Benralizumab is a humanized, afucosylated, anti-interleukin-5 receptor α, 
immunoglobulin G (IgG) 1 κ monoclonal antibody. We developed a population 
pharmacokinetic (PK)/pharmacodynamic (PD) model for benralizumab by analyzing PK 
and blood eosinophil count data from two healthy volunteer studies (N = 48) and 
four studies in patients with asthma (N = 152). Benralizumab PK was 
dose-proportional and adequately described by a two-compartment model with 
first-order elimination from the central compartment and first-order absorption 
from the subcutaneous dosing site. The estimated systemic clearance and volume 
of distribution were typical for human IgG. Body weight and high-titer antidrug 
antibodies were identified as relevant covariates influencing the PK of 
benralizumab. Depletion of blood eosinophil counts was depicted by a modified 
transit model in which benralizumab induced depletion of eosinophils in each age 
compartment. Stochastic simulations supported an every-8-week dosing schedule of 
benralizumab for a phase IIb study in patients with uncontrolled asthma.