Tail-phase safety, tolerability, and pharmacokinetics of long-acting injectable cabotegravir in HIV-uninfected adults: a secondary analysis of the HPTN 077 trial

Antiretroviral Postexposure Prophylaxis After Sexual, Injection Drug Use, or Other Nonoccupational Exposure to HIV - CDC Recommendations, United States, 2025

Nonoccupational postexposure prophylaxis (nPEP) for HIV is recommended when a nonoccupational (e.g., sexual, needle, or other) exposure to nonintact skin or mucous membranes that presents a substantial risk for HIV transmission has occurred, and the source has HIV without sustained viral suppression or their viral suppression information is not known. A rapid HIV test (also referred to as point-of-care) or laboratory-based antigen/antibody combination HIV test is recommended before nPEP initiation. Health care professionals should ensure the first dose of nPEP is provided as soon as possible, and ideally within 24 hours, but no later than 72 hours after exposure. The initial nPEP dose should not be delayed due to pending results of any laboratory-based testing, and the recommended length of nPEP course is 28 days. The recommendations in these guidelines update the 2016 nPEP guidelines (CDC. Updated guidelines for antiretroviral postexposure prophylaxis after sexual, injection drug use, or other nonoccupational exposure to HIV - United States, 2016. Atlanta, GA: US Department of Health and Human Services, CDC; 2017). These 2025 nPEP guidelines update recommendations and considerations for use of HIV nPEP in the United States to include newer antiretroviral (ARV) agents, updated nPEP indication considerations, and emerging nPEP implementation strategies. The guidelines also include considerations for testing and nPEP regimens for persons exposed who have received long-acting injectable ARVs in the past. Lastly, testing recommendations for persons who experienced sexual assault were updated to align with the most recent CDC sexually transmitted infection treatment guidelines. These guidelines are divided into two sections: Recommendations and CDC Guidance. The preferred regimens for most adults and adolescents are now bictegravir/emtricitabine/tenofovir alafenamide or dolutegravir plus (tenofovir alafenamide or tenofovir disoproxil fumarate) plus (emtricitabine or lamivudine). However, the regimen can be tailored to the clinical circumstances. Medical follow-up for persons prescribed nPEP also should be tailored to the clinical situation; recommended follow-up includes a visit at 24 hours (remote or in person) with a medical provider, and clinical follow-up 4-6 weeks and 12 weeks after exposure for laboratory testing. Persons initiating nPEP should be informed that pre-exposure prophylaxis for HIV (PrEP) can reduce their risk for acquiring HIV if they will have repeat or continuing exposure to HIV after the end of the nPEP course. Health care professionals should offer PrEP options to persons with ongoing indications for PrEP and create an nPEP-to-PrEP transition plan for persons who accept PrEP.

HIV diagnosis during acute infection: implications of long-acting preexposure prophylaxis and other evolving challenges

PURPOSE OF REVIEW

Tests for HIV may perform differently in some circumstances such as with preexposure prophylaxis (PrEP) or other HIV prevention agents. Testing algorithms may not account for this, with a risk of false negative or positive HIV results. In this review we have explored the challenges of HIV testing in these special circumstances.

RECENT FINDINGS

Long-acting injectable PrEP using cabotegravir or lenacapavir has been studied in large randomized controlled trials (HPTN083/084 and PURPOSE1/2 respectively). Injectable PrEP was significantly more efficacious than oral PrEP, but infections still occurred risking the emergence of HIV drug-resistance. HIV diagnostic test results were atypical in those receiving injectable PrEP, with low or undetectable HIV viral loads, delayed or diminished antibody, and HIV detection assays reverting from reactive to unreactive; so-called long acting early viral inhibition (LEVI) syndrome. In these cases, missed or delayed HIV diagnoses could be reduced with the use of HIV nucleic acid amplification tests in addition to routine testing, but this remains unfeasible in many settings.

SUMMARY

Finding HIV testing strategies that are affordable and practical in low- and middle-income countries that can accurately diagnose HIV in the context of HIV prevention is of high importance, but more research is needed in this area.

Virological History Predicts Non-sustained Viral Suppression With Long-Acting Cabotegravir and Rilpivirine Therapy, Independent of Pharmacokinetic Parameters

BACKGROUND

This study aimed to investigate factors contributing to non-sustained viral suppression, including intermittent viremia and persistent low-level viremia, during cabotegravir (CAB) plus rilpivirine (RPV) long-acting (LA) injectable therapy, with a focus on pharmacokinetics (PK).

METHODS

A prospective cohort study was conducted on people with human immunodeficiency virus (HIV, PWH) transitioning from stable oral antiretroviral therapy (ART) to bimonthly CAB + RPV LA. Standardized follow-up included close monitoring through blood sampling for plasma human immunodeficiency virus type 1 (HIV-1) viral load (VL) and multiple plasma drug concentrations measurements to analyze the connection between PK parameters and virologic outcomes.

RESULTS

Among 173 patients with a median (interquartile range [IQR]) follow-up of 11.1(7.1-13.2) months and 789 pre-dose measurements, 38.7% experienced VL ≥ 20 copies/mL, and 16.2% had levels ≥50 copies/mL. Intermittent viremia occurred in 34.7% of patients, and persistent low-level viremia in 4%. Virological failure developed in 2 cases. Predictors of non-sustained viral suppression included VL at HIV diagnosis (adjusted hazard ratio [AHR]: 1.49 per log10 VL, 95% confidence interval [CI]: 1.04-2.12, P = .027), detectable viremia on oral ART (AHR: 2.45, 95% CI: 1.29-4.65, P = .006), and the level of viral suppression at transition (AHR: 0.38, 95% CI: .19-.75, P = .004). We found a significant association between low trough concentrations of CAB and RPV and episodes of detectable viremia exceeding 50 copies/mL. However, none of the assessed PK covariates predicted non-sustained viral suppression in multivariable models.

CONCLUSIONS

Non-sustained viral suppression in PWH transitioning from stable oral ART to CAB + RPV LA was linked to preexisting factors before transition. Higher VL pre-ART and incomplete suppression on oral therapy increased the risk, independent of PK parameters.

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.

A review of pharmacokinetic data describing long-acting injectable cabotegravir during pregnancy

INTRODUCTION

Eliminating vertical human immunodeficiency virus (HIV) transmission is a global health objective. Significant progress has been accomplished through advancements in antiretroviral therapy (ART) and pre-exposure prophylaxis (PrEP). Long-acting cabotegravir (CAB-LA) is a novel strategy addressing daily oral adherence challenges for both treatment and prevention of HIV. For treatment, CAB-LA is currently approved in combination with long-acting rilpivirine (RPV-LA). Despite its promise, there are limited data surrounding the utilization of CAB-LA in pregnancy. Understanding potential CAB-LA pharmacokinetic (PK) changes during pregnancy is necessary to ensure effectiveness and safety.

AREAS COVERED

Current PK data for CAB-LA in pregnant individuals, including physiological changes affecting PK, physiologically based PK modeling, and clinical PK data.

