New approaches to antiretroviral drug delivery: challenges and opportunities associated with the use of long-acting injectable agents

Injectable long acting antiretroviral for HIV treatment and prevention: perspectives of potential users

BACKGROUND

The use of long acting injectable (LAA) antiretroviral drugs may be an alternative option for HIV treatment and prevention. Our study focused on patient perspectives to understand which individuals, among people with HIV (PWH) and pre-exposure prophylaxis (PrEP) users, would constitute the preferential target for such treatments in terms of expectations, tolerability, adherence and quality of life.

METHODS

The study consisted in one self-administrated questionnaire. Data collected included lifestyle issues, medical history, perceived benefits and inconveniences of LAA. Groups were compared using Wilcoxon rank tests or Fisher's exact test.

RESULTS

In 2018, 100 PWH and 100 PrEP users were enrolled. Overall, 74% of PWH and 89% of PrEP users expressed interest for LAA with a significantly higher rate for PrEP users (p = 0.001). No characteristics were associated with acceptance of LAA in both groups in term of demographics, lifestyle or comorbidities.

CONCLUSION

PWH and PrEP users expressed a high level of interest in LAA, since a large majority seems to be in favor of this new approach. Further studies should be conducted to better characterize targeted individuals.

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).

Perspectives of injectable long acting antiretroviral therapies for HIV treatment or prevention: understanding potential users' ambivalences

Recent clinical trial data showed that injectable long-acting antiretroviral treatment (LA-ART) every four or eight weeks could become an alternative option for HIV treatment or prevention. The purpose of our study was to explore perceptions and potential users' points of views of this new mode of administration through individuals' therapeutic itinerary and their singular history with ART. Between 2018 and 2019, a qualitative study was conducted in two University Hospitals in Paris, France. In-depth interviews were conducted with 15 virologically controlled People Living with HIV (PLWH) and 13 men on pre-exposure prophylaxis (PrEP) for at least six months. Interviews, focused on the daily experience with ART, were recorded, transcribed, and analyzed using thematic content analysis. Collected discourses were organized around three emergent concerns: social, material and experimental. Each of these concerns was perceived as ambivalent, balanced by skepticism and hope. It revealed the complexity of each individual's relationship to their HIV treatment or PrEP, leading to balance the injectable LA-ART popularity reported within clinical trials. This new mode of administration may be a suitable alternative for some PLWH and PrEP users, a "simplification" compared to the oral route. It opens a window for "customizable" ART-treatment according to individuals' lives.

Acceptability and Predictors of Uptake of Anti-retroviral Pre-exposure Prophylaxis (PrEP) Among Fishing Communities in Uganda: A Cross-Sectional Discrete Choice Experiment Survey

We used a discrete choice experiment to assess the acceptability and potential uptake of HIV pre-exposure prophylaxis (PrEP) among 713 HIV-negative members of fishing communities in Uganda. Participants were asked to choose between oral pill, injection, implant, condoms, vaginal ring (women), and men circumcision. Product attributes were HIV prevention effectiveness, sexually transmitted infection (STI) prevention, contraception, waiting time, and secrecy of use. Data were analysed using mixed multinomial logit and latent class models. HIV prevention effectiveness was viewed as the most important attribute. Both genders preferred oral PrEP. Women least preferred the vaginal ring and men the implant. Condom use was predicted to decrease by one third among men, and not to change amongst women. Oral PrEP and other new prevention technologies are acceptable among fishing communities and may have substantial demand. Future work should explore utility of multiple product technologies that combine contraception with HIV and other STI prevention.

Synthesis and characterization of a long-acting emtricitabine prodrug nanoformulation

Purpose

A palmitoylated prodrug of emtricitabine (FTC) was synthesized to extend the drug’s half-life, antiretroviral activities and biodistribution.

Methods

A modified FTC prodrug (MFTC) was synthesized by palmitoyl chloride esterification. MFTC’s chemical structure was evaluated by nuclear magnetic resonance. The created hydrophobic prodrug nanocrystals were encased into a poloxamer surfactant and the pharmacokinetics (PK), biodistribution and antiretroviral activities of the nanoformulation (NMFTC) were assessed. The conversion of MFTC to FTC triphosphates was evaluated.

