Broadly neutralizing antibody treatment maintained HIV suppression in children with favorable reservoir characteristics in Botswana

Use of broadly neutralizing antibodies in pediatric HIV for treatment and remission

PURPOSE OF REVIEW

The evolving landscape of HIV treatment for children now extends beyond viremic control with daily antiretroviral treatment (ART), with new approaches that sustain viral suppression while permitting breaks from small molecule ART now reaching the clinical trial stage. Trials involving broadly neutralizing monoclonal antibodies (bNAbs) have commenced in selected pediatric populations. Evidence from adult bNAb studies suggests that bNAbs might reduce latent viral reservoirs, fostering hope that these agents could offer a pathway to posttreatment control, which is seldom achievable with small molecule ART.

RECENT FINDINGS

Few pediatric studies to date have used bNAbs in the setting of existing HIV infection to improve treatment outcomes. Safety and pharmacokinetic (PK) data from IMPAACT 2012, IMPAACT 2008, and the Tatelo Study have been reassuring. The Tatelo Study in Botswana first used combination bNAbs (VRC01LS, 10-1074) as an alternative treatment strategy in children aged 2-5 years who started ART near birth, showing that nearly half of unscreened children could maintain viral suppression with dual bNAbs alone, and identifying predictors for success. From a viral reservoir standpoint, IMPAACT 2008 identified a possible dose-dependent effect of VRC01, with higher plasma VRC01 concentrations being associated with lower HIV-1 DNA. Further reservoir data are expected from Tatelo Plus (IMPAACT 2042), which began enrolling in 2024 and will evaluate a triple bNAb combination (VRC07-504LS, PGDM1400LS, and PGT.121.LS) with the addition of an analytic treatment interruption (ATI) in some children. IMPAACT P1115, which recently reported successful ATI in selected low-reservoir children, is evaluating the addition of VRC01 or VRC-07-523LS on viral reservoir and treatment outcomes. Looking to the future, IMPAACT 2039 will evaluate VRC07-523LS + PGT121.414LS as part of a combination intervention, and the SNOW study will evaluate VRC07-523LS during a series of ATIs.

SUMMARY

This review synthesizes data for ongoing and planned pediatric bNAb treatment studies, focusing on available trial results that underscore the ability of newer and more potent long-acting bNAbs to sustain viral suppression. We discuss the potential impact of bNAbs to reduce the latent viral reservoir and their use as a strategy to achieve viral remission in children with HIV.

Human models that inform antiretroviral therapy-free remission with perinatally acquired HIV infection

PURPOSE OF REVIEW

Rare persons who achieve disease-control despite high viral loads (viraemic nonprogressors) or maintain virologic control in the absence of antiretroviral therapy (ART) (elite controllers) or following ART interruption (posttreatment controllers) possess protective factors that can be harnessed for interventions to achieve ART-free remission. This review broadly summarizes these phenotypes in adults and children, and updates on findings important in informing strategies for ART-free remission in children with HIV.

RECENT FINDINGS

To date, only a few individual cases of posttreatment control have been described in children. Smaller HIV reservoir size with very early ART initiation in neonates with in-utero acquired HIV associates with improved virological and immunological outcomes. Nine new cases of ART-free remission in children were recently described - 4 from the P1115 trial, and 5 males from the Ucwaningo Lwabantwana study in South Africa. A striking reduction in the decay of intact proviruses was observed over three decades on suppressive ART in two early-treated twins with HIV.

SUMMARY

The unique environment of perinatal HIV infection favours effective restriction and decay of the HIV-1 reservoir with suppressive ART initiated very early. Sex and population differences require consideration in ongoing studies to inform ART-free remission.

Monoclonal Antibodies for Pediatric Viral Disease Prevention and Treatment

Medical advancements over the last century have improved our ability to treat pediatric infectious diseases, significantly reducing associated morbidity and mortality worldwide. Although vaccines have been pivotal in this progress, many viral pathogens still do not currently have effective vaccines. The COVID-19 pandemic highlighted the need for rapid responses to emerging viral pathogens and introduced new tools to combat them. This review addresses human monoclonal antibodies (mAbs) as a strategy for treating and preventing viral infections in pediatric populations. We discuss previously used and currently available mAbs and advancements in mAb discovery. We address the future of mAb therapy by describing novel approaches in drug production and delivery platforms in addition to alternative antibody classes. Finally, we review the challenges and limitations of mAb therapy development for newborns and children.