EXPERT OPINION

Long-acting therapies represent the future of HIV treatment and prevention. Available data demonstrate no clinically significant change in CAB PK, supporting CAB-LA for PrEP in pregnant individuals. However, available data for oral RPV and RPV-LA during pregnancy demonstrate lower drug concentrations, which limit CAB-LA utilization for HIV treatment until alternative partner drugs are available. Other long-acting prevention and treatment strategies are in development. Future studies assessing long-acting strategies are necessary during drug development to ensure equitable and timely access to novel therapies for all individuals.

A Qualitative Study Exploring How the Perspectives and Experiences of Cisgender Black Women Inform Their Readiness to Consider Pre-Exposure Prophylaxis for HIV Prevention

Attention to increasing pre-exposure prophylaxis (PrEP) use among cisgender Black women (CBW) in the southern United States (U.S.) is necessary to achieve national 2030 Ending the HIV Epidemic (EHE) goals. Qualitative exploration of CBW's readiness to use PrEP is necessary to discern whether practical solutions to addressing PrEP uptake within this HIV-vulnerable population are feasible. Focus group discussions (n = 5) and key informant interviews (n = 3) in two EHE jurisdictions in Houston and Austin, Texas were used to explore how perspectives and lived experiences may serve as facilitators and/or barriers to PrEP readiness among 20 CBW. Codes highlighted facilitators and barriers to PrEP readiness. Facilitators involved positive experiences with the healthcare system, high perceived HIV vulnerability, and prioritizing PrEP as self-care. Barriers encompassed concerns with sexual relationship dynamics, mental health implications, and access to humane treatment within the healthcare system. High perceived vulnerability of HIV acquisition is related to an awareness that CBW may not know the entirety of their partner's sexual activities. Findings indicate precursors of PrEP readiness and challenge the notion that CBW have low perceived vulnerability of acquiring HIV.

Preferential Initiation of Long-Acting Injectable Versus Oral HIV Pre-Exposure Prophylaxis Among Women Who Inject Drugs

Fifty-five of 62 women who inject drugs (WWID) selected long-acting cabotegravir (CAB-LA) over oral PrEP, and 51/55 received a first injection. More recent injection drug use and number of sexual partners were associated with selecting CAB-LA (P < .05). Findings provide preliminary evidence of a strong preference for longer-acting products among WWID.

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.

Safety of combined long-acting injectable cabotegravir and long-acting injectable rilpivirine in virologically suppressed adolescents with HIV (IMPAACT 2017/MOCHA): a phase 1/2, multicentre, open-label, non-comparative, dose-finding study

BACKGROUND

Long-acting cabotegravir and long-acting rilpivirine constitute a completely intramuscular antiretroviral therapy (ART) regimen for adults with HIV. We aimed to assess the safety, antiviral activity, and pharmacokinetics of oral cabotegravir and rilpivirine followed by a combination of long-acting cabotegravir and long-acting rilpivirine in virologically suppressed adolescents with HIV.

METHODS

The IMPAACT 2017/MOCHA study is a phase 1/2, multicentre, open-label, non-comparative, dose-finding trial being conducted at 18 sites across Botswana, South Africa, Thailand, Uganda, and the USA. In cohort 2 of this study, adolescents (aged 12-18 years; weight ≥35 kg) with HIV and no serious comorbidities who were receiving stable combination ART with confirmed virological suppression and had either previously enrolled in the first cohort or had not previously participated in the study were eligible for inclusion. Participants stopped their background combination ART and received oral cabotegravir 30 mg once daily and oral rilpivirine 25 mg once daily orally for 4-6 weeks, followed by long-acting injectable cabotegravir 600 mg (3 mL) and long-acting injectable rilpivirine 900 mg (3 mL) intramuscularly at weeks 4 and 8, and every 8 weeks thereafter. The primary outcome was safety, including all adverse events, at week 24. Primary safety outcome measures were summarised as frequencies, percentages, and exact Clopper-Pearson 95% CIs in the evaluable analysis population, which included participants who were treated exclusively with the regimen and either completed all scheduled treatments or experienced severe adverse events, permanently discontinued the treatment, or died, whichever occurred first; and in the all-treated analysis population, which included all participants who received at least one dose of any study product. This study is registered with ClinicalTrials.gov (NCT3497676) and is ongoing.

FINDINGS

Between July 26, 2021, and Aug 27, 2022, 44 (80·0%) of 55 adolescents who participated in cohort 1 and 100 (87·0%) of 115 screened study-naive adolescents were enrolled in cohort 2. 74 (51·4%) participants were female and 70 (48·6%) were male. Overall, 15 (10·8% [95% CI 6·2-17·2]) of all 139 participants in the evaluable analysis population had at least one adverse event of grade 3 or above by week 24. Among 142 participants who received at least one injection, 43 (30%) experienced at least one injection site reaction (ISR). All 106 ISRs were either grade 1 (98 [92·5%]) or grade 2 (eight [7·5%]), and 97 (91·5%) resolved within 7 days. No participant experienced a drug-related serious adverse event or prematurely discontinued treatment due to a drug-related adverse event.

INTERPRETATION

Long-acting injectable cabotegravir and long-acting injectable rilpivirine, administered to adolescents at recommended adult dosages every 8 weeks, showed no unanticipated safety concerns in the 24 weeks following administration.

FUNDING

National Institutes of Health, ViiV Healthcare, and Johnson & Johnson.

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.

Thigh Injections of Cabotegravir + Rilpivirine in Virally Suppressed Adults With Human Immunodeficiency Virus Type 1: A Substudy of the Phase 3b ATLAS-2M Study

BACKGROUND

Cabotegravir + rilpivirine (CAB + RPV) administered via intramuscular gluteal injections is the first complete long-acting regimen for maintaining human immunodeficiency virus type 1 (HIV-1) virologic suppression. We present substudy results on short-term repeat intramuscular CAB + RPV long-acting thigh injections in participants with ≥3 years of experience with gluteal administration during the ATLAS-2M study.

METHODS

Substudy phases included screening, thigh injection (day 1-week 16), and return to gluteal injection (week 16-week 24). The injection schedule was unchanged from the main study. Outcomes included pharmacokinetics, safety, tolerability, efficacy, and patient-reported outcomes. Pharmacokinetic parameters were determined using noncompartmental analysis and mixed-effects modeling. Population pharmacokinetic simulations were performed.

RESULTS

There were 118 participants. In the arm that received injections every 2 months (Q2M), first CAB thigh injection including area under the concentration-time curve and maximum observed concentration (Cmax) and first RPV thigh injection Cmax and all last RPV thigh injection parameters were statistically higher vs gluteal injections (paired comparison). No significant differences occurred with once-monthly (QM) dosing. No participants had HIV-1 RNA ≥50 copies/mL after thigh injections. Overall, 4%-7% of injection site reactions (ISRs) were grade 3. Five participants withdrew due to an ISR or injection intolerability. Overall, 30% preferred thigh vs gluteal injections. Simulations demonstrated the potential for chronic/continuous QM or ≤2 consecutive Q2M thigh injections.

CONCLUSIONS

These data demonstrate the potential use of chronic/continuous QM and rotational/short-term QM or Q2M (≤4 months of continuous dosing), CAB + RPV long-acting intramuscular thigh administration for HIV-1 treatment.

