Looking forward: novel therapeutic approaches in chronic and advanced phases of myelofibrosis

Myelofibrosis (MF) is complex at the pathobiologic level and heterogeneous at the clinical level. The advances in molecular characterization of MF provide important insight into the mechanisms driving this chronic myeloid malignancy, refine risk stratification, offer novel therapeutic targets, and serve to measure therapeutic response. Although JAK2 inhibition has been the focus of laboratory and clinical efforts over the last decade, current experimental therapeutic approaches have broadened to include inhibitors of key alternative signaling pathways, epigenetic modulators, anti-fibrotics, and immunotherapies. Based on compelling preclinical rationale, a number of JAK2 inhibitor based combination therapies are now actively being evaluated in the clinic with the goal of disease course modification. The role and timing of hematopoietic stem cell transplant (HSCT) for MF has been challenged with the availability of commercial ruxolitinib and the plethora of experimental treatment options that exist. Integration of preconditioning JAK2 inhibition, reduced intensity conditioning regimens, and alternative donor sources are all being explored in an attempt to optimize this potentially curative modality. This review will summarize modern MF risk stratification, current clinical research approaches to chronic and advance phase MF focusing on novel agents alone and in combination, and update the reader on new directions in HSCT.