The Proviral Reservoirs of Human Immunodeficiency Virus (HIV) Infection

Human Immunodeficiency Virus (HIV) proviral reservoirs are cells that harbor integrated HIV proviral DNA within their nuclear genomes. These cells form a heterogeneous group, represented by peripheral blood mononuclear cells (PBMCs), tissue-resident lymphoid and monocytic cells, and glial cells of the central nervous system. The importance of studying the properties of proviral reservoirs is connected with the inaccessibility of integrated HIV proviral DNA for modern anti-retroviral therapies (ARTs) that block virus reproduction. If treatment is not effective enough or is interrupted, the proviral reservoir can reactivate. Early initiation of ART improves the prognosis of the course of HIV infection, which is explained by the reduction in the proviral reservoir pool observed in the early stages of the disease. Different HIV subtypes present differences in the number of latent reservoirs, as determined by structural and functional differences. Unique signatures of patients with HIV, such as elite controllers, have control over viral replication and can be said to have achieved a functional cure for HIV infection. Uncovering the causes of this phenomenon will bring humanity closer to curing HIV infection, potential approaches to which include stem cell transplantation, clustered regularly interspaced short palindromic repeats (CRISPR)/cas9, "Shock and kill", "Block and lock", and the application of broad-spectrum neutralizing antibodies (bNAbs).

Research Toward a Cure for Perinatal HIV

In virtually all people living with HIV-1 (PLWH), including children, HIV-1 integrates and becomes latent in CD4+ T cells, forming a latent HIV-1 reservoir that current antiretroviral drugs and immune surveillance mechanisms cannot target. This latent infection in CD4+ T cells renders HIV-1 infection lifelong and incurable. Consequently, there is intense research focused on identifying therapeutic strategies to reduce and control the latent reservoir, aiming to avert a lifetime of antiretroviral therapy for PLWH. This review discusses the global efforts for children and adolescents living with HIV-1.

Human Immunodeficiency Virus and Breastfeeding: Clinical Considerations and Mechanisms of Transmission in the Modern Era of Combined Antiretroviral Therapy

Combined antiretroviral therapy has significantly reduced perinatal human immunodeficiency virus (HIV) transmission risk through breastfeeding, prompting shifts in clinical guidance to support breastfeeding for women with HIV who have sustained viral suppression. This review examines the current evidence on HIV transmission via breast milk, including risk factors, mechanisms, and risk reduction strategies to inform patient-centered and evidence-driven clinical care.

A novel HIV triple broadly neutralizing antibody (bNAb) combination-based passive immunization of infant rhesus macaques achieves durable protective plasma neutralization levels and mediates anti-viral effector functions

To eliminate vertical HIV transmission and achieve therapy-free viral suppression among children living with HIV, novel strategies beyond antiretroviral therapy (ART) are necessary. Our group previously identified a triple broadly neutralizing antibody (bNAb) combination comprising of 3BNC117, PGDM1400 and PGT151 that mediates robust in vitro neutralization and non-neutralizing effector functions against a cross-clade panel of simian human immunodeficiency viruses (SHIVs). In this study, we evaluated the safety, pharmacokinetics, and antiviral potency of this bNAb combination in infant rhesus macaques (RMs). We demonstrate that subcutaneous infusion of the triple bNAb regimen was well tolerated in pediatric monkeys and resulted in durable systemic and mucosal distribution. Plasma obtained from passively-immunized RMs demonstrated potent HIV-neutralizing and Fc-mediated antiviral effector functions. Finally, using the predicted serum neutralization 80% inhibitory dilution titer (PT80) biomarker threshold of >200, which was recently identified as a surrogate endpoint for evaluation of the preventative efficacy of bNAbs against mucosal viral acquisition in human clinical trials, we demonstrated that our regimen has PT80>200 against a large panel of plasma and breast milk-derived HIV strains and cross-clade SHIV variants. This data will guide the development of combination bNAbs for eliminating vertical HIV transmission and for achieving ART-free viral suppression among children living with HIV.