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.

Comparative Analyses of Antiviral Potencies of Second-Generation Integrase Strand Transfer Inhibitors (INSTIs) and the Developmental Compound 4d Against a Panel of Integrase Quadruple Mutants

Second-generation integrase strand transfer inhibitors (INSTIs) are strongly recommended for people living with HIV-1 (PLWH). The emergence of resistance to second-generation INSTIs has been infrequent and has not yet been a major issue in high-income countries. However, the delayed rollouts of these INSTIs in low- to middle-income countries during the COVID-19 pandemic combined with increased transmission of drug-resistant mutants worldwide are leading to an increase in INSTI resistance. Herein, we evaluated the antiviral potencies of our lead developmental INSTI 4d and the second-generation INSTIs dolutegravir (DTG), bictegravir (BIC), and cabotegravir (CAB) against a panel of IN quadruple mutants. The mutations are centered around G140S/Q148H, including positions L74, E92, and T97 combined with E138A/K/G140S/Q148H. All of the tested INSTIs lose potency against these IN quadruple mutants compared with the wild-type IN. In single-round infection assays, compound 4d retained higher antiviral potencies (EC50 values) than second-generation INSTIs against a subset of quadruple mutants. These findings may advance understanding of mechanisms that contribute to resistance and, in so doing, facilitate development of new INSTIs with improved antiviral profiles.

HIV Prevention in Syringe Service Programs Since the Start of COVID-19: Where Do We Go From Here?

PURPOSE

This narrative review addresses post-2020, specific, complex challenges for use of and adherence to pre-exposure prophylaxis (PrEP) for HIV prevention among out-of-treatment people who use drugs (PWUD) at syringe services programs (SSPs).

RECENT FINDINGS

The COVID-19 pandemic and its associated changes to the provision of healthcare have significantly impacted HIV prevention, especially for PWUD. Through a synthesis of literature and clinical experience, we (1) characterize the operational changes imposed by the pandemic on SSPs that shaped the current HIV prevention landscape; (2) describe three levels of current challenges for PWUD, including consumer attitudes, non-medical and medical provider attitudes, and structural and scalability barriers; (3) characterize current models for PrEP in SSPs; and (4) offer practical recommendations for HIV prevention in harm reduction programs. PrEP is a highly effective prevention tool if taken as prescribed. It has been enthusiastically promoted by members of the research, public health and provider communities. Despite its efficacy, PWUD struggle to engage with the PrEP care continuum. We highlight opportunities to advance HIV prevention for PWUD by enhancing tailored, whole-person approaches that may set aside PrEP in favor of other risk reduction routes. For most PWUD who receive services at SSPs, PrEP is a single tool and not realistic until other social and structural determinants of health are addressed.

Evaluation of long-acting cabotegravir safety and pharmacokinetics in pregnant women in eastern and southern Africa: a secondary analysis of HPTN 084

INTRODUCTION

Long-acting injectable cabotegravir (CAB-LA) for pre-exposure prophylaxis significantly reduced HIV acquisition in HPTN 084. We report on the safety and CAB-LA pharmacokinetics in pregnant women during the blinded period of HPTN 084.

METHODS

Participants were randomized 1:1 to either active cabotegravir (CAB) plus tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) placebo or active TDF/FTC plus CAB placebo. Pregnancy testing was performed at each visit; participants with a positive test had study product withheld and were offered open-label TDF/FTC. Pregnancies were confirmed on two tests at least 4 weeks apart. All participants with a positive pregnancy test prior to November 5, 2020 are included in this analysis. Pregnancy incidence, maternal adverse event (AE) incidence, pregnancy outcomes (including composite outcome of spontaneous abortion <20 weeks, intrauterine foetal death or stillbirth ≥20 weeks, premature birth <37 weeks, or small for gestational age) were assessed. The apparent terminal phase half-life (t1/2app) of CAB-LA in pregnant women in HPTN 084 was compared to non-pregnant women from the phase 2a HPTN 077 trial. Multivariable models assessed associations with t1/2app. RESULTS: Fifty-seven pregnancies (30 CAB-LA, 27 TDF/FTC) were confirmed over 3845 person-years [py] (incidence 1.5/100 py, 95% CI 1.1-1.9). CAB-LA group participants had a median 342 days (IQR 192, 497) of CAB-LA exposure prior to pregnancy detection. Grade 2 or higher maternal AE incidence did not differ by study arm (CAB 157, 95% CI 91-271 per 100 py vs. TDF/FTC 217, 95% CI 124-380 per 100 py; p = 0.256). Most pregnancies (81%) resulted in live births (25 CAB-LA, 22 TDF/FTC). Composite poor pregnancy outcomes did not differ significantly by group (CAB 6/30 vs. TDF/FTC 4/27; p = 0.476). No congenital anomalies were observed. The CAB t1/2app geometric mean was 52.8 days (95% CI 40.7-68.4) in pregnant women compared to 60.3 days (95% CI 47.7-76.3; p = 0.66) in non-pregnant women; neither pregnancy nor body mass index were significantly associated with t1/2app.

CONCLUSIONS

CAB-LA concentrations post-cessation of injections were generally well tolerated in pregnant women. The t1/2app was comparable between pregnant and non-pregnant women. Ongoing studies will examine the safety and pharmacology of CAB-LA in women who choose to continue CAB-LA through pregnancy and lactation.

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.

Pre-Exposure Prophylaxis for HIV: Bioethical, Clinical, and Epidemiological Considerations

Public health authorities are broadly promoting a strategy known as pre-exposure prophylaxis (PrEP) for the prevention of human immunodeficiency virus (HIV) transmission in the context of high-risk sexual activity and injection drug use. However, there are several limitations to this strategy that are underrecognized. This article reviews the primary literature supporting the use of PrEP and explores the unintended consequences associated with its use. Current public health messaging indicates that PrEP reduces the risk of HIV transmission during sex by 99 percent; however, this figure is based on modeling rather than study findings, and real-world efficacy may be significantly lower. PrEP has been associated with increased rates of sexually transmitted infections, risk compensation, HIV drug resistance, low adherence, and drug side effects. To make fully informed decisions, medical professionals and patients should be aware of these pitfalls. Additionally, this article explores the bioethical implications of prescribing PrEP from a Catholic perspective. Although not always morally illicit, PrEP is most often prescribed in the context of sexual activity outside of marriage between a biological male and female, placing the prescriber in cooperation with activity deemed to be immoral by the Catholic Church. While all medical professionals seeking the common good should aim to reduce the transmission of HIV, not all means are morally licit. Conscience protection for medical professionals opposed to this strategy has become increasingly relevant. Thoughtful discernment is necessary when considering PrEP. Summary: The use of CDC material (figure 1) in this article does not imply endorsement by CDC. The material is in the public domain and available on the CDC website free of charge.

