SSPN formulations demonstrated undetectable viral loads (700 copies/mL detection limit), and HIV RNA remained undetectable 28 days post-infection in plasma, spleen, lung, and liver. The in vivo data presented here demonstrate that the combined prodrug/SSPN approach can provide a dramatically extended pharmacokinetic half-life across multiple preclinical species. Species differences in renal clearance of FTC mean that longer exposures are likely to be achievable in humans than in preclinical models.

Predicted effects of the introduction of long-acting injectable cabotegravir pre-exposure prophylaxis in sub-Saharan Africa: a modelling study

BACKGROUND

Long-acting injectable cabotegravir pre-exposure prophylaxis (PrEP) is recommended by WHO as an additional option for HIV prevention in sub-Saharan Africa, but there is concern that its introduction could lead to an increase in integrase-inhibitor resistance undermining treatment programmes that rely on dolutegravir. We aimed to project the health benefits and risks of cabotegravir-PrEP introduction in settings in sub-Saharan Africa.

METHODS

With HIV Synthesis, an individual-based HIV model, we simulated 1000 setting-scenarios reflecting both variability and uncertainty about HIV epidemics in sub-Saharan Africa and compared outcomes for each with and without cabotegravir-PrEP introduction. PrEP use is assumed to be risk-informed and to be used only in 3-month periods (the time step for the model) when having condomless sex. We consider three groups at risk of integrase-inhibitor resistance emergence: people who start cabotegravir-PrEP after (unknowingly) being infected with HIV, those who seroconvert while on PrEP, and those with HIV who have residual cabotegravir drugs concentrations during the early tail period after recently stopping PrEP. We projected the outcomes of policies of cabotegravir-PrEP introduction and of no introduction in 2022 across 50 years. In 50% of setting-scenarios we considered that more sensitive nucleic-acid-based HIV diagnostic testing (NAT), rather than regular antibody-based HIV rapid testing, might be used to reduce resistance risk. For cost-effectiveness analysis we assumed in our base case a cost of cabotegravir-PrEP drug to be similar to oral PrEP, resulting in a total annual cost of USD$144 per year ($114 per year and $264 per year considered in sensitivity analyses), a cost-effectiveness threshold of $500 per disability-adjusted life years averted, and a discount rate of 3% per year.

FINDINGS

Reflecting our assumptions on the appeal of cabotegravir-PrEP, its introduction is predicted to lead to a substantial increase in PrEP use with approximately 2·6% of the adult population (and 46% of those with a current indication for PrEP) receiving PrEP compared with 1·5% (28%) without cabotegravir-PrEP introduction across 20 years. As a result, HIV incidence is expected to be lower by 29% (90% range across setting-scenarios 6-52%) across the same period compared with no introduction of cabotegravir-PrEP. In people initiating antiretroviral therapy, the proportion with integrase-inhibitor resistance after 20 years is projected to be 1·7% (0-6·4%) without cabotegravir-PrEP introduction but 13·1% (4·1-30·9%) with. Cabotegravir-PrEP introduction is predicted to lower the proportion of all people on antiretroviral therapy with viral loads less than 1000 copies per mL by 0·9% (-2·5% to 0·3%) at 20 years. For an adult population of 10 million an overall decrease in number of AIDS deaths of about 4540 per year (-13 000 to -300) across 50 years is predicted, with little discernible benefit with NAT when compared with standard antibody-based rapid testing. AIDS deaths are predicted to be averted with cabotegravir-PrEP introduction in 99% of setting-scenarios. Across the 50-year time horizon, overall HIV programme costs are predicted to be similar regardless of whether cabotegravir-PrEP is introduced (total mean discounted annual HIV programme costs per year across 50 years is $151·3 million vs $150·7 million), assuming the use of standard antibody testing. With antibody-based rapid HIV testing, the introduction of cabotegravir-PrEP is predicted to be cost-effective under an assumed threshold of $500 per disability-adjusted life year averted in 82% of setting-scenarios at the cost of $144 per year, in 52% at $264, and in 87% at $114.

INTERPRETATION

Despite leading to increases in integrase-inhibitor drug resistance, cabotegravir-PrEP introduction is likely to reduce AIDS deaths in addition to HIV incidence. Long-acting cabotegravir-PrEP is predicted to be cost-effective if delivered at similar cost to oral PrEP with antibody-based rapid HIV testing.

FUNDING

Bill & Melinda Gates Foundation, National Institute of Allergy and Infectious Diseases of the National Institutes of Health.

Antiviral supramolecular polymeric hydrogels by self-assembly of tenofovir-bearing peptide amphiphiles

The development of long-acting antiviral therapeutic delivery systems is crucial to improve the current treatment and prevention of HIV and chronic HBV. We report here on the conjugation of tenofovir (TFV), an FDA approved nucleotide reverse transcriptase inhibitor (NRTI), to rationally designed peptide amphiphiles (PAs), to construct antiviral prodrug hydrogelators (TFV-PAs). The resultant conjugates can self-assemble into one-dimensional nanostructures in aqueous environments and consequently undergo rapid gelation upon injection into 1× PBS solution to create a drug depot. The TFV-PA designs containing two or three valines could attain instantaneous gelation, with one displaying sustained release for more than 28 days in vitro. Our studies suggest that minor changes in peptide design can result in differences in supramolecular morphology and structural stability, which impacted in vitro gelation and release. We envision the use of this system as an important delivery platform for the sustained, linear release of TFV at rates that can be precisely tuned to attain therapeutically relevant TFV plasma concentrations.

Recommendations for the Management of Drug-Drug Interactions Between the COVID-19 Antiviral Nirmatrelvir/Ritonavir (Paxlovid) and Comedications

The coronavirus disease 2019 (COVID-19) antiviral nirmatrelvir/ritonavir (Paxlovid) has been granted authorization or approval in several countries for the treatment of patients with mild to moderate COVID-19 at high risk of progression to severe disease and with no requirement for supplemental oxygen. Nirmatrelvir/ritonavir will be primarily administered outside the hospital setting as a 5-day course oral treatment. The ritonavir component boosts plasma concentrations of nirmatrelvir through the potent and rapid inhibition of the key drug-metabolizing enzyme cytochrome P450 (CYP) 3A4. Thus nirmatrelvir/ritonavir, even given as a short treatment course, has a high potential to cause harm from drug-drug interactions (DDIs) with other drugs metabolized through this pathway. Options for mitigating risk from DDIs with nirmatrelvir/ritonavir are limited due to the clinical illness, the short window for intervention, and the related difficulty of implementing clinical monitoring or dosage adjustment of the comedication. Pragmatic options are largely confined to preemptive or symptom-driven pausing of the comedication or managing any additional risk through counseling. This review summarizes the effects of ritonavir on drug disposition (i.e., metabolizing enzymes and transporters) and discusses factors determining the likelihood of having a clinically significant DDI. Furthermore, it provides a comprehensive list of comedications likely to be used in COVID-19 patients which are categorized according to their potential DDI risk with nirmatrelvir/ritonavir. It also discusses recommendations for the management of DDIs which balance the risk of harm from DDIs with a short course of ritonavir, against unnecessary denial of nirmatrelvir/ritonavir treatment.

