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

Inclusion Criteria:

   - Definitive diagnosis of alopecia areata with a current episode lasting at least 6
   months and not exceeding 10 years at the time of Screening. Total disease duration
   greater than 10 years is permitted.

   - At least 50% scalp hair loss, as defined by a Severity of Alopecia Tool (SALT) score
   ≥50, at Screening and Baseline.

   - Clinical lab results within the normal range

Exclusion Criteria:

   - Active scalp inflammation, psoriasis, or seborrheic dermatitis requiring topical
   treatment to the scalp, significant trauma to the scalp, or untreated actinic
   keratosis on the scalp.

   - Treatment with systemic immunosuppressive medications or biologics.

   - Vaccination with herpes zoster vaccine or any live virus within 6 weeks of screening
   or during the study