Ultra-long-acting removable drug delivery system for HIV treatment and prevention

Antiretroviral (ARV) Properties Dictate Long-Acting Release and Tissue Partitioning Behaviors in Multidrug Subcutaneous Implants

Subcutaneous implants can provide patients with long-acting, compliance-independent drug dosing. For this reason, subcutaneous implants have shown emerging interest in human immunodeficiency virus (HIV) prevention. However, any successful long-acting HIV-prevention device will require multidrug dosing, which poses a challenge for formulation considering the physicochemically diverse selection of antiretroviral (ARV) candidates. As a method that has shown the capacity of efficient multidrug delivery, we assessed electrospun fiber implants composed of three synergistically potent ARVs and a biodegradable polymer selected by in vitro release studies. In mice, subcutaneous electrospun fiber implants exhibit burst release of the more hydrophilic drugs maraviroc (MVC) and raltegravir (RAL), which could be reduced via simple prewash treatments of the implants. Over an extended 120 day time frame, fiber implants show drug-specific differences in release time frames and magnitudes in blood serum. However, end-point drug tissue concentrations show that the most hydrophobic drug etravirine (ETR) remains in high concentrations within the implant and in local skin tissue biopsies. Furthermore, ETR is found to be capable of significant partitioning into lymph nodes, the lower female reproductive tract, and the rectum. Topologically smooth film implants also exhibit the same drug-dependent trends. Therefore, we illustrate that drug release and drug tissue partitioning are largely dictated by drug properties. Further, we find that the properties of ETR enable significant drug quantities within the tissues most relevant to HIV protection. Evidence from this work emphasizes the need for a greater focus on drug properties and prodrug strategies to enable relevant, extended, and targeted drug release.

Combination of compound screening with an animal model identifies pentamidine to prevent Chlamydia trachomatis infection

Chlamydia trachomatis (Ct) is the most common cause for bacterial sexually transmitted infections (STIs) worldwide with a tremendous impact on public health. With the aim to unravel novel targets of the chlamydia life cycle, we screen a compound library and identify 28 agents to significantly reduce Ct growth. The known anti-infective agent pentamidine-one of the top candidates of the screen-shows anti-chlamydia activity in low concentrations by changing the metabolism of host cells impairing chlamydia growth. Furthermore, it effectively decreases the Ct burden upon local or systemic application in mice. Pentamidine also inhibits the growth of Neisseria gonorrhea (Ng), which is a common co-infection of Ct. The conducted compound screen is powerful in exploring antimicrobial compounds against Ct in a medium-throughput format. Following thorough in vitro and in vivo assessments, pentamidine emerges as a promising agent for topical prophylaxis or treatment against Ct and possibly other bacterial STIs.

Injectable long-acting formulations (ILAFs) and manufacturing techniques

INTRODUCTION

Most therapeutics delivered using short-acting formulations need repeated administration, which can harm patient compliance and raise failure risks related to inconsistent treatment. Injectable long-acting formulations (ILAFs) are controlled/sustained-release formulations fabricated to deliver active pharmaceutical ingredients (APIs) and extend their half-life over days to months. Longer half-lives of ILAFs minimize the necessity for frequent doses, increase patient compliance, and reduce the risk of side effects from intravenous (IV) infusions. Using ILAF technologies, the immediate drug release can also be controlled, thereby minimizing potential adverse effects due to high initial drug blood concentrations.

AREA COVERED

In this review, we have discussed various ILAFs, their physiochemical properties, fabrication technologies, advantages, and practical issues, as well as address some major challenges in their application. Especially, the approved ILAFs are highlighted.

EXPERT OPINION

ILAFs are sustained-release formulations with extended activity, which can improve patient compliance. ILAFs are designed to deliver APIs like proteins and peptides and extend their half-life over days to months. The specific properties of each ILAF preparation, such as extended-release and improved drug targeting capabilities, make them an effective approach for precise and focused therapy. Furthermore, this is especially helpful for biopharmaceuticals with short biological half-lives and low stability since most environmental conditions can protect them from sustained-release delivery methods.

3D printing of dolutegravir-loaded polylactide filaments as a long-acting implantable system for HIV treatment

3D printing was used to prepare implantable systems or tablets loaded with dolutegravir to explore their potential as long-acting implantables (LAIs). Our strategy relies on preparing a polylactide (PLA) filament loaded with the anti-HIV drug. Subsequently, 3D printing was performed under conditions that allowed the PLA to be simultaneously melted and the drug encapsulated within the printed strand. The dolutegravir release profiles indicated its sustained release for 47 days. Furthermore, neat and drug-loaded tablets were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA), while their morphology was assessed by scanning electron microscopy (SEM). Finally, their biocompatibility was proved by MTT assay against ISO standards recommended L929 mouse and human Hs68 skin fibroblast cells. All the results indicated that the 3D printing of PLA-based tablets could produce customized medications with potential applications against HIV.

Antiviral potency of long-acting islatravir subdermal implant in SHIV-infected macaques

Treatment nonadherence is a pressing issue in people living with HIV (PLWH), as they require lifelong therapy to maintain viral suppression. Poor adherence leads to antiretroviral (ARV) resistance, transmission to others, AIDS progression, and increased morbidity and mortality. Long-acting (LA) ARV therapy is a promising strategy to combat the clinical drawback of user-dependent dosing. Islatravir (ISL) is a promising candidate for HIV treatment given its long half-life and high potency. Here we show constant ISL release from a subdermal LA nanofluidic implant achieves viral load reduction in SHIV-infected macaques. Specifically, a mean delivery dosage of 0.21 ± 0.07 mg/kg/day yielded a mean viral load reduction of -2.30 ± 0.53 log10 copies/mL at week 2, compared to baseline. The antiviral potency of the ISL delivered from the nanofluidic implant was higher than oral ISL dosed either daily or weekly. At week 3, viral resistance to ISL emerged in 2 out of 8 macaques, attributable to M184V mutation, supporting the need of combining ISL with other ARV for HIV treatment. The ISL implant produced moderate reactivity in the surrounding tissue, indicating tolerability. Overall, we present the ISL subdermal implant as a promising approach for LA ARV treatment in PLWH.

Advancements in Cell-Based Therapies for HIV Cure

The treatment of human immunodeficiency virus (HIV-1) has evolved since the establishment of combination antiretroviral therapy (ART) in the 1990s, providing HIV-infected individuals with approaches that suppress viral replication, prevent acquired immunodeficiency syndrome (AIDS) throughout their lifetime with continuous therapy, and halt HIV transmission. However, despite the success of these regimens, the global HIV epidemic persists, prompting a comprehensive exploration of potential strategies for an HIV cure. Here, we offer a consolidated overview of cell-based therapies for HIV-1, focusing on CAR-T cell approaches, gene editing, and immune modulation. Persistent challenges, including CAR-T cell susceptibility to HIV infection, stability, and viral reservoir control, underscore the need for continued research. This review synthesizes current knowledge, highlighting the potential of cellular therapies to address persistent challenges in the pursuit of an HIV cure.