Transitioning Long-Acting Products to a Generic Marketplace: What's Missing?

Development of and increased access to generic oral medications to treat high-burden diseases including human immunodeficiency virus (HIV), tuberculosis, viral hepatitis, and malaria have had a major impact on reducing global morbidity and mortality. However, access and adherence to these life-saving treatments remains limited for some of the most vulnerable and underserved populations, for whom stigma, control, and discretion are critical to decisions around care. Current efforts to develop long-acting formulations to treat and prevent these conditions could overcome many of these barriers. However, generic manufacturing of these innovative products will be required to ensure affordable access to the communities and patients in greatest need. Strategic investments in new infrastructure will be required even before markets and manufacturing costs are clear, to ensure that access to these new products is not delayed, particularly for patients in low- and middle-income countries. Unlike conventional oral medications, long-acting products require greater investment for formulation, packaging, and delivery. The requirement for long-term bioequivalence studies will introduce additional delays in regulatory approval of generic long-acting products, and expedited approval pathways must be developed. Lessons learned from the development of long-acting hormonal contraceptives and long-acting antiretroviral products may provide a way forward.

What Clinicians Need to Know About the Development of Long-Acting Formulations

We encourage readers of this Supplement to find articles that are relevant to the current and future practice of infectious diseases medicine. Access to long-acting products and formulations in low- and middle-income countries remains a key determinant of the impact of these advances on global health.

The LEAP Process: Streamlining the Development of Long-Acting Products and Formulations for Infectious Diseases

Developing long-acting products and formulations for infectious diseases is a nontrivial undertaking that is frequently classified as high risk and low reward by the pharmaceutical industry. The Long-Acting/Extended Release Antiretroviral Research Resource Program (LEAP) was founded in 2015 with the support of the National Institutes of Health to encourage, promote, and accelerate the development of such products. Assessment methodology for any new proposal brought to this group is part of a framework-the LEAP Process-that includes a landscape analysis of what is currently available in the public domain. This is followed by in silico modeling and simulation offered as a service to the relevant scientific community. A variety of preclinical and clinical outcome metrics are applied to each new agent as part of a continuous feedback loop to improve product characteristics. This allows us to catalog knowledge gaps and barriers that can be addressed by engaged stakeholders. Results are communicated in scientific articles, reviews, and position papers. This undertaking serves to de-risk discovery, development, and implementation by bridging the gaps between academic, regulatory, and industrial investigators, and by engaging those in the community who will be the eventual users of these medicines. The LEAP Process has supported formulations now approved for human immunodeficiency virus, as well as products in clinical and preclinical development for tuberculosis and hepatitis viruses B and C.

Leveraging the therapeutic, biological, and self-assembling potential of peptides for the treatment of viral infections

Peptides and peptide-based materials have an increasing role in the treatment of viral infections through their use as active pharmaceutical ingredients, targeting moieties, excipients, carriers, or structural components in drug delivery systems. The discovery of peptide-based therapeutic compounds, coupled with the development of new stabilization and formulation strategies, has led to a resurgence of antiviral peptide therapeutics over the past two decades. The ability of peptides to bind cell receptors and to facilitate membrane penetration and subsequent intracellular trafficking enables their use in various antiviral systems for improved targeting efficiency and treatment efficacy. Importantly, the self-assembly of peptides into well-defined nanostructures provides a vast library of discrete constructs and supramolecular biomaterials for systemic and local delivery of antiviral agents. We review here the recent progress in exploiting the therapeutic, biological, and self-assembling potential of peptides, peptide conjugates, and their supramolecular assemblies in treating human viral infections, with an emphasis on the treatment strategies for Human Immunodeficiency Virus (HIV).

The future of long-acting agents for preexposure prophylaxis

PURPOSE OF REVIEW

The main reason for the failure of oral preexposure prophylaxis (PrEP) regimens for HIV is poor adherence. Intramuscular cabotegravir was recently approved for PrEP, and a number of other long-acting antiretroviral formulations and products are currently in clinical development. This includes subcutaneous and intravenous injections, implants, and microarray (microneedle) patches, as well as extended duration oral drugs. The success and future uptake of these products will depend on a variety of factors.

RECENT FINDINGS

Long-acting delivery of antiretroviral agents for PrEP confers significant advantages over short-acting oral delivery. This is exemplified by the superior efficacy of intramuscular cabotegravir given every eight weeks as compared to daily oral co-formulated tenofovir disoproxil fumarate and emtricitabine. There is also evidence for PrEP efficacy for a broadly neutralizing monoclonal antibody given intravenously every eight weeks. One of the leading candidates for long-acting PrEP, islatravir, was being studied as a monthly oral drug or a nonerodable subcutaneous implant inserted for up to 12 months. However, clinical studies of this agent were put on hold in late 2021 because of unanticipated lymphopenia.

SUMMARY

Long-acting antiretroviral products have substantial promise for PrEP and have particular advantages over daily oral drugs based mainly on improved adherence. However, there are barriers to further uptake that include the need for more intensive interaction with systems of healthcare delivery, greater expense and complexity of implementation, and unexpected long-term toxicities.

Prescribing Nirmatrelvir-Ritonavir: How to Recognize and Manage Drug-Drug Interactions

Nirmatrelvir–ritonavir (NMV/r) is now being used to treat high-risk patients with mild to moderate COVID-19. This article provides advice to clinicians regarding recognition of medications likely to interact with NMV/r and suggests approaches to managing such drug–drug interactions. An algorithm is provided to assist in decision making.

Supramolecular nanomedicines through rational design of self-assembling prodrugs

Advancements in the development of nanomaterials have led to the creation of a plethora of functional constructs as drug delivery vehicles to address many dire medical needs. The emerging prodrug strategy provides an alternative solution to create nanomedicines of extreme simplicity by directly using the therapeutic agents as molecular building blocks. This Review outlines different prodrug-based drug delivery systems, highlights the advantages of the prodrug strategy for therapeutic delivery, and demonstrates how combinations of different functionalities - such as stimuli responsiveness, targeting propensity, and multidrug conjugation - can be incorporated into designed prodrug delivery systems. Furthermore, we discuss the opportunities and challenges facing this rapidly growing field.

