Project Summary / Abstract Bronchopulmonary dysplasia (BPD) is the most common respiratory sequelae of prematurity and is often fatal. Montelukast is FDA-approved and already shows promise in small neonatal trials. Because of limited pharmacokinetic (PK)/pharmacodynamics (PD) research, the optimal montelukast dose for premature infants to avoid BPD is unknown. We propose the Pharmacokinetic and pharmacodynamic study of montelukast in infants with developing BPD (PRISM) trial, a dose-escalating open-label pharmacokinetic, safety and preliminary efficacy trial in premature infants (born < 29 weeks’ gestation) at high risk for BPD (requiring positive pressure ventilation between 29-33 weeks). Our central premise is that re-purposing a non-steroid anti-inflammatory agent will be safe and show preliminary efficacy in preventing BPD. Our objective is to perform population-specific PK/PD analyses under FDA regulatory guidance to identify the optimal montelukast dose to use in a definitive phase III trial. The trial will begin with a low-dose (0.75 mg/kg/day) cohort, and will proceed sequentially to the medium- (1.5 mg/kg/day) and high-dose (2.25 mg/kg/day) cohorts after safety reviews. Dosing will last 4 weeks involving 90 infants (30/cohort) at up to 8 experienced neonatal sites. A comparator cohort of placebo-treated NICHD-trial infants with similar age and disease severity will serve as historical controls. The primary outcome will be the drug clearance (CL/F), which is the key determinant of maintenance dosing. Secondary outcomes will include safety (determined by total adverse events) and exposure-response relationships between montelukast and change in BPD risk over the treatment period. Our first aim will be to characterize the PK of montelukast in premature infants. We hypothesize that the clearance in the infants ≤ 28 weeks post-menstrual age (PMA) (i.e. PMA = gestational age + postnatal age) will be at least 30% reduced compared to infants > 28 weeks. Our second aim is to characterize the safety profile of montelukast in premature infants; we hypothesize that the montelukast adverse event rate will not increase with montelukast exposure. Lastly, we aim to determine preliminary efficacy of montelukast in premature infants; we hypothesize that the change in moderate-severe BPD risk calculated from a population PK/PD linear regression model will decrease by 30% with increasing montelukast AUC0-24.The PRISM PK/PD results will be submitted to the FDA, and will help determine the optimal dose of montelukast to reduce BPD. The impact of the PRISM trial could be monumental in the field of neonatology.