Benefits and risks of JAK inhibition

On 16 November 2011, the US Food and Drug Administration (FDA) approved ruxolitinib, a small-molecule inhibitor of JAK1/2, for the treatment of patients with intermediate- or high-risk myelofibrosis, including primary myelofibrosis, post-polycythemia vera myelofibrosis, and post-essential thrombocythemia myelofibrosis. In this issue of Blood, Porpaczy et al report findings of a study showing that JAK1/2 inhibitor treatment is associated with an increased risk for aggressive B-cell lymphomas.