Pharmacokinetics and Safety of the Abacavir/Lamivudine/Lopinavir/Ritonavir Fixed-Dose Granule Formulation (4-in-1) in Neonates: PETITE Study

The urgency of now to end HIV vertical transmission for pregnant and breastfeeding women and their children in Asia and the Pacific

The global strategy to #EndAIDS is underpinned by a call to end all inequities and to ensure no-one is left behind; but inequities continue, and people are still being left behind. Despite the advances seen in some populations and in some geographical areas, with ongoing high rates of HIV vertical transmission, ending HIV for pregnant and breastfeeding women and their children must be prioritised urgently. Focused on Asia and the Pacific, the region with the second largest number of people with HIV, in this viewpoint we highlight the heterogenous nature of global and regional success in eliminating vertical transmission of HIV. We highlight the gaps of the HIV care cascades of pregnant and breastfeeding women and their children in the region that we need to address and galvanise increased attention, and resources for to set us on a path to the elimination of HIV vertical transmission or reverse the slow decline in transmission needed to achieve the last mile. We conclude that the time is now: we need action to improve maternal and child health in our regional response to HIV if we are to ensure we end AIDS for all.

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.

Advancing research and development of anti-infectives for children with a focus on antiretroviral therapy: A clinical development perspective

The HIV treatment landscape for adults has progressed dramatically in recent decades; however, paediatric populations continue to experience delayed and limited access to effective and safe antiretroviral therapy options. Despite current incentive programmes, formulation research and development and approved drug dosing for children have been limited, particularly for neonates (aged <4 wk). Regulatory approval of drug formulations and dosing in children may lag behind adult approvals by years. Formulation and trial design adjustments complicate paediatric drug development, all of which are vital to accommodate for physiological differences, organ maturation, and rapid weight gain, which are most significant in the youngest children. To facilitate more rapid anti-infective drug development for paediatric populations, regulatory agencies provide guidelines that include extrapolating efficacy and safety data from relevant populations; using pharmacokinetic (PK) bridging and modelling to reduce sample sizes and limit the number of PK studies needed before efficacy analyses; and enrolling age- or weight-based cohorts in parallel rather than sequentially for clinical trials. Ensuring access to approved drugs poses an additional challenge, as uncertainty in demand leads to manufacturing and supply complexity with potentially higher costs that can be a barrier to uptake. Here we summarise challenges in drug development for children living with HIV, which are not unique to antiretrovirals. We aim to propose strategies for how model-based approaches and global partnerships can overcome some of these barriers to accelerate paediatric drug development, with particular reference to HIV, and how lessons learnt from HIV could be extended to other anti-infectives.

Paediatric abacavir-lamivudine fixed-dose dispersible tablets and ritonavir-boosted lopinavir granules in neonates exposed to HIV (PETITE study): an open-label, two-stage, single-arm, phase 1/2, pharmacokinetic and safety trial

BACKGROUND

Existing solid antiretroviral fixed-dose combination formulations are preferred over liquid formulations in children, but their suitability for neonates is unknown. We evaluated the pharmacokinetics and safety of paediatric abacavir-lamivudine fixed-dose dispersible tablets and ritonavir-boosted lopinavir granules in neonates.

METHODS

In this open-label, two-stage, single-arm, phase 1/2, pharmacokinetic and safety trial, generic abacavir- lamivudine (120:60 mg) double-scored dispersible tablets and lopinavir boosted with ritonavir (40:10 mg) granules were studied. Neonates exposed to HIV (≥37 weeks gestational age) of no more than 3 days of age with birthweights of 2000-4000 g were identified through routine care in a tertiary hospital in Cape Town, South Africa. In stage 1, the pharmacokinetics and safety of two single doses were assessed to select the multidose strategy for stage 2. Neonates received a single dose of abacavir-lamivudine (30:15 mg, a quarter of a tablet) and lopinavir boosted with ritonavir (40:10 mg - one sachet) orally between 3 days and 14 days of age, and a second dose of a quarter tablet of abacavir-lamivudine and lopinavir boosted with ritonavir (80:20 mg, two sachets) 10-14 days later in stage 1. The multidose strategy selected in stage 2 was a quarter of the abacavir-lamivudine (30:15 mg) fixed-dose dispersible tablet once per day and two sachets of the lopinavir boosted with ritonavir (80:20 mg) granules twice per day from birth to age 28 days. In both stages two intensive pharmacokinetic visits were done, one at less than 14 days of life (pharmacokinetics 1) and another 10-14 days later (pharmacokinetics 2). Safety visits were done 1-2 weeks after each pharmacokinetic visit. Primary objectives were to assess pharmacokinetics and safety of abacavir, lamivudine, and lopinavir. Pharmacokinetic endpoints were area under the concentration time curve (AUC), maximum concentration, and concentration at end of dosing interval in all participants with at least one evaluable pharmacokinetic visit. Safety endpoints included grade 3 or worse adverse events, and grade 3 or worse treatment-related adverse events, occurring between study drug initiation and end of study. This completed trial is registered with the Pan African Clinical Trials Registry (PACTR202007806554538).

