Review of Baricitinib in the Treatment of Alopecia Areata

September 2023 | Volume 22 | Issue 9 | 935 | Copyright © September 2023


Published online August 21, 2023

doi:10.36849/JDD.7357

Rohan Singh BSa, Marcia S. Driscoll MD PharmDa,b

aSchool of Medicine, University of Maryland, Baltimore, MD
bDepartment of Dermatology, University of Maryland School of Medicine, Baltimore, MD

Abstract
Background: Alopecia areata (AA) is a debilitating autoimmune disease that results in non-scarring hair loss. Baricitinib is the Food and Drug Administration (FDA) approved treatment for AA. 
Objective: Review the mechanism of action, pharmacokinetics, pharmacodynamics, efficacy, and safety of baricitinib in the treatment of AA. 
Methods: A literature review was conducted using the MEDLINE (PubMed) and EMBASE databases for articles published between January 2010 to November 2022. Articles in English discussing baricitinib's efficacy and safety in AA, pharmacodynamic, and pharmacokinetic profiles were included.
Results: Two identical phase III trials (BRAVE-AA1 and BRAVE-AA2) were evaluated. A greater percentage of subjects receiving baricitinib 4 mg or 2 mg dose achieved a Severity of Alopecia Tool score equal to or less than 20 vs placebo. In BRAVE-AA1, for 4 mg, 2 mg, and placebo, respectively, these values were 38.8%, 22.8%, and 6.2%; in BRAVE-AA2, these values were 35.9%, 19.4%, and 3.3% (P<0.001).
Discussion: Baricitinib is the first FDA-approved treatment for AA. Other treatments for AA are used off-label with variable efficacy. Baricitinib is associated with black-box warnings due to adverse effects (AEs) associated with other Janus Kinase (JAK) inhibitors or use in other diseases. In the two large AA trials, AEs were considered mild or moderate; those reported more often with baricitinib than placebo included acne, elevations of low- and high-density lipoprotein cholesterol, and elevation of creatinine kinase. Baricitinib is a relatively tolerable and safe therapeutic alternative for severe AA, although additional study is needed to assess its long-term efficacy and safety. 

Citation: Singh R, Driscoll MS. Review of baricitinib in the treatment of alopecia areata. J Drugs Dermatol. 2023;22(9):935-939. doi:10.36849/JDD.7357

INTRODUCTION

Alopecia areata (AA) is an autoimmune disease that results in non-scarring hair loss. Although the scalp is most commonly affected, AA may cause hair loss in any hair-bearing area of the body and most commonly presents as sudden onset loss of well-circumscribed focal patches of hair that can either be persistent or have a relapsing-remitting course.1 Within the United States, AA has a cumulative lifetime incidence of approximately 2% and a prevalence of approximately 0.1 to 0.2% in the general population.2 AA may affect both males and females equally, however approximately 80% of cases occur prior to the age of 40, with mean onset age of 25 to 36 years.2 

Although mild AA with a duration less than 12 months may resolve spontaneously, extensive or long-standing AA is less likely to resolve without treatment.3 Baricitinib, an oral Janus Kinase (JAK) 1 and 2 inhibitor, was approved by the US Food and Drug Administration (FDA) on June 13, 2022, to treat severe alopecia areata. It is the FDA approved treatment for AA.4 Prior to this approval, treatment of AA largely consisted of off-label treatments with variable efficacy and included topical, systemic, or intralesional corticosteroids, contact immunotherapy, and other immunosuppressive agents.5 

The objective of this review is to assess the mechanism of action, pharmacokinetics, pharmacodynamics, efficacy, and safety of baricitinib in the treatment of AA. 

MATERIALS AND METHODS

A review of literature was conducted using the MEDLINE (PubMed) and EMBASE databases in June 2022 using the terms “baricitinib” and “alopecia areata.” A total of 36 articles were identified and peer-reviewed articles in English discussing use of baricitinib in the treatment of AA and baricitinib’s pharmacodynamic and pharmacokinetic profiles published between January 2010 to June 2022 were included. References from included articles were searched for relevant citations. A ClinicalTrials.gov search was used to review ongoing or unpublished studies. Two phase III trials were identified. 

Mechanism of Action 
JAK inhibitors are a family of intracellular enzymes which modulate signals from growth factor receptors and cytokines involved in the function of immune cells (4 types: JAK 1, 2, 3, and tyrosine kinase (TYK) 2).4,6 Various JAKs can form homo- or heterodimers, which once activated, phosphorylate and subsequently activate signal transducers and activators of 
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