Comparative Study of JAK Inhibitors Vs TNF Inhibitors in Patients With Rheumatoid Arthritis

Rheumatoid arthritis is a systemic autoimmune disease characterized by inflammatory synovitis and progressive joint destruction, which are associated with severe disability and increased mortality. It occurs at an incidence of 5 per 1000 with Women being 2 times more likely to be affected by Rheumatoid Arthritis than men. The peak incidence in both groups is in the sixth decade of life.

Management of RA has improved substantially in recent years. In addition to the reduction of signs and symptoms, improvement of physical function, and inhibition of structural damage, better patient outcomes, and clinical remission are now considered achievable goals. Therefore, the current recommended primary target for the treatment of RA should be a state of clinical remission.

Methotrexate (MTX) should be initiated, typically as monotherapy. If treatment response is inadequate, other Disease-modifying antirheumatic drugs (DMARDs) may be added to (rather than replacing) methotrexate to enhance efficacy and reduce the potential for the formation of anti-drug antibodies. TNF inhibitors are the first-line biologic therapies used in the event of incomplete response or adverse reaction to conventional DMARDs as TNF alpha is an important proinflammatory cytokine produced by macrophages and other cells, with myriad actions relevant to the pathogenesis of RA, including stimulation of other proinflammatory cytokine production, expression of endothelial cell adhesion molecules, production of metalloproteinases, and stimulation of osteoclasts. Activated Janus kinases (JAKs) play pivotal roles in intracellular signaling from cell-surface receptors for multiple cytokines implicated in the pathologic processes of rheumatoid arthritis. Baricitinib, an orally available small molecule, provides reversible inhibition of Janus Kinase 1 (JAK1) and Janus Kinase 2 (JAK2) and has shown clinical efficacy in studies involving patients with moderate to severely active Rheumatoid Arthritis who are either intolerant to MTX treatment or who have had an inadequate response to DMARDs, either conventional or biologic.