INTRODUCTION
Baricitinib is a reversible Janus kinase (JAK) 1 and 2 inhibitor approved for use in the European Union and the United States for various dermatological conditions. In the US, current US Food and Drug Administration (FDA) indications for baricitinib include alopecia areata (AA), rheumatoid arthritis (RA), and COVID-19. Despite this, baricitinib has also been used as an off-label treatment for other conditions when other treatment options may have failed or proved inefficacious.
JAK inhibition is a therapeutic strategy for immune and inflammatory diseases through mediating the JAK-STAT pathway.1 Since cytokines that depend on JAK are important factors in immunopathology, JAK inhibitors seek to prevent proinflammatory downstream signaling. Barictinib is a reversible JAK1/JAK2 inhibitor that was first approved in the European Union in February 2017. Other JAK inhibitors differ in target selectivity and downstream effects. For example, ruxolitinib, which was the first approved JAK inhibitor, targets JAK1/JAK2 and has been used in the treatment of psoriasis and AA.1 Tofacitinib, which is used to treat rheumatoid arthritis (RA), psoriatic arthritis, and ulcerative colitis, is a potent inhibitor of JAK3 and also inhibits JAK1, but is less selective for JAK2.2 Lastly, upadacitinib, which is used to treat active RA, is a JAK1 inhibitor and inhibitor of IL-3, GM-CSF, and G-CSF.2
Conditions in which baricitinib has been used may be broadly categorized into connective tissue diseases, eczematous dermatoses, alopecias, vascular disorders, granulomatous diseases, neutrophilic dermatoses, vitiligo, psoriasis, lichenoid disorders, and other miscellaneous disorders. Herein, we review potential off-label uses of baricitinib.
MATERIALS AND METHODS
The Pubmed/MEDLINE database was queried with the search "baricitinib" OR "Olumiant" OR "LY3009104" OR "INCB028050". The US National Library of Medicine (ClinicalTrials.gov) database was queried with the terms "baricitinib", "Olumiant", "LY3009104", and "INCB028050". After removing duplicate articles, remaining studies were screened by title and abstract for off-label uses of baricitinib in dermatology. Full text screening was then conducted to identify articles that described clinical outcomes for patients using baricitinib for dermatologic conditions. The only dermatology-related FDA indication for baricitinib is AA. The other indications are for COVID-19 hospitalized patients and RA. Non-English articles and articles that described on-label use were not included. No time restrictions were applied and searches were performed in July 2022. As atopic dermatitis (AD) has been approved for use in the European Medicine Agency (EMA), non-randomized control trial studies of baricitinib treatment for AD, including case reports and retrospective studies, will not be covered here; but they are referenced for reviewing below.
Connective Tissue Diseases
Systemic lupus erythematosus
Type 1 and Type 2 interferons that are present in systemic lupus erythematosus (SLE) depend on the JAK/STAT pathway.3 Moreover, literature indicates that inhibiting this JAK/STAT pathway plays an important role in reducing SLE inflammation.4 The literature documents reports of using baricitinib to treat chilblain lupus, cutaneous lupus erythematosus, and refractory systemic lupus erythematosus.
The strongest evidence comes from a double-blind, randomized, placebo-controlled, phase 2 trial in patients (n=314) with SLE.5-6
