Pharmacokinetics and Drug-Drug Interactions of Long-Acting Intramuscular Cabotegravir and Rilpivirine

Hormones, microbes, and PrEP drugs in the female genital tract

INTRODUCTION

For HIV medications intended for HIV prevention, it is critical to achieve exposures in that will provide reliable protection to the FGT. The female genital tract (FGT) is a complex and heterogenous environment.

AREAS COVERED

We reviewed what is known about drug transport and metabolism specific to female genital tissues. We performed a literature search using key words in PubMed and Google Scholar on articles published inclusive of August 2024. We then discuss the impact of sex steroid hormones and vaginal microbiome on the genital tract pharmacology of drugs used for PrEP.

EXPERT OPINION

Better characterization of FGT pharmacology can improve PrEP options for women. Better models that can fully capture the complexities of the FGT to evaluate pharmacokinetic-pharmacodynamic relationships in the context of the complex microenvironment of the FGT will need to be developed and validated to move the field forward.

Assessing the utilization of HIV genotype resistance testing: Insight from Italian Infectious Diseases Units

PURPOSE

We aimed to assess the utilization of genotype resistance testing (GRT) by Infectious Diseases Units across Italy.

METHODS

A cross-sectional study was conducted involving a questionnaire distributed to the Infectious Diseases Unit in Italy. A web-based survey using Google Forms software was utilized and spread via email or cellphone.

RESULTS

Responses were obtained from 101 Infectious Diseases Units. Among these centres, only seven (6.9%) reported not performing GRT at any time. Of the 94 centres performing GRT, 52 (55.3%) sent blood samples to external laboratories. Notably, only 6/35 (17.1%) small centres had internal laboratories, compared to 14/35 (40.0%) medium centres and 22/24 (91.7%) large centres (P < 0.001). Most centres requested GRT for treatment-naïve individuals and all cases of virological failure. Only 24 (25.5%) requested GRT of HIVDNA before treatment changes. Regarding virological failure, most centres (38, 40.4%) requested GRT when HIV-RNA levels exceeded 200 copies/mL, while 26 (27.7%) requested it at levels exceeding 50 copies/mL. Additionally, 18 (19.1%) and 12 (12.8%) centres requested GRT at thresholds of 500 copies/mL and 1000 copies/mL, respectively. Regarding the specific GRT test used, 34 (36.2%) were unsure, while 16 (17.0%) reported using both next-generation sequencing and Sanger methods. Furthermore, 30 (31.9%) and 14 (14.9%) centres exclusively used next-generation sequencing and Sanger, respectively. Most centres reported receiving GRT results within 1 month (n = 72, 76.6%), while 22 (23.4%) centres obtained results within 2 weeks. However, 22 (23.4%) centres typically experienced more than 1-month delays. Finally, most participants (86, 91.5%) regarded GRT as a crucial routine test for the treatment of naïve people living with HIV.

CONCLUSIONS

This study demonstrates that most Infectious Diseases Units in Italy continue to consider GRT an essential test for newly diagnosed people living with HIV in clinical practice. However, the utilization of GRT on HIV-DNA remains limited. Further efforts are required to decrease turnaround time in centres experiencing prolonged delays in obtaining results.

A Randomized Phase 1 Study Evaluating Pharmacokinetics, Safety, and Tolerability of a High-Concentration, Long-Acting Cabotegravir Formulation in Adults Without HIV

Long-acting (LA) cabotegravir 200-mg/mL (CAB200) injections are approved for HIV-1 prevention and as a complete LA HIV-1 treatment regimen with rilpivirine. A high-concentration suspension formulation, cabotegravir 400 mg/mL (CAB400-D), was developed to enable less frequent dosing and self-administration. This phase 1, double-blind, randomized study (NCT04484337) evaluated intramuscular (IM) gluteal, subcutaneous (SC) abdominal, and IM thigh CAB400-D injections (200-800 mg [0.5-2.0 mL]) in adults without HIV, using CAB200 injections as active control. Co-administration with recombinant human hyaluronidase (rHuPH20), topical nonsteroidal anti-inflammatory drug, or topical steroid was evaluated for some SC injections. Pharmacokinetics, adverse events (AEs), and participant-reported outcomes were assessed. Overall, 138 participants were enrolled. Absorption was faster with CAB400-D versus CAB200. Within 4 weeks, CAB400-D plasma exposures were similar across administration routes and higher than those of CAB200. Co-administration with rHuPH20 increased the spontaneous absorption rate of CAB400-D but not CAB200. No deaths or drug-related serious AEs were observed. Five (4%) participants discontinued treatment due to AEs (injection-site reactions [ISRs], n = 3 discontinuations). Most (99%) participants experienced ≥ 1 ISR. Participants reported good acceptability of injections. Although CAB400-D injections demonstrated acceptable safety/tolerability, faster absorption than CAB200 limited potential dosing intervals to monthly dosing. Alternative cabotegravir formulations with longer dosing intervals are under clinical evaluation.

Long-Acting Injectable Antiretroviral Therapy for Treatment of Human Immunodeficiency Virus: A Review

PURPOSE OF REVIEW

Long-acting injectable (LAI) antiretroviral therapy (ART) for treatment of HIV-1 are approved both as a complete treatment regimen (cabotegravir/rilpivirine) and as an additional treatment option (lenacapavir) for those with multidrug resistant HIV-1. Here, we review the data supporting these approvals, pharmacokinetics, and additional patient populations that many benefit from LAI ART.

RECENT FINDINGS

Persons with HIV and adherence challenges as well as those in low-and-middle income countries have high rates of adherence and viral suppression with LAI ART. LAI cabotegravir/rilpivirine (CAB/RPV) offers an alternative treatment approach to daily oral ART for people with HIV-1 infection that is associated with high rates of patient satisfaction when compared to daily oral ART. LAI CAB/RPV is currently only approved in those with HIV-1 viral suppression, however recent data support the use of LAI ART in populations with adherence challenges. Furthermore, given high rates of NNRTI resistance globally, CAB/RPV is not recommended in low-and-middle income countries presently, although this recommendation is likely to change based on recently published data. More research is needed among groups that may benefit from long-acting treatments for HIV-1.

Question and answers on long-acting therapy with cabotegravir and rilpivirine in people with HIV

Modern ART is evolving, allowing the use of new drug formulations and alternative routes of administration to oral therapy. Long-acting (LA) cabotegravir and rilpivirine, the first fully injectable antiretroviral regimen approved for clinical use, is a test case for this new route of administration, and an innovation with implications for the quality of life of people with HIV (PWH). However, its use requires a reorganization of outpatient clinics and outpatient services, and a number of issues remain to be defined regarding the management of PWH on LA drugs, including the correct selection of people who can be treated with LA cabotegravir and rilpivirine. There is also ongoing debate about the best way to monitor both efficacy and tolerability of LA treatment and whether the management of virological failures and blips should be different from that reserved for oral regimens. The present article reviews the data on the use and management of LA cabotegravir and rilpivirine in different settings, with a review of clinical trial data and also the first available real-life experiences. The article focuses on the following: the reasons for the use of LA drugs; the implementation of their use in clinical practice; and the monitoring of treated people over time.

