Biological therapies directed at proinflammatory cytokines have irrevocably changed the landscape of treatment of rheumatoid arthritis (RA) and other autoimmune diseases. With the advances in our knowledge in cytokine signaling, the question emerges whether targeting intracellular signaling might also be a safe and efficacious strategy. Janus kinases or Jaks are critical for a large family of cytokines and the first Jak inhibitor has been approved by the FDA for the treatment of myelofibrosis. Late phase clinical trials have been completed for another Jakinib in RA. It is therefore timely to consider this new category of drugs and reflect on their potential roles, present and future, in the treatment of RA and related disorders.

Immunotherapy of cancer with checkpoint inhibitors has been associated with a spectrum of autoimmune and systemic inflammatory reactions known as immune-related adverse events (irAEs). Rheumatic irAEs are infrequently reported and extensively described. Here, we report our experience over an 18-month period with 15 patients evaluated in the rheumatology department for rheumatic irAEs. We identified 13 patients without pre-existing autoimmune disease (AID) who subsequently developed rheumatic irAEs, and two with established AID referred pre-emptively. irAEs encountered included: inflammatory arthritis, sicca syndrome, polymyalgia rheumatica-like symptoms and myositis. All cases required glucocorticoids, and three required a biological agent. Rheumatic irAEs led to temporary or permanent cessation of immunotherapy in all but five patients. One patient with pre-existing AID experienced a flare after starting immunotherapy. Our findings underscore that rheumatic irAEs are complex, at times require additional immunosuppressive therapy, and may influence ongoing immunotherapy regimens for the primary disease. Similar irAEs will be increasingly seen as checkpoint inhibitors adopted as standard of care in the community.

Cytokines are critical for normal cell growth and immunoregulation but also contribute to growth of malignant cells and drive immune-mediated disease. A major subset of immunoregulatory cytokines, roughly 60, use the type I and type II cytokine receptors and pharmacological targeting of these cytokines/cytokines receptors has proven to be efficacious in treating immune and inflammatory diseases. These receptors rely on Janus family of kinases (Jaks) for signal transduction and recently the first Jak inhibitor has been approved by the FDA. Many other Jakinibs are likely to follow and in this brief review, we will discuss the state-of-the art of this new class of pharmacological agents.