In November 2011, ruxolitinib (Jakafi; Incyte/Novartis), a small-molecule inhibitor of Janus kinases, was approved by the US Food and Drug Administration for the treatment of patients with intermediate or high-risk myelofibrosis, including primary myelofibrosis, post-polycythaemia vera myelofibrosis and post-essential thrombocythaemia myelofibrosis.

Primary myelofibrosis, polycythaemia vera (PV) and essential thrombocythaemia (ET) are a group of myeloproliferative neoplasms (MPNs). They have clinical characteristics that in advanced cases include progressive myelofibrosis, anaemia and enlargement of the spleen, and symptoms that include fatigue and bone pain (1, 2). Standard treatments for these MPNs, such as myelosuppressive therapy with hydroxyurea, do not significantly affect the natural history of the disease, and are also not very effective in managing disease symptoms (1, 2).