Development of long-acting injectable suspensions by continuous antisolvent crystallization: An integrated bottom-up process

Our present work elucidated the operational feasibility of direct generation and stabilization of long-acting injectable (LAI) suspensions of a practically insoluble drug, itraconazole (ITZ), by combining continuous liquid antisolvent crystallization with downstream processing (i.e., centrifugal filtration and reconstitution). A novel microchannel reactor-based bottom-up crystallization setup was assembled and optimized for the continuous production of micro-suspension. Based upon the solvent screening and solubility study, N-methyl pyrrolidone (NMP) was selected as the optimal solvent and an impinging jet Y-shaped microchannel reactor (MCR) was selected as the fluidic device to provide a reproducible homogenous mixing environment. Operating parameters such as solvent to antisolvent ratio (S/AS), total jet liquid flow rates (TFRs), ITZ feed solution concentration and the maturation time in spiral tubing were tailored to 1:9 v/v, 50 mL/min, 10 g/100 g solution, and 96 h, respectively. Vitamin E TPGS (0.5% w/w) was found to be the most suitable excipient to stabilize ITZ particles amongst 14 commonly used stabilizers screened. The effect of scaling up from 25 mL to 15 L was evaluated effectively with in situ monitoring of particle size distribution (PSD) and solid-state form. Thereafter, the suspension was subjected to centrifugal filtration to remove excess solvent and increase ITZ solid fraction. As an alternative, an even more concentrated wet pellet was reconstituted with an aqueous solution of 0.5% w/w Vitamin E TPGS as resuspending agent. The ITZ LAI suspension (of 300 mg/mL solid concentration) has the optimal PSD with a D10 of 1.1 ± 0.3 µm, a D50 of 3.53 ± 0.4 µm and a D90 of 6.5 ± 0.8 µm, corroborated by scanning electron microscopy (SEM), as remained stable after 548 days of storage at 25 °C. Finally, in vitro release methods using Dialyzer, dialysis membrane sac were investigated for evaluation of dissolution of ITZ LAI suspensions. The framework presented in this manuscript provides a useful guidance for development of LAI suspensions by an integrated bottom-up approach using ITZ as model API.

Long-acting injectable multipurpose prevention technology for prevention of HIV and unplanned pregnancy

Only condoms are proven to protect against both HIV and unplanned pregnancy, however, poor user acceptability and lack of partner cooperation impede effectiveness. We developed an injectable ultra-long-acting, biodegradable, and removable in-situ forming implant (ISFI) as multipurpose prevention technology (MPT). MPT ISFIs co-formulated an antiretroviral (dolutegravir (DTG)) or cabotegravir (CAB)), and a hormonal contraceptive (etonogestrel (ENG) or medroxyprogesterone acetate (MPA)). All formulations were well-tolerated in mice with no signs of chronic local or systemic inflammation. Plasma CAB and DTG concentrations were above 4× PA-IC90 for 90 days with zero-order and diffusion-controlled absorption, respectively, and no differences when co-formulated with either hormone. Plasma ENG and MPA concentrations were quantifiable for 90 days. Complete removal of CAB/MPA ISFIs resulted in MPA concentrations falling below the limit of quantification after 24 h post-removal, but incomplete CAB elimination from plasma. Collectively, we demonstrated the ability to co-formulate antiretrovirals with contraceptives in an ISFI that is well-tolerated with sustained plasma concentrations up to 90 days.

Layer-by-layer reinforced-mediated sustained-release nanoantioxidants for long-lasting prevention against drug-induced liver injury

Drug-induced liver injury (DILI) is a commonly encountered and diagnostically complex etiology of acute liver failure, characterized by early indications of hepatic oxidative stress. The most economical approach for DILI treatment is effective and durable oxidative stress prevention. Herein, we propose a long-lasting nanoantioxidant called PDA-Zn-BAI NPs characterized by sustained-release of baicalein (a natural antioxidant) for the long-lasting prevention of DILI. It is constructed using dopamine as an intermediate and layer-by-layer reinforcement strategy based on Zn2+-mediated coordination bonding, π-π stacking, and steric hindrance made of polydopamine network. Optimized PDA-Zn-BAI NPs performed a satisfactory sustained-release effect (36.67% ± 6.67 in normal condition and 60.32% ± 3.19 in acid condition of cumulative release within 5 days). Furthermore, it's been found that PDA-Zn-BAI NPs could continuously be accumulated in the liver with negligible hepatotoxicity and were activated to effectively scavenge reactive oxygen species to break off the damage of acetaminophen to the liver within 5 days (ALT as an indicator, > 70% prevention effect lasts for 5 days), which was vital for the long-lasting prevention of DILI. The long-lasting detoxification by PDA-Zn-BAI NPs in patients with DILI suggested a potential clinical application, especially for those patients who need prolonged administration of hepatotoxic drugs.

Prevention, treatment and cure of HIV infection

The development of antiretroviral therapy for the prevention and treatment of HIV infection has been marked by a series of remarkable successes. However, the efforts to develop a vaccine have largely failed, and efforts to discover a cure are only now beginning to gain traction. In this Review, we describe recent progress on all fronts - pre-exposure prophylaxis, vaccines, treatment and cure - and we discuss the unmet needs, both current and in the coming years. We describe the emerging arsenal of drugs, biologics and strategies that will hopefully address these needs. Although HIV research has largely been siloed in the past, this is changing, as the emerging research agenda is marked by multiple cross-discipline synergies and collaborations. As the limitations of antiretroviral drugs as a means to truly end the epidemic are becoming more apparent, there is a great need for continued efforts to develop an effective preventative vaccine and a scalable cure, both of which remain formidable challenges.

EFdA efficiently suppresses HIV replication in the male genital tract and prevents penile HIV acquisition

Sexually transmitted HIV infections in heterosexual men are acquired through the penis. Low adherence to condom usage and the fact that 40% of circumcised men are not protected indicate the need for additional prevention strategies. Here, we describe a new approach to evaluate the prevention of penile HIV transmission. We demonstrated that the entire male genital tract (MGT) of bone marrow/liver/thymus (BLT) humanized mice is repopulated with human T and myeloid cells. The majority of the human T cells in the MGT express CD4 and CCR5. Direct penile exposure to HIV leads to systemic infection including all tissues of the MGT. HIV replication throughout the MGT was reduced 100-1,000-fold by treatment with 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA), resulting in the restoration of CD4+ T cell levels. Importantly, systemic preexposure prophylaxis with EFdA effectively protects from penile HIV acquisition. IMPORTANCE Over 84.2 million people have been infected by the human immunodeficiency virus type 1 (HIV-1) during the past 40 years, most through sexual transmission. Men comprise approximately half of the HIV-infected population worldwide. Sexually transmitted HIV infections in exclusively heterosexual men are acquired through the penis. However, direct evaluation of HIV infection throughout the human male genital tract (MGT) is not possible. Here, we developed a new in vivo model that permits, for the first time, the detail analysis of HIV infection. Using BLT humanized mice, we showed that productive HIV infection occurs throughout the entire MGT and induces a dramatic reduction in human CD4 T cells compromising immune responses in this organ. Antiretroviral treatment with novel drug EFdA suppresses HIV replication in all tissues of the MGT, restores normal levels of CD4 T cells and is highly efficient at preventing penile transmission.

The Integrase: An Overview of a Key Player Enzyme in the Antiviral Scenario

Integration of a desossiribonucleic acid (DNA) copy of the viral ribonucleic acid (RNA) into host genomes is a fundamental step in the replication cycle of all retroviruses. The highly conserved virus-encoded Integrase enzyme (IN; EC 2.7.7.49) catalyzes such a process by means of two consecutive reactions named 3'-processing (3-P) and strand transfer (ST). The Authors report and discuss the major discoveries and advances which mainly contributed to the development of Human Immunodeficiency Virus (HIV) -IN targeted inhibitors for therapeutic applications. All the knowledge accumulated over the years continues to serve as a valuable resource for the design and development of effective antiretroviral drugs.

Osmolality of Excipients for Parenteral Formulation Measured by Freezing Point Depression and Vapor Pressure - A Comparative Analysis

PURPOSE

To investigate the difference in methods to determine the osmolality in solutions of stabilizers used for long-acting injectable suspensions.

