Beyond JAK inhibitor therapy in myelofibrosis

Abstract

Myelofibrosis (MF), including primary MF, postpolycythemia vera MF, and postessential thrombocythemia MF, is a clonal stem cell disorder characterized by BM fibrosis, extramedullary hematopoiesis, and a variable propensity to transform into acute leukemia. Allogeneic stem cell transplantation is the only known cure for MF, but its applicability is limited by the advanced age of most patients and by comorbid conditions. In the past decade, there has been an explosion of information on the molecular-genetic features associated with these diseases, fueled recently by the discovery of the JAK2V617F mutation. The development of JAK inhibitors has represented a significant therapeutic advance for these diseases; however, their use in MF has not yet been associated with eradication or a significant suppression of the malignant clone. In this era, much remains to be understood about MF, but it is likely that the identification of key pathogenetic drivers of the disease, coupled with the availability of novel molecularly targeted agents, will result in the discovery of new agents that significantly alter the natural history of the disease. This review focuses on recent and ongoing efforts in the development of novel agents in MF that go beyond the field of JAK inhibitors.