Interactive effects of morphine and the HIV integrase inhibitor, cabotegravir, in male and female mice

Cabotegravir is a novel therapeutic option for HIV prevention. Similar to the opioid morphine, cabotegravir, undergoes glucuronidation through the enzymes uridine diphosphate glucuronosyltransferase (UGT) in the liver. We hypothesize that their combination could lead to drug-drug interactions, and this notion was explored in both male and female mice. Our findings indicate a better analgesic response to morphine in females compared to male animals, which was to be mediated by μ-opioid receptors and proteins associated with synaptic plasticity. Co-administration with cabotegravir appears to intensify morphine concentrations in the brain and the analgesic response in male animals only. Moreover, cabotegravir-induced fluctuations in the expression of the UGT enzymes correlated with alterations in drug metabolism and excretion and in the production of inflammatory cytokines primarily driven by morphine in the brains and cabotegravir in the liver. The increased levels of inflammatory cytokines in males aligned with noticeable morphological changes in the liver. In summary, co-exposure with cabotegravir changed the biodistribution in the brain, affected liver metabolism, and altered kidney excretion, leading to changes in gene expression and inflammatory effects that could disrupt morphine analgesia responses.

An Ultra-Long-Acting Dimeric Bictegravir Prodrug Defined by a Short Pharmacokinetic Tail

Ultra-long-acting (ULA) antiretroviral parenteral formulations, with low injection volumes, high resistance barriers, and short pharmacokinetic (PK) tails, can transform HIV-1 therapeutics. Here, we converted bictegravir (BIC), a potent daily oral antiretroviral drug, into monomeric and homodimeric ester prodrugs. The homodimeric prodrug nanosuspension, NMXBIC, shows sustained plasma BIC levels >16 times the protein-adjusted 95% inhibitory concentration (PA-IC95) for six months after a single injection in Sprague Dawley rats. The results paralleled a short PK tail with the potential for late dose forgiveness. The monomeric prodrug nanosuspension, NM2BIC, shows lower year-long plasma BIC concentrations above PA-IC95 after a single injection in Sprague Dawley rats. After repeated injections, NMXBIC and NM2BIC are well tolerated in New Zealand White rabbits. NMXBIC's physicochemical properties and high BIC loading/unit mass of the prodrug contribute to its unique ULA PK profile. These results support its development as a ULA formulation for HIV-1 treatment and prevention.

Willingness to Switch to Long-Acting Injectable Cabotegravir and Rilpivirine Every 2 Months for People Living with HIV in Nanjing, China

Daily oral medication is currently the most common antiretroviral therapy (ART) for people living with human immunodeficiency virus (PLWH). As the first complete long-acting (LA) ART regimen, cabotegravir (CAB) and rilpivirine (RPV), offer a novel treatment approach with less frequent administration, via bimonthly infusion. Due to the upcoming availability of this regimen in China, the study aimed to analyze the willingness and reasons of PLWH to switch to CAB+RPV therapy. A questionnaire survey among PLWH receiving oral ART was carried out between March 25 and April 8, 2023, in the Second Hospital of Nanjing, China. Participants were asked about their willingness to switch to the CAB+RPV LA regimen and provided reasons for their decision. We analyzed the reasons for switching, and the factors affecting their willingness were analyzed by multinomial logistic regression. Among 693 participants, 56.7% expressed willingness to switch to the CAB+RPV regimen, 32.6% were uncertain, and 10.7% were unwilling. The primary reason for switching to CAB+RPV therapy was not being concerned about daily adherence to ART (22.6%). Uncertainty about switching was mainly associated with participants' concerns in terms of price (31.6%) and safety (31.1%) of the novel drugs. Unwillingness was mainly due to participants' satisfaction with their current treatment regimen (20.3%). In multivariate analysis, higher education (odds ratio [OR]: 2.990; 95% confidence interval [CI]: 1.171-7.636) was positively associated with willingness to switch, whereas the age of ≥60 (OR: 0.142; 95% CI: 0.036-0.554) was negatively associated. Our survey demonstrated that the majority of PLWH were willing to switch to CAB+RPV therapy, mainly due to its improved convenience and reduced risk of disease exposure. However, their concerns regarding price, efficacy, and safety could be the key challenges for the clinical implementation of the CAB+RPV LA regimen in the future.

Strategies for long-acting drug design

With advances of drug design and preparation technology, the development of long-acting drugs has become an important research focus in precision medicine and chronic disease management. These drugs are designed to improve the patients' compliance and quality of life by achieving prolonged maintenance of an effective drug concentration in the body with a reduced dosing frequency. Small molecule drugs, monoclonal antibodies and nucleic acid drugs all have their own difficulties in achieving long actions, which can be especially challenging for the latter two because of their structural complexity. This review provides an overview of the strategies for designing long-acting small molecule drugs, monoclonal antibodies, and nucleic acid drugs.

Learning From Full Characterization of HIV Proviruses in People Receiving Long-Acting Cabotegravir/Rilpivirine With a History of Replication on the Antiretroviral Classes

Background

To better understand factors associated with virologic response, we retrospectively characterized the HIV proviruses of 7 people with HIV who received long-acting cabotegravir/rilpivirine (CAB/RPV-LA) and were selected according to the following criteria: virologic control achieved despite a history of viral replication on 1 or both corresponding antiretroviral classes (n = 6) and virologic failure (VF) after CAB/RPV-LA initiation (n = 1).

Methods

Last available blood samples before the initiation of CAB/RPV-LA were analyzed retrospectively. Near full-length HIV DNA genome haplotypes were inferred from Nanopore sequencing by the in vivo Genome Diversity Analyzer to search for archived drug resistance mutations (DRMs) and evaluate the frequency and intactness of proviruses harboring DRMs.

Results

Archived DRMs including G-to-A mutations were found in samples from 3 patients who maintained virologic control. Genomes harboring DRMs were majorly in minority variants (<20%) and were defective in all cases except for 1 participant. In this participant, intact genomes with the H221Y mutation on reverse transcriptase were detected representing 11 copies per 106 peripheral blood mononuclear cells. The other mutations observed in the participants of the study resulted most likely from hypermutations. The patient with VF presented archived mutations, all associated with defects. Other factors could explain this VF.

Conclusions

Our findings highlight the difficulty in interpreting the clinical significance of DRMs when detected in proviral DNA and the need to filter out hypermutated sequences. Detected DRMs could be harbored by defective archived genomes unlikely to contribute to treatment failure.

Individualizing Antiretroviral Therapy in the Older Patient

Owing to widespread availability of potent and tolerable antiretroviral therapy, life expectancy of people with human immunodeficiency virus (HIV) has significantly increased. Consequently, the population of people with HIV are ageing, with over 50% over the age of 50 years, and it is expected that 25% will be over the age of 65 years by 2030. People diagnosed with HIV at older age tend to have more advanced disease, and may already be experiencing comorbidities that will influence the choice of initial antiretroviral treatment. Despite the well described changes in pharmacokinetics associated with ageing, there are a paucity of pharmacokinetics studies of contemporary antiretroviral drugs to help guide treatment for HIV. Irrespective of this, integrase inhibitor-based regimens have been shown to have similar treatment outcomes in older and young adults and are the preferred regimens for initiation and switching therapy in older adults. Non-acquired immunodeficiency syndrome (AIDS) comorbidities are more common in people with HIV owing to chronic immune activation and inflammation even in the presence of virological suppression on antiretroviral treatment. Screening and risk assessment of comorbidities is crucial as the presence of geriatric syndrome, frailty or neurocognitive impairment may impact medication adherence. Simplification of complex regimens, both antiretroviral and comorbidity treatments, is recommended to improve adherence. Regular medication reviews under the guidance of an experienced HIV pharmacist are recommended to identify adverse drug-drug interactions and inappropriate prescribing of drugs with potential adverse effects, such as falls risk. Antiretroviral stewardship has been shown to improve patient outcomes and quality of life for ageing people with HIV.