METHODS

The osmolality was measured by freezing point depression and vapor pressure for 11 different polymers and surfactants (PEG 3350, 4000, 6000, 8000, 20,000, PVP K12, K17 and K30, poloxamer 188, 388 and 407, HPMC E5, Na-CMC, polysorbate 20 and 80, vitamin E-TPGS, phospholipid, DOSS and SDS) in different concentrations.

RESULTS

Independently of the measuring method, an increase in osmolality with increasing concentration was observed for all polymers and surfactants, as would be expected due to the physicochemical origin of the osmolality. No correlation was found between the molecular weight of the polymers and the measured osmolality. The osmolality values were different for PVPs, PEGs, and Na-CMC using the two different measurement methods. The values obtained by the freezing point depression method tended to be similar or higher than the ones provided by vapor pressure, overall showing a significant difference in the osmolality measured by the two investigated methods.

CONCLUSIONS

For lower osmolality values (e.g. surfactants), the choice of the measuring method was not critical, both the freezing point depression and vapor pressure could be used. However, when the formulations contained higher concentrations of excipients and/or thermosensitive excipients, the data suggests that the vapor pressure method would be more suited.

Accelerated reactive dissolution model of drug release from long-acting injectable formulations

Long-acting injectable formulations represent a rapidly emerging category of drug delivery systems that offer several advantages compared to orally administered medicines. Rather than having to frequently swallow tablets, the medication is administered to the patient by intramuscular or subcutaneous injection of a nanoparticle suspension that forms a local depot from which the drug is steadily released over a period of several weeks or months. The benefits of this approach include improved medication compliance, reduced fluctuations of drug plasma level, or the suppression of gastrointestinal tract irritation. The mechanism of drug release from injectable depot systems is complex, and there is a lack of models that would enable quantitative parametrisation of the process. In this work, an experimental and computational study of drug release from a long-acting injectable depot system is reported. A population balance model of prodrug dissolution from asuspension with specific particle size distribution has been coupled with the kinetics of prodrug hydrolysis to its parent drug and validated using in vitro experimental data obtained from an accelerated reactive dissolution test. Using the developed model, it is possible to predict the sensitivity of drug release profiles to the initial concentration and particle size distribution of the prodrug suspension, and subsequently simulate various drug dosing scenarios. Parametric analysis of the system has identified the boundaries of reaction- and dissolution-limited drug release regimes, and the conditions for the existence of a quasi-steady state. This knowledge is crucial for the rational design of drug formulations in terms of particle size distribution, concentration and intended duration of drug release.

Dose-Ranging Plasma and Genital Tissue Pharmacokinetics and Biodegradation of Ultra-Long-Acting Cabotegravir In Situ Forming Implant

HIV continues to affect millions of men and women worldwide. The development of long-acting injectables for HIV prevention can overcome adherence challenges with daily oral prevention regimens by reducing dosing frequency and stigma. We previously developed an ultra-long-acting injectable, biodegradable, and removeable in situ forming implant (ISFI) with cabotegravir (CAB) that demonstrated protection after multiple rectal SHIV challenges in female macaques. Here, we sought to further characterize CAB ISFI pharmacokinetics (PK) in mice by assessing the effect of dose and number of injections on CAB PK, time to completion of CAB release and polymer degradation, long-term genital tissue PK, and CAB PK tail after implant removal. CAB concentrations in plasma were above the benchmark for protection for 11-12 months with proportionality between dose and drug exposure. CAB ISFI exhibited high concentrations in vaginal, cervical, and rectal tissues for up to 180 days. Furthermore, depots were easily retrievable up to 180 days post-administration with up to 34% residual CAB and near complete (85%) polymer degradation quantified in depots ex vivo. After depot removal, results demonstrated a median 11-fold decline in CAB plasma concentrations across all doses. Ultimately, this study provided critical PK information for the CAB ISFI formulation that could aid in its future translation to clinical studies.

Long-acting Parenteral Drug Delivery Systems for the Treatment of Chronic Diseases

The management of chronic conditions often requires patients to take daily medication for an extended duration. However, the need for daily dosing can lead to nonadherence to the therapy, which can result in the recurrence of the disease. Long-acting parenteral drug delivery systems have the potential to improve the treatment of chronic conditions. These systems use various technologies, such as oil-based injectables, PLGA-based microspheres, and in situ forming gel-based depots, to deliver different types of drugs. The use of long-acting parenteral formulations for the treatment of chronic infections such as HIV/AIDS and tuberculosis is a recent development in the field. Researchers are also exploring the use of long-acting parenteral formulations for the treatment of malaria, with the aim of reducing dosing frequency and improving adherence to treatment. This review discusses various aspects of long-acting formulation development, including the impact of the physicochemical properties of the drug, the type of long-acting formulation, and the route of administration. The clinical significance of long-acting formulations and recent advances in the field, such as long-acting nanoformulations and long-acting products currently in clinical trials, have also been highlighted.

Ultra-long-acting in-situ forming implants with cabotegravir protect female macaques against rectal SHIV infection

Ultra-long-acting delivery platforms for HIV pre-exposure prophylaxis (PrEP) may increase adherence and maximize public health benefit. We report on an injectable, biodegradable, and removable in-situ forming implant (ISFI) that is administered subcutaneously and can release the integrase inhibitor cabotegravir (CAB) above protective benchmarks for more than 6 months. CAB ISFIs are well-tolerated in female mice and female macaques showing no signs of toxicity or chronic inflammation. In macaques, median plasma CAB concentrations exceed established PrEP protection benchmarks within 3 weeks and confer complete protection against repeated rectal SHIV challenges. Implant removal via a small incision in 2 macaques at week 12 results in a 7- to 48-fold decrease in plasma CAB levels within 72 hours. Modeling to translate CAB ISFI dosing suggests that a 3 mL injection would exceed protective benchmarks in humans for over 5 months post administration. Our results support the clinical advancement of CAB ISFIs for ultra-long-acting PrEP in humans.

Investigational drugs for HIV: trends, opportunities and key players

INTRODUCTION

Since the first antiretroviral drug was described, the field of HIV treatment and prevention has undergone two drug-based revolutions: the first one, enabled by the virtually concomitant discovery of non-nucleoside reverse transcriptase and protease inhibitors, was the inception of combined antiretroviral therapy. The second followed the creation of integrase strand-transfer inhibitors with improved safety, potency, and resistance profiles. Long-acting antiretroviral drugs, including broadly neutralizing antibodies, now offer the opportunity for a third transformational change in HIV management.

AREAS COVERED

Our review focused on HIV treatment and prevention with investigational drugs that offer the potential for infrequent dosing, including drugs not yet approved for clinical use. We also discussed approved drugs for which administration modalities or formulations are being optimized. We performed a literature search in published manuscripts, conference communications, and registered clinical trials.

EXPERT OPINION

While the field focuses on extending dosing intervals, we identify drug tissue penetration as an understudied opportunity to improve HIV care. We repeat that self-administration remains an essential milestone to reach the full potential of long-acting drugs. Treatments and prevention strategies based on broadly neutralizing antibodies require a deeper understanding of their antiretroviral properties.

Safety and efficacy of a biodegradable implant releasing tenofovir alafenamide for vaginal protection in a macaque model

OBJECTIVES

To advance the initiative of ending the global epidemic, long-lasting HIV protection is needed through sustained release of antiretroviral drugs for months to years. We investigated in macaques the safety and efficacy of biodegradable polycaprolactone implants releasing tenofovir alafenamide for HIV pre-exposure prophylaxis (PrEP).

METHODS

Implants were administered subcutaneously in the arm using a contraceptive trocar. Efficacy against vaginal simian-HIV (SHIV) infection was investigated in six pigtailed macaques that received two tenofovir alafenamide implants (0.35 mg/day), one in each arm, for a total release rate of tenofovir alafenamide at 0.7 mg/day. Macaques were exposed to SHIV twice weekly for 6 weeks. Statistical analyses were used to compare outcome with eight untreated controls. Histological assessments were performed on skin biopsies collected near implantation sites.