Results

MFTC coated with poloxamer formed stable nanocrystals (NMFTC). NMFTC demonstrated an average particle size, polydispersity index and zeta potential of 350 nm, 0.24 and −20 mV, respectively. Drug encapsulation efficiency was 90%. NMFTC was readily taken up by human monocyte-derived macrophages yielding readily detected intracellular FTC triphosphates and an extended PK profile.

Conclusion

NMFTC shows improved antiretroviral activities over native FTC. This is coordinate with its extended apparent half-life. The work represents an incremental advance in the development of a long-acting FTC formulation.

Injectable long-acting human immunodeficiency virus antiretroviral prodrugs with improved pharmacokinetic profiles

While highly active antiretroviral therapy (HAART) has significantly reduced mortality rates in patients with human immunodeficiency virus type 1 (HIV-1), its efficacy may be impeded by emergence of drug resistance caused by lack of patient adherence. A therapeutic strategy that requires infrequent drug administration as a result of sustained release of antiretroviral drugs would put less burden on the patient. Long-acting antiretroviral prodrugs for HIV therapy were synthesized through modification of the active drugs, emtricitabine (FTC) and elvitegravir (EVG), with docosahexaenoic acid (DHA) in one-step, one-pot, high-yielding reactions. The in vitro drug release profiles of these synthetic conjugates demonstrated sustained and controlled release of the active drug over a period of 3-4 weeks attributable to the hydrolysis of the chemical linker in conjunction with the hydrophilicity of the parent drug. Both conjugates exhibited superior antiviral activities in tissue culture models of HIV replication as compared to those of the free drugs, strengthening their role as potent prodrugs for HIV therapy. Pharmacokinetic analysis in CD1 mice further confirmed the long-acting aspect of these conjugates with released drug concentrations in plasma detected at their respective IC₉₀/IC₉₅ values over a period of 2 weeks and discernable amounts of active drug even at 6 weeks. Our findings suggest that the injectable small molecule conjugates could be used as long-acting controlled release of FTC and EVG in attempts to mitigate adherence-related HIV resistance.

Qualitative Consumer Research on Acceptance of Long-Acting Pre-Exposure Prophylaxis Products Among Men Having Sex with Men and Medical Practitioners in the United States

Pre-exposure prophylaxis (PrEP) with oral Truvada^® prevents HIV infection. However, the adherence to pill taking required for efficacy has sparked interest in developing new antiretroviral delivery systems that decrease such demands. Long-acting formulations, such as injections and implants, represent promising options that require less frequent adherence. It is important, however, that development of these new modalities be driven by understanding of the value seen in them by target users to maximize their uptake. To identify the key product features that impact user acceptance, we used a three-phase marketing research approach. In this study, we describe the results of the first-phase, qualitative focus group research performed in Chicago and San Francisco that explored subjective perceptions of oral versus alternative PrEP modalities among men having sex with men (MSM) and medical practitioners caring for MSM. Data revealed that potential value in long-acting PrEP lies more in simplifying the lives of users rather than in making them more confident in their adherence. The results provide an important guidance for designing and promoting these future long-acting products to enhance their contribution to increasing the current limited uptake of PrEP that will better stem the HIV epidemic.

Long acting systemic HIV pre-exposure prophylaxis: an examination of the field

Oral pre-exposure prophylaxis for the prevention of HIV-1 transmission (HIV PrEP) has been widely successful as demonstrated by a number of clinical trials. However, studies have also demonstrated the need for patients to tightly adhere to oral dosing regimens in order to maintain protective plasma and tissue concentrations. This is especially true for women, who experience less forgiveness from dose skipping than men in clinical trials of HIV PrEP. There is increasing interest in long-acting (LA), user-independent forms of HIV PrEP that could overcome this adherence challenge. These technologies have taken multiple forms including LA injectables and implantables. Phase III efficacy trials are ongoing for a LA injectable candidate for HIV PrEP. This review will focus on the design considerations for both LA injectable and implantable platforms for HIV PrEP. Additionally, we have summarized the existing LA technologies currently in clinical and pre-clinical studies for HIV PrEP as well as other technologies that have been applied to HIV PrEP and contraceptives. Our discussion will focus on the potential application of these technologies in low resource areas, and their use in global women's health.