SHIV remission in macaques with early treatment initiation and ultra long-lasting antiviral activity

Studies in SIV-infected macaques show that the virus reservoir is particularly refractory to conventional suppressive antiretroviral therapy (ART). We posit that optimized ART regimens designed to have robust penetration in tissue reservoirs and long-lasting antiviral activity may be advantageous for HIV or SIV remission. Here we treat macaques infected with RT-SHIV with oral emtricitabine/tenofovir alafenamide and long-acting cabotegravir/rilpivirine without (n = 4) or with (n = 4) the immune activator vesatolimod after the initial onset of viremia. We document full suppression in all animals during treatment (4-12 months) and no virus rebound after treatment discontinuation (1.5-2 years of follow up) despite CD8 + T cell depletion. We show efficient multidrug penetration in virus reservoirs and persisting rilpivirine in plasma for 2 years after the last dose. Our results document a type of virus remission that is achieved through early treatment initiation and provision of ultra long-lasting antiviral activity that persists after treatment cessation.

Pharmacologic evaluation of delayed long-acting cabotegravir administration among cisgender women in HPTN 084

HPTN 084 demonstrated the superiority of long-acting injectable cabotegravir (CAB-LA) compared with daily oral tenofovir disoproxil fumarate-emtricitabine (F/TDF) for HIV prevention in women. CAB-LA (600 mg) or placebo injections were administered 4 weeks after an initial dose (loading dose) and every 2 months (Q2M) thereafter; this is the approved regimen. Participants experienced both loading dose and Q2M delays during the trial. CAB concentrations were evaluated before a delay, at the visit associated with the delay, and the visit after a delayed injection was administered. During the blinded phase of the trial, 194 participants randomized to CAB-LA experienced at least one injection delay. Plasma CAB concentrations were maintained above the 4× protein adjusted 90% inhibitory concentration (4× PA-IC90; protocol-specific threshold) for all loading dose and 98% of Q2M delays when injections were administered up to 6 weeks late. The feasibility of shifting to an every 3-month (Q3M) regimen in females was interrogated via simulation studies using a population pharmacokinetic model. Q3M injections in both CAB-naïve (with a loading dose) and previously CAB-exposed females were predicted to yield higher steady-state exposures than in males on the approved Q2M regimen. Although there is observed forgiveness following an isolated delayed CAB-LA injection and simulations suggest acceptable CAB-LA exposures in women with a 600 mg CAB-LA Q3M regimen, empirical efficacy of this regimen has not been established, and transitioning to this dosing schema is not recommended. Future pharmacokinetic bridging studies are aimed at evaluating higher dose CAB-LA formulations administered less frequently.

CLINICAL TRIALS

This study is registered with ClinicalTrials.gov as NCT03164564.

New Therapies and Strategies to Curb HIV Infections with a Focus on Macrophages and Reservoirs

More than 80 million people worldwide have been infected with the human immunodeficiency virus (HIV). There are now approximately 39 million individuals living with HIV/acquired immunodeficiency syndrome (AIDS). Although treatments against HIV infection are available, AIDS remains a serious disease. Combination antiretroviral therapy (cART), also known as highly active antiretroviral therapy (HAART), consists of treatment with a combination of several antiretroviral drugs that block multiple stages in the virus replication cycle. However, the increasing usage of cART is inevitably associated with the emergence of HIV drug resistance. In addition, the development of persistent cellular reservoirs of latent HIV is a critical obstacle to viral eradication since viral rebound takes place once anti-retroviral therapy (ART) is interrupted. Thus, several efforts are being applied to new generations of drugs, vaccines and new types of cART. In this review, we summarize the antiviral therapies used for the treatment of HIV/AIDS, both as individual agents and as combination therapies, and highlight the role of both macrophages and HIV cellular reservoirs and the most recent clinical studies related to this disease.

Fixed-dose antiretroviral combinations in children living with human immunodeficiency virus type 1 (HIV-1): a systematic review

Fixed-Dose antiretroviral Combinations (FDCs) are the most used drug regimes in adult patients with human-immunodeficiency virus 1 infection, since they increase adherence to antiretroviral therapy and enable good quality of life. The European AIDS Clinical Society guidelines recommend the use of FDCs in paediatrics. However, the use of FDCs in paediatric population is restricted since studies in children and adolescents are mostly conducted in small sample sizes and are heterogeneous in settings and design. This systematic review aims to summarize the current knowledge about the use of FDCs in paediatric population, highlighting the relevant outcomes regarding efficacy and effectiveness, adherence, safety, and adverse events of these regimens.

Current status of the small molecule anti-HIV drugs in the pipeline or recently approved

Human Immunodeficiency Virus (HIV) is the causative agent of Acquired Immunodeficiency Syndrome (AIDS) with high morbidity and mortality rates. Treatment of AIDS/HIV is being complicated by increasing resistance to currently used antiretroviral (ARV) drugs, mainly in low- and middle-income countries (LMICs) due to drug misuse, poor drug supply and poor treatment monitoring. However, progress has been made in the development of new ARV drugs, targeting different HIV components (Fig. 1). This review aims at presenting and discussing the progress made towards the discovery of new ARVs that are at different stages of clinical trials as of July 2024. For each compound, the mechanism of action, target biomolecule, genes associated with resistance, efficacy and safety, class, and phase of clinical trial are discussed. These compounds include analogues of nucleoside reverse transcriptase inhibitors (NRTIs) - islatravir and censavudine; non-nucleoside reverse transcriptase inhibitors (NNRTIs) - Rilpivirine, elsulfavirine and doravirine; integrase inhibitors namely cabotegravir and dolutegravir and chemokine coreceptors 5 and 2 (CC5/CCR2) antagonists for example cenicriviroc. Also, fostemsavir is being developed as an attachment inhibitor while lenacapavir, VH4004280 and VH4011499 are capsid inhibitors. Others are maturation inhibitors such as GSK-254, GSK3532795, GSK3739937, GSK2838232, and other compounds labelled as miscellaneous (do not belong to the classical groups of anti-HIV drugs or to the newer classes) such as obefazimod and BIT225. There is a considerable progress in the development of new anti-HIV drugs and the effort will continue since HIV infections has no cure or vaccine till now. Efforts are needed to reduce the toxicity of available drugs or discover new drugs with new classes which can delay the development of resistance.

Effect of Obesity on the Exposure of Long-acting Cabotegravir and Rilpivirine: A Modeling Study

BACKGROUND

Obesity is increasingly prevalent among people with human immunodeficiency virus (HIV, PWH). Obesity can reduce drug exposure; however, limited data are available for long-acting (LA) antiretrovirals. We performed in silico trials using physiologically based pharmacokinetic (PBPK) modeling to determine the effect of obesity on the exposure of LA cabotegravir and rilpivirine after the initial injection and after multiple injections.

METHODS

Our PBPK model was verified against available clinical data for LA cabotegravir and rilpivirine in normal weight/ overweight (body mass index [BMI] <30 kg/m2) and in obese (BMI >30 kg/m2). Cohorts of virtual individuals were generated to simulate the exposure of LA cabotegravir/rilpivirine up to a BMI of 60 kg/m2. The fold change in LA cabotegravir and rilpivirine exposures (area under the curve [AUC]) and trough concentrations (Cmin) for monthly and bimonthly administration were calculated for various BMI categories relative to normal weight (18.5-25 kg/m2).

RESULTS

Obesity was predicted to impact more cabotegravir than rilpivirine with a decrease in cabotegravir AUC and Cmin of >35% for BMI >35 kg/m2 and in rilpivirine AUC and Cmin of >18% for BMI >40 kg/m2 at steady-state. A significant proportion of morbidly obese individuals were predicted to have both cabotegravir and rilpivirine Cmin below the target concentration at steady-state with the bimonthly administration, but this was less frequent with the monthly administration.

