Used in the treatment of autoimmune diseases such as rheumatoid arthritis, decernotinib works by selectively inhibiting Janus kinase 3 (JAK3), which plays a key role in the signaling pathways of cytokines involved in immune responses. By blocking JAK3, it helps reduce inflammation and immune system overactivity that contribute to joint damage and symptoms in patients. It has been investigated in clinical trials for its potential to improve physical function and slow disease progression with a favorable safety profile compared to broader immunosuppressive therapies.