Population Pharmacokinetic Model Development and Simulation for Recombinant Erwinia Asparaginase Produced in Pseudomonas fluorescens (JZP-458).

JZP-458 is a recombinant Erwinia asparaginase produced using a novel Pseudomonas fluorescens expression platform that yields an enzyme expected to lack immunologic cross-reactivity to Escherichia coli-derived asparaginases. It is being developed as part of a multiagent chemotherapeutic regimen to treat acute lymphoblastic leukemia or lymphoblastic lymphoma patients who develop E coli-derived asparaginase hypersensitivity. A population pharmacokinetic (PopPK) model was developed for JZP-458 using serum asparaginase activity (SAA) data from a phase 1, single-dose study (JZP458-101) in healthy adults. Effects of intrinsic covariates (body weight, body surface area, age, sex, and race) on JZP-458 PK were evaluated. The model included SAA data from 24 healthy adult participants from the phase 1 study who received JZP-458: intramuscular (IM) data at 12.5 mg/m (N = 6) and 25 mg/m (N = 6), and intravenous (IV) data at 25 mg/m (N = 6) and 37.5 mg/m (N = 6). Model simulations of adult and pediatric SAA profiles were performed to explore the likelihood of achieving a therapeutic target nadir SAA (NSAA) level ≥0.1 IU/mL based on different administration strategies. PopPK modeling and simulation suggest JZP-458 is expected to achieve 72-hour NSAA levels ≥0.1 IU/mL in 100% of adult or pediatric populations receiving IM administration at 25 mg/m , and in 80.9% of adult and 94.5% of pediatric populations receiving IV administration at 37.5 mg/m on a Monday/Wednesday/Friday (M/W/F) dosing schedule. Based on these results, the recommended starting dose for the phase 2/3 pivotal study is 25 mg/m IM or 37.5 mg/m IV on a M/W/F dosing schedule in pediatric and adult patients.