CONCLUSIONS

Morbidly obese PWH are at risk of presenting suboptimal Cmin for cabotegravir/rilpivirine after the first injection but also at steady-state particularly with the bimonthly administration. Therapeutic drug monitoring is advised to guide dosing interval adjustment.

Consensus recommendations for use of long-acting antiretroviral medications in the treatment and prevention of HIV-1: Endorsed by the American Academy of HIV Medicine, American College of Clinical Pharmacy, Canadian HIV and Viral Hepatitis Pharmacists Network, European AIDS Clinical Society, and Society of Infectious Diseases Pharmacists

Five long-acting (LA) antiretrovirals (ARVs) are currently available in a limited number of countries worldwide for HIV-1 prevention or treatment-cabotegravir, rilpivirine, lenacapavir, ibalizumab, and dapivirine. Implementing use of LA ARVs into routine clinical practice requires significant changes to the current framework of HIV-1 prevention, treatment, and service provision. Given the novelty, complexity, and interdisciplinary requirements needed to safely and optimally utilize LA ARVs, consensus recommendations on the use of LA ARVs will assist clinicians in optimizing use of these agents. The purpose of these recommendations is to provide guidance for the clinical use of LA ARVs for HIV-1 treatment and prevention. In addition, future areas of research are also identified and discussed.

Low cabotegravir trough concentrations without oral lead-in in patients with HIV-1 switching to long-acting cabotegravir and rilpivirine

In a cohort of 72 consecutive virologically-suppressed patients with HIV-1 switching to long-acting cabotegravir and rilpivirine, we observed low cabotegravir trough concentrations 1 and 3 months after the first injection, with a significant association with no oral lead-in at 1 month [odds ratio (OR) = 6.3 [95% confidence interval (CI) 1.7-29.5], P = 0.01] and three months (OR = 5.6 [95% CI 1.3-29.7], P = 0.03), and with high BMI at 1 month (OR = 1.3 [95% CI 1.1-1.6], P = 0.007).

An update on drug-drug interactions in older adults living with human immunodeficiency virus (HIV)

INTRODUCTION

People with HIV are living longer due to advances in antiretroviral therapy. With improved life expectancy comes an increased lifetime risk of comorbid conditions - such as cardiovascular disease and cancer - and polypharmacy. Older adults, particularly those living with HIV, are more vulnerable to drug interactions and adverse effects, resulting in negative health outcomes.

AREA COVERED

Antiretrovirals are involved in many potential drug interactions with medications used to treat common comorbidities and geriatric conditions in an aging population of people with HIV. We review the mechanisms and management of significant drug-drug interactions involving antiretroviral medications and non-antiretroviral medications commonly used among older people living with HIV. The management of these interactions may require dose adjustments, medication switches to alternatives, enhanced monitoring, and considerations of patient- and disease-specific factors.

EXPERT OPINION

Clinicians managing comorbid conditions among older people with HIV must be particularly vigilant to side effect profiles, drug-drug interactions, pill burden, and cost when optimizing treatment. To support healthier aging among people living with HIV, there is a growing need for antiretroviral stewardship, multidisciplinary care models, and advances that promote insight into the correlations between an individual, their conditions, and their medications.

Long-acting cabotegravir pharmacokinetics with and without oral lead-in for HIV PrEP

Long-acting cabotegravir is approved for pre-exposure prophylaxis and combination HIV treatment, both initiated with optional short-term oral lead-in (OLI). We evaluated the impact of OLI on long-acting cabotegravir pharmacokinetics. Cabotegravir plasma concentrations were compared between HIV-positive participants initiating injections with (n = 278) or without (n = 110) OLI in phase III treatment study FLAIR and in HIV-negative participants using OLI (n = 263) in pivotal pre-exposure prophylaxis studies HPTN 083 and HPTN 084. Cabotegravir pharmacokinetic profiles were simulated in three populations (assigned-male-at-birth, 50%-assigned-female-at-birth, and assigned-female-at-birth) under three scenarios: first injection given (A) 1 or (B) 3 days after final OLI dose (OLI-injection gap) or (C) without OLI. The PK objective was 80% of participants achieving 4× in vitro protein-adjusted 90% maximal inhibitory concentration (PA-IC90) and 50% achieving 8× PA-IC90. Observed trough concentrations (Cτ) were similar with and without OLI (P > 0.3). With a 3-day OLI-injection gap, simulated pre-injection Cτ remained above PK objective. Approximately 1-2 weeks after the first injection, simulated PK profiles became nearly identical among all scenarios. Without OLI, it was predicted that 80% of participants achieve 4× PA-IC90 in 1.2, 1.8, and 2.8 days after the first injection in each population, respectively, and 50% achieve 8× PA-IC90 in 1.4, 2.1, and 3.8 days, respectively. Observed long-acting cabotegravir exposure was similar with or without OLI, supporting optional OLI use. Cabotegravir exposure was predicted to remain above PK objective for OLI-injection gaps of ≤3 days and rapidly achieve PK objective after first injection without OLI. Findings are consistent between assigned-male-at-birth and assigned-female-at-birth populations.

CLINICAL TRIALS

This study is registered with ClinicalTrials.gov as NCT02720094.

Physiologically based Pharmacokinetic Model Validated to Enable Predictions Of Multiple Drugs in a Long-acting Drug-combination Nano-Particles (DcNP): Confirmation with 3 HIV Drugs, Lopinavir, Ritonavir, and Tenofovir in DcNP Products

Drug-Combination Nanoparticles (DcNP) are a novel drug delivery system designed for synchronized delivery of multiple drugs in a single, long-acting, and targeted dose. Unlike depot formulations, slowly releasing drug at the injection site into the blood, DcNP allows multiple-drug-in-combination to collectively distribute from the injection site into the lymphatic system. Two distinct classes of long-acting injectables products are proposed based on pharmacokinetic mechanisms. Class I involves sustained release at the injection site. Class II involves a drug-carrier complex composed of lopinavir, ritonavir, and tenofovir uptake and retention in the lymphatic system before systemic access as a part of the PBPK model validation. For clinical development, Class II long-acting drug-combination products, we leverage data from 3 nonhuman primate studies consisting of nine PK datasets: Study 1, varying fixed-dose ratios; Study 2, short multiple dosing with kinetic tails; Study 3, long multiple dosing (chronic). PBPK validation criteria were established to validate each scenario for all drugs. The models passed validation in 8 of 9 cases, specifically to predict Study 1 and 2, including PK tails, with ritonavir and tenofovir, fully passing Study 3 as well. PBPK model for lopinavir in Study 3 did not pass the validation due to an observable time-varying and delayed drug accumulation, which likely was due to ritonavir's CYP3A inhibitory effect building up during multiple dosing that triggered a mechanism-based drug-drug interaction (DDI). Subsequently, the final model enables us to account for this DDI scenario.

Two-drug regimens for the treatment of HIV in Africa

Two-drug regimens for the treatment of HIV are increasingly available. The oral regimen of dolutegravir plus lamivudine is recommended as a preferred option in multiple national guidelines but is not currently included in WHO HIV treatment guidelines nor widely used in Africa. Long-acting injectable cabotegravir and rilpivirine is being rolled out in the USA, Europe, and Australia but its use in sub-Saharan Africa is currently restricted to clinical trials. Given the increasing life expectancy, rising prevalence of non-communicable diseases, and resulting polypharmacy among people living with HIV, there are potential advantages to the use of two-drug regimens, particularly in African women, adolescents, and older adults. This Viewpoint reviews existing evidence and highlights the risks, benefits, and key knowledge gaps for the use of two-drug regimens in settings using the public health approach in Africa. We suggest that a two-drug regimen of dolutegravir and lamivudine can be safely used as a switch option for virologically suppressed individuals in settings using the public health approach once chronic hepatitis B has been excluded. Individuals with HIV who are switched to two-drug regimens should receive a full course of hepatitis B vaccinations. More efficacy data is needed to support dolutegravir plus lamivudine combination in the test and treat approach, and long-acting cabotegravir and rilpivirine in the public health system in sub-Saharan Africa.