Randomized Trial of Ruxolitinib in Antiretroviral-Treated Adults With Human Immunodeficiency Virus

BACKGROUND

Inflammation is associated with end-organ disease and mortality for people with human immunodeficiency virus (PWH). Ruxolitinib, a Jak 1/2 inhibitor, reduces systemic inflammation for individuals without human immunodeficiency virus (HIV) and HIV reservoir markers ex vivo. The goal of this trial was to determine safety and efficacy of ruxolitinib for PWH on antiretroviral therapy (ART).

METHODS

AIDS Clinical Trials Group (ACTG) A5336 was an open-label, multisite, randomized controlled trial (RCT). Participants were randomly assigned (2:1) using centralized software to ruxolitinib (10 mg twice daily) plus stable ART for 5 weeks vs ART alone, stratified by efavirenz use. Eligible participants were suppressed on ART for ≥2 years, without comorbidities, and had >350 CD4+ T cells/µL. Primary endpoints were premature discontinuation, safety events, and change in plasma interleukin 6 (IL-6). Secondary endpoints included other measures of inflammation/immune activation and HIV reservoir.

RESULTS

Sixty participants were enrolled from 16 May 2016 to 10 January 2018. Primary safety events occurred in 2.5% (1 participant) for ruxolitinib and 0% for controls (P = .67). Three participants (7.5%) prematurely discontinued ruxolitinib. By week 5, differences in IL-6 (mean fold change [FC], 0.93 vs 1.10; P = .18) and soluble CD14 (mean FC, 0.96 vs 1.08; relative FC, 0.96 [90% confidence interval {CI}, .90-1.02]) levels for ruxolitinib vs controls was observed. Ruxolitinib reduced CD4+ T cells expressing HLA-DR/CD38 (mean difference, -0.34% [90% CI, -.66% to -.12%]) and Bcl-2 (mean difference, -3.30% [90% CI, -4.72% to -1.87%]).

CONCLUSIONS

In this RCT of healthy, virologically suppressed PWH on ART, ruxolitinib was well-tolerated. Baseline IL-6 levels were normal and showed no significant reduction. Ruxolitinib significantly decreased markers of immune activation and cell survival. Future studies of Jak inhibitors should target PWH with residual inflammation despite suppressive ART.

CLINICAL TRIALS REGISTRATION

NCT02475655.

Impact of long-acting therapies on the global HIV epidemic

Long-acting antiretroviral drugs have emerged as exciting treatment and preexposure prophylaxis (PrEP) options for people with HIV and at risk of HIV. Long-acting regimens may improve dosing convenience, tolerability and cost compared with current daily-based oral therapy. They can also circumvent stigma associated with oral therapy for both treatment and PrEP, thereby improving adherence and outcomes. Yet, multiple challenges remain, many specific to low-income and middle-income countries (LMICs), where the epidemic is most concentrated and HIV prevention and treatment options are limited. To optimize the use of long-acting formulations, key outstanding questions must be addressed. Uncertain costing, scale-up manufacturing, complex delivery systems and implementation challenges are potential barriers when considering the scalability of long-acting ARVs for global use.

Preferences of Persons with or at Risk for Hepatitis C for Long-Acting Treatments

BACKGROUND

Whereas safe, curative treatments for hepatitis C virus (HCV) have been available since 2015, there are still 58 million infected persons worldwide, and global elimination may require new paradigms. We sought to understand the acceptability of long-acting HCV treatment approaches.

METHODS

A cross-sectional, 43-question survey was administered to 1457 individuals with HCV or at risk of HCV at 28 sites in 9 countries to assess comparative interest in a variety of long-acting strategies in comparison to oral pills.

RESULTS

Among HCV-positive participants, 37.7% most preferred an injection, 5.6% an implant, and 6% a gastric residence device, as compared to 50.8% who stated they would most prefer taking 1 to 3 pills per day. When compared directly to taking pills, differences were observed in the relative preference for an injection based on age (p<0.001), location (p<0.001), and prior receipt of HCV treatment (p=0.005), but not sex. When an implant was compared to pills, greater preference was represented by women (p=0.01) and adults of younger ages (p=0.012 per 5 years). Among participants without HCV, 49.5% felt that injections are stronger than pills, and 34.7% preferred taking injections to pills. Among those at-risk participants who had received injectable medications in the past, 123 out of 137 (89.8%) expressed willingness to receive one in the future.

CONCLUSIONS

These data point to high acceptability of long-acting treatments, which for a substantial minority, might even be preferred to pills for the treatment of HCV infection. Long-acting treatments for HCV infection might contribute to global efforts to eliminate hepatitis C.

Toward Consensus on Correct Interpretation of Protein Binding in Plasma and Other Biological Matrices for COVID-19 Therapeutic Development

The urgent global public health need presented by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) has brought scientists from diverse backgrounds together in an unprecedented international effort to rapidly identify interventions. There is a pressing need to apply clinical pharmacology principles and this has already been recognized by several other groups. However, one area that warrants additional specific consideration relates to plasma and tissue protein binding that broadly influences pharmacokinetics and pharmacodynamics. The principles of free drug theory have been forged and applied across drug development but are not currently being routinely applied for SARS-CoV-2 antiviral drugs. Consideration of protein binding is of critical importance to candidate selection but requires correct interpretation, in a drug-specific manner, to avoid either underinterpretation or overinterpretation of its consequences. This paper represents a consensus from international researchers seeking to apply historical knowledge, which has underpinned highly successful antiviral drug development for other viruses, such as HIV and hepatitis C virus for decades.

The potential role of long-acting injectable cabotegravir-rilpivirine in the treatment of HIV in sub-Saharan Africa: a modelling analysis

BACKGROUND

The use of a combination of the integrase inhibitor, cabotegravir, and the non-nucleoside reverse transcriptase inhibitor, rilpivirine, in a long-acting injectable form is being considered as an antiretroviral treatment option for people with HIV in sub-Saharan Africa. We aimed to model the effects of injectable cabotegravir-rilpivirine to help to inform its potential effectiveness and cost-effectiveness under different possible policies for its introduction.

METHODS

We used an existing individual-based model of HIV to predict the effects of introducing monthly injections of cabotegravir-rilpivirine for people with HIV in low-income settings in sub-Saharan Africa. We evaluated policies in the context of 1000 setting scenarios that reflected characteristics of HIV epidemics and programmes in sub-Saharan Africa. We compared three policies for introduction of injectable cabotegravir-rilpivirine with continued use of dolutegravir-based oral regimens for: all individuals on antiretroviral therapy (ART); individuals with a recently measured viral load of more than 1000 copies per mL (signifying poor adherence to oral drugs, and often associated with drug resistance); and individuals with a recently measured viral load of less than 1000 copies per mL (a group with a lower prevalence of pre-existing drug resistance). We also did cost-effectiveness analysis, taking a health system perspective over a 10 year period, with 3% discounting of disability-adjusted life-years (DALYs) and costs. A cost-effectiveness threshold of US$500 per DALY averted was used to establish if a policy was cost-effective.

