A plain language summary on ritlecitinib treatment for adults and adolescents with alopecia areata

Immunotherapy. 2023 Oct;15(14):1093-1103. doi: 10.2217/imt-2023-0069. Epub 2023 Jul 5.


What is this summary about?: This is a summary of the results of the ALLEGRO phase 2b/3 clinical trial, originally published in The Lancet. ALLEGRO-2b/3 looked at how well and safely the study medicine, ritlecitinib, works in treating people with alopecia areata ('AA' for short). The immune system protects your body from outside invaders such as bacteria and viruses. AA is an autoimmune disease, meaning a disease in which one's immune system attacks healthy cells of the body by mistake. In AA, the immune system attacks hair follicles, causing hair to fall out. AA causes hair loss ranging from small bald patches to complete hair loss on the scalp, face, and/or body. Ritlecitinib is a medicine taken as a pill every day, by mouth, that is approved for the treatment of severe AA. It blocks processes that are known to play a role in causing hair loss in patients with AA.

What were the results of the study?: Adults and adolescents (12 years and older) took part in the ALLEGRO-2b/3 study. They either took ritlecitinib for 48 weeks or took a placebo (a pill with no medicine) for 24 weeks. Participants taking placebo later switched to taking ritlecitinib for 24 weeks. The study showed that participants taking ritlecitinib had more hair regrowth on their scalp after 24 weeks than those taking the placebo. Hair regrowth was also seen on the eyebrows and eyelashes in participants taking ritlecitinib. Hair regrowth continued to improve to week 48 with continued ritlecitinib treatment. In addition, more participants taking ritlecitinib reported that their AA had 'moderately' or 'greatly' improved after 24 weeks than those taking the placebo. Similar numbers of participants taking ritlecitinib or placebo had side effects after 24 weeks. Most side effects were mild or moderate.

What do the results of the study mean?: Ritlecitinib was an effective and well-tolerated treatment over 48 weeks for people with AA. Clinical Trial Registration: NCT03732807 (phase 2b/3 ALLEGRO study).

Keywords: adolescents; alopecia areata; hair loss; ritlecitinib.

Publication types

  • Review

MeSH terms

  • Adolescent
  • Adult
  • Alopecia Areata* / drug therapy
  • Carbazoles / therapeutic use
  • Humans
  • Immunologic Factors / therapeutic use
  • Protein Kinase Inhibitors / therapeutic use
  • Tryptamines / therapeutic use


  • frovatriptan
  • Carbazoles
  • Tryptamines
  • Protein Kinase Inhibitors
  • Immunologic Factors

Supplementary concepts

  • Diffuse alopecia

Associated data

  • ClinicalTrials.gov/NCT03732807