Population Pharmacokinetics of Cabotegravir Following Oral Administration and Long-Acting Intramuscular Injection in Real-World People with HIV

Long-acting cabotegravir has been studied mainly in the stringent framework of clinical trials, which does not necessarily reflect the situation of people with HIV (PWH) in routine clinical settings. The present population pharmacokinetic analysis aims to build real-world reference percentile curves of cabotegravir concentrations, accounting for patient-related factors that may affect cabotegravir exposure. The second objective is to simulate whether dosing interval adjustments of cabotegravir could be considered in specific subpopulations. Overall, 238 PWH contributed to 1,038 cabotegravir levels (186 during the initial oral administration phase and 852 after intramuscular injection). Cabotegravir pharmacokinetics was best described using a one-compartment model with distinct first order-absorption for oral and intramuscular administrations, and identical volume and clearance. Our model showed almost 40% faster absorption and 30% higher clearance than previously reported, resulting in a time to steady-state of 8 months and an elimination half-life of 4.6 weeks for long-acting cabotegravir. Sex and body mass index significantly influenced absorption, and bodyweight affected clearance. Model-based simulations showed that cabotegravir trough concentrations in females were 25% lower 4 weeks after the intramuscular loading dose, but 42% higher during the late maintenance phase. Finally, simulations indicated that in females, despite significantly higher cabotegravir concentrations, longer intervals between injections may not consistently ensure levels above the 4-fold protein-adjusted 90% inhibitory target concentration.

Rilpivirine and cabotegravir trough concentrations in people with HIV on long-term treatment with long-acting injectable antiretrovirals

OBJECTIVE

Large inter-individual variability in the pharmacokinetics of rilpivirine and cabotegravir has been reported in the first weeks after starting long-acting injectable (LAI) therapy. Here, we assessed the distribution of rilpivirine and cabotegravir trough concentrations in people with HIV (PWH) on long-term LAI treatment.

METHODS

Adult PWH treated with LAI for at least 32 weeks with an assessment of drug plasma trough concentrations were considered. The proportion of rilpivirine and cabotegravir plasma trough concentrations below four-times the protein-adjusted concentrations required for 90% inhibition of viral replication (4×PA-IC90) was estimated.

RESULTS

Sixty-seven PWH were identified. LAI treatment duration was 216 ± 80 weeks (range 32-320 weeks). Cabotegravir concentrations were associated with lower inter-individual variability compared with rilpivirine (45% versus 84%; P < 0.05). No differences were found in rilpivirine (160 ± 118 versus 189 ± 81 ng/mL; P = 0.430) and cabotegravir (1758 ± 807 versus 1969 ± 802 ng/mL; P = 0.416) trough concentrations in males (n = 55) versus females (n = 12). A non-significant trend for lower cabotegravir concentrations was found in PWH with a body mass index >30 kg/m2 (n = 9) versus non-obese participants (1916 ± 905 versus 1606 ± 576 ng/mL; P = 0.131). Three out of the 67 PWH had at least one drug concentration <4×PA-IC90: 100% of PWH had undetectable HIV viral load.

CONCLUSIONS

At steady state, optimal systemic exposure of cabotegravir and rilpivirine was found in most PWH; cabotegravir trough concentrations were associated with lower inter-individual variability compared with rilpivirine. The study was not powered to assess the contribution of sex and/or body weight on LAI exposure due to the small number of females and obese PWH included.

Development of a physiologically-based pharmacokinetic model to simulate the pharmacokinetics of intramuscular antiretroviral drugs

There is growing interest in the use of long-acting (LA) injectable drugs to improve treatment adherence. However, their long elimination half-life complicates the conduct of clinical trials. Physiologically-based pharmacokinetic (PBPK) modeling is a mathematical tool that allows to simulate unknown clinical scenarios for LA formulations. Thus, this work aimed to develop and verify a mechanistic intramuscular PBPK model. The framework describing the release of a LA drug from the depot was developed by including both the physiology of the injection site and the physicochemical properties of the drug. The framework was coded in Matlab® 2020a and implemented in our existing PBPK model for the verification step using clinical data for LA cabotegravir, rilpivirine, and paliperidone. The model was considered verified when the simulations were within twofold of observed data. Furthermore, a local sensitivity analysis was conducted to assess the impact of various factors relevant for the drug release from the depot on pharmacokinetics. The PBPK model was successfully verified since all predictions were within twofold of observed clinical data. Peak concentration, area under the concentration-time curve, and trough concentration were sensitive to media viscosity, drug solubility, drug density, and diffusion layer thickness. Additionally, inflammation was shown to impact the drug release from the depot. The developed framework correctly described the release and the drug disposition of LA formulations upon intramuscular administration. It can be implemented in PBPK models to address pharmacological questions related to the use of LA formulations.

Drug Exposure of Long-Acting Cabotegravir and Rilpivirine in Older People With Human Immunodeficiency Virus: A Pharmacokinetic Modeling Study

Background

The life expectancy of people with human immunodeficiency virus (PWH) has significantly increased, thanks to combined antiretrovirals with improved potency and tolerability. One further step has been achieved with the development of long-acting (LA) injectable antiretrovirals, which allow for infrequent dosing. However, the pharmacokinetics of LA antiretrovirals has been poorly characterized in older PWH, as they are generally excluded from trials. We performed virtual studies using physiologically based pharmacokinetic (PBPK) modeling to determine the anticipated exposure of LA cabotegravir/rilpivirine in older individuals.

Methods

Our PBPK model was verified against available observed data for LA cabotegravir and rilpivirine. Cohorts of virtual individuals aged 20-50, 50-65, or 65-85 years were generated to simulate the exposure of LA cabotegravir/rilpivirine for each age group. The fold changes in trough concentration (Cmin) and in drug exposure (area under the time-concentration curve [AUC]) were determined for older relative to young individuals.

Results

The verified PBPK models predicted an increase in exposure within the 0.8-1.25 fold range for monthly LA cabotegravir/rilpivirine. The Cmin and AUC were predicted to be 29% and 26% higher in older compared with young adults for LA cabotegravir administered bimonthly (every 2 months) and 46% and 41% higher for LA rilpivirine bimonthly. The Cmin and AUC of LA cabotegravir and rilpivirine were predicted to be modestly increased in female compared with male individuals for all age groups.

Conclusions

LA cabotegravir/rilpivirine exposure and trough concentrations are predicted to be higher in older than in young PWH; thus, older adults could have a lower risk to present suboptimal concentrations during the dosing interval.

Direct switch from an efavirenz-based regimen to intramuscular long-acting cabotegravir plus rilpivirine: A case report

Switching from oral antiretroviral treatment to intramuscular (IM) cabotegravir (CAB) + rilpivirine (RPV) has an optional oral lead-in to ensure tolerability. The British HIV Association guidelines advise against directly switching from oral antiretroviral (ART) combinations containing strong/moderate cytochrome inducers like efavirenz (EFV) to IM CAB + RPV. EFV has a prolonged elimination half-life, leading to a residual induction of UGT1A1 and CYP3A4 after discontinuation. These enzymes are responsible for CAB and RPV metabolism and their induction might lead to sub-optimal concentrations of CAB and RPV, risking drug resistance. When switching from EFV to oral CAB + RPV, the ATLAS and ATLAS 2M studies showed reduced RPV concentrations but with maintained viral suppression during the oral lead-in and subsequent long-acting injectable (LAI) phases. Also, a recent pharmacokinetic modelling study indicated reduced RPV concentrations, without viral implication, when switching from EFV to IM CAB + RPV. However, there are limited real-world data on direct switching from EFV-based therapy to long-acting IM CAB + RPV. We describe a case where oral intake was impossible in a critical care scenario, switching from emitricitabine/tenofovir-DF (FTC/TDF) 200/245 mg + 600 mg EFV to IM CAB + RPV for treatment optimisation.