RESULTS

Median (range) tenofovir diphosphate level in PBMCs was 1519 (1068-1898) fmol/106 cells. All macaques with tenofovir alafenamide implants were protected against vaginal SHIV infection. In contrast, 7/8 controls were infected after a median of 4 SHIV exposures (P = 0.0047). Histological assessment of tissues near tenofovir alafenamide implant sites showed inflammation and necrosis in 5/6 animals, which were not evident by visual inspection.

CONCLUSIONS

We demonstrated complete protection against vaginal SHIV infection with two implants releasing a total of 0.7 mg of tenofovir alafenamide per day. We also identified tenofovir diphosphate concentrations in PBMCs associated with complete vaginal protection. Consistent with previous findings, we observed adverse local toxicity and necrosis near the tenofovir alafenamide implant site. Improved tenofovir alafenamide implants that are safe and maintain high efficacy have the potential to provide long-lasting protection against vaginal HIV infection.

Long-acting HIV Pre-exposure Prophylaxis (PrEP) approaches: Recent advances, emerging technologies and development challenges

Introduction:

Poor or inconsistent adherence to daily oral pre-exposure prophylaxis (PrEP) has emerged as a key barrier to effective HIV prevention. The advent of potent long-acting (LA) antiretrovirals (ARVs) in conjunction with advances in controlled release technologies has enabled LA ARV drug delivery systems (DDS) capable of providing extended dosing intervals and overcome the challenge of suboptimal drug adherence with daily oral dosing.

Areas covered:

This review discusses the current state of the LA PrEP field, recent advances, and emerging technologies, including ARV prodrug modifications and new DDS. Technological challenges, knowledge gaps, preclinical testing considerations, and future directions important in the context of clinical translation and implementation of LA HIV PrEP are discussed.

Expert opinion:

The HIV prevention field is evolving faster than ever and the bar for developing next-generation LA HIV prevention options continues to rise. The requirements for viable LA PrEP products to be implemented in resource-limited settings are challenging, necessitating proactive consideration and product modifications during the design and testing of promising new candidates. If successfully translated, next-generation LA PrEP that are safe, affordable, highly effective, and accepted by both end-users and key stakeholders will offer significant potential to curb the HIV pandemic.

Impact of Excipients and Seeding on the Solid-State Form Transformation of Indomethacin during Liquid Antisolvent Precipitation

Long-acting injectables are a unique drug formulation strategy, providing a slow and sustained release of active pharmaceutical ingredients (APIs). In this study, a novel approach that combines liquid antisolvent precipitation with seeding to obtain a stable form of the API indomethacin while achieving the desired particle size distribution is described. It was proven that when a metastable form of indomethacin was initially nucleated, the rate of its transformation to the stable form was influenced by the presence of excipients and seeds (17.10 ± 0.20 μm), decreasing from 48 to 4 h. The final particle size (D50) of the indomethacin suspension produced without seeding was 7.33 ± 0.38 μm, and with seeding, it was 5.61 ± 0.14 μm. Additionally, it was shown that the particle size distribution of the seeds and the time point of seed addition were critical to obtain the desired solid-state form and that excipients played a crucial role during nucleation and polymorphic transformation. This alternative, energy-efficient bottom-up method for the production of drug suspensions with a reduced risk of contamination from milling equipment and fewer processing steps may prove to be comparable in terms of stability and particle size distribution to current industrially accepted top-down approaches.

A long-acting formulation of rifabutin is effective for prevention and treatment of Mycobacterium tuberculosis

Tuberculosis (TB) is a communicable disease caused by Mycobacterium tuberculosis (Mtb) and is a major cause of morbidity and mortality. Successful treatment requires strict adherence to drug regimens for prolonged periods of time. Long-acting (LA) delivery systems have the potential to improve adherence. Here, we show the development of LA injectable drug formulations of the anti-TB drug rifabutin made of biodegradable polymers and biocompatible solvents that solidifies after subcutaneous injection. Addition of amphiphilic compounds increases drug solubility, allowing to significantly increase formulation drug load. Solidified implants have organized microstructures that change with formulation composition. Higher drug load results in smaller pore size that alters implant erosion and allows sustained drug release. The translational relevance of these observations in BALB/c mice is demonstrated by (1) delivering high plasma drug concentrations for 16 weeks, (2) preventing acquisition of Mtb infection, and (3) clearing acute Mtb infection from the lung and other tissues.

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.

Transformation of dolutegravir into an ultra-long-acting parenteral prodrug formulation

Ultra-long-acting integrase strand transfer inhibitors were created by screening a library of monomeric and dimeric dolutegravir (DTG) prodrug nanoformulations. This led to an 18-carbon chain modified ester prodrug nanocrystal (coined NM2DTG) with the potential to sustain yearly dosing. Here, we show that the physiochemical and pharmacokinetic (PK) formulation properties facilitate slow drug release from tissue macrophage depot stores at the muscle injection site and adjacent lymphoid tissues following single parenteral injection. Significant plasma drug levels are recorded up to a year following injection. Tissue sites for prodrug hydrolysis are dependent on nanocrystal dissolution and prodrug release, drug-depot volume, perfusion, and cell-tissue pH. Each affect an extended NM2DTG apparent half-life recorded by PK parameters. The NM2DTG product can impact therapeutic adherence, tolerability, and access of a widely used integrase inhibitor in both resource limited and rich settings to reduce HIV-1 transmission and achieve optimal treatment outcomes.

Preferences for Multipurpose Technology and Non-oral Methods of Antiretroviral Therapy Among Women Living With HIV in Western Kenya: A Survey Study

Introduction

Understanding interests in and preferences for multipurpose technology (MPT) for the co-administration of contraception and antiretroviral therapy (ART) and alternative, non-oral ART methods among women living with HIV (WLHIV) is vital to successful implementation of future treatment options, such as long-acting injectable ART.

Methods

Between May 2016 and March 2017 we conducted a cross-sectional telephone survey of 1,132 WLHIV of reproductive potential with prior experience using intermediate- or long-acting contraceptive methods in western Kenya. We present descriptive statistics and multinomial logistic regression to evaluate predictors of interest in specific MPT and non-oral ART methods.

Results

Two-thirds (67%) reported interest in MPT, with the most common reason for interest being ease of using a single medication for both purposes of HIV treatment and pregnancy prevention (26%). Main reasons for lack of interest in MPT were need to stop/not use contraception while continuing ART (21%) and risk of side effects (16%). Important characteristics of MPT were effectiveness for pregnancy prevention (26%) and HIV treatment (24%) and less than daily dosing (19%). Important characteristics of non-oral ART methods were less than daily dosing (47%), saving time accessing ART (16%), and effectiveness of HIV treatment (15%). The leading preferred methods for both MPT and non-oral ART were injectables (50 and 54%) and implants (32 and 31%). Prior use of a contraceptive implant or injectable predicted interest in similar methods for both MPT and non-oral ART methods, while this relationship did not appear to vary between younger vs. older WLHIV.

Discussion

Most WLHIV in western Kenya are interested in MPT for HIV treatment and contraception. Prior exposure to contraceptive implants or injectables appears to predict interest in similar methods of MPT and non-oral ART. Developers of MPT and non-oral ART methods should strongly consider WLHIV's preferences, including their changing reproductive desires.

