Long-acting injectable ART: next revolution in HIV?

The long wait for long-acting HIV prevention and treatment formulations

Large randomised studies of new long-acting medications for the prevention and treatment of HIV have shown high effectiveness and acceptability. Although modelling studies indicate these agents could be fundamental in HIV elimination, coordination of their entry into health-care markets is crucial, especially in low-income and middle-income countries with high HIV prevalence, where coordination is low despite UNAIDS flagging that global HIV targets will not be met. Research and implementation projects are tightly controlled by originator pharmaceutical companies, with only a small percentage of eligible people living with or affected by HIV benefiting from these projects. WHO, financial donors, manufacturers, and governments need to consider urgent coordinated action from stakeholders worldwide, akin to the successful introduction of dolutegravir into treatment programmes across low-income and middle-income countries. Without this immediate coordination, large-scale access to long-acting agents for HIV will be delayed, potentially extending into the 2030s. This delay is unacceptable considering the established global HIV targets.

Long-acting refillable nanofluidic implant confers protection against SHIV infection in nonhuman primates

The impact of pre-exposure prophylaxis (PrEP) on slowing the global HIV epidemic hinges on effective drugs and delivery platforms. Oral drug regimens are the pillar of HIV PrEP, but variable adherence has spurred development of long-acting delivery systems with the aim of increasing PrEP access, uptake, and persistence. We have developed a long-acting subcutaneous nanofluidic implant that can be refilled transcutaneously for sustained release of the HIV drug islatravir, a nucleoside reverse transcriptase translocation inhibitor that is used for HIV PrEP. In rhesus macaques, the islatravir-eluting implants achieved constant concentrations of islatravir in plasma (median 3.14 nM) and islatravir triphosphate in peripheral blood mononuclear cells (median 0.16 picomole per 10⁶ cells) for more than 20 months. These drug concentrations were above the established PrEP protection threshold. In two unblinded, placebo-controlled studies, islatravir-eluting implants conferred 100% protection against infection with SHIV_SF162P3 after repeated low-dose rectal or vaginal challenge in male or female rhesus macaques, respectively, compared to placebo control groups. The islatravir-eluting implants were well tolerated with mild local tissue inflammation and no signs of systemic toxicity over the 20-month study period. This refillable islatravir-eluting implant has potential as a long-acting drug delivery system for HIV PrEP.

What is polypharmacy in people living with HIV/AIDS? A systematic review

Polypharmacy in people living with HIV/AIDS (PLWHA) is a rising morbidity that exacts hefty economic burden on health budgets in addition to other adverse clinical outcomes. Despite recent advances, uncertainty remains around its exact definition in PLWHA. In this systematic review and Meta-analysis, we explored relevant databases (PUBMED, EMBASE, CROI) for studies evaluating polypharmacy in PLWHA from January 2000 to August 2021 to ascertain the exact numerical threshold that defines this morbidity. Two independent reviewers extracted and reviewed relevant variables for analyses. The review included a total of 31 studies involving n = 53,347 participants with a mean age of 49.5 (SD ± 17.0) years. There was a total of 36 definitions, with 93.5% defining polypharmacy as the concomitant use of 5 or more medications. We found significant variation in the numerical definition of polypharmacy, with studies reporting it as "minor" (N = 3); "major" (N = 29); "severe" (N = 2); "excessive" (N = 1); and "higher" (N = 1). Most studies did not incorporate a duration (84%) in their definition and excluded ART medications (67.7%). A plurality of studies in PLWHA have established that polypharmacy in this cohort of patients is the intake of ≥ 5 medications (including both ART and non-ART). To standardize the approach to addressing this rising morbidity, we recommend incorporation of this definition into national and international PLWHA treatment guidelines.

Impact of long-acting therapies on the global HIV epidemic

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

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.