Optimising Paediatric HIV Treatment: Recent Developments and Future Directions

Treatment options for children living with HIV have historically been less effective, less practical and more difficult to implement compared with those for adults, as the research and development of new drugs for children has lagged behind. Significant progress has been achieved in response to the paediatric HIV epidemic over the last decade. Several optimised paediatric antiretroviral formulations are currently available or in development, including fixed-dose combination tablets containing a complete World Health Organization-recommended regimen. Despite these advancements, virological suppression rates in children are generally lower than in adults. Even when oral fixed-dose combinations with the optimal target profiles are developed, for some children virological suppression is not achievable for reasons such as adherence challenges, intolerance, toxicity and genotypic resistance. New safe, effective, well-tolerated antiretroviral agents from existing and novel classes, as well as innovative administration strategies are essential. To achieve the UNAIDS target of virological suppression in 95% of children receiving antiretroviral therapy, concerted efforts are required. This includes identifying priority drugs in line with latest developments, focusing drug development studies on these priorities, ensuring a timely technical knowledge transfer between originator and generic companies, accelerating regulatory approvals and facilitating procurement and implementation in countries. Success in these efforts depends on collaboration among all stakeholders, including communities, researchers, pharmaceutical companies, guideline and policymakers, governments, funders, regulators and healthcare providers. This review outlines which paediatric antiretroviral therapies are currently available, those which are under development and the future directions of paediatric HIV treatment.

A comprehensive engineering strategy improves potency and manufacturability of a near pan-neutralizing antibody against HIV

Anti-HIV envelope broadly neutralizing antibodies (bnAbs) are alternatives to conventional antiretrovirals with the potential to prevent and treat infection, reduce latent reservoirs, and/or mediate a functional cure. Clinical trials with "first generation" bnAbs used alone or in combination show promising antiviral effects but also highlight that additional engineering of "enhanced" antibodies will be required for optimal clinical utility, while preserving or enhancing cGMP manufacturing capability. Here we report the engineering of an anti-CD4 binding-site (CD4bs) bnAb, N49P9.3, purified from the plasma of an HIV elite-neutralizer. Through a series of rational modifications we produced a variant that demonstrates: enhanced potency; superior antiviral activity in combination with other bnAbs; low polyreactivity; and longer circulating half-life. Additional engineering for manufacturing produced a final variant, eN49P9, with properties conducive to cGMP production. Overall, these efforts demonstrate the feasibility of developing enhanced anti-CD4bs bnAbs with greatly improved antiviral properties as well as potential translational value.

Sustained aviremia despite anti-retroviral therapy non-adherence in male children after in utero HIV transmission

After sporadic reports of post-treatment control of HIV in children who initiated combination anti-retroviral therapy (cART) early, we prospectively studied 284 very-early-cART-treated children from KwaZulu-Natal, South Africa, after vertical HIV transmission to assess control of viremia. Eighty-four percent of the children achieved aviremia on cART, but aviremia persisting to 36 or more months was observed in only 32%. We observed that male infants have lower baseline plasma viral loads (P = 0.01). Unexpectedly, a subset (n = 5) of males maintained aviremia despite unscheduled complete discontinuation of cART lasting 3-10 months (n = 4) or intermittent cART adherence during 17-month loss to follow-up (n = 1). We further observed, in vertically transmitted viruses, a negative correlation between type I interferon (IFN-I) resistance and viral replication capacity (VRC) (P < 0.0001) that was markedly stronger for males than for females (r = -0.51 versus r = -0.07 for IFN-α). Although viruses transmitted to male fetuses were more IFN-I sensitive and of higher VRC than those transmitted to females in the full cohort (P < 0.0001 and P = 0.0003, respectively), the viruses transmitted to the five males maintaining cART-free aviremia had significantly lower replication capacity (P < 0.0001). These data suggest that viremic control can occur in some infants with in utero-acquired HIV infection after early cART initiation and may be associated with innate immune sex differences.