Of Mice, Macaques, and Men: Broadly Neutralizing Antibody Immunotherapy for HIV-1

The neutralizing antibodies targeting the HIV-1 envelope protein have been a major focus for HIV therapy. Early studies with anti-HIV-1 neutralizing monoclonal antibodies (mAbs) administered to infected individuals showed some promise, as they resulted in transient reductions in plasma viremia in some recipients. However, resistant viral variants rapidly emerged. A major development during the past 6 to 7 years has been the isolation and characterization of highly potent and broadly neutralizing mAbs (bNAbs) from infected individuals known as "elite neutralizers." These "next-generation" bNAbs have been tested in animal model systems and shown to effectively control virus replication, particularly following combination immunotherapy. The success of these preclinical animal studies has led to human clinical trials using an individual bNAb for therapy. This review examines recent findings from animal models and human clinical trials and discusses the future use of bNAbs for HIV-1 treatment.

The Vaginal Microbiome and its Potential to Impact Efficacy of HIV Pre-exposure Prophylaxis for Women

PURPOSE OF REVIEW

This review describes existing evidence addressing the potential modulation of pre-exposure prophylaxis (PrEP) products, specifically 1% tenofovir (TFV) gel and oral tenofovir-based PrEP, by vaginal dysbiosis and discusses future considerations for delivering novel, long-acting PrEP products to women at high risk for vaginal dysbiosis and HIV.

RECENT FINDINGS

We describe results from analyses investigating the modification of PrEP efficacy by vaginal dysbiosis and studies of biological mechanisms that could render PrEP ineffective in the presence of specific microbiota. A secondary analysis from the CAPRISA-004 cohort demonstrated that there is no effect of the 1% TFV gel in the presence of non-Lactobacillus dominant microbiota. Another recent analysis comparing oral tenofovir-based PrEP efficacy among women with and without bacterial vaginosis in the Partners PrEP Study found that oral PrEP efficacy is not modified by bacterial vaginosis. Gardnerella vaginalis, commonly present in women with vaginal dysbiosis, can rapidly metabolize TFV particularly when it is locally applied and thereby prevent TFV integration into cells. Given that vaginal dysbiosis appears to modulate efficacy for 1% TFV gel but not for oral tenofovir-based PrEP, vaginal dysbiosis is potentially less consequential to HIV protection from TFV in the context of systemic drug delivery and high product adherence. Vaginal dysbiosis may undermine the efficacy of 1% TFV gel to protect women from HIV but not the efficacy of oral PrEP. Ongoing development of novel ring, injectable, and film-based PrEP products should investigate whether vaginal dysbiosis can reduce efficacy of these products, even in the presence of high adherence.

Long-acting injectable atovaquone nanomedicines for malaria prophylaxis

Chemoprophylaxis is currently the best available prevention from malaria, but its efficacy is compromised by non-adherence to medication. Here we develop a long-acting injectable formulation of atovaquone solid drug nanoparticles that confers long-lived prophylaxis against Plasmodium berghei ANKA malaria in C57BL/6 mice. Protection is obtained at plasma concentrations above 200 ng ml-1 and is causal, attributable to drug activity against liver stage parasites. Parasites that appear after subtherapeutic doses remain atovaquone-sensitive. Pharmacokinetic-pharmacodynamic analysis indicates protection can translate to humans at clinically achievable and safe drug concentrations, potentially offering protection for at least 1 month after a single administration. These findings support the use of long-acting injectable formulations as a new approach for malaria prophylaxis in travellers and for malaria control in the field.

The WHO public health approach to HIV treatment and care: looking back and looking ahead

In 2006, WHO set forth its vision for a public health approach to delivering antiretroviral therapy. This approach has been broadly adopted in resource-poor settings and has provided the foundation for scaling up treatment to over 19·5 million people. There is a global commitment to end the AIDS epidemic as a public health threat by 2030 and, to support this goal, there are opportunities to adapt the public health approach to meet the ensuing challenges. These challenges include the need to improve identification of people with HIV infection through expanded approaches to testing; further simplify and improve treatment and laboratory monitoring; adapt the public health approach to concentrated epidemics; and link HIV testing, treatment, and care to HIV prevention. Implementation of these key public health principles will bring countries closer to the goals of controlling the HIV epidemic and providing universal health coverage.

Lack of interaction of lopinavir solid drug nanoparticles with cells of the immune system

AIM

We previously demonstrated that solid drug nanoparticles (SDNs) lopinavir (LPV) dispersed into aqueous media display favorable pharmacokinetics.

METHODS

The impact of LPV SDNs on the function and phenotype of primary human T cells and macrophages (primary sites of HIV replication) was investigated.