PrEP Method Switching: Will it Yield Greater Coverage of HIV Protection? Applying Lessons Learned from Family Planning to Guide Future Research in the Context of PrEP Choice

PURPOSE OF REVIEW

Despite the growing availability of oral PrEP, coverage remains suboptimal. Through the introduction of additional PrEP methods, including vaginal rings and long-acting injectable formulations, health systems globally are on the cusp of offering PrEP methods that vary by route of administration, efficacy, and frequency of use. With PrEP choice, it will be important to explore PrEP use patterns to better understand how the ability to choose and switch products affects coverage and continuation. In this review, we draw parallels with family planning (FP) by summarizing how method choice and product switching affected contraceptive coverage globally, synthesize what is known about PrEP product switching, and outline evidence gaps to help guide future research on PrEP switching in the context of choice.

RECENT FINDINGS

Decades of research in FP has demonstrated that product switching is common and can lead to more satisfaction and increases in contraceptive use. While research on PrEP product switching is nascent, findings suggest switching is common, and that providing more than one PrEP option can increase coverage. Key evidence gaps include understanding product switching in the context of full versus constrained choice, switching in the context of temporary need, and developing interventions that promote product switching for those who could benefit. Providing choice and allowing people to start, stop, and switch products according to their needs and desires is a core component of a rights-based approach to HIV prevention. More research is needed to better understand what drives use patterns, including switching, and how to leverage choice to improve coverage. Standard definitions -some of which have been proposed in this review-are needed to inform comparable measurement. Finally, there is a need to holistically frame PrEP use to acknowledge changes in need over the life course, thus making method switching a standard part of HIV prevention.

HIV Pre-Exposure Prophylaxis

Pre-exposure prophylaxis (PrEP) of human immunodeficiency virus (HIV) represents the most significant breakthrough in the HIV prevention field over the past decade. PrEP is an effective strategy in preventing the transmission of HIV across all populations, providing high adherence. The current PrEP options include oral daily and on-demand tenofovir-based regimens, long-acting injections of cabotegravir, and a 1-month dapivirine vaginal ring. As a component of a multifaceted prevention approach, extensive deployment of PrEP holds the promise to significantly reduce the global HIV epidemic. Nonetheless, barriers still exist in terms of uptake, adherence, and persistence, while disparities in PrEP accessibility remain a concern.

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.

HIV preexposure prophylaxis in adolescents and young adults: an update

PURPOSE OF REVIEW

This review provides an update of evidence for HIV preexposure prophylaxis (PrEP), including efficacy and safety of newly available medications. It discusses barriers to care that are unique to adolescents and young adults as well as interventions that may help increase uptake, adherence, and retention in care.

RECENT FINDINGS

Tenofovir alafenamide-emtricitabine and cabotegravir are both newly approved medications for the prevention of HIV and are well tolerated and effective for adolescents. These medications, along with tenofovir disoproxil-emtricitabine, offer a variety of PrEP options to choose from.

SUMMARY

Adolescents and young adults have many options when it comes to HIV prevention, but barriers persist in terms of uptake and adherence to PrEP and retention in care. Technology-based interventions, provider education, navigation support, and multiple access options are all tools to help increase PrEP use in young people.

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.

Adult Human Brain Tissue Cultures to Study NeuroHIV

HIV-associated neurocognitive disorders (HAND) persist under antiretroviral therapy as a complex pathology that has been difficult to study in cellular and animal models. Therefore, we generated an ex vivo human brain slice model of HIV-1 infection from surgically resected adult brain tissue. Brain slice cultures processed for flow cytometry showed >90% viability of dissociated cells within the first three weeks in vitro, with parallel detection of astrocyte, myeloid, and neuronal populations. Neurons within brain slices showed stable dendritic spine density and mature spine morphologies in the first weeks in culture, and they generated detectable activity in multi-electrode arrays. We infected cultured brain slices using patient-matched CD4+ T-cells or monocyte-derived macrophages (MDMs) that were exposed to a GFP-expressing R5-tropic HIV-1 in vitro. Infected slice cultures expressed viral RNA and developed a spreading infection up to 9 days post-infection, which were significantly decreased by antiretrovirals. We also detected infected myeloid cells and astrocytes within slices and observed minimal effect on cellular viability over time. Overall, this human-centered model offers a promising resource to study the cellular mechanisms contributing to HAND (including antiretroviral toxicity, substance use, and aging), infection of resident brain cells, and new neuroprotective therapeutics.

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.

Long-acting prescriptions and therapy for HIV-1 from market launch to the present in Germany (May 2021 to December 2023)

Background

In Europe, the combination of cabotegravir (CAB) with rilpivirine (RPV) has been approved as a dual injection long-acting (LA) therapy for the treatment of human immunodeficiency virus type 1 (HIV-1) infections in adults since December 2020. Studies have shown that between 36 and 61% of people living with HIV (PLWHIV) prefer LA therapy. However, there are no real-world data on the number of people receiving LA therapy, in Germany or internationally. The aim of this study was to assess the current situation and trends in usage of LA therapy for the treatment of HIV-1 in Germany.

Methods

Based on pharmacy prescription data derived from Insight Health, the monthly number of prescriptions for oral CAB, CAB-LA, and RPV-LA over the entire period of availability in Germany was analyzed and evaluated (May 2021 to December 2023). The number of 1st and 2nd initiation injections and subsequent maintenance injections was calculated on the basis of the prescriptions for oral CAB initiation.

Results

The bimonthly schedule resulted in two growing cohorts from September 2021 with an estimated 14,523 CAB-LA prescriptions over the entire period. Accordingly, in December 2023, there were approximately 1,364 PLWHIV receiving LA therapy, of whom 1,318 were receiving maintenance therapy. Only treatments with bimonthly regimens were carried out. Accounting for people not covered by statutory health insurance (~13%), a total of ~1,600 PLWHIV were receiving LA therapy in Germany in December 2023. The average rounded annual cost of therapy in 2023 was €11,940 (maintenance therapy with initiation) and €10,950 (maintenance therapy without initiation).

Conclusion

To our knowledge, this is the first study of real-world use and number of people receiving LA therapy. A strength of our study is the nearly complete coverage of people with statutory health insurance in Germany. The predicted demand for LA therapy does not match the actual number of people receiving LA therapy. Although the number of PLWHIV receiving LA therapy increased steadily, they accounted for just under 2% of the estimated total number of people receiving HIV therapy in Germany in 2023, almost 2 years after the market launch. No significant increase in prescriptions is expected; on the contrary, the trend is leveling off and is unlikely to change drastically in the near future. Hence, the need for this mode of therapy in Germany appears to be limited. Follow-up studies at regular intervals on the further course would be useful and are recommended, as well as investigations into the possible reasons for the slow uptake to inform public health experts and possibly broaden treatment options.

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.

Challenges, risks, and opportunities of antiretroviral drugs in women of reproductive potential

INTRODUCTION

The HIV/AIDS epidemic has been one of the greatest challenges in global health, significantly affecting women of reproductive potential. Considerable advances in antiretroviral therapy for women living with HIV have contributed to improvements in quality of life, better reproductive and birth outcomes, and a reduced risk of perinatal transmission.

AREAS COVERED

Despite the progress made, persistent challenges in access and adherence to antiretroviral drugs may limit their benefits for some women. More pharmacokinetic and safety studies in pregnant and lactating women are urgently needed, as are prospective surveillance systems to evaluate associations between fetal and infant antiretroviral exposures, drug-drug interactions, and pregnancy outcomes.