Effects of Injection Volume and Route of Administration on Dolutegravir In Situ Forming Implant Pharmacokinetics

Due to the versatility of the in situ forming implant (ISFI) drug delivery system, it is crucial to understand the effects of formulation parameters for clinical translation. We utilized ultrasound imaging and pharmacokinetics (PK) in mice to understand the impact of administration route, injection volume, and drug loading on ISFI formation, degradation, and drug release in mice. Placebo ISFIs injected subcutaneously (SQ) with smaller volumes (40 μL) exhibited complete degradation within 30–45 days, compared to larger volumes (80 μL), which completely degraded within 45–60 days. However, all dolutegravir (DTG)-loaded ISFIs along the range of injection volumes tested (20–80 μL) were present at 90 days post-injection, suggesting that DTG can prolong ISFI degradation. Ultrasound imaging showed that intramuscular (IM) ISFIs flattened rapidly post administration compared to SQ, which coincides with the earlier T_max for drug-loaded IM ISFIs. All mice exhibited DTG plasma concentrations above four times the protein-adjusted 90% inhibitory concentration (PA-IC90) throughout the entire 90 days of the study. ISFI release kinetics best fit to zero order or diffusion-controlled models. When total administered dose was held constant, there was no statistical difference in drug exposure regardless of the route of administration or number of injections.

A nanofiber based antiviral (TAF) prodrug delivery system

HIV and hepatitis B are two of the most prevalent viruses globally, and despite readily available preventive treatments unforgiving treatment regimens still exist, such as daily doses of medicine that are challenging to maintain especially in poorer countries. More advanced and longer-lasting delivery vehicles can potentially overcome this problem by reducing maintenance requirements and significantly increase access to medicine. Here, we designed a technology to control the delivery of an antiviral drug over a long timeframe via a nanofiber based delivery scaffold that is both easy to produce and use. An antiviral prodrug containing tenofovir alafenamide (TAF) was synthesized by initial conjugation to glycerol monomethacrylate followed by polymerization to form a diblock copolymer (pTAF) using reversible addition-fragmentation chain transfer (RAFT). In order to generate an efficient drug delivery system this copolymer was fabricated into an electrospun nanofiber (ESF) scaffold using blend electrospinning with poly(caprolactone) (PCL) as the carrier polymer. SEM images revealed that the pTAF-PCL ESFs were uniform with an average diameter of (787 ± 0.212 nm), while XPS analysis demonstrated that the pTAF was overrepresented at the surface of the ESFs. Additionally, the pTAF exhibited a sustained release profile over a 2 month period in human serum (HS), suggesting that these types of copolymer-based drugamers can be used in conjunction with electrospinning to produce long-lasting drug delivery systems.

Long-acting and extended-release implant and nanoformulations with a synergistic antiretroviral two-drug combination controls HIV-1 infection in a humanized mouse model

The HIV pandemic has affected over 38 million people worldwide with close to 26 million currently accessing antiretroviral therapy (ART). A major challenge in the long-term treatment of HIV-1 infection is nonadherence to ART. Long-acting antiretroviral (LA-ARV) formulations, that reduce dosing frequency to less than once a day, are an urgent need that could tackle the adherence issue. Here, we have developed two LA-ART interventions, one an injectable nanoformulation, and the other, a removable implant, for the delivery of a synergistic two-drug ARV combination comprising a pre-clinical nonnucleoside reverse transcriptase inhibitor (NNRTI), Compound I, and the nucleoside reverse transcriptase inhibitor (NRTI), 4'-ethynyl-2-fluoro-2'-deoxyadenosine. The nanoformulation is poly(lactide-co-glycolide)-based and the implant is a copolymer of ω-pentadecalactone and p-dioxanone, poly(PDL-co-DO), a novel class of biocompatible, biodegradable materials. Both the interventions, packaged independently with each ARV, released sustained levels of the drugs, maintaining plasma therapeutic indices for over a month, and suppressed viremia in HIV-1-infected humanized mice for up to 42 days with maintenance of CD4+ T cells. These data suggest promise in the use of these new drugs as LA-ART formulations in subdermal implant and injectable mode.

A new engineering process of biodegradable polymeric solid implants for ultra-long-acting drug delivery

We present a long-acting (LA) biodegradable polymeric solid implant (PSI) fabricated using a new process combining in-situ phase inversion and compression. This robust process allows fabrication of solid implants that can have different shapes and sizes, accommodate high drug payloads, and provide sustained drug release over several months. Herein the integrase inhibitor dolutegravir (DTG) was used to develop PSIs for HIV prevention. PSIs were fabricated using a three-step process by (a) phase inversion of DTG-loaded polymer solution to form an initial in-situ forming implant in an aqueous solution, (b) micronization of dried DTG-loaded solid implants, and (c) compression of the micronized DTG-loaded solid implants to form the PSI. High drug loading (up to 85 wt%) was achieved in the PSIs. DTG exhibited minimum burst release in the first 24 h (<6%) and sustained release kinetics over 6 months. The release kinetics of DTG can be fine-tuned by varying drug-loading concentration, the ratio of polymer (poly(lactic-co-glycolic acid), PLGA) to solvent (N-methyl-2-pyrrolidone, NMP) and polymer (PLGA) molecular weight in the precursor solution. The physical/chemical properties of DTG were retained post-storage under accelerated storage conditions (40 °C/75% relative humidity) for 6 months. The versatility of this technology makes it an attractive drug delivery platform for HIV prevention applications.

Long-acting antiretrovirals: a new era for the management and prevention of HIV infection

The long-acting antiretroviral cabotegravir and rilpivirine combination has just received FDA, EMA and Health Canada approval. This novel drug delivery approach is about to revolutionize the therapy of people living with HIV, decreasing the 365 daily pill burden to only six intramuscular injections per year. In addition, islatravir, a first-in-class nucleoside reverse transcriptase translocation inhibitor, is intended to be formulated as an implant with a dosing interval of 1 year or more. At present, long-acting antiretroviral therapies (LA-ARTs) are given at fixed standard doses, irrespectively of the patient's weight and BMI, and without consideration for host genetic and non-genetic factors likely influencing their systemic disposition. Despite a few remaining challenges related to administration (e.g. pain, dedicated medical procedure), the development and implementation of LA-ARTs can overcome long-term adherence issues by improving patients' privacy and reducing social stigma associated with the daily oral intake of anti-HIV treatments. Yet, the current 'one-size-fits-all' approach does not account for the recognized significant inter-individual variability in LA-ART pharmacokinetics. Therapeutic drug monitoring (TDM), an important tool for precision medicine, may provide physicians with valuable information on actual drug exposure in patients, contributing to improve their management in real life. The present review aims to update the current state of knowledge on these novel promising LA-ARTs and discusses their implications, particularly from a clinical pharmacokinetics perspective, for the future management and prevention of HIV infection, issues of ongoing importance in the absence of curative treatment or an effective vaccine.

Multipurpose Prevention Technologies: Oral, Parenteral, and Vaginal Dosage Forms for Prevention of HIV/STIs and Unplanned Pregnancy

There is a high global prevalence of HIV, sexually transmitted infections (STIs), and unplanned pregnancies. Current preventative daily oral dosing regimens can be ineffective due to low patient adherence. Sustained release delivery systems in conjunction with multipurpose prevention technologies (MPTs) can reduce high rates of HIV/STIs and unplanned pregnancies in an all-in-one efficacious, acceptable, and easily accessible technology to allow for prolonged release of antivirals and contraceptives. The concept and development of MPTs have greatly progressed over the past decade and demonstrate efficacious technologies that are user-accepted with potentially high adherence. This review gives a comprehensive overview of the latest oral, parenteral, and vaginally delivered MPTs in development as well as drug delivery formulations with the potential to advance as an MPT, and implementation studies regarding MPT user acceptability and adherence. Furthermore, there is a focus on MPT intravaginal rings emphasizing injection molding and hot-melt extrusion manufacturing limitations and emerging fabrication advancements. Lastly, formulation development considerations and limitations are discussed, such as nonhormonal contraceptive considerations, challenges with achieving a stable coformulation of multiple drugs, achieving sustained and controlled drug release, limiting drug-drug interactions, and advancing past preclinical development stages. Despite the challenges in the MPT landscape, these technologies demonstrate the potential to bridge gaps in preventative sexual and reproductive health care.

