Leveraging JAK-STAT regulation in myelofibrosis to improve outcomes with allogeneic hematopoietic stem-cell transplant

Primary myelofibrosis (PMF) is a disease characterized by bone marrow fibrosis, extramedullary hematopoiesis, risk of transformation to acute myeloid leukemia, and a substantial symptom burden with diminished quality of life. Allogeneic hematopoietic cell transplantation (HCT) is the only curative option; however, disease relapse and graft versus host disease (GVHD) are significant barriers to long-term survival. The discovery of the JAK2 V617F mutation, and subsequent development of JAK inhibitors, resulted in improved survival and significant improvements in spleen volumes and symptom scores. Though the effect of JAK inhibition on transplant outcome is poorly understood, using JAK inhibition to achieve maximal response prior to HCT is standard practice at major centers. After allogeneic HCT, a significant proportion of patients with steroid-refractory GVHD have clinical responses to JAK inhibition. Targeting this pathway is a key component in the management of patients with PMF before and after allogeneic HCT.