Analytical treatment interruption in children living with HIV: position statement from the EPIICAL consortium

Analytical treatment interruption (ATI) is widely acknowledged as an essential component of studies to advance our understanding of HIV cure, but discussion has largely been focused on adults. To address this gap, we reviewed evidence related to the safety and utility of ATI in paediatric populations. Three randomised ATI trials using CD4 T-cell and clinical criteria to guide restart of antiretroviral therapy (ART) have been conducted. These trials found low risks associated with ATI in children, including reassuring findings pertaining to neurocognitive outcomes. Similar to adults treated during acute infection, infants treated early in life have shifts in virological and immunological parameters that increase their likelihood of achieving ART-free viral control. Early ART limits the size and diversity of the viral reservoir and shapes effective innate and HIV-specific humoral and cellular responses. Several cases of durable ART-free viral control in early treated children have been reported. We recommend that, where appropriate for the study question and where adequate monitoring is available, ATI should be integrated into ART-free viral control research in children living with HIV. Paediatric participants have the greatest likelihood of benefiting and potentially the most years to prospectively realise those benefits. Excluding children from ATI trials limits the evidence base and delays access to interventions.

The Current Pipeline of Antiretroviral Therapy: Expanding Options and Filling Gaps

Highly effective antiretroviral therapy (ART) has transformed human immunodeficiency virus (HIV) care in the past 3 decades. 30 years ago, how many would have imagined that a single-tablet daily ART regimen containing different drug classes could achieve sustained HIV-1 suppression and halt disease progression to acquired immunodeficiency syndrome (AIDS)? Despite this remarkable achievement, challenges in HIV care remain that require further innovation for ART. In this review, we focus on newly approved antiretroviral agents and those undergoing phase 2/3 clinical trials. These new antiretrovirals hold great promise to expand treatment options and fill gaps in HIV care.

Neutralizing the threat: harnessing broadly neutralizing antibodies against HIV-1 for treatment and prevention

Broadly neutralizing antibodies (bnAbs) targeting the human immunodeficiency virus-1 (HIV-1) have played a crucial role in elucidating and characterizing neutralization-sensitive sites on the HIV-1 envelope spike and in informing vaccine development. Continual advancements in identifying more potent bnAbs, along with their capacity to trigger antibody-mediated effector functions, coupled with modifications to extend their half-life, position them as promising candidates for both HIV-1 treatment and prevention. While current pharmacological interventions have made significant progress in managing HIV-1 infection and enhancing quality of life, no definitive cure or vaccines have been developed thus far. Standard treatments involve daily oral anti-retroviral therapy, which, despite its efficacy, can lead to notable long-term side effects. Recent clinical trial data have demonstrated encouraging therapeutic and preventive potential for bnAb therapies in both HIV-1-infected individuals and those without the infection. This review provides an overview of the advancements in HIV-1-specific bnAbs and discusses the insights gathered from recent clinical trials regarding their application in treating and preventing HIV-1 infection.

Pediatric immunotherapy and HIV control

PURPOSE OF REVIEW

Highlighting opportunities/potential for immunotherapy by understanding dynamics of HIV control during pediatric HIV infection with and without antiretroviral therapy (ART), as modeled in Simian immunodeficiency virus (SIV) and Simian-human immunodeficiency virus (SHIV)-infected rhesus macaques and observed in clinical trials. This review outlines mode of transmission, pathogenesis of pediatric HIV, unique aspects of the infant immune system, infant macaque models and immunotherapies.

RECENT FINDINGS

During the earliest stages of perinatal HIV infection, the infant immune system is characterized by a unique environment defined by immune tolerance and lack of HIV-specific T cell responses which contribute to disease progression. Moreover, primary lymphoid organs such as the thymus appear to play a distinct role in HIV pathogenesis in children living with HIV (CLWH). Key components of the immune system determine the degree of viral control, targets for strategies to induce viral control, and the response to immunotherapy. The pursuit of highly potent broadly neutralizing antibodies (bNAbs) and T cell vaccines has revolutionized the approach to HIV cure. Administration of HIV-1-specific bNAbs, targeting the highly variable envelope improves humoral immunity, and T cell vaccines induce or improve T cell responses such as the cytotoxic effects of HIV-1-specific CD8+ T cells, both of which are promising options towards virologic control and ART-free remission as evidenced by completed and ongoing clinical trials.

