The efficacy and safety of deuruxolitinib in adolescent subjects with severe alopecia areata will be evaluated in this study, beginning with a double-blind, randomized, placebo-controlled Treatment Period of 24 weeks. Subjects 12 to \<18 years of age having at least 50% hair loss as measured by SALT and meeting eligibility criteria will be randomized to deuruxolitinib or placebo treatment. In the Open-label Extension part of the study, participants from the Treatment Period will receive deuruxolitinib for 52 weeks.