FINDINGS

In our model, all policies involving the introduction of injectable cabotegravir-rilpivirine were predicted to lead to an increased proportion of people with HIV on ART, increased viral load suppression, and decreased AIDS-related mortality, with lesser benefits in people with a recently measured viral load of less than 1000 copies per mL. Its introduction is also predicted to lead to increases in resistance to integrase inhibitors and non-nucleoside reverse transcriptase inhibitors if introduced in all people with HIV on ART or in those with a recently measured viral load of less than 1000 copies per mL, but to a lesser extent if introduced in people with more than 1000 copies per mL due to concentration of its use in people less adherent to oral therapy. Consistent with the effect on AIDS-related mortality, all approaches to the introduction of injectable cabotegravir-rilpivirine are predicted to avert DALYs. Assuming a cost of $120 per person per year, use of this regimen in people with a recently measured viral load of more than 1000 copies per mL was borderline cost-effective (median cost per DALY averted across setting scenarios $404). The other approaches considered for its use are unlikely to be cost-effective unless the cost per year of injectable cabotegravir-rilpivirine is considerably reduced.

INTERPRETATION

Our modelling suggests that injectable cabotegravir-rilpivirine offers potential benefits; however, to be a cost-effective option, its introduction might need to be carefully targeted to individuals with HIV who might otherwise have suboptimal adherence to ART. As data accumulate from trials and implementation studies, such findings can be incorporated into the model to better inform on the full consequences of policy alternatives.

FUNDING

Bill & Melinda Gates Foundation, including through the HIV Modelling Consortium (OPP1191655).

Long-acting drugs and formulations for the treatment and prevention of HIV infection

Long-acting and extended-release formulations represent one of the most important approaches to improving the treatment and prevention of chronic HIV infection. Long-acting small molecules and monoclonal antibodies have demonstrated potent anti-HIV activity in early- and late-stage clinical trials. Strategies to manage toxicity and falling drug concentrations after missed doses, as well as primary and secondary resistance to current drugs and monoclonal antibodies are important considerations. Long-acting injectable nanoformulations of the integrase inhibitor cabotegravir and the non-nucleoside reverse transcriptase inhibitor rilpivirine were safe, well tolerated and efficacious in large randomised phase 3 studies. Regulatory approval for this two-drug combination for HIV maintenance therapy was granted in Canada in 2020 and is expected in the USA during 2021. 4'-Ethynyl-2-fluoro-2'-deoxyadenosine (islatravir) is a novel nucleoside reverse transcriptase inhibitor in clinical development as a long-acting oral drug and as a long-acting subcutaneous polymer implant. GS-6207 is a novel HIV capsid inhibitor that is injected subcutaneously every 3 months. Broadly-neutralising monoclonal antibodies have potent antiviral activity in early human trials, however there is substantial baseline resistance and rapid development of resistance to these antibodies if used as monotherapy. Limitations of these antiretroviral approaches include management of toxicities and prevention of drug resistance when these drugs are discontinued and drug concentrations are slowly reduced over time. These approaches appear to be especially attractive for patients complaining of pill fatigue and for those experiencing HIV-associated stigma. As these formulations are shown to be safe, well tolerated and economical, they are likely to gain broader appeal.

Allogeneic bone marrow transplantation with post-transplant cyclophosphamide for patients with HIV and haematological malignancies: a feasibility study

BACKGROUND

Allogeneic blood or marrow transplantation (alloBMT) is a potentially life-saving treatment for individuals with HIV and haematological malignancies; challenges include identifying donors and maintaining antiretroviral therapy (ART). The objectives of our study were to investigate interventions to expand donor options and to prevent ART interruptions for patients with HIV in need of alloBMT.

METHODS

This single-arm, interventional trial took place at the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center (Baltimore, MD, USA). Individuals with HIV who were at least 18 years of age and referred for alloBMT for a standard clinical indication were eligible. The only exclusion criterion was a history of documented resistance to enfuvirtide. We used post-transplant cyclophosphamide as graft-versus-host disease (GVHD) prophylaxis to expand donor options and an optimised ART strategy of avoiding pharmacoenhancers and adding subcutaneous enfuvirtide during post-transplant cyclophosphamide and during oral medication intolerance. Our primary outcome was the proportion of participants who maintained ART through day 60 after alloBMT. We measured the HIV latent reservoir using a quantitative viral outgrowth assay. This study is registered on ClinicalTrials.gov, NCT01836068.

FINDINGS

Between June 1, 2013, and August 27, 2015, nine patients who were referred for transplant provided consent. Two patients had relapsed malignancy before donor searches were initiated. Seven patients had suitable donors identified (two matched sibling, two matched unrelated, two haploidentical, and one single-antigen mismatched unrelated) and proceeded to alloBMT. All patients maintained ART through day 60 and required ART changes (median 1, range 1-3) in the first 90 days. One patient stopped ART and developed HIV rebound with grade 4 meningoencephalitis at day 146. Among six patients who underwent alloBMT and had longitudinal measurements available, the HIV latent reservoir was not detected post-alloBMT in four patients with more than 95% donor chimerism, consistent with a 2·06-2·54 log10 reduction in the HIV latent reservoir. In the two patients with less than 95% donor chimerism, the HIV latent reservoir remained stable.

INTERPRETATION

By using post-transplant cyclophosphamide as GVHD prophylaxis, we successfully expanded alloBMT donor options for patients with HIV. Continuing ART with a regimen that includes enfuvirtide post-alloBMT was safe, but life-threatening viral rebound can occur with ART interruption.

FUNDING

amfAR (the Foundation for AIDS Research), Johns Hopkins University Center for AIDS Research, and National Cancer Institute.

Rifampicin effect on intracellular and plasma pharmacokinetics of tenofovir alafenamide

OBJECTIVES

Tenofovir alafenamide produces lower plasma tenofovir and higher intracellular tenofovir diphosphate (DP) concentrations than tenofovir disoproxil fumarate but it is likely a victim of interactions with rifampicin. We aimed to investigate the pharmacokinetics of tenofovir alafenamide/emtricitabine with rifampicin.

PATIENTS AND METHODS

Healthy volunteers received tenofovir alafenamide/emtricitabine at 25/200 mg once daily, followed by tenofovir alafenamide/emtricitabine + rifampicin daily followed by tenofovir disoproxil fumarate. Plasma tenofovir alafenamide, tenofovir, emtricitabine and intracellular tenofovir-DP and emtricitabine triphosphate pharmacokinetics and genetic polymorphisms were assessed.