RESULTS

LPV significantly increased IL-1β (ninefold higher than untreated cells; p = 0.045) and TNF-α (sixfold higher than untreated cells; p = 0.018) secretion from monocyte-derived macrophages, whereas LPV SDNs did not elicit these responses at comparable drug concentrations. LPV SDNs were demonstrated to be immunologically inert to human T cells and monocyte-derived macrophages.

CONCLUSION

The LPV SDN was demonstrated to exhibit comparable, or favorable behavior compared with an LPV aqueous solution in the employed biocompatibility assessments.

Dual-stimuli responsive injectable microgel/solid drug nanoparticle nanocomposites for release of poorly soluble drugs

An in situ forming implant (ISFI) for drug delivery combines the potential to improve therapeutic adherence for patients with simple administration by injection. Herein, we describe the preparation of an injectable nanocomposite ISFI composed of thermoresponsive poly(N-isopropylacrylamide) based microgels and solid drug nanoparticles. Monodisperse poly(N-isopropylacrylamide) or poly(N-isopropylacrylamide-co-allylamine) microgels were prepared by precipitation polymerisation with mean diameters of approximately 550 nm at 25 °C. Concentrated dispersions of these microgels displayed dual-stimuli responsive behaviour, forming shape persistent bulk aggregates in the presence of both salt (at physiological ionic strength) and at body temperature (above the lower critical solution temperature of the polymer). These dual-stimuli responsive microgels could be injected into an agarose gel tissue mimic leading to rapid aggregation of the particles to form a drug depot. Additionally, the microgel particles aggregated in the presence of other payload nanoparticles (such as dye-containing polystyrene nanoparticles or lopinavir solid drug nanoparticles) to form nanocomposites with high entrapment efficiency of the payload. The resulting microgel and solid drug nanoparticle nanocomposites displayed sustained drug release for at least 120 days, with the rate of release tuned by blending microgels of poly(N-isopropylacrylamide) with poly(N-isopropylacrylamide-co-allylamine) microgels. Cytotoxicity studies revealed that the microgels were not toxic to MDCK-II cells even at high concentrations. Collectively, these results demonstrate a novel, easily injectable, nanocomposite ISFI that provides long-term sustained release for poorly water-soluble drugs without a burst release.

Preferences for Long-Acting Pre-exposure Prophylaxis (PrEP), Daily Oral PrEP, or Condoms for HIV Prevention Among U.S. Men Who Have Sex with Men

HIV prevention method preferences were evaluated among 512 U.S. men who have sex with men (MSM; median age: 22 years). Approximately 90 % consistently preferred one option across pairwise comparisons of condoms, daily oral pre-exposure prophylaxis (PrEP), and long-acting PrEP delivered via either an injectable or one of two types of PrEP implants differing in visibility. Condoms were most frequently preferred (33.8 %), followed by non-visible implants (21.5 %), and oral PrEP (17.0 %); HIV risk was reported by more choosing implants. In a follow-up question comparing the four PrEP options only, daily oral pills and non-visible implants were most frequently preferred (35.5 and 34.3 %, respectively), followed by injections (25.2 %) and visible implants (4.3 %). An inductive, open-coding approach determined that convenience, duration of protection, and privacy were the most commonly cited reasons for a PrEP method choice, and associated with self-report of HIV risk. Tailoring PrEP product development to privacy and other concerns important to those at highest HIV risk may improve HIV prevention.

Injectable agents for pre-exposure prophylaxis: lessons learned from contraception to inform HIV prevention

PURPOSE OF REVIEW

Long-acting injectable (LAI) forms of preexposure prophylaxis (PrEP) are in clinical trials, generating much hope for HIV prevention. But this is not the first time that an injectable form of preventive medication has emerged: the contraceptive agent depomedroxyprogesterone acetate (DMPA) has an important precedent. DMPA's long journey, its initial reception, and ongoing implementation challenges can help inform the field of HIV prevention as we plan for approval, acceptance, and scale-up of LAI-PrEP.

RECENT FINDINGS

DMPA faced a long regulatory journey in the USA, with a lag of 25 years from initial application (1967) to approval (1992). Acceptance after introduction was rapid, but challenges hampered scale-up. Specific lessons learned include that extensive acceptability work is needed in parallel to product development. Also, low continuation rates, challenges with timing of initiation, and difficulty ensuring access for the most vulnerable populations have limited DMPA's impact. A new subcutaneous formulation presents opportunities for administration outside of clinical settings and for self-administration.

