INTRODUCTION
Dysregulation of Janus kinase (JAK) pathways from uncontrolled cytokine signaling comprises the pathological basis for many complex inflammatory disorders.1 Since JAK-family receptors are activated by numerous ligands, including several interleukins (IL), interferons (IFN), and hematopoietic growth factors, JAK inhibition can interfere with many different cellular pathways, potentially resulting in both desired efficacy as well as side effects.2
While most JAK inhibitors are US Food and Drug Administration (FDA)-approved for treating rheumatic conditions and are often used in patients not responding to disease-modifying antirheumatic drugs and biologics, there are several other inflammatory indications for which JAK inhibitors have demonstrated clinical promise.3,4 For example, JAK-mediated signaling pathways are involved in many immune-related dermatologic conditions, including atopic dermatitis (IL-4/5/13), psoriasis (IL-23/17), dermatomyositis (IFN-α/β, IL-6/15), and vitiligo (IFN-γ), among others.1,4 Additionally, in cases of cytokines that do not involve JAK pathways, JAK inhibitors have demonstrated utility by indirectly suppressing related molecules including upstream precursors that are later involved with JAK mechanisms, suggesting broader benefits of this drug class.4
Upadacitinib is an oral JAK inhibitor associated with reductions in IL-6 and IFN-γ that selectively targets JAK1, and is an example of an agent approved for use in rheumatoid arthritis, atopic dermatitis, and psoriatic arthritis, in addition to non-cutaneous autoimmune conditions.3,5,6 Tofacitinib is an oral JAK 1/3 inhibitor disrupting IL-2/4/15/21 signaling, and is approved for broader use in rheumatoid arthritis, psoriatic arthritis, ulcerative colitis, and polyarticular course juvenile idiopathic arthritis.3,7
In this report, we present different inflammatory systemic disorders that failed conventional treatment but were treated successfully with upadacitinib or tofacitinib, including dermatomyositis (DM), hidradenitis suppurativa (HS), cutaneous lupus, and cutaneous Crohn’s disease.