Abstract
Myelofibrosis (MF) is a chronic myeloid neoplasm characterized by either primary myelofibrosis, or secondary MF following essential thrombocythemia or polycythemia vera. Historically, therapy has been symptom directed; however, in 2011, the first janus kinase inhibitor (JAK-i) - ruxolitinib - was approved for treatment. This medication was found to be effective in reduction of symptom burden and spleen size; however, the median duration of response is about 3 years. In addition, many patients are intolerant or develop toxicities to ruxolitinib, including patients with anemia, as well as thrombocytopenia. Therefore, there is a critical need for alternate therapeutic options for patients with MF. Additional JAK-i have been developed over the last 8 years, including fedratinib, momelotinib, and pacritinib. Fedratinib recently received approval for treatment of MF both in the first-line and second-line setting. It has shown efficacy in the first-line setting, as well as in 30% of patients who are refractory/intolerant of ruxolitinib. This review covers the trials that have led to the approval of ruxolitinib as well as fedratinib, as well as reviews of two JAK inhibitors that are still under clinical investigation: momelotinib and pacritinib.