Lamivudine, Doravirine, and Cabotegravir Downregulate the Expression of Human Endogenous Retroviruses (HERVs), Inhibit Cell Growth, and Reduce Invasive Capability in Melanoma Cell Lines

This study explores the impact of antiretroviral administration on the expression of human endogenous retroviruses (HERVs), cell growth, and invasive capability of human melanoma cell lines in culture. We investigated three antiretrovirals-lamivudine, doravirine, and cabotegravir-in A375, FO-1, and SK-Mel-28, BRAF-mutated, and in MeWo, P53-mutated, melanoma cell lines. The findings indicate a general capability of these drugs to downregulate the expression of HERV-K Pol and Env genes and hinder cell viability, mobility, and colony formation capacity of melanoma cells. The antiretroviral drugs also demonstrate selectivity against malignant cells, sparing normal human epithelial melanocytes. The study reveals that the integrase inhibitor cabotegravir is particularly effective in inhibiting cell growth and invasion across different cell lines in comparison with lamivudine and doravirine, which are inhibitors of the viral reverse transcriptase enzyme. The investigation further delves into the molecular mechanisms underlying the observed effects, highlighting the potential induction of ferroptosis, apoptosis, and alterations in cell cycle regulatory proteins. Our findings showed cytostatic effects principally revealed in A375, and SK-Mel-28 cell lines through a downregulation of retinoblastoma protein phosphorylation and/or cyclin D1 expression. Signs of ferroptosis were detected in both A375 cells and FO-1 cells by a decrease in glutathione peroxidase 4 and ferritin expression, as well as by an increase in transferrin protein levels. Apoptosis was also detected in FO-1 and SK-Mel-28, but only with cabotegravir treatment. Moreover, we explored the expression and activity of the stimulator of interferon genes (STING) protein and its correlation with programmed death-ligand 1 (PD-L1) expression. Both the STING activity and PD-L1 expression were decreased, suggesting that the antiretroviral treatments may counteract the detrimental effects of PD-L1 expression activation through the STING/interferon pathway triggered by HERV-K. Finally, this study underscores the potential therapeutic significance of cabotegravir in melanoma treatment. The findings also raise the prospect of using antiretroviral drugs to downregulate PD-L1 expression, potentially enhancing the therapeutic responses of immune checkpoint inhibitors.

Improving Adherence to the Target Window for Cabotegravir + Rilpivirine Long-Acting Injections Through the CHORUS™ App and Web Portal: A Cluster Randomized Trial

BACKGROUND

We evaluated the impact of the CHORUS™ app on adherence to the cabotegravir and rilpivirine long-acting injectable (CAB + RPV LAI) monthly injections schedule.

METHODS

Healthcare centers (HCCs) were randomized to access CHORUS™ CAB + RPV LAI features (intervention) or not (control) from 01OCT2021-31JAN2022. Target window adherence (maintenance injections ≤7 days before/after target day) was assessed with multivariate logistic regression (generalized estimating equations).

RESULTS

CAB + RPV LAI was administered to 188 and 79 individuals at intervention and control HCCs, respectively. Intervention was not associated with improved target window adherence (adjusted odds ratio: 0.61 [95% CI: 0.30-1.25]). However, app use was associated with increased odds of adherence compared to no app use among all intervention HCCs (2.98 [1.26-7.06]) and at smaller HCCs (3.58 [1.31-9.80]).

CONCLUSIONS

While access to CHORUS™ CAB + RPV LAI features did not improve target window adherence, app use did, especially at smaller HCCs which may not have established LAI management procedures.

TRIAL REGISTRATION

https://clinicaltrials.gov/show/NCT04863261.

Long-Acting Cabotegravir/Rilpivirine Concentrations in Combination With Intravenous Rifampin: A Case Report

As antiretroviral therapy advancements focus on long-acting medications, there is a need to assess the potential impact of drug-drug interactions. We present a real-world case of long-acting cabotegravir/rilpivirine co-administered with intravenous rifampin. The combination resulted in both cabotegravir and rilpivirine concentrations falling below 4 times the protein-adjusted IC90.

Efficacy and safety of long-acting cabotegravir compared with daily oral tenofovir disoproxil fumarate plus emtricitabine to prevent HIV infection in cisgender men and transgender women who have sex with men 1 year after study unblinding: a secondary analysis of the phase 2b and 3 HPTN 083 randomised controlled trial

BACKGROUND

Injectable cabotegravir was superior to daily oral tenofovir disoproxil fumarate plus emtricitabine for HIV prevention in two clinical trials. Both trials had the primary aim of establishing the HIV prevention efficacy of long-acting injectable cabotegravir pre-exposure prophylaxis (PrEP) compared with tenofovir disoproxil fumarate plus emtricitabine daily oral PrEP. Long-acting PrEP was associated with diagnostic delays and integrase strand-transfer inhibitor (INSTI) resistance. This report presents findings from the first unblinded year of the HIV Prevention Trials Network (HPTN) 083 study.

METHODS

The HPTN 083 randomised controlled trial enrolled HIV-uninfected cisgender men and transgender women at elevated HIV risk who have sex with men, from 43 clinical research sites in Africa, Asia, Latin America, and the USA. Inclusion criteria included: a negative HIV serological test at the screening and study entry, undetectable HIV RNA levels within 14 days of study entry, age 18 years or older, overall good health as determined by clinical and laboratory evaluations, and a creatinine clearance of 60 mL/min or higher. Participants were randomly allocated to receive long-acting injectable cabotegravir or daily oral tenofovir disoproxil fumarate plus emtricitabine PrEP. After study unblinding, participants remained on their original regimen awaiting an extension study. HIV infections were characterised retrospectively at a central laboratory. Here we report the secondary analysis of efficacy and safety for the first unblinded year. The primary outcome was incident HIV infection. Efficacy analyses were done on the modified intention-to-treat population using a Cox regression model. Adverse events were compared across treatment groups and time periods (blinded vs unblinded). This trial is registered with ClinicalTrials.gov, NCT02720094.

FINDINGS

Of the 4488 participants who contributed person-time to the blinded analysis, 3290 contributed person-time to the first unblinded year analysis between May 15, 2020, and May 14, 2021. Updated HIV incidence in the blinded phase was 0·41 per 100 person-years for long-acting injectable cabotegravir PrEP and 1·29 per 100 person-years for daily oral tenofovir disoproxil fumarate plus emtricitabine PrEP (hazard ratio [HR] 0·31 [95% CI 0·17-0·58], p=0·0003). HIV incidence in the first unblinded year was 0·82 per 100 person-years for long-acting PrEP and 2·27 per 100 person-years for daily oral PrEP (HR 0·35 [0·18-0·69], p=0·002). Adherence to both study products decreased after study unblinding. Additional infections in the long-acting PrEP group included two with on-time injections; three with one or more delayed injections; two detected with long-acting PrEP reinitiation; and 11 more than 6 months after their last injection. Infection within 6 months of cabotegravir exposure was associated with diagnostic delays and INSTI resistance. Adverse events were generally consistent with previous reports; incident hypertension in the long-acting PrEP group requires further investigation.

