A phase 2a randomized, placebo-controlled study to evaluate the efficacy and safety of the oral Janus kinase inhibitors ritlecitinib and brepocitinib in alopecia areata: 24-week results

J Am Acad Dermatol. 2021 Aug;85(2):379-387. doi: 10.1016/j.jaad.2021.03.050. Epub 2021 Mar 20.


Background: Alopecia areata (AA) is an autoimmune form of hair loss with limited treatments.

Objective: To evaluate the efficacy and safety of the Janus kinase inhibitors ritlecitinib and brepocitinib in patients who have AA with ≥ 50% scalp hair loss.

Methods: Patients were randomized to once-daily ritlecitinib, brepocitinib, or placebo. The primary efficacy endpoint was a 24-week change from baseline in the Severity of Alopecia Tool (SALT) score. The key secondary efficacy endpoint was the proportion of patients achieving 30% improvement in SALT score (SALT30).

Results: The ritlecitinib, brepocitinib, and placebo groups included 48, 47, and 47 patients, respectively. At week 24, least-squares mean difference from placebo in SALT score change from baseline was 31.1 (95% confidence interval [CI], 18.8-43.5) for ritlecitinib and 49.2 (95% CI, 36.6-61.7) for brepocitinib (P < .0001 for both comparisons with placebo). SALT30 was achieved by 50% (90% CI, 38%-62%) of patients receiving ritlecitinib, 64% (90% CI, 51%-75%) receiving brepocitinib, and 2% (90% CI, 0%-9%) receiving placebo. Two patients experienced a serious adverse event (rhabdomyolysis) in the brepocitinib group only.

Limitations: Only a single-dosage regimen of each study drug was included.

Conclusion: Treatment with ritlecitinib or brepocitinib for 24 weeks was efficacious and generally well tolerated.

Keywords: Janus kinase inhibitor; alopecia areata; brepocitinib; efficacy; phase 2; ritlecitinib; safety.

Publication types

  • Clinical Trial, Phase II
  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Alopecia Areata / drug therapy*
  • Double-Blind Method
  • Female
  • Humans
  • Janus Kinase Inhibitors / therapeutic use*
  • Male
  • Middle Aged
  • Protein Kinase Inhibitors / therapeutic use*
  • Pyrazoles / therapeutic use*
  • Pyrimidines / therapeutic use*
  • Pyrroles / therapeutic use*
  • Time Factors
  • Treatment Outcome
  • Young Adult


  • Janus Kinase Inhibitors
  • PF-06651600
  • Protein Kinase Inhibitors
  • Pyrazoles
  • Pyrimidines
  • Pyrroles
  • PF-06700841