Patient-reported outcomes for HIV: the future of long-acting injectables and antiretroviral therapy evaluations

Patient-reported outcomes (PROs) are an increasingly important aspect of patient care, as they offer a perspective from the patient themselves in the treatment and management of a particular disease state. They have a potential role in helping clinicians select an appropriate drug regimen in human immunodeficiency virus-1 (HIV-1)-infected individuals, as well as those with HIV/hepatitis C (HCV) co-infection. They can also provide insight for individuals receiving long-acting (LA) injectable antiretroviral therapy (ART). Studies found from PROs that participants on an LA injectable ART regimen reported greater preference and treatment satisfaction compared with those on an oral ART regimen. Some additional studies have also used PROs to evaluate the switch to single-tablet regimens and compare different ART in treating HIV-1. Current PROs and how they can be improved for LA injectables were also discussed.

Preventive efficacy of a tenofovir alafenamide fumarate nanofluidic implant in SHIV-challenged nonhuman primates

Pre-exposure prophylaxis (PrEP) using antiretroviral oral drugs is effective at preventing HIV transmission when individuals adhere to the dosing regimen. Tenofovir alafenamide (TAF) is a potent antiretroviral drug, with numerous long-acting (LA) delivery systems under development to improve PrEP adherence. However, none has undergone preventive efficacy assessment. Here we show that LA TAF using a novel subcutaneous nanofluidic implant (nTAF) confers partial protection from HIV transmission. We demonstrate that sustained subcutaneous delivery through nTAF in rhesus macaques maintained tenofovir diphosphate concentration at a median of 390.00 fmol/106 peripheral blood mononuclear cells, 9 times above clinically protective levels. In a non-blinded, placebo-controlled rhesus macaque study with repeated low-dose rectal SHIVSF162P3 challenge, the nTAF cohort had a 62.50% reduction (95% CI: 1.72% to 85.69%; p=0.068) in risk of infection per exposure compared to the control. Our finding mirrors that of tenofovir disoproxil fumarate (TDF) monotherapy, where 60.00% protective efficacy was observed in macaques, and clinically, 67.00% reduction in risk with 86.00% preventive efficacy in individuals with detectable drug in the plasma. Overall, our nanofluidic technology shows potential as a subcutaneous delivery platform for long-term PrEP and provides insights for clinical implementation of LA TAF for HIV prevention.

Feasibility of Implementing Long-Acting Injectable Antiretroviral Therapy to Treat HIV: A Survey of Health Providers from the 13 Countries Participating in the ATLAS-2M Trial

Long-acting (LA) injectable antiretroviral therapy (ART) was found noninferior to daily oral ART in Phase 3 trials with high patient satisfaction. Limited information on provider experiences with LA ART exists, which is critical to inform real-world implementation. An online survey of health providers from the 13 countries participating in the Phase 3b ATLAS-2M trial was conducted. A total of 293 providers responded to questions on LA ART feasibility. Multivariable regression was utilized to identify factors related to the feasibility of LA ART every month and every 2 months within routine care such as the characteristics, experiences, and attitudes of providers, and perceptions of patient benefits and barriers. A majority of providers indicated that it would be very feasible (62.8%) or somewhat feasible (32.1%) to administer monthly LA ART. Feasibility scores were higher for delivering LA ART every 2 months versus monthly (mean 28.3 vs. 26.9; p value <.001). African providers had higher odds of perceived overall feasibility of monthly LA ART [adjusted odds ratio (aOR) 2.9, 95% confidence interval (CI) 1.9-4.4] versus those from other regions, as did providers reporting a greater number of benefits for patients (aOR 1.1, 95% CI 1.0-1.1) versus those reporting less. Providers reporting a greater number of patient barriers to adhere to clinic appointments had lower odds of perceived feasibility of monthly LA ART (aOR 0.8, 95% CI 0.7-1.0) versus those reporting less. Findings highlight the need for further implementation research regarding barriers, facilitators, and strategies to optimize the introduction of LA ART outside of clinical trials.