Biodegradable polymeric solid implants for ultra-long-acting delivery of single or multiple antiretroviral drugs

Lack of adherence is a key barrier to a successful human immunodeficiency virus (HIV) treatment and prevention. We report on an ultra-long-acting (ULA) biodegradable polymeric solid implant (PSI) that can accommodate one or more antiretrovirals (e.g., dolutegravir (DTG) and rilpivirine (RPV)) at translatable human doses (65% wt.) in a single implant. PSIs are fabricated using a three-step process: (a) phase inversion of a drug/polymer solution to form an initial in-situ forming solid implant, (b) micronization of dried drug-loaded solid implants, and (c) compression of the micronized drug-loaded solid powder to generate the PSI. DTG and RPV can be pre-combined in a single PLGA-based solution to make dual-drug PSI; or formulated individually in PLGA-based solutions to generate separate micronized powders and form a bilayer dual-drug PSI. Results showed that in a single or bilayer dual-drug PSI, DTG and RPV exhibited physicochemical properties similar to their pure drug analogues. PSIs were well tolerated in vivo and effectively delivered drug(s) over 180 days with concentrations above 4× PA-IC90 after a single subcutaneous administration. While biodegradable and do not require removal, these PSIs can safely be removed to terminate the treatment if required. The versatility of this technology makes it attractive as an ULA drug delivery platform for HIV and various therapeutic applications.

Long-acting implants to treat and prevent HIV infection

PURPOSE OF REVIEW

Subcutaneous implants are a promising technology to enable long-acting parenteral delivery of antiretroviral drugs (ARV) because they may be able to provide protective drugs concentrations for a year or longer following a single implant. The present review covers the current status of preclinical and clinical development of antiretroviral implants.

RECENT FINDINGS

Over the past three decades, subcutaneous implants have been widely used for long-acting hormonal contraception and the treatment of hormonally-driven malignancies. They are economical and scalable to manufacture, but require special procedures for insertion and removal. They are generally well tolerated, and can remain in place for up to five years. As long-acting delivery of ARV would confer significant advantages, a few investigational implants are under development for the delivery of ARV; most remain at preclinical stages of development. Islatravir, a potent nucleoside analog reverse transcriptase translocation inhibitor that shows particular promise, has entered clinical testing in implant form. Investigational implants containing tenofovir alafenamide and nevirapine, and entecavir (for hepatitis B virus) have been developed and tested in animal models, with varying degrees of success. There is also burgeoning interest in bioerodable implant formulations of established ARVs.

SUMMARY

LARV implants are a promising new technology, but are in early stages of clinical development. Their potential advantages include more consistent and predictable drug release than that provided by intramuscular injections, the possibility of combining several partner drugs into one implant, and the fact that implants can be removed in the case of a desire to stop treatment or the development of adverse events.

Topical delivery of long-acting antiretrovirals to prevent HIV acquisition

PURPOSE OF REVIEW

Although tremendous successes in HIV treatment and prevention have occurred in the past decade, existing HIV prevention options are inadequate, unacceptable or inaccessible to many. Topical antiretroviral-based preexposure prophylaxis (PrEP) options may offer effective, long-acting prevention to those who do not desire systemic exposure to anti-HIV drugs or who want greater control over their own prevention.

RECENT FINDINGS

Among long-acting topical PrEP agents, the dapivirine vaginal ring has advanced the furthest in product development; recent studies have shown high adherence and persistence and evidence of HIV protection in open-label studies as well as a well tolerated safety profile, across the life cycle in women. A range of other long-acting topical PrEP products for vaginal or rectal drug delivery are under development. Rigorous end-user research has explored how to develop products that are behaviorally congruent for the population at risk and has shown that no single product option will be desired by all, but rather different options will achieve the greatest prevention coverage.

SUMMARY

Topically delivered, long-acting antiretroviral PrEP options are being designed to align with user preferences and lifestyles, providing the potential to more effectively expand the HIV prevention method mix and use and achieve an important impact on HIV globally.

Long-Acting Formulations: A Promising Approach for the Treatment of Chronic Diseases

Medication and patient adherence are the two main aspects of any successful treatment of chronic disease. Even though diseases and its treatment existed for several hundred years, the treatment optimization for a given patient is still a researcher question for scientists. There are differences in treatment duration, prognostic signs and symptoms between patient to patient. Hence, designing ideal formulation to suit individual patient is a challenging task. The conventional formulations like oral solids and liquids gives a partial or incomplete treatment because the patient needs to follow the daily pills for a longer time. In such cases, the long-acting formulations will have better patient compliances as drug will be released for a longer duration. Many such approaches are under the clinical investigation. The favorable pharmacokinetic and pharmacodynamic relationships, will be promising option for the treatment of chronic diseases. In this review, we have highlighted the importance of long-acting formulations in the treatment of chronic diseases and the advent of newer formulation technologies.

Efficacy of silk fibroin biomaterial vehicle for in vivo mucosal delivery of Griffithsin and protection against HIV and SHIV infection ex vivo

Introduction

The majority of new HIV infections occur through mucosal transmission. The availability of readily applicable and accessible platforms for anti‐retroviral (ARV) delivery is critical for the prevention of HIV acquisition through sexual transmission in both women and men. There is a compelling need for developing new topical delivery systems that have advantages over the pills, gels and rings, which currently fail to guarantee protection against mucosal viral transmission in vulnerable populations due to lack of user compliance. The silk fibroin (SF) platform offers another option that may be better suited to individual circumstances and preferences to increase efficacy through user compliance. The objective of this study was to test safety and efficacy of SF for anti‐HIV drug delivery to mucosal sites and for viral prevention.

Methods

We formulated a potent HIV inhibitor Griffithsin (Grft) in a mucoadhesive silk fibroin (SF) drug delivery platform and tested the application in a non‐human primate model in vivo and a pre‐clinical human cervical and colorectal tissue explant model. Both vaginal and rectal compartments were assessed in rhesus macaques (Mucaca mulatta) that received SF (n = 4), no SF (n = 7) and SF‐Grft (n = 11). In this study, we evaluated the composition of local microbiota, inflammatory cytokine production, histopathological changes in the vaginal and rectal compartments and mucosal protection after ex vivo SHIV challenge.

Results

Effective Grft release and retention in mucosal tissues from the SF‐Grft platform resulted in protection against HIV in human cervical and colorectal tissue as well as against SHIV challenge in both rhesus macaque vaginal and rectal tissues. Mucoadhesion of SF‐Grft inserts did not cause any inflammatory responses or changes in local microbiota.

Conclusions

We demonstrated that in vivo delivery of SF‐Grft in rhesus macaques fully protects against SHIV challenge ex vivo after two hours of application and is safe to use in both the vaginal and rectal compartments. Our study provides support for the development of silk fibroin as a highly promising, user‐friendly HIV prevention modality to address the global disparity in HIV infection.

