Janus Kinase (JAK) Inhibitor‑Associated Infection

Overview

Janus kinase (JAK) inhibitors are a class of oral or injectable medicines that block the activity of one or more of the JAK enzymes (JAK1, JAK2, JAK3, and TYK2) involved in cytokine signaling. By dampening the inflammatory cascade, they are effective for several autoimmune and inflammatory conditions, including rheumatoid arthritis, psoriatic arthritis, ulcerative colitis, atopic dermatitis, and some myeloproliferative neoplasms.

Because JAK pathways also play a critical role in normal immune defense against bacteria, viruses, fungi, and parasites, inhibiting them can predispose patients to infections. The term JAK inhibitor‑associated infection refers to any infection that occurs at a higher frequency or with greater severity in patients receiving a JAK inhibitor compared with the general population or with patients on non‑JAK therapies.

Who it affects: Adults and adolescents prescribed a JAK inhibitor for approved indications. Although anyone can be infected, the risk is highest in those who have additional immunosuppressive conditions (e.g., diabetes, chronic lung disease, or concomitant corticosteroids).

Prevalence: Large post‑marketing safety analyses have reported infection rates ranging from 15 % to 30 % per year