SUMMARY

Those involved in LAI-PrEP development and those who plan to be involved in its future implementation must consider these lessons and possible solutions from DMPA to ensure a successful future for this new HIV prevention modality.

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.

The mixed lineage kinase-3 inhibitor URMC-099 improves therapeutic outcomes for long-acting antiretroviral therapy

During studies to extend the half-life of crystalline nanoformulated antiretroviral therapy (nanoART) the mixed lineage kinase-3 inhibitor URMC-099, developed as an adjunctive neuroprotective agent was shown to facilitate antiviral responses. Long-acting ritonavir-boosted atazanavir (nanoATV/r) nanoformulations co-administered with URMC-099 reduced viral load and the numbers of HIV-1 infected CD4+ T-cells in lymphoid tissues more than either drug alone in infected humanized NOD/SCID/IL2Rγc-/- mice. The drug effects were associated with sustained ART depots. Proteomics analyses demonstrated that the antiretroviral responses were linked to affected phagolysosomal storage pathways leading to sequestration of nanoATV/r in Rab-associated recycling and late endosomes; sites associated with viral maturation. URMC-099 administered with nanoATV induced a dose-dependent reduction in HIV-1p24 and reverse transcriptase activity. This drug combination offers a unique chemical marriage for cell-based viral clearance. From the Clinical Editor: Although successful in combating HIV-1 infection, the next improvement in antiretroviral therapy (nanoART) would be to devise long acting therapy, such as intra-cellular depots. In this report, the authors described the use of nanoformulated antiretroviral therapy given together with the mixed lineage kinase-3 inhibitor URMC-099, and showed that this combination not only prolonged drug half-life, but also had better efficacy. The findings are hoped to be translated into the clinical setting in the future.

Tenofovir-based oral preexposure prophylaxis prevents HIV infection among women

PURPOSE OF REVIEW

Despite tremendous promise as a female-controlled HIV prevention strategy, implementation of preexposure prophylaxis (PrEP) among women has been limited, in part because of disparate efficacy results from randomized trials in this population. This review synthesizes existing evidence regarding PrEP efficacy for preventing HIV infection in women and considerations for delivering PrEP to women.

RECENT FINDINGS

In three efficacy trials, conducted among men and women, tenofovir-based oral PrEP reduced HIV acquisition in subgroups of women by 49-79% in intent-to-treat analyses, and by >85% when accounting for PrEP adherence. Two trials did not demonstrate an HIV prevention benefit from PrEP in women, but substantial evidence indicates those results were compromised by very low adherence to the study medication. Qualitative research has identified risk perception, stigma, and aspects of clinical trial participation as influencing adherence to study medication. Pharmacokinetic studies provide supporting evidence that PrEP offers HIV protection in women who are adherent to the medication.

SUMMARY

Tenofovir-based daily oral PrEP prevents HIV acquisition in women. Offering PrEP as an HIV prevention option for women at high risk of HIV acquisition is a public health imperative and opportunities to evaluate implementation strategies for PrEP for women are needed.

The Art of HIV Elimination: Past and Present Science

INTRODUCTION

Remarkable strides have been made in controlling the HIV epidemic, although not enough to achieve epidemic control. More recently, interest in biomedical HIV control approaches has increased, but substantial challenges with the HIV cascade of care hinder successful implementation. We summarise all available HIV prevention methods and make recommendations on how to address current challenges.

DISCUSSION

In the early days of the epidemic, behavioural approaches to control the HIV dominated, and the few available evidence-based interventions demonstrated to reduce HIV transmission were applied independently from one another. More recently, it has become clear that combination prevention strategies targeted to high transmission geographies and people at most risk of infections are required to achieve epidemic control. Biomedical strategies such as male medical circumcision and antiretroviral therapy for treatment in HIV-positive individuals and as pre-exposure prophylaxis in HIV-negative individuals provide immense promise for the future of HIV control. In resource-rich settings, the threat of HIV treatment optimism resulting in increased sexual risk taking has been observed and there are concerns that as ART roll-out matures in resource-poor settings and the benefits of ART become clearly visible, behavioural disinhibition may also become a challenge in those settings. Unfortunately, an efficacious vaccine, a strategy which could potentially halt the HIV epidemic, remains elusive.