RESULTS

Tenofovir alafenamide exposure decreased when tenofovir alafenamide/emtricitabine + rifampicin was used compared with tenofovir alafenamide/emtricitabine [geometric mean ratio (GMR) (90% CI): 0.45 (0.33-0.60)]. Plasma tenofovir and intracellular tenofovir-DP concentrations decreased with rifampicin [GMR (90% CI): 0.46 (0.40-0.52) and 0.64 (0.54-0.75), respectively]. GMR (90% CI) of intracellular tenofovir-DP AUC0-24 for tenofovir alafenamide/emtricitabine + rifampicin versus tenofovir disoproxil fumarate was 4.21 (2.98-5.95). Rifampicin did not affect emtricitabine pharmacokinetics. CYP3A4*22 rs35599367 was associated with higher plasma tenofovir alafenamide AUC0-24 at day 56.

CONCLUSIONS

Following tenofovir alafenamide/emtricitabine administration with rifampicin, intracellular tenofovir-DP concentrations were still 4.21-fold higher than those achieved by tenofovir disoproxil fumarate, supporting further study during HIV/TB co-infection.

Predicting Drug-Drug Interactions Between Rifampicin and Long-Acting Cabotegravir and Rilpivirine Using Physiologically Based Pharmacokinetic Modeling

BACKGROUND

Cabotegravir and rilpivirine are 2 long-acting (LA) antiretrovirals that can be administered intramuscularly; their interaction with rifampicin, a first-line antituberculosis agent, has not been investigated. The aim of this study was to simulate and predict drug-drug interactions (DDIs) between these LA antiretroviral agents and rifampicin using physiologically based pharmacokinetic (PBPK) modeling.

METHODS

The designed PBPK models were qualified (according to European Medicines Agency guidelines) against observed data for oral formulations of cabotegravir, rilpivirine, and rifampicin. Induction potential of rifampicin was also qualified by comparing the DDI between oral cabotegravir and oral rilpivirine with rifampicin. Qualified PBPK models were utilized for pharmacokinetic prediction of DDIs.

RESULTS

PBPK models predicted a reduction in both area under the curve (AUC0-28 days) and trough concentration (Ctrough, 28th day) of LA cabotegravir of 41%-46% for the first maintenance dose coadministered with 600 mg once-daily oral rifampicin. Rilpivirine concentrations were predicted to decrease by 82% for both AUC0-28 days and Ctrough, 28th day following the first maintenance dose when coadministered with rifampicin.

CONCLUSIONS

The developed PBPK models predicted the theoretical effect of rifampicin on cabotegravir and rilpivirine LA intramuscular formulations. According to these simulations, it is likely that coadministration of rifampicin with these LA formulations will result in subtherapeutic concentrations of both drugs.

Addressing the global burden of hepatitis B virus while developing long-acting injectables for the prevention and treatment of HIV

The first long-acting formulations of HIV drugs are undergoing regulatory review for use in maintenance of viral suppression in people with HIV. Although these novel drug formulations could contribute greatly to HIV treatment and prevention efforts, their lack of activity against hepatitis B virus (HBV) could limit their global impact, particularly in populations with high burdens of both HIV and HBV. An urgent need for greater investment in research and development of long-acting drugs with dual activity against HIV and HBV exists. Access to long-acting HIV drug formulations with dual activity against HBV would be transformative and have a great impact on efforts to prevent, treat, and eradicate both of these important global epidemics.

Anhydrous nanoprecipitation for the preparation of nanodispersions of tenofovir disoproxil fumarate in oils as candidate long-acting injectable depot formulations

The facile formation of drug nanoparticles in injectable/ingestible oils, of water-soluble antiretroviral tenofovir disoproxil fumarate, using a novel nanoprecipitation is presented with studies showing drug release into relevant aqueous media.

Modern Human Immunodeficiency Virus Therapy: Progress and Prospects

Safe and effective lifelong treatment to control human immunodeficiency virus (HIV) infection is one of the greatest scientific and public health achievements of the past century. The majority of infected individuals able to maintain a daily oral regimen now have a normal or near-normal life expectancy. More than 30 approved drugs and dozens of formulations have produced thousands of possible drug combinations used clinically in the past, but today most patients receive only a handful of high priority and rigorously tested regimens. Unique features of antiretroviral therapy include the need for lifelong treatment to control virus replication and the possibility of rapid emergence of permanent drug resistance if these agents are not properly used. Although three-drug combination oral regimens have radically altered the course of this epidemic, the future will include long-acting injectable and implantable drugs and devices to treat and prevent infection.

Modelling the intradermal delivery of microneedle array patches for long-acting antiretrovirals using PBPK

INTRODUCTION

Existing HIV therapy using oral antiretrovirals (ARVs) can result in pill fatigue and sub-optimal adherence. Microneedle array patches (MAPs) offer non-invasive, blood-free and painless drug delivery, and may improve patient adherence. The objective of this study was to develop a novel physiologically-based pharmacokinetic (PBPK) model to simulate the systemic pharmacokinetics of cabotegravir and rilpivirine MAPs using the intradermal route.

METHODS

The developed PBPK models were qualified against observed pharmacokinetic data after intramuscular (IM) and intradermal administration of long-acting nanoformulated rilpivirine to rats, and for IM administration of both drugs to healthy adults. Qualified models were then utilised to estimate suitable MAP characteristics (e.g. nanoformulation dose and release rates) and inform dosing strategies to maintain plasma concentrations above target trough concentrations for the designated dosing interval.

RESULTS

PBPK models simulated q4-weekly loading and maintenance doses of 360 mg and 180 mg for long-acting formulated cabotegravir between the release rates of 1 × 10^-3-3 × 10^-3h^-1 and 1 × 10^-3-1.5 × 10^-3h^-1 respectively, for a 70 kg adult. Estimated patch size was 60 cm² for a 360 mg dose of cabotegravir. For q4-weekly dosing, rilpivirine required a 1080 mg loading dose and a 540 mg maintenance dose with release rates of 1.5 × 10^-3-2.5 × 10^-3h^-1 and 5 × 10^-4-1 × 10^-3h^-1, respectively. Weekly dosing was also evaluated to assess the potential application from a smaller patch size. The ability to self-administer via a patch that is only left in place for a short duration makes longer durations less important than for some other long-acting approaches. Weekly cabotegravir required 60 mg between release rates 7 × 10^-3-9 × 10^-3h^-1 and rilpivirine required 270 mg and 180 mg respectively between release rates of 7 × 10^-3-9 × 10^-3h^-1.

DISCUSSION

This model estimated optimal dose and release rates for cabotegravir and rilpivirine MAPs. Our approach provides a computational platform to support rational development of intradermal administration strategies to tackle problems associated with chronic oral ARV administration.

