The advent of JAK inhibitors (JAKi) inaugurated a novel era in the treatment of myelofibrosis (MF), a myeloproliferative neoplasm with heterogeneous clinical manifestations. Four JAKi have been approved for intermediate or high-risk MF, in the US. Regulatory approval of the first JAK1/2 inhibitor, ruxolitinib, in 2011 transformed the landscape of MF by markedly controlling splenomegaly and constitutional symptoms, improving patients' lives, and prolonging survival. Fedratinib, the …