CONCLUSION

Combination HIV prevention offers a logical approach to HIV control, although what and how the available options should be combined is contextual. Therefore, knowledge of the local or national drivers of HIV infection is paramount. Problems with the HIV care continuum remain of concern, hindering progress towards the UNAIDS target of 90-90-90 by 2020. Research is needed on combination interventions that address all the steps of the cascade as the steps are not independent of each other. Until these issues are addressed, HIV elimination may remain an unattainable goal.

A Shot in the Arm for HIV Prevention? Recent Successes and Critical Thresholds

Efforts to decrease the spread of HIV worldwide continue at a rapid pace. With the development of new biomedical interventions and findings from pivotal clinical trials, a new framework for short-term and long-term prevention strategies is emerging. It is clear that biomedical-based approaches targeted at the highest risk populations have the greatest potential to have a short-term impact. Unfortunately, challenges with adherence in healthy populations at risk are now well-recognized, and competing health care priorities in the context of fragile delivery infrastructures pose formidable obstacles to implementation. We need better ways to identify high-risk populations, sophisticated understanding of the behavioral parameters that can ensure adherence, and the development of better strategies to provide sustained delivery of preexposure prophylaxis (PrEP). In the long term, we need an effective vaccine--a path that has proven to be rocky. Research facilitating an increased understanding of immune responses and what represents effective responses to prevent HIV acquisition should facilitate progress. While we wait for that time, PrEP offers the best strategy for short-term impact.

The promises and challenges of pre-exposure prophylaxis as part of the emerging paradigm of combination HIV prevention

INTRODUCTION

Towards the end of the twentieth century, significant success was achieved in reducing incidence in several global HIV epidemics through ongoing prevention strategies. However, further progress in risk reduction was uncertain. For one thing, it was clear that social vulnerability had to be addressed, through research on interventions addressing health systems and other structural barriers. As soon as antiretroviral treatment became available, researchers started to conceive that antiretrovirals might play a role in decreasing either susceptibility in uninfected people or infectiousness among people living with HIV. In this paper we focus on the origin, present status, and potential contribution of pre-exposure prophylaxis (PrEP) within the combination HIV prevention framework.

DISCUSSION

After a phase of controversy, PrEP efficacy trials took off. By 2015, daily oral PrEP, using tenofovir alone or in combination with emtricitabine, has been proven efficacious, though efficacy seems heavily contingent upon adherence to pill uptake. Initial demonstration projects after release of efficacy results have shown that PrEP can be implemented in real settings and adherence can be high, leading to high effectiveness. Despite its substantial potential, beliefs persist about unfeasibility in real-life settings due to stigma, cost, adherence, and potential risk compensation barriers.

CONCLUSIONS

The strategic synergy of behavioural change communication, biomedical strategies (including PrEP), and structural programmes is providing the basis for the combination HIV prevention framework. If PrEP is to ever become a key component of that framework, several negative beliefs must be confronted based on emerging evidence; moreover, research gaps regarding PrEP implementation must be filled, and appropriate prioritization strategies must be set up. Those challenges are significant, proportional to the impact that PrEP implementation may have in the global response to HIV.

Clinical Treatment Options Infectious Diseases: Update on PrEP Implementation, Adherence, and Advances in Delivery

Pre-exposure prophylaxis (PrEP) is an effective and evidence-based HIV-prevention option and is recommended for individuals with substantial risk for HIV infection [1]. Randomized controlled trials have demonstrated that daily oral PrEP dramatically reduces the risk of HIV infection when it is taken as directed. Concerns regarding widespread emergence of antiretroviral resistance attributable to PrEP and behavioral disinhibition have to date not been observed in clinical trials and open-label demonstration projects. PrEP has great potential as part of an HIV risk reduction strategy and barriers to wider implementation including community education, prescriber availability, and elimination of financial barriers should be aggressively pursued. Adherence is critical to PrEP efficacy and has varied across study populations; developing and refining ways of measuring and supporting adherence is essential to the success of PrEP. Evaluation of long-acting medications and alternative formulations for PrEP is underway and may lead to the wider implementation and impact of PrEP.