Modelling the long-acting administration of anti-tuberculosis agents using PBPK: a proof of concept study

SETTING

Anti-tuberculosis formulations necessitate uninterrupted treatment to cure tuberculosis (TB), but are characterised by suboptimal adherence, which jeopardises therapeutic efficacy. Long-acting injectable (LAI) formulations or implants could address these associated issues.

OBJECTIVE

niazid, rifapentine, bedaquiline and delamanid-in adults for treatment for latent tuberculous infection (LTBI).

DESIGN

PBPK models were developed and qualified against available clinical data by integrating drug physicochemical properties and in vitro and population pharmacokinetic data into a mechanistic description of drug distribution. Combinations of optimal dose and release rates were simulated such that plasma concentrations were maintained over the epidemiological cut-off or minimum inhibitory concentration for the dosing interval.

RESULTS

The PBPK model identified 1500 mg of delamanid and 250 mg of rifapentine as sufficient doses for monthly intramuscular administration, if a formulation or device can deliver the required release kinetics of 0.001-0.0025 h-1 and 0.0015-0.0025 h-1, respectively. Bedaquiline and isoniazid would require weekly to biweekly intramuscular dosing.

CONCLUSION

We identified the theoretical doses and release rates of LAI anti-tuberculosis formulations. Such a strategy could ease the problem of suboptimal adherence provided the associated technological complexities for LTBI treatment are addressed.

Long-acting or extended-release antiretroviral products for HIV treatment and prevention in infants, children, adolescents, and pregnant and breastfeeding women: knowledge gaps and research priorities

Antiretroviral agents with long-acting properties have potential to improve treatment outcomes substantially for people living with HIV. In November 2017, the Long acting/Extended Release Antiretroviral Resource Program (LEAP) convened a workshop with the aim of shaping the research agenda and promoting early development of long-acting or extended release products for key populations: pregnant and lactating women, children aged up to 10 years, and adolescents aged 10-19 years. Goals included strategies and principles to ensure that the needs of children, adolescents, and pregnant and lactating women are considered when developing long-acting formulations. Research should focus not only on how best to transition long-acting products to these populations, but also on early engagement across sectors and among stakeholders. A parallel rather than sequential approach is needed when establishing adult, adolescent, and paediatric clinical trials and seeking regulatory approval. Pregnant and lactating women should be included in adult clinical trials. Adolescent-friendly trial design is needed to improve recruitment and retention of young people.

Long-acting formulations for the treatment of latent tuberculous infection: opportunities and challenges

Long-acting/extended-release drug formulations have proved very successful in diverse areas of medicine, including contraception, psychiatry and, most recently, human immunodeficiency virus (HIV) disease. Though challenging, application of this technology to anti-tuberculosis treatment could have substantial impact. The duration of treatment required for all forms of tuberculosis (TB) put existing regimens at risk of failure because of early discontinuations and treatment loss to follow-up. Long-acting injections, for example, administered every month, could improve patient adherence and treatment outcomes. We review the state of the science for potential long-acting formulations of existing tuberculosis drugs, and propose a target product profile for new formulations to treat latent tuberculous infection (LTBI). The physicochemical properties of some anti-tuberculosis drugs make them unsuitable for long-acting formulation, but there are promising candidates that have been identified through modeling and simulation, as well as other novel agents and formulations in preclinical testing. An efficacious long-acting treatment for LTBI, particularly for those co-infected with HIV, and if coupled with a biomarker to target those at highest risk for disease progression, would be an important tool to accelerate progress towards TB elimination.

Ageing in patients with chronic HIV infection: impact of hypercoagulation

Ageing is the result of biological events that progressively and irreversibly compromise the function of vital organs and eventually result in death. There is a general perception that ageing is accelerated in people living with HIV, with an increasing body of evidence to support this view. With the introduction of effective antiretroviral therapy, the life expectancy of people living with HIV has improved. Since people with HIV are living longer than previously, while also ageing faster than the general population, there is an increase in HIV-positive patients living with age-related comorbidities. This brief overview of ageing and HIV discusses aspects of the complications of HIV infection as they impact the ageing process. How diseases of age affect patients with HIV provides clues to help unravel the interactions between HIV and ageing that ultimately should help clinicians understand the basis of ‘normal’ ageing and manage ageing HIV-positive patients more effectively.

Effect of Antiretroviral Therapy on Plasma Concentrations of Chloroquine and Desethyl-chloroquine

The effect of antiretroviral therapy (ART) on chloroquine and desethyl-chloroquine plasma concentrations was evaluated in clinical trial participants. Concentrations did not differ among participants receiving protease inhibitor-based ART (n = 9), efavirenz-based ART (n = 15), or other ART (n = 8) and those not receiving ART (n = 31). Efavirenz seemed to inhibit chloroquine desethylation.

Long-Acting HIV Drugs for Treatment and Prevention

Antiretroviral drugs have revolutionized the treatment and prevention of HIV infection; however, adherence is critical for sustained efficacy. Current HIV treatment consists of three-drug regimens, and current HIV pre-exposure prophylaxis (PrEP) consists of a two-drug regimen; both generally require adherence to once-daily dosing. Long-acting formulations are useful in the treatment and prevention of other conditions (e.g., contraceptives, antipsychotics) and help promote adherence. Newer long-acting formulations of approved and investigational antiretroviral drugs in existing and newer mechanistic classes are under study for HIV treatment and prevention, including some phase III trials. Although long-acting antiretroviral drugs hold promise, some clinical challenges exist, including managing side effects, drug-drug interactions, pregnancy, and long-lasting drug concentrations that could lead to the development of drug resistance. This review aims to summarize currently available information on long-acting antiretroviral drugs for HIV treatment and prevention.

Harnessing nanostructured systems for improved treatment and prevention of HIV disease

Combination antiretroviral therapy effectively controls human immunodeficiency virus (HIV) viral replication, delaying the progression to acquired immune deficiency syndrome and improving and extending quality of life of patients. However, the inability of antiretroviral therapeutics to target latent virus and their poor penetration of viral reserve tissues result in the need for continued treatment for the life of the patient. Side effects from long-term antiretroviral use and the development of drug resistance due to patient noncompliance are also continuing problems. Nanostructured systems of antiretroviral therapeutics have the potential to improve targeted delivery to viral reservoirs, reduce drug toxicity, and increase dosing intervals, thereby improving treatment outcomes and enhancing patient adherence. Despite these advantages, very few nanostructured antiretroviral delivery systems have made it to clinical trials due to challenges in preclinical and clinical development. In this context, we review the current challenges in HIV disease management, and the recent progress in leveraging the unique performance of nanostructured systems in therapeutic delivery for improved treatment and prevention of this incurable human disease.