EXPERT OPINION

Multipurpose technologies, such as combined HIV and other STI or unintended pregnancy prevention, and innovative delivery methods, such as the development of long-acting antiretrovirals, have the potential to reduce adherence challenges and enhance quality of life for women with HIV. Parallel advances in drug safety testing and surveillance are needed to ensure the health and safety of women with or at risk for HIV and children at risk for perinatal transmission.

How Would You Manage HIV Pre-exposure Prophylaxis in This Patient With Medical Comorbidities? : Grand Rounds Discussion From Beth Israel Deaconess Medical Center

Despite advances in treatment, HIV infection remains an important cause of morbidity and mortality, with more than 30 000 new cases diagnosed in the United States each year. There are several interventions traditionally used to prevent HIV transmission, but these vary in effectiveness and there are challenges to their implementation. In 2014, the Centers for Disease Control and Prevention published initial guidance on the use of antiretroviral pre-exposure prophylaxis (PrEP) to prevent transmission of HIV infection in persons at risk based on multiple studies that showed it to be highly efficacious in various populations. It was updated in 2021 to reflect new drug options. The U.S. Preventive Services Task Force also recently updated its recommendations for PrEP, which strongly support its use in persons at risk. Despite its well-established effectiveness, the implementation of PrEP in clinical practice has been variable, especially among populations underserved by the medical system and marginalized by society. Fewer than one third of persons in the United States who are eligible for PrEP currently receive it. Here, 2 physicians experienced in HIV PrEP debate how best to identify patients who might benefit from PrEP, how to decide what regimen to use, and how to monitor therapy.

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.

Perspectives on Injectable HIV Pre-Exposure Prophylaxis: A Qualitative Study of Health Care Providers in the United States

The introduction of injectable HIV pre-exposure prophylaxis (PrEP) has the potential to significantly change the biomedical HIV prevention landscape. However, effective implementation will require health care providers to adopt, prescribe, and administer injectable PrEP within clinical settings. This study qualitatively examined challenges and benefit of injectable PrEP implementation from the perspective of health care providers. From April to August 2022, we conducted 19 in-depth interviews with current PrEP-prescribing health care providers in New York State, including 3 physician assistants, 5 physicians, and 11 nurse practitioners. Interviews were audio-recorded, transcribed verbatim, and thematically analyzed to report semantic-level themes regarding injectable PrEP implementation. More than half of participants (61%) were aware of injectable PrEP; only 21% had experience prescribing it. Qualitative findings highlighted five themes. Three themes represented implementation challenges, including speculative concerns about side effects, appointment compliance, and practical and logistical considerations. The remaining two themes described benefits of injectable PrEP relative to oral PrEP, which included greater convenience and enhanced privacy. Findings from this qualitative study make significant applied contributions to the sparse knowledge on health care provider perspectives of injectable PrEP post-US Food and Drug Administration approval and their concerns and considerations regarding implementation in real-world clinical settings.

Safety and pharmacokinetics of oral and long-acting injectable cabotegravir or long-acting injectable rilpivirine in virologically suppressed adolescents with HIV (IMPAACT 2017/MOCHA): a phase 1/2, multicentre, open-label, non-comparative, dose-finding study

BACKGROUND

Combined intramuscular long-acting cabotegravir and long-acting rilpivirine constitute the first long-acting combination antiretroviral therapy (ART) regimen approved for adults with HIV. The goal of the IMPAACT 2017 study (MOCHA [More Options for Children and Adolescents]) was to assess the safety and pharmacokinetics of these drugs in adolescents.

METHODS

In this phase 1/2, multicentre, open-label, non-comparative, dose-finding study, virologically suppressed adolescents (aged 12-17 years; weight ≥35 kg; BMI ≤31·5 kg/m2) with HIV-1 on daily oral ART were enrolled at 15 centres in four countries (Botswana, South Africa, Thailand, and the USA). After 4-6 weeks of oral cabotegravir (cohort 1C) or rilpivirine (cohort 1R), participants received intramuscular long-acting cabotegravir or long-acting rilpivirine every 4 weeks or 8 weeks per the adult dosing regimens, while continuing pre-study ART. The primary outcomes were assessments of safety measures, including all adverse events, until week 4 for oral cabotegravir and until week 16 for long-acting cabotegravir and long-acting rilpivirine, and pharmacokinetic measures, including the area under the plasma concentration versus time curve during the dosing interval (AUC0-tau) and drug concentrations, at week 2 for oral dosing of cabotegravir and at week 16 for intramuscular dosing of cabotegravir and rilpivirine. Enrolment into cohort 1C or cohort 1R was based on the participant's pre-study ART, meaning that masking was not done. For pharmacokinetic analyses, blood samples were drawn at weeks 2-4 after oral dosing and weeks 4-16 after intramuscular dosing. Safety outcome measures were summarised using frequencies, percentages, and exact 95% CIs; pharmacokinetic parameters were summarised using descriptive statistics. This trial is registered at ClinicalTrials.gov, NCT03497676, and is closed to enrolment.

FINDINGS

Between March 19, 2019, and Nov 25, 2021, 55 participants were enrolled: 30 in cohort 1C and 25 in cohort 1R. At week 16, 28 (97%, 95% CI 82-100) of the 29 dose-evaluable participants in cohort 1C and 21 (91%; 72-99) of the 23 dose-evaluable participants in cohort 1R had reported at least one adverse event, with the most common being injection-site pain (nine [31%] in cohort 1C; nine [39%] in cohort 1R; none were severe). One (4%, 95% CI 0-22) participant in cohort 1R had an adverse event of grade 3 or higher, leading to treatment discontinuation, which was defined as acute rilpivirine-related allergic reaction (self-limiting generalised urticaria) after the first oral dose. No deaths or life-threatening events occurred. In cohort 1C, the week 2 median cabotegravir AUC0-tau was 148·5 (range 37·2-433·1) μg·h/mL. The week 16 median concentrations for the every-4-weeks and every-8-weeks dosing was 3·11 μg/mL (range 1·22-6·19) and 1·15 μg/mL (<0·025-5·29) for cabotegravir and 52·9 ng/mL (31·9-148·0) and 39·1 ng/mL (27·2-81·3) for rilpivirine, respectively. These concentrations were similar to those in adults.

INTERPRETATION

Study data support using long-acting cabotegravir or long-acting rilpivirine, given every 4 weeks or 8 weeks, per the adult dosing regimens, in virologically suppressed adolescents aged 12 years and older and weighing at least 35 kg.

FUNDING

The National Institutes of Health and ViiV Healthcare.

The potential benefits of long-acting injectable cabotegravir in pregnant and breastfeeding women and their infants

BACKGROUND

Pregnant and breastfeeding women (PBW) in sub-Saharan Africa have high HIV incidence rates and associated risk of vertical transmission to their infants. Oral preexposure prophylaxis (PrEP) and injectable PrEP (long-acting cabotegravir, or CAB-LA) can potentially reduce this HIV transmission, but population-level impacts are uncertain.

