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.