A Phase 1, Open-Label Study of the Pharmacokinetics of Ritlecitinib in Children Aged 6-12 Years With Alopecia Areata.

Background: Alopecia areata (AA) is an autoimmune disease characterized by hair loss that can negatively impact quality of life. AA has a significant pediatric prevalence; however, no systemic treatments are approved for AA in patients aged < 12 years. Ritlecitinib, a JAK3/TEC family kinase inhibitor, is approved to treat adults and adolescents with severe AA aged ≥ 12 years. This study evaluated ritlecitinib pharmacokinetic (PK) parameters and safety in pediatric patients with AA aged 6 to < 12 years.

Methods: In this single-group, uncontrolled, open-label study, participants received ritlecitinib 20 mg once daily for 7 days. PK parameters of ritlecitinib on Day 7 were measured and summarized descriptively. Safety outcomes, including incidence of adverse events (AEs), were evaluated.

Results: Fifteen participants were enrolled and 14 (93.3%) completed the study. The median time to maximum concentration (Tmax) for plasma concentrations of ritlecitinib on Day 7 was ~0.5 h. The mean half-life of ritlecitinib was ~1.19 h. Geometric means (% coefficient of variation) for area under the curve from 0 to 24 h (AUC24) and maximum concentration (Cmax) were 437.5 ng·h/mL (30%) and 208.7 ng/mL (38%), respectively. Four AEs were experienced by 3 participants, with 1 AE of urticaria resulting in permanent discontinuation. No severe AEs, serious AEs, or clinically meaningful laboratory abnormalities were reported.

Conclusions: Ritlecitinib PK parameters in pediatric patients were successfully characterized in the present study. Ritlecitinib 20 mg once daily was generally well tolerated in pediatric patients with AA. Background: NCT05650333.