Study to Evaluate the Safety and Efficacy of CTP-543 in Adults With Moderate to Severe Alopecia Areata

This is a double-blind, randomized, placebo-controlled multi-center study consisting of 3 cohorts to assess the safety and efficacy of CTP-543. Each Cohort will be initiated sequentially in ascending dose order. Participants will be randomized to either an active dose of CTP-543 or placebo for a 24-week treatment period.