In Silico Dose Prediction for Long-Acting Rilpivirine and Cabotegravir Administration to Children and Adolescents

BACKGROUND AND OBJECTIVES

Long-acting injectable antiretrovirals represent a pharmacological alternative to oral formulations and an innovative clinical option to address adherence and reduce drug costs. Clinical studies in children and adolescents are characterised by ethical and logistic barriers complicating the identification of dose optimisation. Physiologically-based pharmacokinetic modelling represents a valuable tool to inform dose finding prior to clinical trials. The objective of this study was to simulate potential dosing strategies for existing long-acting injectable depot formulations of cabotegravir and rilpivirine in children and adolescents (aged 3-18 years) using physiologically-based pharmacokinetic modelling.

METHODS

Whole-body physiologically-based pharmacokinetic models were developed to represent the anatomical, physiological and molecular processes and age-related changes in children and adolescents through allometric equations. Models were validated for long-acting injectable intramuscular cabotegravir and rilpivirine in adults. Subsequently, the anatomy and physiology of children and adolescents were validated against available literature. The optimal doses of monthly administration of cabotegravir and rilpivirine were identified in children and adolescents, to achieve trough concentrations over the target concentrations derived in a recent efficacy trial of the same formulations.

RESULTS

Pharmacokinetic data generated through the physiologically-based pharmacokinetic simulations were similar to observed clinical data in adults. Optimal doses of long-acting injectable antiretrovirals cabotegravir and rilpivirine were predicted using the release rate observed for existing clinical formulations, for different weight groups of children and adolescents. The intramuscular loading dose and maintenance dose of cabotegravir ranged from 200 to 600 mg and from 100 to 250 mg, respectively, and for rilpivirine it ranged from 250 to 550 mg and from 150 to 500 mg, respectively, across various weight groups of children ranging from 15 to 70 kg.

CONCLUSIONS

The reported findings represent a rational platform for the identification of suitable dosing strategies and can inform prospective clinical investigation of long-acting injectable formulations in children and adolescents.

The challenge of polypharmacy in an aging population and implications for future antiretroviral therapy development

: It is estimated that by 2030 nearly three-quarters of persons living with HIV will be 50 years and older. The aging HIV population presents a new clinical concern for HIV providers: adverse effects from polypharmacy. An aging population means more comorbidities and potentially more drug-drug interactions for providers to manage. This review discusses major comorbidities including cardiovascular disease, anticoagulation, hypertension, diabetes mellitus and malignancy and considerations for drug-interactions with antiretrovirals.

The Effect of Chloroquine on Immune Activation and Interferon Signatures Associated with HIV-1

Immune activation associated with HIV-1 infection contributes to morbidity and mortality. We studied whether chloroquine, through Toll-like receptor (TLR) antagonist properties, could reduce immune activation thought to be driven by TLR ligands, such as gut-derived bacterial elements and HIV-1 RNAs. AIDS Clinical Trials Group A5258 was a randomized, double-blind, placebo-controlled study in 33 HIV-1-infected participants off antiretroviral therapy (ART) and 37 participants on ART. Study participants in each cohort were randomized 1:1 to receive chloroquine 250 mg orally for the first 12 weeks then cross over to placebo for 12 weeks or placebo first and then chloroquine. Combining the periods of chloroquine use in both arms of the on-ART cohort yielded a modest reduction in the proportions of CD8 T cells co-expressing CD38 and DR (median decrease = 3.0%, p = .003). The effect on immune activation in the off-ART cohort was likely confounded by increased plasma HIV-1 RNA during chloroquine administration (median 0.29 log10 increase, p < .001). Transcriptional analyses in the off-ART cohort showed decreased expression of interferon-stimulated genes in 5 of 10 chloroquine-treated participants and modest decreases in CD38 and CCR5 RNAs in all chloroquine-treated participants. Chloroquine modestly reduced immune activation in ART-treated HIV-infected participants. Clinical Trials Registry Number: NCT00819390.

Physiologically Based Pharmacokinetic Modelling to Inform Development of Intramuscular Long-Acting Nanoformulations for HIV

BACKGROUND AND OBJECTIVES

Antiretrovirals are currently used for the treatment and prevention of HIV infection. However, poor adherence and low tolerability of some existing oral formulations can hinder their efficacy. Long-acting (LA) injectable nanoformulations could help address these complications by simplifying antiretroviral administration. The aim of this study is to inform the optimisation of intramuscular LA formulations for eight antiretrovirals through physiologically based pharmacokinetic (PBPK) modelling.

METHODS

A whole-body PBPK model was constructed using mathematical descriptions of molecular, physiological and anatomical processes defining pharmacokinetics. These models were validated against available clinical data and subsequently used to predict the pharmacokinetics of injectable LA formulations

RESULTS

The predictions suggest that monthly intramuscular injections are possible for dolutegravir, efavirenz, emtricitabine, raltegravir, rilpivirine and tenofovir provided that technological challenges to control their release rate can be addressed.

CONCLUSIONS

These data may help inform the target product profiles for LA antiretroviral reformulation strategies.

Population pharmacokinetic drug-drug interaction pooled analysis of existing data for rifabutin and HIV PIs

OBJECTIVES

Extensive but fragmented data from existing studies were used to describe the drug-drug interaction between rifabutin and HIV PIs and predict doses achieving recommended therapeutic exposure for rifabutin in patients with HIV-associated TB, with concurrently administered PIs.

METHODS

Individual-level data from 13 published studies were pooled and a population analysis approach was used to develop a pharmacokinetic model for rifabutin, its main active metabolite 25-O-desacetyl rifabutin (des-rifabutin) and drug-drug interaction with PIs in healthy volunteers and patients who had HIV and TB (TB/HIV).

RESULTS

Key parameters of rifabutin affected by drug-drug interaction in TB/HIV were clearance to routes other than des-rifabutin (reduced by 76%-100%), formation of the metabolite (increased by 224% in patients), volume of distribution (increased by 606%) and distribution to the peripheral compartment (reduced by 47%). For des-rifabutin, clearance was reduced by 35%-76% and volume of distribution increased by 67%-240% in TB/HIV. These changes resulted in overall increased exposure to rifabutin in TB/HIV patients by 210% because of the effects of PIs and 280% with ritonavir-boosted PIs.

CONCLUSIONS

Given together with non-boosted or ritonavir-boosted PIs, rifabutin at 150 mg once daily results in similar or higher exposure compared with rifabutin at 300 mg once daily without concomitant PIs and may achieve peak concentrations within an acceptable therapeutic range. Although 300 mg of rifabutin every 3 days with boosted PI achieves an average equivalent exposure, intermittent doses of rifamycins are not supported by current guidelines.

