Xeljanz is the first new oral disease-modifying antirheumatic drug approved for rheumatoid arthritis in more than ten years and the first rheumatoid arthritis treatment in a new class of medicines known as Janus kinase (JAK) inhibitors. Unlike biologic therapies, which work outside the cell, Xeljanz targets the inflammation associated with rheumatoid arthritis from inside the cell. Specifically, Xeljanz inhibits the JAK pathways, which are signaling pathways inside cells that are used by pro-inflammatory cytokines (proteins that facilitate communication between cells).

Approved in the U.S. for the treatment of adults with moderately to severely active rheumatoid arthritis who have had an inadequate response or intolerance to methotrexate, Xeljanz is currently under review by several regulatory agencies around the world.