Efficacy and safety of baricitinib in patients with alopecia areata: evidence to date

Alopecia areata (AA) is a chronic, tissue-specific autoimmune disorder, characterized by non-scaring hair loss, with a global prevalence of approximately 2%. Typically, it affects a young population, with initial onset frequently occurring before the age of 30 years. Even though the exact pathogenesis of AA remains unclear, the predominant hypothesis is the breakdown of immune privilege of the hair follicle, resulting in increased self-antigen and major histocompatibility complex expression in the follicular epithelium. The relapsing nature of the disease negatively impacts patients’ quality of life and makes them more susceptible to developing psychiatric comorbidities. Although many treatment modalities have been proposed, there are no currently available treatments able to induce and sustain disease remission. Traditional treatment modalities, despite being widely used, present limited results and a high risk of adverse effects. Hence, there exists an unfulfilled requirement for treatments that are both more efficient and safer. The latest understanding of the pathophysiology of AA and its connection to the JAK–STAT pathway has prompted the advancement of JAK inhibitors. These small-molecule agents function by obstructing the JAK–STAT intracellular signalling pathway. Baricitinib an orally administered, selective JAK1 and JAK2 inhibitor is a promising alternative to the available treatments, and is already approved for the treatment of AA.