High-Dose Lopinavir/Ritonavir in Highly Treatment-Experienced HIV-1 Patients: Efficacy, Safety, and Predictors of Response

OBJECTIVE

To investigate the efficacy and safety of high-dose lopinavir/ritonavir (LPV/r) therapy in multiple protease inhibitor, non-nucleoside reverse transcriptase inhibitor (NNRTI)-experienced subjects.

METHOD

Thirty-six HIV-1-infected subjects were randomized to LPV/r 400/300 mg or 667/167 mg bid in a 48-week, open-label study. Subjects also received investigator-selected nucleoside reverse transcriptase inhibitors (NRTIs). Primary outcomes were the proportion of subjects with HIV-1 RNA levels <50 copies/mL at week 24 and time until loss of virologic response through week 48.

RESULTS

Six of 17 (35%) and 10 of 19 (53%) subjects in the 400/300 and 667/167 groups, respectively, completed 48 weeks of treatment. Median durations of follow-up in discontinued subjects and all subjects were 15 weeks and 32 weeks, respectively. Forty-four percent of subjects achieved HIV-1 RNA <50 copies/mL at least once; 18% (400/300 mg) and 21% (667/167 mg) of subjects achieved HIV-1 RNA <50 copies/mL at week 24 (intent-to-treat analysis). Corresponding results at week 48 were 18% (400/300 mg) and 26% (667/167 mg). No statistically significant differences in adverse event incidence occurred between treatment groups, except for a higher vomiting rate in the 400/300 mg dose group. Predictors of response included baseline LPV inhibitory quotient and number of active NRTIs.

CONCLUSION

Higher doses of LPV/r may provide substantial antiviral activity in multiple class-experienced subjects.

Factors associated with CD8+ T-cell activation in HIV-1-infected patients on long-term antiretroviral therapy

BACKGROUND

Abnormal levels of CD8 T-cell activation persist in HIV-1-infected patients on suppressive antiretroviral therapy (ART) and may be deleterious.

METHODS

CD8 T-cell activation (% coexpressing CD38/HLA-DR) was analyzed on blood specimens from 833 HIV-1-infected patients on ART for ≥96 weeks with concurrent plasma HIV RNA (vRNA) ≤200 copies per milliliter. Factors associated with CD8 T-cell activation were assessed using generalized estimating equations to incorporate longitudinal measurements (median 4/participant).

RESULTS

Participants were 84% men, 47% white, 28% black, and 22% Hispanic, with median pre-ART age 38 years and median ART exposure 144 weeks. CD8 T-cell activation was higher at timepoints when vRNA was 51-200 versus ≤50 copies per milliliter [mean CD8 T-cell activation 23.4% vs. 19.7%; adjusted difference: 1.7% (95% confidence interval: 0.1 to 3.4), P = 0.042]. Restricting to vRNA ≤50 copies per milliliter, multivariable models showed the following factors associated with higher CD8 T-cell activation: older age [≥45 vs. ≤30 years: 3.6% (1.4 to 5.7), P = 0.004], hepatitis C virus antibody positivity [3.6% (0.9 to 6.2), P = 0.032], Hispanic vs. white [7.2% (5.3 to 9.0), P < 0.001], lower concurrent CD4 count [≤200 vs. >500 cells/mm: 2.2% (0.7 to 3.7), P < 0.001], lower concurrent CD4/CD8 ratio [-2.6% (-3.7 to -1.5) per 0.5 unit increase, P < 0.001], and higher pre-ART CD8 T-cell activation [2.0% (1.6 to 2.5) per 10% higher, P < 0.001].

CONCLUSIONS

In participants included in our analysis, residual low-level viremia between 51 and 200 copies per milliliter during ART was shown to be associated with greater CD8 T-cell activation than full suppression to <50 copies per milliliter. Older age, hepatitis C virus antibody positivity, race/ethnicity, higher pre-ART CD8 T-cell activation, and lower concurrent CD4/CD8 ratio and CD4 T-cell count also contribute to greater CD8 T-cell activation during suppressive ART.

Simplification of antiretroviral therapy: a necessary step in the public health response to HIV/AIDS in resource-limited settings

The global scale-up of antiretroviral therapy (ART) over the past decade represents one of the great public health and human rights achievements of recent times. Moving from an individualized treatment approach to a simplified and standardized public health approach has been critical to ART scale-up, simplifying both prescribing practices and supply chain management. In terms of the latter, the risk of stock-outs can be reduced and simplified prescribing practices support task shifting of care to nursing and other non-physician clinicians; this strategy is critical to increase access to ART care in settings where physicians are limited in number. In order to support such simplification, successive World Health Organization guidelines for ART in resource-limited settings have aimed to reduce the number of recommended options for first-line ART in such settings. Future drug and regimen choices for resource-limited settings will likely be guided by the same principles that have led to the recommendation of a single preferred regimen and will favour drugs that have the following characteristics: minimal risk of failure, efficacy and tolerability, robustness and forgiveness, no overlapping resistance in treatment sequencing, convenience, affordability, and compatibility with anti-TB and anti-hepatitis treatments.

Racial differences in response to antiretroviral therapy for HIV infection: an AIDS clinical trials group (ACTG) study analysis

BACKGROUND

In the United States, black individuals infected with human immunodeficiency virus (HIV) have higher rates of virologic failure on antiretroviral therapy (ART) and of death compared to white individuals. The cause for these disparities is uncertain. We sought to examine differences in virologic outcomes among antiretroviral-naive clinical trial participants starting randomized ART and to investigate factors to explain the differences.

METHODS

Individual-level data from participants initiating ART in 5 AIDS Clinical Trials Group studies were analyzed. Included studies were those conducted during 1998-2006 with a primary outcome of virologic failure. The primary outcome measure was time to virologic failure, regardless of ART changes.

RESULTS

A total of 2495 individuals (1151 black; 1344 white) were included with a median follow-up of 129 weeks. Compared to whites, blacks had an increased hazard of virologic failure (hazard ratio [HR]; 1.7; 95% confidence interval [CI], 1.4-1.9; P < .001), with no evidence of heterogeneity across regimens (P = .97); the association remained after adjustment for measured confounders (HR, 1.4; 95% CI, 1.2-1.6; P < .001). Increased hazard of virologic failure was associated with younger age, higher pretreatment HIV type 1 RNA level, lower pretreatment CD4 cell count, hepatitis C antibody, less education, and recent nonadherence to treatment. Sensitivity analyses with different endpoint definitions demonstrated similar results.

CONCLUSIONS

In this analysis, blacks had a 40% higher virologic failure risk than whites that was not explained by measured confounders. The observation was consistent over a range of regimens, suggesting that the difference may be driven by social factors; however, biological factors cannot be ruled out. Further research should identify the sources of racial disparities and develop strategies to reduce them.