Advances in Humanized Mouse Models to Improve Understanding of HIV-1 Pathogenesis and Immune Responses

Although antiretroviral therapy has transformed human immunodeficiency virus-type 1 (HIV-1) from a deadly infection into a chronic disease, it does not clear the viral reservoir, leaving HIV-1 as an uncurable infection. Currently, 1.2 million new HIV-1 infections occur globally each year, with little decrease over many years. Therefore, additional research is required to advance the current state of HIV management, find potential therapeutic strategies, and further understand the mechanisms of HIV pathogenesis and prevention strategies. Non-human primates (NHP) have been used extensively in HIV research and have provided critical advances within the field, but there are several issues that limit their use. Humanized mouse (Hu-mouse) models, or immunodeficient mice engrafted with human immune cells and/or tissues, provide a cost-effective and practical approach to create models for HIV research. Hu-mice closely parallel multiple aspects of human HIV infection and disease progression. Here, we highlight how innovations in Hu-mouse models have advanced HIV-1 research in the past decade. We discuss the effect of different background strains of mice, of modifications on the reconstitution of the immune cells, and the pros and cons of different human cells and/or tissue engraftment methods, on the ability to examine HIV-1 infection and immune response. Finally, we consider the newest advances in the Hu-mouse models and their potential to advance research in emerging areas of mucosal infections, understand the role of microbiota and the complex issues in HIV-TB co-infection. These innovations in Hu-mouse models hold the potential to significantly enhance mechanistic research to develop novel strategies for HIV prevention and therapeutics.

Harnessing molecular recognition for localized drug delivery

A grand challenge in drug delivery is providing the right dose, at the right anatomic location, for the right duration of time to maximize therapeutic efficacy while minimizing off-target toxicity and other deleterious side-effects. Two general modalities are receiving broad attention for localized drug delivery. In the first, referred to as "targeted accumulation", drugs or drug carriers are engineered to have targeting moieties that promote their accumulation at a specific tissue site from circulation. In the second, referred to as "local anchoring", drugs or drug carriers are inserted directly into the tissue site of interest where they persist for a specified duration of time. This review surveys recent advances in harnessing molecular recognition between proteins, peptides, nucleic acids, lipids, and carbohydrates to mediate targeted accumulation and local anchoring of drugs and drug carriers.

The LAIs Are Coming! Implementation Science Considerations for Long-Acting Injectable Antiretroviral Therapy in the United States: A Scoping Review

Long-acting injectable antiretroviral therapy (LAI-ART) is one of the latest advancements in HIV control with the potential to overcome oral ART barriers to adherence. The objective of this article is to anticipate and examine implementation considerations for LAI-ART using components of the PRISM model, a Practical, Robust Implementation and Sustainability Model for integrating research findings into practice. We conducted a scoping review from January to August 2020 of the growing literature on LAI-ART implementation and other fields using LAI therapies. Key considerations regarding LAI-ART were parsed from the searches and entered into the PRISM implementation science framework. The PRISM framework posed multiple questions for consideration in the development of an optimal implementation strategy for LAI-ART in the United States. These questions revealed the necessity for more data, including acceptability of LAI-ART among many different subgroups of people living with HIV (PLWH), cost effectiveness, patient satisfaction, and patient-reported outcomes, as well as more detailed information related to the external environment for optimal LAI-ART implementation. Ethical considerations of LAI-ART will also need to be considered. The anticipation of, and excitement for, LAI-ART represent the hope for a new direction for HIV treatment that reduces adherence barriers and improves prognoses for PLWH. We have a unique window of opportunity to anticipate implementation considerations for LAI-ART, so this new therapy can be used to its fullest potential. Outstanding questions remain, however, that need to be addressed to help achieve HIV suppression goals in diverse populations.

Microneedles for Extended Transdermal Therapeutics: A Route to Advanced Healthcare

Sustained release of drugs over a pre-determined period is required to maintain an effective therapeutic dose for variety of drug delivery applications. Transdermal devices such as polymeric microneedle patches and other microneedle-based devices have been utilized for sustained release of their payload. Swift clearing of drugs can be prevented either by designing a slow-degrading polymeric matrix or by providing physiochemical triggers to different microneedle-based devices for on-demand release. These long-acting transdermal devices prevent the burst release of drugs. This review highlights the recent advances of microneedle-based devices for sustained release of vaccines, hormones, and antiretrovirals with their prospective safe clinical translation.

Leveraging advances in chemistry to design biodegradable polymeric implants using chitosan and other biomaterials

The metamorphosis of biodegradable polymers in biomedical applications is an auspicious myriad of indagation. The utmost challenge in clinical conditions includes trauma, organs failure, soft and hard tissues, infection, cancer and inflammation, congenital disorders which are still not medicated efficiently. To overcome this bone of contention, proliferation in the concatenation of biodegradable materials for clinical applications has emerged as a silver bullet owing to eco-friendly, nontoxicity, exorbitant mechanical properties, cost efficiency, and degradability. Several bioimplants are designed and fabricated in a way to reabsorb or degrade inside the body after performing the specific function rather than eliminating the bioimplants. The objective of this comprehensive is to unfurl the anecdote of emerging biological polymers derived implants including silk, lignin, soy, collagen, gelatin, chitosan, alginate, starch, etc. by explicating the selection, fabrication, properties, and applications. Into the bargain, emphasis on the significant characteristics of current discernment and purview of nanotechnology integrated biopolymeric implants has also been expounded. This robust contrivance shed light on recent inclinations and evolution in tissue regeneration and targeting organs followed by precedency and fly in the ointment concerning biodegradable implants evolved by employing fringe benefits provided by 3D printing technology for building tissues or organs construct for implantation.

Fully synthetic injectable depots with high drug content and tunable pharmacokinetics for long-acting drug delivery

Clinical studies have validated that antiretroviral (ARV) drugs can serve as an HIV pre-exposure prophylactic (PrEP) strategy. Dosing adherence remains a crucial factor determining the final efficacy outcomes, and both long-acting implants and injectable depot systems are being developed to improve patient adherence. Here, we describe an injectable depot platform that exploits a new mechanism for both formation and controlled release. The depot is a polymeric prodrug synthesized from monomers that incorporate an ARV drug tenofovir alafenamide (TAF) with degradable linkers that can be designed to control release rates. The prodrug monomers are synthetically incorporated into homopolymer or block designs that exhibit high drug weight percent (wt%) and also are hydrophobized in these prodrug segments to drive depot formation upon injection. Drug release converts those monomers to more hydrophilic pendant groups via linker cleavage, and as this drug release proceeds, the polymer chains losing hydrophobicity are then disassociated from the depot and released over time to provide a depot dissolution mechanism. We show that long-acting TAF depots can be designed as block copolymers or as homopolymers. They can also be designed with different linkers, for example with faster or slower degrading p-hydroxybenzyloxycarbonyl (Benzyl) and ethyloxycarbonyl (Alkyl) linkers, respectively. Diblock designs of p(glycerol monomethacrylate)-b-p(Alkyl-TAF-methacrylate) and p(glycerol monomethacrylate)-b-p(Benzyl-TAF-methacrylate) were first characterized in a mouse subcutaneous injection model. The alkylcarbamate linker design (TAF 51 wt%) showed excellent sustained release profiles of the key metabolite tenofovir (TFV) in skin and plasma over a 50-day period. Next, the homopolymer design with a high TAF drug wt% of 73% was characterized in the same model. The homopolymer depots with p(Alkyl-TAFMA) exhibited sustained TFV and TAF release profiles in skin and blood over 60 days, and TFV-DP concentrations in peripheral blood mononuclear cells (PBMC) were found to be at least 10-fold higher than the clinically suggested minimally EC90 protective concentration of 24 fmol/10⁶ cells. These are the first reports of sustained parent TAF dosing observed in mouse and TFV-DP in mouse PBMC. IVIS imaging of rhodamine labeled homopolymer depots showed that degradation and release of the depot coincided with the sustained TAF release. Finally, these polymers showed excellent stability in accelerated stability studies over a six-month time period, and exceptional solubility of over 700 mg/mL in the DMSO formulation solvent. The homopolymer designs have a drug reservoir potential of well over a year at mg/day dosing and may not require cold chain storage for global health and developed world long-acting drug delivery applications.

