Clinical Yield of Laboratory Monitoring During Ritlecitinib Treatment for Alopecia Areata: A Prospective Real-World Cohort Study.

Abstract

Routine laboratory monitoring is recommended during JAK inhibitor therapy, but its clinical yield in patients with alopecia areata has not been prospectively characterized. To characterize the incidence, timing, severity, and clinical significance of laboratory abnormalities during ritlecitinib treatment. In this prospective cohort, patients aged 12 years or older received ritlecitinib 50 mg once daily. Complete blood count, liver, and renal function parameters were assessed. Treatment-emergent abnormalities were predefined using local reference intervals and graded using CTCAE 5.0. Exploratory Cox regression was performed to identify factors associated with first laboratory abnormality. Among 162 patients contributing 62.9 patient-years, 99 (61.1%) developed at least one treatment-emergent laboratory abnormality; 67 first events (67.7%) occurred within 3 months. Abnormalities were predominantly mild: 97 patients had maximum grade 1 abnormalities, 2 had grade 2 abnormalities, and none had grade 3 or higher abnormalities. Prior systemic treatment was associated with higher hazard on univariable analysis (HR, 1.52; 95% CI, 1.02-2.28; P = .041), but no independent predictor remained after multivariable adjustment. Single-center design, Chinese cohort, and incomplete scheduled monitoring. Laboratory abnormalities during ritlecitinib therapy were common but mild and rarely actionable, supporting potential reconsideration of monitoring intensity.