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How We Treat Patients with Myelofibrosis

Amongst the c lass ic Philadelphia chromosomenegative myeloproliferative neoplasms (Ph-negative MPNs), primary myelofibrosis (PMF) is associated with the poorest outcome. Most recent estimates of median survival range from six to seven years. Approximately 90 percent of patients have an identifiable “driver” mutation— JAK2 V617F in 50 to 60 percent of patients, CALR exon 9 mutations in 20 to 30 percent, and MPL mutations in five to 10 percent. About 10 percent of patients have “triple negative” disease, which has been associated with inferior outcomes. Pathologic hallmarks of PMF include megakaryocyte proliferation and atypia and varying degrees of reticulin or collagen fibrosis in the bone marrow and peripheral blood leukoerythroblastosis. Typical clinical features include anemia, splenomegaly and a range of constitutional symptoms. Treatment is directed at improving these clinical features, as well as changing the natural course of the disease and improving survival. Management of patients with post-PV/ET myelofibrosis is approached in the same way.