SUMMARY

Understanding early events during HIV infection and disease progression in CLWH serves as a foundation for predicting or targeting later outcomes by harnessing the immune system's natural responses. The developing pediatric immune system offers multiple opportunities for specific long-term immunotherapies capable of improving quality of life during adolescence and adulthood.

Immune targeting of HIV-1 reservoir cells: a path to elimination strategies and cure

Successful approaches for eradication or cure of HIV-1 infection are likely to include immunological mechanisms, but remarkably little is known about how human immune responses can recognize and interact with the few HIV-1-infected cells that harbour genome-intact viral DNA, persist long term despite antiretroviral therapy and represent the main barrier to a cure. For a long time regarded as being completely shielded from host immune responses due to viral latency, these cells do, on closer examination with single-cell analytic techniques, display discrete footprints of immune selection, implying that human immune responses may be able to effectively engage and target at least some of these cells. The failure to eliminate rebound-competent virally infected cells in the majority of persons likely reflects the evolution of a highly selected pool of reservoir cells that are effectively camouflaged from immune recognition or rely on sophisticated approaches for resisting immune-mediated killing. Understanding the fine-tuned interplay between host immune responses and viral reservoir cells will help to design improved interventions that exploit the immunological vulnerabilities of HIV-1 reservoir cells.

Neutralizing antibodies to block viral entry and for identification of entry inhibitors

Neutralizing antibodies (NAbs) are naturally produced by our immune system to combat viral infections. Clinically, neutralizing antibodies with potent efficacy and high specificity have been extensively used to prevent and treat a wide variety of viral infections, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Human Immunodeficiency Virus (HIV), Dengue Virus (DENV) and Hepatitis B Virus (HBV). An overwhelmingly large subset of clinically effective NAbs operates by targeting viral envelope proteins to inhibit viral entry into the host cell. Binding of viral envelope protein to the host receptor is a critical rate limiting step triggering a cascade of downstream events, including endocytosis, membrane fusion and pore formation to allow viral entry. In recent years, improved structural knowledge on these processes have allowed researchers to also leverage NAbs as an indispensable tool in guiding discovery of novel antiviral entry inhibitors, providing drug candidates with high efficacy and pan-genus specificity. This review will summarize the latest progresses on the applications of NAbs as effective entry inhibitors and as important tools to develop antiviral therapeutics by high-throughput drug screenings, rational design of peptidic entry inhibitor mimicking NAbs and in silico computational modeling approaches.

Caregivers of children with HIV in Botswana prefer monthly IV Broadly Neutralizing Antibodies (bNAbs) to daily oral ART

INTRODUCTION

Monthly intravenous infusion of broadly neutralizing monoclonal antibodies may be an attractive alternative to daily oral antiretroviral treatment for children living with HIV. However, acceptability among caregivers remains unknown.

METHODS

We evaluated monthly infusion of dual bNAbs (VRCO1LS and 10-1074) as a treatment alternative to ART among children participating in the Tatelo Study in Botswana. Eligible children aged 2-5 years received 8-32 weeks of bNAbs overlapping with ART, and up to 24 weeks of bNAbs alone as monthly intravenous infusion. Using closed-ended questionnaires, we evaluated caregiver acceptability of each treatment strategy prior to the first bNAb administration visit (pre-intervention) and after the completion of the final bNAb administration visit (post-intervention).

RESULTS

Twenty-five children completed the intervention phase of the study, and acceptability data were available from 24 caregivers at both time points. Responses were provided by the child's mother at both visits (60%), an extended family member at both visits (28%), or a combination of mother and an extended family member (12%). Caregiver acceptance of monthly bNAb infusions was extremely high both pre-and post-intervention, with 21/24 (87.5%) preferring bNAbs to ART pre-intervention, and 21/25 (84%) preferring bNAbs post-intervention. While no caregiver preferred ART pre-intervention, 2/25 preferred it post-intervention. Pre-intervention, 3 (13%) caregivers had no preference between monthly bNAbs or daily ART, and 2 (8%) had no preference post-intervention. Pre-intervention, the most common reasons for preferring bNAbs over ART were the perception that bNAbs were better at suppressing the virus than ART (n = 10) and the fact that infusions were dosed once monthly compared to daily ART (n = 9). Post-intervention, no dominant reason for preferring bNAbs over ART emerged from caregivers.

