JAK Inhibitors for Psoriasis and Psoriatic Arthritis

Abstract

Janus kinase (JAK) inhibitors represent a growing class of medications for the targeted treatment of psoriatic disease that can be administered orally or formulated into topical preparations. This article reviews the utility and clinical significance of JAK inhibitors for the treatment of psoriatic disease—both psoriatic arthritis and plaque psoriasis—as demonstrated in clinical trials. Tofacitinib, the most widely studied of the JAK inhibitors in psoriatic disease, has demonstrated significant efficacy for the treatment of both psoriatic arthritis and plaque psoriasis. However, while it received approval from the US Food and Drug Association for the former indication, it was denied for the latter. This has not deterred the development of newer JAK inhibitors which hope to provide a balance of efficacy and safety that would allow for their approval. Topical ruxolitinib has also demonstrated efficacy for the treatment of plaque psoriasis. JAK inhibitors function by blocking the JAK-STAT pathway, which is crucial to the signaling of the numerous cytokines implicated in the pathogenesis of psoriasis. While oral tofacitinib and topical ruxolitinib are the most well-studied medications for this indication, newer JAK inhibitors—filgotinib and upadacitinib, in particular—are proving promising in more recent clinical trials.