Used in the treatment of moderate to severe rheumatoid arthritis, particularly in patients who have shown inadequate response to conventional therapies. It functions as a selective inhibitor of Janus kinase (JAK), specifically targeting JAK1, which plays a key role in the signaling pathways of various pro-inflammatory cytokines involved in autoimmune conditions. By modulating this pathway, it helps reduce joint inflammation, slow disease progression, and improve physical function. Currently under clinical investigation to evaluate long-term safety, efficacy, and potential use in other inflammatory disorders.