CONCLUSIONS

Monthly intravenous bNAb infusions were highly acceptable to caregivers of children with HIV in Botswana and preferred over standard ART by the majority of caregivers.

CLINICAL TRIAL NUMBER

NCT03707977.

Age at ART initiation and proviral reservoir size in perinatal HIV-1 infection: considerations for ART-free remission

PURPOSE OF REVIEW

Achieving ART-free remission without the need for lifelong antiretroviral treatment (ART) is a new objective in HIV-1 therapeutics. This review comprehensively examines the literature to evaluate whether the age at ART initiation in children with perinatal HIV-1 influences the size and decay of the HIV-1 reservoir. The insights gathered from this review serve to inform the field on the unique dynamics of HIV-1 reservoir size in perinatal HIV-1 infection as a function of age at ART initiation, as well as inform biomarker profiling and timing of ART-free remission strategies for children living with HIV-1 globally.

RECENT FINDINGS

Recent studies demonstrate that initiating very early effective ART in neonates is feasible and limits HIV-1 reservoir size. The clinical relevance of limiting the HIV-1 reservoir size in perinatal infection was recently demonstrated in the Tatelo Study, which investigated a treatment switch from ART to two broadly neutralizing antibodies (bNAbs) in very early treated children. Low proviral reservoir size was associated with sustained virologic control for 24 weeks on bNAbs.

SUMMARY

Immediate and early ART initiation for neonates and infants with perinatal HIV-1 is essential to restricting HIV-1 reservoir size that may enable ART-free remission.

Preventing breast milk HIV transmission using broadly neutralizing monoclonal antibodies: One size does not fit all

Passive immunoprophylaxis with broadly neutralizing monoclonal antibodies (bNAbs) could be a game changer in the prevention of human immunodeficiency virus (HIV) acquisition. The prevailing view is that available resources should be focused on identifying a fixed combination of at least three bNAbs for universal use in therapeutic and preventive protocols, regardless of target populations or routes of transmission. HIV transmission through breastfeeding is unique: it involves free viral particles and cell‐associated virus from breast milk and, in the case of acute/recent maternal infection, a viral population with restricted Env diversity. HIV transmission through breastfeeding in high incidence/prevalence areas could potentially be eliminated by subcutaneous administration to all newborns of one or two long‐acting bNAbs with extended breadth, high potency, and effector properties (ADCC, phagocytosis) against circulating HIV strains.

More than the Infinite Monkey Theorem: NHP Models in the Development of a Pediatric HIV Cure

PURPOSE OF REVIEW

An HIV cure that eliminates the viral reservoir or provides viral control without antiretroviral therapy (ART) is an urgent need in children as they face unique challenges, including lifelong ART adherence and the deleterious effects of chronic immune activation. This review highlights the importance of nonhuman primate (NHP) models in developing an HIV cure for children as these models recapitulate the viral pathogenesis and persistence.

RECENT FINDINGS

Several cure approaches have been explored in infant NHPs, although knowledge gaps remain. Broadly neutralizing antibodies (bNAbs) show promise for controlling viremia and delaying viral rebound after ART interruption but face administration challenges. Adeno-associated virus (AAV) vectors hold the potential for sustained bNAb expression. Therapeutic vaccination induces immune responses against simian retroviruses but has yet to impact the viral reservoir. Combining immunotherapies with latency reversal agents (LRAs) that enhance viral antigen expression should be explored. Current and future cure approaches will require adaptation for the pediatric immune system and unique features of virus persistence, for which NHP models are fundamental to assess their efficacy.

Broadly neutralizing antibodies: "The next thing" to treat children with HIV?

Monthly treatment with two neutralizing antibodies maintained HIV suppression in almost half of children who received early antiretroviral treatment (Shapiro et al.).