Safety and tolerability of injectable Rilpivirine LA in HPTN 076: A phase 2 HIV pre-exposure prophylaxis study in women

BACKGROUND

Daily oral TDF/FTC is protective against HIV infection when used for pre-exposure prophylaxis (PrEP). However, daily adherence to oral PrEP is difficult for many; therefore, finding alternative PrEP strategies remains a priority. HPTN 076 evaluated the long-acting injectable form of rilpivirine (RPV), known as RPV LA for safety, pharmacokinetics and acceptability.

METHODS

HPTN 076 (NTC 02165202) was a phase 2, double-blind, 2:1 randomized trial comparing the safety of 1200mg RPV LA (LA) to placebo (P). The study included a 28-day oral run-in phase of daily, self- administered oral RPV (25 mg), with directly observed oral dosing about six times. Of 136 enrolled sexually active, HIV-uninfected, low HIV-risk African (100) and US (36) adult women, injectable product was administered in two gluteal, intramuscular (IM) injections once every eight weeks to 122 participants following the oral run-in phase. A maximum of six injection time points occurred over a 48-week period. Acceptability, safety, tolerability and pharmacokinetic (PK) data were collected throughout the study. This paper includes primary endpoint data collected up to the week 52 post enrollment.

FINDINGS

The median age of the enrolled population was 31 years (IQR: 25,38), median weight 75 kg (IQR: 64, 89), median body mass index (BMI) 30 (IQR: 27, 35), 46% married, 94% Black and 60% unemployed. A total of 122 (80 LA, 42 P) women received at least one injection and 98 (64 LA, 34 P) received all six injections. During the injection phase, three women withdrew from the study (2 LA, 1 P) and 16 women discontinued study product (10 LA, 6 P). Fourteen women (11 LA and 3 P) discontinued oral study product and did not enter the injection phase. Study product discontinuations were not significantly different between the two arms throughout. Of the product discontinuations in the injection phase, 8% in LA and 5% in P arm were due to adverse events (AEs), including one randomized to the P arm with prolonged QTc interval on EKG. The proportion of women who experienced Grade 2 or higher AEs during the injection phase as the primary outcome was not significantly different between the two arms [73.8%, 95% CI: (63.2%, 82.1%) for LA and 73.8%, 95% CI: (58.9%, 84.7%), p>0.99]. Transient Grade ≥2 liver abnormalities occurred in 14% of women in the LA arm compared with 12% in P arm. Three LA women (4%) developed Grade 3 injection site reactions compared with none in P arm. In participants who received at least 1 injection, the geometric mean of overall RPV trough concentrations (Ctrough) was 62.2 ng/mL. In participants who received all six injections, the geometric mean of CTrough through the injection phase and after the last injection were 72.8 ng/mL and 100.9 ng/mL, respectively. At week 52 (eight weeks after last injection), the geometric mean of RPV Ctrough was 75.0 ng/mL. At the last injection visit (Week 44), 80 % of women who answered acceptability questions strongly agreed that they would think about using- and 68% that they would definitely use a PrEP injectable in the future.

INTERPRETATION

RPV LA IM injections every eight weeks in African and US women were safe and acceptable. Overall, despite more injection site reactions and pain in the participants receiving RPV LA the injections were well tolerated. Data from this study support the further development of injectable PrEP agents.

Discovery of 2-isoxazol-3-yl-acetamide analogues as heat shock protein 90 (HSP90) inhibitors with significant anti-HIV activity

