Extrapolating Pharmacodynamic Effects From Adults to Pediatrics: A Case Study of Ustekinumab in Pediatric Patients With Moderate to Severe Plaque Psoriasis

Ustekinumab (STELARA) is a human monoclonal antibody against interleukins-12 and -23 for the treatment of adult and adolescent (>= 12 to < 18 years of age) patients with moderate-to-severe plaque psoriasis. A phase III study was recently completed in pediatric patients (>= 6 to < 12 years of age) with psoriasis. The objectives of the current analysis were to develop a population pharmacokinetic (PK) model and a joint longitudinal exposure-response model using ordered categorial end points derived from Psoriasis Area and Severity Index (PASI) and Physician's Global Assessment (PGA) scores (namely a joint PASI response criteria (PRC) and PGA model) to characterize the PK and exposure-response relationship of ustekinumab in pediatric patients with psoriasis. The developed pediatric models reasonably predicted the PK of ustekinumab, as well as the PRC and PGA clinical response in pediatric patients with psoriasis. In addition, the joint PRC and PGA modeling framework was able to adequately extrapolate clinical response in pediatric patients using data collected from clinical studies in adult patients with psoriasis.