METHODS

We extended a previously developed model of HIV and PrEP in South Africa to allow for variable PrEP duration and preference in PBW. We considered three potential scenarios for PrEP provision to PBW: oral PrEP only, CAB-LA only, and allowing oral/CAB-LA choice, with uptake and retention assumptions informed by South African data, each compared with a 'base' scenario without PrEP for PBW.

RESULTS

Without PrEP for PBW, the model estimates 1.31 million new infections will occur between 2025 and 2035 in South African adults and children, including 100 000 in PBW, 16 800 in infants at/before birth, and 35 200 in children through breastmilk. In the oral PrEP-only scenario, these numbers would reduce by 1.2% (95% CI: 0.7-1.7%), 8.6% (4.8-12.9%), 4.0% (2.1-5.8%), and 5.3% (3.0-8.2%) respectively. In the CAB-LA-only scenario, the corresponding reductions would be 6.1% (2.9-9.6%), 41.2% (19.8-65.0%), 12.6% (6.0-19.4%), and 29.5% (13.9-46.8%), respectively, and in the oral/CAB-LA choice scenario, similar reductions would be achieved [5.6% (3.4-8.0%), 39% (23.4-55.9%), 12.4% (7.4-16.8%) and 27.6% (16.5-39.9%) respectively].

CONCLUSION

CAB-LA has the potential to be substantially more effective than oral PrEP in preventing HIV acquisition in PBW and vertical transmission, and can also modestly reduce HIV incidence at a population level.

Asian participants' experience in phase 3/3b studies of long-acting cabotegravir and rilpivirine: Efficacy, safety, pharmacokinetic, and virological outcomes through week 96

OBJECTIVES

Cabotegravir + rilpivirine (CAB + RPV) dosed monthly or every 2 months is the first complete long-acting (LA) regimen recommended by treatment guidelines for the maintenance of HIV-1 virological suppression. This post hoc analysis summarizes outcomes for Asian participants through week 96.

METHODS

Data from Asian participants naive to CAB + RPV randomized to receive dosing every 4 weeks (Q4W) or every 8 weeks (Q8W) in the FLAIR (NCT02938520) and ATLAS-2M (NCT03299049) phase 3/3b studies were pooled. The proportion of participants with plasma HIV-1 RNA ≥50 and <50 copies/mL (per FDA Snapshot algorithm), incidence of confirmed virological failure (CVF; two consecutive HIV-1 RNA ≥200 copies/mL), pharmacokinetics, safety, and tolerability through week 96 were assessed.

RESULTS

Overall, 41 Asian participants received CAB + RPV (Q8W, n = 17; Q4W, n = 24). At week 96, 83% (n = 34/41) of participants maintained HIV-1 RNA <50 copies/mL, none had HIV-1 RNA ≥50 copies/mL, and 17% (n = 7/41) had no virological data. No Asian participant met the CVF criterion. Drug-related adverse events occurred in 44% (n = 18/41) of participants; none were Grade ≥3. All injection site reactions were Grade 1 or 2; median duration was 2 days and most resolved within 7 days (90%, n = 390/435). CAB and RPV trough concentrations remained well above their respective protein-adjusted 90% inhibitory concentrations (CAB, 0.166 μg/mL; RPV, 12 ng/mL) through week 96.

CONCLUSIONS

CAB + RPV LA demonstrated high efficacy, with no participants having CVF, and an acceptable safety profile in Asian participants through week 96. These data support CAB + RPV LA as a complete regimen for the maintenance of HIV-1 virological suppression in Asian individuals.

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

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

Guidance for the Interpretation of Long-Acting Cabotegravir and Rilpivirine Concentrations Based on Real-World Therapeutic Drug Monitoring Data and Documented Failures

The interpretation of long-acting cabotegravir and rilpivirine concentrations is complicated by the lack of consensus on the threshold to consider. Building on real-world therapeutic drug monitoring data and documented virologic failures, this article provides a reappraisal of the existing thresholds and guidance for the interpretation of cabotegravir and rilpivirine concentrations.

Pharmacokinetic Modeling to Guide Preclinical Development of an Islatravir-Eluting Reservoir-Style Biodegradable Implant for Long-Acting HIV PrEP

Long-acting injectable cabotegravir is more effective than daily oral PrEP at preventing HIV transmission due to improved adherence, but requires bi-monthly large-volume intramuscular injections. Subcutaneous (SC) contraceptive implants can be formulated with antiretrovirals for extended-duration HIV PrEP. Islatravir (ISL) is a first-in-class, investigational antiretroviral with pharmacologic properties well-suited for implant delivery. We performed preclinical studies for the development of a reservoir-style, poly(ε-caprolactone) ISL-eluting implant by conducting a single-dose SC ISL dose-ranging pharmacokinetic (PK) study of 0.1, 0.3, and 1 mg/kg in adult Wistar rats. Non-compartmental analysis was conducted, and dose proportionality assessed for ISL plasma and intracellular islatravir-triphosphate (ISL-tp). Population PK models estimated ISL's unit impulse response to deconvolve ISL-implant in vivo absorption rate (mg/day) and cumulative mass (mg) from published rat plasma PK (n = 10). Drug release was interpreted using four kinetic models. Dose proportionality was affirmed for ISL and ISL-tp. A first-order, two-compartment model fitted the SC ISL bolus data. Mean (SD) absorption rate from 0 to 154 days was 0.072 ± 0.024 mg/day, and cumulative mass at 154 days was 8.67 ± 3.22 mg. ISL absorption was well-described by zero-order (r2 = 0.95) and Ritger-Peppas (r2 = 0.98). Our zero-order ISL-release poly(ε-caprolactone) implant is projected to achieve clinical PK above ISL-tp's PrEP efficacy threshold. Continued development for HIV PrEP applications is warranted.

Pharmacokinetics and tolerability of cabotegravir and rilpivirine long-acting intramuscular injections to the vastus lateralis (lateral thigh) muscles of healthy adult participants

Cabotegravir + rilpivirine administered via intramuscular gluteal injections is the first complete long-acting (LA) regimen approved for maintaining HIV-1 virologic suppression. The vastus lateralis (lateral) thigh muscle could be a potential alternative site of administration in circumstances such as injection site fatigue, intolerability, or contraindication for gluteal administration. Cabotegravir and rilpivirine pharmacokinetics and participant tolerability were evaluated following single intramuscular injections to the lateral thigh. Healthy adult participants received 4 weeks of daily oral cabotegravir (30 mg) and rilpivirine (25 mg), followed by a 10- to 14-day washout and single 3 mL intramuscular injections of cabotegravir LA 600 mg and rilpivirine LA 900 mg to the lateral thigh. Safety, tolerability, and pharmacokinetics were evaluated through 52 weeks post injection. Pharmacokinetic parameters were estimated using non-compartmental analysis. Fifteen participants (female at birth, n = 6) enrolled. Median age was 33 years. Median weight was 93.6 kg. Median body mass index was 31.4 kg/m2. One participant withdrew due to pregnancy after oral dosing before receiving an injection. Plasma concentrations at Weeks 4 and 8 were 15.4- and 5.3-fold above the protein-adjusted 90% inhibitory concentration for cabotegravir and 4.7- and 2.4-fold for rilpivirine, respectively. The most common injection site reactions were pain [28/28 (100%)], induration [15/28 (54%)], and swelling [12/28 (42%)]; 94% were Grade 1 or 2. Cabotegravir and rilpivirine plasma pharmacokinetic profiles observed in this study support further evaluation of thigh administration in target populations of people living with HIV-1. Tolerability of cabotegravir + rilpivirine LA intramuscular lateral thigh injections was similar to gluteal administration.

