Tofacitinib is in development for the treatment of polyarticular juvenile idiopathic arthritis (JIA). JIA is defined as arthritis of unknown aetiology that manifests itself before the age of 16 years and persists for at least 6 weeks, while excluding other known conditions. Polyarticular JIA, a subgroup of JIA is characterised by the involvement of five or more joints during the first 6 months of the disease and can be considered rheumatoid factor positive or negative. The most common symptoms include joint swelling, pain and limited range of motion. Currently available treatment of JIA aims to control symptoms, reduce the possibility of joint damage and improve quality of life.
Tofacitinib works by blocking the action of enzymes known as Janus kinases. These enzymes play an important role in the inflammatory process. By blocking the enzymes’ action, tofacitinib helps reduce the inflammation and other symptoms of these diseases. Tofacitinib is an oral alternative to the available biological medicines for children with JIA, most of which are administered by injection. If licensed, tofacitinib may offer an additional treatment option for polyarticular JIA with the potential advantage of improving the quality of life of children due to its oral formulation.
Upadacitinib acts by selectively blocking a protein called Janus-Associated Kinase 1 (JAK1 and JAK1/3). JAKs contribute to the processes within the cell to produce an immune or inflammatory response. There is an emerging body of evidence establishing that JAK dependent enzymes are major contributors to the progression of immunemediated diseases such as AS and that blocking such enzymes can be beneficial. Upadacitinib is taken orally and if licensed, it will offer an additional treatment option for patients with active AS.