Sustained-release nanoART formulation for the treatment of neuroAIDS

A novel approach was developed for the coencapsulation of an anti-HIV drug (tenofovir) and a latency-breaking agent (vorinostat), using magnetically guided layer-by-layer (LbL) assembled nanocarriers for the treatment of neuroAIDS. Ultrasmall iron oxide (Fe3O4) nanoparticles (10±3 nm) were synthesized and characterized. The LbL technique was used to achieve a sustained release profile, and application of 2 bilayers ([tenofovir+dextran sulphate]2+vorinostat) to magnetic nanoparticles resulted in a 2.8 times increase in drug (tenofovir) loading and also resulted in an increase in the drug release period by 30-fold, with 100% drug release in sustained manner over a period of 5 days with the simultaneous stimulation of latent HIV expression. Nanoformulation showed a good blood-brain barrier transmigration ability (37.95%±1.5%) with good in vitro antiviral efficacy (~33% reduction of p24 level) over a period of 5 days after HIV infection in primary human astrocytes, with good cell viability (>90%). Hence, LbL arrangements of drugs on magnetic nanoparticles provides sustained release and, therefore, may improve the patient's adherence to therapy and lead to better compliance.

Opposing regulation of endolysosomal pathways by long-acting nanoformulated antiretroviral therapy and HIV-1 in human macrophages

BACKGROUND

Long-acting nanoformulated antiretroviral therapy (nanoART) is designed to improve patient regimen adherence, reduce systemic drug toxicities, and facilitate clearance of human immunodeficiency virus type one (HIV-1) infection. While nanoART establishes drug depots within recycling and late monocyte-macrophage endosomes, whether or not this provides a strategic advantage towards viral elimination has not been elucidated.

RESULTS

We applied quantitative SWATH-MS proteomics and cell profiling to nanoparticle atazanavir (nanoATV)-treated and HIV-1 infected human monocyte-derived macrophages (MDM). Native ATV and uninfected cells served as controls. Both HIV-1 and nanoATV engaged endolysosomal trafficking for assembly and depot formation, respectively. Notably, the pathways were deregulated in opposing manners by the virus and the nanoATV, likely by viral clearance. Paired-sample z-scores, of the proteomic data sets, showed up- and down- regulation of Rab-linked endolysosomal proteins. NanoART and native ATV treated uninfected cells showed limited effects. The data was confirmed by Western blot. DAVID and KEGG bioinformatics analyses of proteomic data showed relationships between secretory, mobility and phagocytic cell functions and virus and particle trafficking.

CONCLUSIONS

We posit that modulation of endolysosomal pathways by antiretroviral nanoparticles provides a strategic path to combat HIV infection.

Hyperbranched polydendrons: a new nanomaterials platform with tuneable permeation through model gut epithelium

The development of nanomaterials for advanced therapies requires the formation of versatile platforms that may be tuned to maximize beneficial attributes and minimize unwanted negative behaviour. Additionally, the optimum route of administration is a key consideration of any new treatment and much work has been focused on direct injection into the systemic circulation rather than oral delivery. Here we describe a new approach to polymeric nanoparticle design and present initial results showing the potential for tuneable permeation through a gut epithelium model. Through the use of mixed initiators and branched vinyl polymerization, a series of systematically varying branched polymers have been synthesized and nanoprecipitated. The surprisingly uniform structures have undergone preliminary pharmacological evaluation to establish low cytotoxicity and enhanced permeation through model intestinal epithelial cells. This presents potential opportunities for future developments that may allow oral dosing to result in circulating polymeric nanoparticles; behaviour that may prove clinically desirable to many non-terminal or chronic diseases that utilise nanomedicines but wish to avoid regular or repeated intravenous administration.

ARV-based HIV prevention for women - where we are in 2014

Women continue to be at special risk for HIV acquisition due to a complex mix of biological, behavioural, structural, cultural and social factors, with unacceptable rates of new infection. Scientific advances over the past decade have highlighted the use of antiretroviral (ARV) drugs as pre-exposure prophylaxis (PrEP) to prevent HIV acquisition (sexually, parenterally and vertically) and ARV treatment (ART) for HIV-positive patients to prevent onward transmission (treatment as prevention – TasP). This paper reviews the evidence base for PrEP and TasP, describes new products in development and the need to translate research findings into programmes with impact at the population level.

Parenteral antiretroviral formulations are still urgently needed: a case report and commentary

This case report highlights a challenging clinical dilemma to administer antiretroviral therapy in a critically-ill human immunodeficiency virus-infected patient who presented with multiple opportunistic infections and a non-functional gastrointestinal tract. The need for parenteral antiretroviral drug options is discussed and investigational drugs are briefly reviewed.