Challenges with pediatric antiretroviral therapy administration: Qualitative perspectives from caregivers and HIV providers in Kenya

BACKGROUND

Current formulations of pediatric antiretroviral therapy (ART) for children with HIV present significant barriers to adherence, leading to drug resistance, ART ineffectiveness, and preventable child morbidity and mortality. Understanding these challenges and how they contribute to suboptimal adherence is an important step in improving outcomes. This qualitative study describes how regimen-related challenges create barriers to adherence and impact families.

METHODS

We conducted key informant interviews (KIIs) with 30 healthcare providers and 9 focus group discussions (FGDs) with a total of 72 caregivers, across three public hospitals in Siaya and Mombasa Kenya. The KIIs and FGDs were audio recorded, translated, and transcribed verbatim. The transcripts were hand coded based on emergent and a-priori themes.

RESULTS

Caregivers discussed major regimen-related challenges to adherence included poor palatability of current formulations, complex preparation, and administration (including measuring, crushing, dissolving, mixing), complex drug storage, and frequent refill appointments and how these regimen-related challenges contributed to individual and intrapersonal barriers to adherence. Caregivers discussed how poor taste led to child anxiety, refusal of medications, and the need for caregivers to use bribes or threats during administration. Complex preparation led to concerns and challenges about maintaining privacy and confidentiality, especially during times of travel. Providers corroborated this patient experience and described how these challenges with administration led to poor infant outcomes, including high viral load and preventable morbidity. Providers discussed how the frequency of refills could range from every 2 weeks to every 3 months, depending on the patient. Caregivers discussed how these refill frequencies interrupted work and school schedules, risked unwanted disclosure to peers, required use of financial resources for travel, and ultimately were a challenge to adherence.

CONCLUSION

These findings highlight the need for improved formulations for pediatric ART to ease the daily burden on caregivers and children to increase adherence, improve child health, and overall quality of life of families.

Real-world trough concentrations and effectiveness of long-acting cabotegravir and rilpivirine: a multicenter prospective observational study in Switzerland

Background

The efficacy and tolerability of long-acting cabotegravir and rilpivirine were demonstrated in Phase III trials. However, low concentrations combined with other risk factors have been associated with an increased risk of virologic failure. This study aims to verify whether drug concentrations measured in a real-world setting are consistent with those previously reported.

Methods

SHCS-879 is a nationwide observational study within the Swiss HIV Cohort Study for the monitoring of people with HIV (PWH) on long-acting cabotegravir plus rilpivirine. Samples were collected from March 2022 to March 2023.

Findings

Overall, 725 samples were obtained from 186 PWH. Our data show a large inter-individual variability in cabotegravir and rilpivirine concentrations, with some individuals exhibiting repeatedly low concentrations. Rilpivirine trough concentrations were consistent with those from Phase III trials, while cabotegravir concentrations were lower. The first concentrations quartile was only slightly above the target of 664 ng/mL. Exploratory statistical analyses found 35% (p < 0·01) lower cabotegravir trough in males compared to females. Overall, 172 PWH (92%) remained suppressed and three experienced virologic failures (1·6%), of those, two had sub-optimal drug exposure. No association was found between low trough levels and detectable viral load.

Interpretation

Real-world cabotegravir concentrations are substantially lower than previously reported. However, these concentrations appear sufficient to ensure sustained virological suppression in almost every PWH. These reassuring data challenge the rather conservative thresholds adopted to date, which may raise unnecessary concerns. Yet, our study reveals that some PWH have repeatedly very low drug levels, for reasons that remain to be elucidated.

Funding

This work was funded by the Swiss National Science Foundation, grant number N◦ 324730_192449. This study received no support from pharmaceutical industries. This study was performed within the framework of the Swiss HIV Cohort Study, supported by the Swiss National Science Foundation (grant #201369), by SHCS project #879, and by the SHCS research foundation. The SHCS data were gathered by the Five Swiss University Hospitals, two Cantonal Hospitals, 15 affiliated hospitals and 36 private physicians (listed in http://www.shcs.ch/180-health-care-providers).

Considerations for long-acting antiretroviral therapy in older persons with HIV

People with HIV (PWH) can now enjoy longer, healthier lives due to safe and highly effective antiretroviral therapy (ART), and improved care and prevention strategies. New drug formulations such as long-acting injectables (LAI) may overcome some limitations and issues with oral antiretroviral therapy and strengthen medication adherence. However, challenges and questions remain regarding their use in aging populations. Here, we review unique considerations for LAI-ART for the treatment of HIV in older PWH, including benefits, risks, pharmacological considerations, implementation challenges, knowledge gaps, and identify factors that may facilitate uptake of LA-ART in this population.

HIV Pre-Exposure Prophylaxis: New and Upcoming Drugs to Address the HIV Epidemic

Human immunodeficiency virus (HIV) pre-exposure prophylaxis (PrEP) provides a critical intervention toward ending the HIV epidemic and protecting people with reasons to utilize PrEP. PrEP options continue to expand as new administration modalities offer the potential to tailor PrEP use for individual success. We have provided the evidence for new and emerging antiretroviral agents for PrEP (cabotegravir, lenacapavir, dapivirine, and broadly neutralizing antibodies), divided into pharmacology, animal model, and human data, accompanied by a summary and suggested place in therapy. Cabotegravir is a US Food and Drug Administration (FDA)-approved intramuscular injection given every 2 months with a strong body of evidence demonstrating efficacy for HIV PrEP, lenacapavir administered subcutaneously every 6 months is currently under investigation for HIV PrEP, dapivirine vaginal ring is an available PrEP option for women in certain areas of Africa, and broadly neutralizing monoclonal antibodies have been challenged in demonstrating efficacy in phase 1-2 study for HIV PrEP to date. Clinical literature for individual agents is discussed with data from major studies summarized in tables. This review provides a detailed overview of recently available and premier candidate PrEP drugs.

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.