FINDINGS

Between Aug 18, 2021, and Aug 18, 2022, 24 neonates were enrolled into the trial and received study drugs. Eight neonates completed stage 1, meeting interim pharmacokinetic and safety criteria. In stage 2, 16 neonates received study drugs. Geometric mean abacavir and lamivudine exposures (AUC0-24) were higher at 6-14 days (51·7 mg × h/L for abacavir and 17·2 mg × h/L for lamivudine) than at 19-24 days of age (25·0 mg × h/L and 11·3 mg × h/L), whereas they were similar for lopinavir over this period (AUC 0-12 58·5 mg × h/L vs 46·4 mg × h/L). Abacavir geometric mean AUC0-24 crossed the upper reference range at pharmacokinetics 1, but rapidly decreased. Lamivudine and lopinavir AUC0-tau were within range. No grade 2 or worse adverse events were related to study drugs. One neonate had a grade 1 prolonged corrected QT interval using the Fridericia method that spontaneously resolved.

INTERPRETATION

Abacavir-lamivudine dispersible tablets and ritonavir-boosted lopinavir granules in neonates were safe and provided drug exposures similar to those in young infants. Although further safety data are needed, this regimen presents a new option for HIV prevention and treatment from birth. Accelerating neonatal pharmacokinetic studies of novel antiretroviral therapies is essential for neonates to also benefit from state-of-the-art treatments.

FUNDING

Unitaid.

Novel Approaches to Postnatal Prophylaxis to Eliminate Vertical Transmission of HIV

Despite progress in providing antiretroviral therapy to pregnant women living with HIV, a substantial number of vertical transmissions continue to occur. Novel approaches leveraging modern potent, safe, and well-tolerated antiretroviral drugs are urgently needed.

Drugs for neglected tropical diseases: availability of age-appropriate oral formulations for young children

It is recognised that paediatric indications and age-appropriate formulations are required to ensure that paediatric populations receive appropriate pharmacotherapeutic treatment. The lack of information on dosing, efficacy and safety data (labelling) is a well-recognised problem for all diseases affecting children. For neglected tropical diseases, the fact that they affect to a large extent poor and marginalised populations in low- and middle-income countries means that there is a low economic return on investment into paediatric development activities compared to other diseases [e.g. human immunodeficiency virus (HIV)]. This review provides an introduction to issues affecting the availability and development of paediatric population-relevant data and appropriate formulations of drugs for NTDs. We are summarising why age-appropriate formulations are important to ensure treatment efficacy, safety and effectiveness, outline initiatives to increase the number of paediatric indications/labelling and age-appropriate formulations, provide an overview of publicly available information on the formulations of oral drugs for NTDs relative to age appropriateness and give an introduction to options for age-appropriate formulations. The review completes with 'case studies' of recently developed paediatric formulations for NTDs, complemented by case studies for fixed-dose combinations for HIV infection in children since such formulations have not been developed for NTDs.

What babies need: accelerating access to current and novel antiretroviral drugs in neonates through pharmacokinetic studies

Although 23 antiretroviral drugs are approved for use in adults, only six are approved by regulatory authorities for use in term neonates born to women with HIV, with even fewer options for preterm neonates. A major hurdle for approvals is the delay in the generation of pharmacokinetic and safety data for antiretrovirals in neonates. The median time between the year of approval from the US Food and Drug Administration of an antiretroviral agent for adults and the first publication date for pharmacokinetic data in neonates less than 4 weeks old is 8 years (range 2-23 years). In this Viewpoint, we address pharmacokinetic research gaps and priorities for current and novel antiretroviral use in neonates. We also consider the challenges and provide guidance on neonatal clinical pharmacology research on antiretroviral agents with the goal of stimulating research and expediting the availability of safe medications for the prevention and treatment of HIV in this vulnerable population.