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.

A systematic review of the genetic mechanisms of dolutegravir resistance

Background

Characterizing the mutations selected by the integrase strand transfer inhibitor (INSTI) dolutegravir and their effects on susceptibility is essential for identifying viruses less likely to respond to dolutegravir therapy and for monitoring persons with virological failure (VF) on dolutegravir therapy.

Methods

We systematically reviewed dolutegravir resistance studies to identify mutations emerging under dolutegravir selection pressure, the effect of INSTI resistance mutations on in vitro dolutegravir susceptibility, and the virological efficacy of dolutegravir in antiretroviral-experienced persons.

Results and conclusions

We analysed 14 studies describing 84 in vitro passage experiments, 26 studies describing 63 persons developing VF plus INSTI resistance mutations on a dolutegravir-containing regimen, 41 studies describing dolutegravir susceptibility results, and 22 clinical trials and 16 cohort studies of dolutegravir-containing regimens. The most common INSTI resistance mutations in persons with VF on a dolutegravir-containing regimen were R263K, G118R, N155H and Q148H/R, with R263K and G118R predominating in previously INSTI-naive persons. R263K reduced dolutegravir susceptibility ∼2-fold. G118R generally reduced dolutegravir susceptibility >5-fold. The highest levels of reduced susceptibility occurred in viruses containing Q148 mutations in combination with G140 and/or E138 mutations. Dolutegravir two-drug regimens were highly effective for first-line therapy and for virologically suppressed persons provided dolutegravir’s companion drug was fully active. Dolutegravir three-drug regimens were highly effective for salvage therapy in INSTI-naive persons provided one or more of dolutegravir’s companion drugs was fully active. However, dolutegravir monotherapy in virologically suppressed persons and functional dolutegravir monotherapy in persons with active viral replication were associated with a non-trivial risk of VF plus INSTI resistance mutations.

Long-acting approaches for delivery of antiretroviral drugs for prevention and treatment of HIV: a review of recent research

INTRODUCTION

Despite significant advances in treatment and prevention of HIV-1 infection, poor adherence to daily combination antiretroviral therapy (ART) regimens remains a major obstacle toward achieving sustained viral suppression and prevention. Adherence to ART could also be compromised by adverse drug reactions and societal factors that limit access to therapy. Therefore, medicines that aim to improve adherence by limiting ART side effects, frequency of dosing and socially acceptable regimens are becoming more attractive.

AREAS COVERED

This review highlights recent advances and challenges in the development of long-acting drug delivery strategies for HIV prevention and treatment. Approaches for extended oral and transdermal deliveries, microbicides, broadly neutralizing antibodies, and long-acting implantable and injectable deliveries are reviewed.

EXPERT OPINION

Emerging approaches on long-acting antiretroviral therapies and broadly neutralizing antibody technologies are currently at various stages of development. Such efforts, if successful and become broadly accepted by clinicians and users, will provide newer and simpler options for prevention and treatment of HIV infection.

Modeling the health impact and cost threshold of long-acting ART for adolescents and young adults in Kenya

BACKGROUND

Despite high efficacy of oral antiretroviral therapy (ART), viral suppression among adolescents and young adults (AYA) living with HIV in sub-Saharan Africa (SSA) remains low. Compared to daily oral ART, bimonthly long-acting injectable ART (LA-ART) may simplify adherence, improve clinical outcomes, and decrease HIV transmission in this priority population. However, LA-ART will likely cost more than oral ART and the cost threshold at which LA-ART will be cost effective in SSA has not been evaluated.

METHODS

We adapted a mathematical model of HIV transmission and progression in Kenya to include HIV acquisition and viral suppression among AYA (age 10-24). We projected the population-level health and economic impact of providing LA-ART to AYA over a 10-year time horizon assuming oral ART costs of US$233 annually and a two-month duration of viral suppression per LA-ART injection. We calculated the maximum cost at which switching from oral to LA-ART would be considered cost-effective, using thresholds of $500 and $1,508 per disability-adjusted life year averted (WHO's threshold of HIV treatment interventions and Kenya's gross domestic product per capita).

FINDINGS

Assuming 85% of AYA switch from oral to injectable formulations, LA-ART is estimated to prevent 40,540 infections and 20,480 deaths over 10 years. The maximum increase in the annual per-person cost of receiving LA-ART is estimated to be $89 and $236 for LA-ART to be cost-effective under the thresholds of $500 and $1,508 per DALY averted, respectively. The cost threshold was lower when non-adherent oral ART AYA users were assumed to be less likely to switch to LA-ART.

INTERPRETATION

Providing LA-ART to AYA can be cost-effective in Kenya if it is less than twice the cost of oral ART. Long-acting injectable ART for priority populations with low viral suppression has the potential to cost-effectively avert disability and death.

FUNDING

National Institutes of Health (R01 HD085807; PI: Kohler).

A year-long extended release nanoformulated cabotegravir prodrug

Long-acting cabotegravir (CAB) extends antiretroviral drug administration from daily to monthly. However, dosing volumes, injection site reactions and health-care oversight are obstacles towards a broad usage. The creation of poloxamer-coated hydrophobic and lipophilic CAB prodrugs with controlled hydrolysis and tissue penetrance can overcome these obstacles. To such ends, fatty acid ester CAB nanocrystal prodrugs with 14, 18 and 22 added carbon chains were encased in biocompatible surfactants named NMCAB, NM2CAB and NM3CAB and tested for drug release, activation, cytotoxicity, antiretroviral activities, pharmacokinetics and biodistribution. Pharmacokinetics studies, performed in mice and rhesus macaques, with the lead 18-carbon ester chain NM2CAB, showed plasma CAB levels above the protein-adjusted 90% inhibitory concentration for up to a year. NM2CAB, compared with NMCAB and NM3CAB, demonstrated a prolonged drug release, plasma circulation time and tissue drug concentrations after a single 45 mg per kg body weight intramuscular injection. These prodrug modifications could substantially improve CAB's effectiveness.

Can the United States achieve 90-90-90?

PURPOSE OF REVIEW

To summarize recent trends in knowledge of HIV status, care and viral suppression, and the status of implementation of relevant contextual requirements for the United States to achieve the 90-90-90 goals. Recently, the US government announced a plan to decrease HIV incidence by over 90% by 2030. Reaching this goal may require higher targets than 90-90-90.

RECENT FINDINGS

The United States is on course to reach 90-90-90 goals in the near future, with 86% of persons with HIV aware of their infection, 74% of persons with diagnosed infection in care, and 83% of persons in care with viral suppression in 2016. Some high-burden subnational jurisdictions have already achieved these goals.

SUMMARY

The United States is likely to reach 90-90-90 targets in the near future. However, to reduce HIV incidence by at least 90% by 2030, the United States will need to rapidly meet the new 95-95-95 targets and deploy a comprehensive strategy with novel approaches to testing, retaining persons with HIV on treatment, and preventing new infections with preexposure prophylaxis and comprehensive syringe services programs.

Understanding Normal and Malignant Human Hematopoiesis Using Next-Generation Humanized Mice

Rodent models for human diseases contribute significantly to understanding human physiology and pathophysiology. However, given the accelerating pace of drug development, there is a crucial need for in vivo preclinical models of human biology and pathology. The humanized mouse is one tool to bridge the gap between traditional animal models and the clinic. The development of immunodeficient mouse strains with high-level engraftment of normal and diseased human immune/hematopoietic cells has made in vivo functional characterization possible. As a patient-derived xenograft (PDX) model, humanized mice functionally correlate putative mechanisms with in vivo behavior and help to reveal pathogenic mechanisms. Combined with single-cell genomics, humanized mice can facilitate functional precision medicine such as risk stratification and individually optimized therapeutic approaches.