INTERPRETATION

Long-acting injectable cabotegravir PrEP retained high efficacy for HIV prevention in men and transgender women who have sex with men during the first year of open-label follow-up, with a near-identical HR for HIV risk reduction between long-acting injectable cabotegravir and daily oral tenofovir disoproxil fumarate plus emtricitabine PrEP during the first year after unblinding compared with the blinded period. Extended follow-up further defined the risk period for diagnostic delays and emergence of INSTI resistance.

FUNDING

Division of AIDS at the National Institute of Allergy and Infectious Diseases, ViiV Healthcare, and Gilead Sciences.

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

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

Clinical Relevance of Drug Interactions in People Living with Human Immunodeficiency Virus on Antiretroviral Therapy-Update 2022: Systematic Review

BACKGROUND

The clinical outcomes of antiretroviral drugs may be modified through drug interactions; thus, it is important to update the drug interactions in people living with HIV (PLHIV).

AIM

To update clinically relevant drug interactions in PLHIV on antiretroviral therapy with novel drug interactions published from 2017 to 2022.

METHODS

A systematic review in Medline/PubMed database from July 2017 to December 2022 using the Mesh terms antiretroviral agents and drug interactions or herb-drug interactions or food-drug interactions. Publications with drug interactions in humans, in English or Spanish, and with full-text access were retrieved. The clinical relevance of drug interactions was grouped into five levels according to the gravity and probability of occurrence.

RESULTS

A total of 366 articles were identified, with 219 (including 87 citation lists) were included, which allowed for the identification of 471 drug interaction pairs; among them, 291 were systematically reported for the first time. In total 42 (14.4%) and 137 (47.1%) were level one and two, respectively, and 233 (80.1%) pairs were explained with the pharmacokinetic mechanism. Among these 291 pairs, protease inhibitors (PIs) and ritonavir/cobicistat-boosted PIs, as well as integrase strand transfer inhibitors (InSTIs), with 70 (24.1%) and 65 (22.3%) drug interaction pairs of levels one and two, respectively, were more frequent.

CONCLUSIONS

In PLHIV on antiretroviral therapy, we identify 291 drug interaction pairs systematically reported for the first time, with 179 (61.5%) being assessed as clinically relevant (levels one and two). The pharmacokinetic mechanism was the most frequently identified. PIs, ritonavir/cobicistat-boosted PIs, and InSTIs were the antiretroviral groups with the highest number of clinically relevant drug interaction pairs (levels one and two).

The New Era of Long-Acting Antiretroviral Therapy: When and Why to Make the Switch

PURPOSE OF REVIEW

Despite the availability of safe and effective oral combination antiretroviral therapy, barriers to maintaining viral suppression remain a challenge to ending the HIV epidemic. Long-acting injectable antiretroviral therapy was developed as an alternative to daily oral therapy. This review summarizes the current literature on the efficacy of long-acting cabotegravir plus rilpivirine for the treatment of HIV-1, reasons to switch to injectable therapy, and barriers to switching.

RECENT FINDINGS

Long-acting cabotegravir plus rilpivirine is safe and effective in maintaining HIV-1 virologic suppression. Ideal candidates for switching to long-acting cabotegravir plus rilpivirine are virologically suppressed on oral regimens with good adherence and no history of virologic failure or baseline resistance. Indications to switch to injectable therapy include patient preference, the potential for improved adherence, and avoidance of adverse effects. Implementation research is needed to assess and overcome system barriers. Long-acting cabotegravir plus rilpivirine is a novel alternative to oral antiretrovirals, with the potential to improve adherence and quality of life in people with HIV.

Pillars of long-term antiretroviral therapy success

BACKGROUND

Meeting the challenge of antiretroviral therapy (ART) whose efficacy can last a lifetime requires continuous updating of the virological, pharmacological, and quality of life outcomes to be pursued and a continuous review of literature data on the efficacy and tolerability of new drugs and therapeutic strategies.

METHODS

With the aim of identifying open questions and answers about the current controversies in modern ART, we adapted the Design Thinking methodology to the needs of the design phase of a scientific article, involving a team of experts in HIV care.

RESULTS

Five main pillars of treatment success were discussed: sustained virologic suppression over time; immunological recovery; pharmacological attributes; long-term tolerability and safety of ART; and people's satisfaction and quality of life. The definition of the outcomes to be achieved in each thematic area and the tools to achieve them were reviewed and discussed.

CONCLUSIONS

Long-term treatment success should be intended as a combination of HIV-RNA suppression, immune recovery, and high quality of life. To achieve this, the regimen should be well-tolerated, with high potency, genetic barrier, and forgiveness, and should be tailored by a person-centered perspective, based on individual needs, preferences, and therapeutic history.

Long-acting lenacapavir protects macaques against intravenous challenge with simian-tropic HIV

BACKGROUND

Long-acting subcutaneous lenacapavir (LEN), a first-in-class HIV capsid inhibitor approved by the US FDA for the treatment of multidrug-resistant HIV-1 with twice yearly dosing, is under investigation for HIV-1 pre-exposure prophylaxis (PrEP). We previously derived a simian-tropic HIV-1 clone (stHIV-A19) that encodes an HIV-1 capsid and replicates to high titres in pigtail macaques (PTM), resulting in a nonhuman primate model well-suited for evaluating LEN PrEP in vivo.

METHODS

Lenacapavir potency against stHIV-A19 in PTM peripheral blood mononuclear cells in vitro was determined and subcutaneous LEN pharmacokinetics were evaluated in naïve PTMs in vivo. To evaluate the protective efficacy of LEN PrEP, naïve PTMs received either a single subcutaneous injection of LEN (25 mg/kg, N = 3) or vehicle (N = 4) 30 days before a high-dose intravenous challenge with stHIV-A19, or 7 daily subcutaneous injections of a 3-drug control PrEP regimen starting 3 days before stHIV-A19 challenge (N = 3).

FINDINGS

In vitro, LEN showed potent antiviral activity against stHIV-A19, comparable to its potency against HIV-1. In vivo, subcutaneous LEN displayed sustained plasma drug exposures in PTMs. Following stHIV-A19 challenge, while all vehicle control animals became productively infected, all LEN and 3-drug control PrEP animals were protected from infection.

INTERPRETATION

These findings highlight the utility of the stHIV-A19/PTM model and support the clinical development of long-acting LEN for PrEP in humans.

FUNDING

Gilead Sciences as part of a Cooperative Research and Development Agreement between Gilead Sciences and Frederick National Lab; federal funds from the National Cancer Institute, National Institutes of Health, under Contract No. 75N91019D00024/HHSN261201500003I; NIH grant R01AI078788.

Advancing the use of Long-Acting Extended Delivery formulations for HIV prevention in sub-Saharan Africa: challenges, opportunities, and recommendations

INTRODUCTION

The burden of HIV in sub-Saharan Africa (SSA) remains unacceptably high, and disproportionately affects girls and women. While the introduction of oral HIV pre-exposure prophylaxis (PrEP) in 2012 revolutionized HIV prevention, its effectiveness is dependent on user adherence and its implementation in SSA has faced numerous challenges. Patient-level, interpersonal and structural barriers, including, for example, daily pill burden, side effects, lack of partner support, testing and disclosure, and costs have been found to reduce adherence to oral PrEP.