The recent burst of explorations on heat shock protein 90 (HSP90) in virus research supports its emergence as a promising target to overcome the drawbacks of current antiviral therapeutic regimen. In continuation of our efforts towards the discovery of novel anti-retroviral molecules, we designed, synthesized fifteen novels 2-isoxazol-3-yl-acetamide based compounds (2a-o) followed by analysis of their anti-HIV activity and cytotoxicity studies. 2a-b, 2e, 2j, and 2l-m were found to be active with inhibitory potentials >80% at their highest non-cytotoxic concentration (HNC). Further characterization of anti-HIV activity of these molecules suggests that 2l has ∼3.5 fold better therapeutic index than AUY922, the second generation HSP90 inhibitor. The anti-HIV activity of 2l is a cell type, virus isolate and viral load independent phenomena. Interestingly, 2l does not significantly modulate viral enzymes like Reverse Transcriptase (RT), Integrase (IN) and Protease (PR) as compared to their known inhibitors in a cell free in vitro assay system at its HNC. Further, 2l mediated inhibition of HSP90 attenuates HIV-1 LTR driven gene expression. Taken together, structural rationale, modeling studies and characterization of biological activities suggest that this novel scaffold can attenuate HIV-1 replication significantly within the host and thus opens a new horizon to develop novel anti-HIV therapeutic candidates.

The Promise of Long-Acting Antiretroviral Therapies: From Need to Manufacture

Antiretroviral therapy has transformed human immunodeficiency virus infections from certain death to a manageable chronic disease. Achieving strict adherence to drug regimens that limit toxicities and viral resistance is an achievable goal. Success is defined by halting viral transmission and by continuous viral restriction. A step towards improving treatment outcomes is in long-acting antiretrovirals. While early results remain encouraging there remain opportunities for improvement. These rest, in part, on the required large drug dosing volumes, local injection-site reactions, and frequency of injections. Thus, implantable devices and long-acting parenteral prodrugs have emerged which may provide more effective clinical outcomes. The recent successes in transforming native antiretrovirals into lipophilic and hydrophobic prodrugs stabilized into biocompatible surfactants can positively affect both. Formulating antiretroviral prodrugs demonstrates improvements in cell and tissue targeting, in drug-dosing intervals, and in the administered volumes of nanosuspensions. As such, the newer formulations also hold the potential to suppress viral loads beyond more conventional therapies with the ultimate goal of HIV-1 elimination when combined with other modalities.

Composite Risk for HIV: A New Approach Towards Integrating Biomedical and Behavioral Strategies in Couples-Based HIV Prevention Research

A substantial number of new HIV infections among gay, bisexual, and other men who have sex with men and transgender women occurs in the context of primary partnerships. Given the diversity of risk reduction needs and various approaches available for reducing risk within couples, condomless sex is no longer the gold standard HIV outcome. We present a novel, comprehensive, and flexible Composite Risk for HIV (CR-HIV) approach for integrating evolving biomedical and behavioral HIV prevention strategies into couples-based HIV prevention intervention and survey research. We provide illustrative examples of the utility of the CR-HIV approach based on couples' HIV status.

Closing the gaps in the HIV care continuum

In a Perspective, Ruanne Barnabas and Connie Celum discuss the implications of the accompanying Link4Health and Engage4Health studies for HIV care in sub-Saharan Africa.

Creation of a nanoformulated cabotegravir prodrug with improved antiretroviral profiles

Long-acting parenteral (LAP) antiretroviral drugs have generated considerable interest for treatment and prevention of HIV-1 infection. One new LAP is cabotegravir (CAB), a highly potent integrase inhibitor, with a half-life of up to 54 days, allowing for every other month parenteral administrations. Despite this excellent profile, high volume dosing, injection site reactions and low body fluid drug concentrations affect broad use for virus infected and susceptible people. To improve the drug delivery profile, we created a myristoylated CAB prodrug (MCAB). MCAB formed crystals that were formulated into nanoparticles (NMCAB) of stable size and shape facilitating avid monocyte-macrophage entry, retention and reticuloendothelial system depot formulation. Drug release kinetics paralleled sustained protection against HIV-1 challenge. After a single 45 mg/kg intramuscular injection to BALB/cJ mice, the NMCAB pharmacokinetic profiles was 4-times greater than that recorded for CAB LAP. These observations paralleled replicate measurements in rhesus macaques. The results coupled with improved viral restriction in human adult lymphocyte reconstituted NOD/SCID/IL2Rγc^-/- mice led us to conclude that NMCAB can improve biodistribution and viral clearance profiles upon current CAB LAP formulations.