[Janus kinase inhibitors : State of the art in clinical use and future perspectives].

backgroundCytokines and associated intracellular signal cascades play a major role in the pathogenesis of autoimmune diseases. Janus kinases (JAK) are part of these intracellular signal transduction processes. A relatively new drug group of targeted synthetic disease-modifying antirheumatic drugs (tsDMARD) are JAK inhibitors (JAKi) and are a promising treatment approach for autoimmune diseases. EFFICACY: Hitherto, three JAKis, Tofacitinib, Baricitinib and Upadacitinib, have been approved for treatment of Rheumatoid Arthritis (RA) in the USA, Switzerland and the EU. Filgotinib, another JAKi, also showed promising results in the treatment of RA. Furthermore, tofacitinib received approval for the treatment of ulcerative colitis and psoriatic arthritis. In addition to the JAKis already mentioned, several other JAKis, e.g. filgotinib and peficitinib, are being and were investigated in various studies on indications, such as atopic dermatitis, ankylosing spondylitis and systemic lupus erythematosus. SAFETY: Being immunosuppressants, JAKis show an elevated incidence of severe infections, comparable to biologics. The increased reactivation of varicella zoster virus is especially noteworthy. Under JAKi treatment cytopenia is also more frequent. Lymphopenia under JAKi treatment is of particular clinical relevance because of its association with an increase in the number of severe infections. Furthermore, an elevated risk of thromboembolic events, particularly pulmonary embolism has been noted. The risks concerning metabolic alterations and the occurrence of malignant neoplasms are comparable to those under treatment with biologics.