DISCUSSION

Long-acting extended delivery (LAED) formulations for PrEP, such as injectable long-acting cabotegravir (CAB-LA) and dapivirine vaginal ring (DPV-VR) are critical additions to the HIV prevention toolkit and are especially important for populations such as adolescent girls and young women (AGYW) and other key populations who remain at significant risk of HIV acquisition while facing substantial barriers to preventive services. These LAED formulations have been shown to result in better adherence and fewer side effects, with CAB-LA being superior to oral PrEP in reducing the risk of HIV acquisition. They can be used to overcome user burden and adherence challenges. However, the successful rollout of the DPV-VR and CAB-LA may be hampered by issues such as a shortage of healthcare providers (HCPs), inadequate parenteral medication infrastructure, increased workload for HCPs, patient concerns, the price of the medications and the possibility of drug resistance.

CONCLUSIONS

SSA must develop laboratory capabilities for monitoring patients on LAED formulations and enhance research on developing more non-injectable LAED formulations. There is a need to train and retain more HCPs, implement task shifting, invest in healthcare infrastructure and integrate healthcare services. To reduce costs and improve availability, the region must advocate for patent license waivers for LAED formulations and procure drugs collectively as a region.

Drug-drug interactions between COVID-19 therapeutics and antiretroviral treatment: the evidence to date

INTRODUCTION

With new effective treatments for SARS-CoV-2, patient outcomes have greatly improved. However, new medications bring a risk of drug interactions with other medications. People living with HIV (PLWH) are at particular risk for these interactions due to heightened risk of immunosuppression, polypharmacy, and overlap in affected organs. It is critical to identify drug interactions are a significant barrier to care for PLWH. Establishing a better understanding of the pharmacologic relationships between COVID-19 therapies and antiretrovirals will improve patient-centered care in COVID-19.

AREAS COVERED

Potential drug-drug interactions between Human Immunodeficiency Virus (HIV) and COVID-19 treatments are detailed and reviewed here. The mechanisms seen in these interactions include alterations in metabolic enzymes, drug transporters, pharmacoenhancement, and organ toxicities. We also review the limitations and solutions that can be used to combat drug-drug interactions between these two disease states.

EXPERT OPINION

While current drug interactions are relatively mild between HIV and COVID-19 therapies, improvements in identifying these beforehand must take place as new therapies are approved. Antiretroviral therapy (ART) is essential in PLWH and must be maintained when treating COVID-19. As advancements in care occur, there is the possibility that newly approved drugs may have additional unknown interactions.

The role of tunneling nanotubes during early stages of HIV infection and reactivation: implications in HIV cure

Tunneling nanotubes (TNTs), also called cytonemes or tumor microtubes, correspond to cellular processes that enable long-range communication. TNTs are plasma membrane extensions that form tubular processes that connect the cytoplasm of two or more cells. TNTs are mostly expressed during the early stages of development and poorly expressed in adulthood. However, in disease conditions such as stroke, cancer, and viral infections such as HIV, TNTs proliferate, but their role is poorly understood. TNTs function has been associated with signaling coordination, organelle sharing, and the transfer of infectious agents such as HIV. Here, we describe the critical role and function of TNTs during HIV infection and reactivation, as well as the use of TNTs for cure strategies.

Gynoid Fat Distribution and Adipocyte Trapping May Explain Virological Failure With Intramuscular Long-Acting Cabotegravir and Rilpivirine

Intramuscular long-acting antiretroviral drugs can improve adherence to lifelong antiretroviral treatment. Nevertheless, adipose tissue thickness and distribution play a critical role with injectable drugs. We describe a virological failure with cabotegravir and rilpivirine in a Black African woman with human immunodeficiency virus type 1 with gynoid fat distribution (ie, adipose tissue prevailing in the pelvis and hip area) and body mass index <30 kg/m2.

Extended Analysis of HIV Infection in Cisgender Men and Transgender Women Who Have Sex with Men Receiving Injectable Cabotegravir for HIV Prevention: HPTN 083

HPTN 083 demonstrated that injectable cabotegravir (CAB) was superior to oral tenofovir disoproxil fumarate-emtricitabine (TDF-FTC) for HIV prevention in cisgender men and transgender women who have sex with men. We previously analyzed 58 infections in the blinded phase of HPTN 083 (16 in the CAB arm and 42 in the TDF-FTC arm). This report describes 52 additional infections that occurred up to 1 year after study unblinding (18 in the CAB arm and 34 in the TDF-FTC arm). Retrospective testing included HIV testing, viral load testing, quantification of study drug concentrations, and drug resistance testing. The new CAB arm infections included 7 with CAB administration within 6 months of the first HIV-positive visit (2 with on-time injections, 3 with ≥1 delayed injection, and 2 who restarted CAB) and 11 with no recent CAB administration. Three cases had integrase strand transfer inhibitor (INSTI) resistance (2 with on-time injections and 1 who restarted CAB). Among 34 CAB infections analyzed to date, diagnosis delays and INSTI resistance were significantly more common in infections with CAB administration within 6 months of the first HIV-positive visit. This report further characterizes HIV infections in persons receiving CAB preexposure prophylaxis and helps define the impact of CAB on the detection of infection and the emergence of INSTI resistance.

Cabotegravir: The First Long-Acting Injectable for HIV Preexposure Prophylaxis

OBJECTIVE

Review the pharmacology, pharmacokinetics, efficacy, safety, and role of long-acting injectable cabotegravir (CAB-LA) in HIV preexposure prophylaxis (PrEP).

DATA SOURCES

A literature search was performed using PubMed and Google Scholar (2012 to April 2022) with the search terms cabotegravir, preexposure prophylaxis, and PrEP. Other resources included abstracts presented at recent conferences, the manufacturer's Web site, prescribing information, and review articles.

STUDY SELECTION AND DATA EXTRACTION

All English-language articles of studies assessing the efficacy and safety of CAB-LA for PrEP were included.

DATA SYNTHESIS

CAB-LA is the first long-acting injectable therapy approved for HIV-1 PrEP in both men and women. It is a suspension given intramuscularly every other month. CAB-LA has been shown to be more effective than daily oral tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) in preventing HIV-1 infection among high-risk individuals. Two phase 3 trials were stopped early on the basis of superior efficacy of CAB-LA. The most common adverse effects were injection site reactions (ISRs), although they tended to decrease over time, and few participants in clinical trials discontinued use due to ISRs.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

CAB-LA may be particularly useful for individuals with known adherence problems to oral therapy, those with renal impairment, and those with decreased bone mineral density. However, CAB-LA is more expensive than generic TDF/FTC and may be associated with weight gain.

CONCLUSIONS

CAB-LA is the first long-acting injectable agent for HIV PrEP. It is more effective than oral TDF/FTC, is well-tolerated aside from ISRs, and has few clinically significant drug-drug interactions.

Long-Acting Antiretroviral Drug Therapy in Adolescents: Current Status and Future Prospects

Approximately 50% of human immunodeficiency virus (HIV)-infected adolescents fail to achieve complete viral suppression, largely due to nonadherence to their antiretroviral drug regimens. Numerous personal, financial, and societal barriers contribute to nonadherence, which may lead to the development of HIV drug resistance. Long-acting antiretroviral drugs hold the promise of improved adherence because they remove the need for swallowing one or more pills daily. Cabotegravir (an integrase strand transfer inhibitor) and rilpivirine (a non-nucleoside reverse transcriptase inhibitor) can now be intramuscularly co-administered to HIV-infected adolescents every 4-8 weeks if they are virologically suppressed and without resistance mutations to cabotegravir or rilpivirine. Adverse effects are few and non-severe. Widespread use of this complete antiretroviral therapy may be limited by drug costs, need for sites and skilled personnel who can administer the injections, and ethical challenges. Other long-acting medications and new antiretroviral therapy delivery systems are under active investigation and show great promise.