Development and validation of an ultra-high performance liquid chromatography-tandem mass spectrometry method for quantifying lenacapavir plasma concentrations: Application to therapeutic monitoring

Although current antiretroviral therapy (ART) effectively suppresses HIV in the blood, regimens may fail due to suboptimal treatment history and non-adherence to ART. In these scenarios, accumulation of viral resistance mutations to ART drug classes may occur. For these treatment-experienced people living with HIV (PLWH), activity against resistant viral strains is required; lack of therapeutic efficacy will result in continued viral replication and progression to acquired immunodeficiency syndrome. New treatment options have emerged. Lenacapavir is a first-in-class long-acting HIV-1 capsid inhibitor approved for the treatment of HIV in treatment-experienced patients. Lenacapavir is approved with an initiation regimen of oral and subcutaneous injection dosing followed by subcutaneous self-injection every 6 months. With infrequent dosing, therapeutic drug monitoring may be necessary to ensure adequate concentrations are consistently achieved in the plasma to assure treatment adherence and prevent further HIV resistance formation. To this end, we developed and validated a highly selective ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method to quantify lenacapavir concentrations in human plasma. A simple protein precipitation with acetonitrile followed by supernatant dilution was performed. Lenacapavir and its stable labeled internal standard were separated at 1.90 min using a multi-step UPLC gradient. The assay for lenacapavir quantification was extensively validated according to the United States Food and Drug Administration Bioanalytical Guidelines over a clinically relevant range of 0.1 to 500 ng/mL with excellent linearity (R2 ≥ 0.9960). This analytical method achieves acceptable performance of trueness (89.7-104.1 %), repeatability, and precision (CV < 15 %). We applied this method to quantify a clinical sample and to determine the percent protein-unbound. This method can be utilized for the therapeutic monitoring of lenacapavir in human plasma for monitoring HIV treatment efficacy.

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

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

Efficacy, safety, tolerability, and pharmacokinetics of long-acting injectable cabotegravir for HIV pre-exposure prophylaxis in transgender women: a secondary analysis of the HPTN 083 trial

BACKGROUND

The HIV Prevention Trials Network (HPTN) 083 trial showed that long-acting injectable cabotegravir was more effective than tenofovir disoproxil fumarate plus emtricitabine in preventing HIV in cisgender men and transgender women who have sex with men. We aimed to characterise the cohort of transgender women included in HPTN 083.

METHODS

HPTN 083 is an ongoing, phase 2b/3, randomised, multicentre, double-blind, double-dummy clinical trial done at 43 sites in seven countries (Argentina, Brazil, Peru, the USA, South Africa, Thailand, and Viet Nam). HIV-negative participants were randomly assigned (1:1) to receive injectable cabotegravir or tenofovir disoproxil fumarate plus emtricitabine. The study design and primary outcomes of the blinded phase of HPTN 083 have already been reported. An enrolment minimum of 10% transgender women was set for the trial. Here we characterise the cohort of transgender women enrolled from Dec 6, 2016, to May 14, 2020, when the study was unblinded. We report sociodemographic characteristics, use of gender affirming hormone therapy, and behavioural assessments of the transgender women participants. Laboratory testing and safety evaluations are also reported. The trial is registered at ClinicalTrials.gov, NCT02720094.

FINDINGS

HPTN 083 enrolled 570 transgender women (304 tenofovir disoproxil fumarate plus emtricitabine; 266 injectable cabotegravir). Transgender women were primarily from Asia (225 [39%]) and Latin America (205 [36%]); 330 (58%) reported using gender affirming hormone therapy. Intimate partner violence was common (270 [47%] reported emotional abuse and 172 [30%] reported physical abuse) and 323 (57%) reported a history of childhood sexual abuse. 159 (28%) transgender women disagreed that they were at risk for HIV, and 142 (25%) screened positive for depressive symptoms. During study follow-up, incidence of syphilis was 16·25% (95% CI 13·28-19·69), rectal gonorrhoea was 11·66% (9·14-14·66), and chlamydia was 20·61% (17·20-24·49). Frequency of adverse events was similar between the treatment groups. Nine seroconversions occurred among transgender women during the blinded phase of the study (seven in the tenofovir disoproxil fumarate plus emtricitabine group and two in the injectable cabotegravir group); overall incidence was 1·19 per 100 person-years (95% CI 0·54-2·25): 1·80 per 100 person-years (0·73-3·72) in the tenofovir disoproxil fumarate plus emtricitabine group and 0·54 per 100 person-years (0·07-1·95) in the injectable cabotegravir group (hazard ratio 0·34 [95% CI 0·08-1·56]). Cabotegravir concentrations did not differ by gender affirming hormone therapy use.

INTERPRETATION

HIV prevention strategies for transgender women cannot be addressed separately from social and structural vulnerabilities. Transgender women were well represented in HPTN 083 and should continue to be prioritised in HIV prevention studies. Our results suggest that injectable cabotegravir is a safe and effective pre-exposure prophylaxis option for transgender women.

FUNDING

National Institute of Allergy and Infectious Diseases and ViiV Healthcare.

Prevention, treatment and cure of HIV infection

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

Advances in long-acting slow effective release antiretroviral therapies for treatment and prevention of HIV infection

Adherence to daily oral antiretroviral therapy (ART) is a barrier to both treatment and prevention of human immunodeficiency virus (HIV) infection. To overcome limitations of life-long daily regimen adherence, long-acting (LA) injectable antiretroviral (ARV) drugs, nanoformulations, implants, vaginal rings, microarray patches, and ultra-long-acting (ULA) prodrugs are now available or in development. These medicines enable persons who are or at risk for HIV infection to be treated with simplified ART regimens. First-generation LA cabotegravir, rilpivirine, and lenacapavir injectables and a dapivirine vaginal ring are now in use. However, each remains limited by existing dosing intervals, ease of administration, or difficulties in finding drug partners. ULA ART regimens provide an answer, but to date, such next-generation formulations remain in development. Establishing the niche will require affirmation of extended dosing, improved access, reduced injection volumes, improved pharmacokinetic profiles, selections of combination treatments, and synchronization of healthcare support. Based on such needs, this review highlights recent pharmacological advances and a future treatment perspective. While first-generation LA ARTs are available for HIV care, they remain far from ideal in meeting patient needs. ULA medicines, now in advanced preclinical development, may close gaps toward broader usage and treatment options.

HIV Pre-Exposure Prophylaxis, Blood Donor Deferral, Occult Infection, and Risk of HIV Transmission by Transfusion: A Fine Balance Between Evidence-Based Donor Selection Criteria and Transfusion Safety

Pre- and postexposure prophylaxis for human immunodeficiency virus (HIV) are key to reducing the transmission of this virus. Furthermore, low-toxicity, long-acting formulations provide additional clinical benefits, in particular easier adherence to treatment and prevention. However, breakthrough HIV infections can occur despite the use of pre-exposure prophylaxis (PrEP), mainly due to suboptimal adherence or multi-drug resistant HIV strains. Albeit rare, PrEP breakthrough infections have also been reported in fully adherent patients. Should such breakthrough infection occur in an eligible blood donor, PrEP might suppress viremia and delay antibody seroconversion, thereby masking the infection and increasing the risk of transfusion transmission. This possibility has raised concerns in the blood transfusion community but remains little documented. Therefore, a literature search was performed to assess the state of knowledge on the risk of PrEP breakthrough infection, with a particular focus on the risk of HIV entering the blood supply. Evidently, PrEP breakthrough infections are rare, although the risk is not zero. Moreover, a fraction of individuals - including blood donors - do not disclose PrEP use according to various surveys and measurements of HIV PrEP analytes. Additionally, viremia and seroconversion may remain undetectable or close to the limit of detection for a long time after cessation of PrEP, particularly with long-acting antiretrovirals. Therefore, current recommendations to defer donors for at least 3 months after the last dose of oral PrEP or 2 years for long-acting PrEP appear justified, as they safeguard the blood supply and public trust toward the system. These recommendations help to safeguard blood safety and public trust in the blood supply.