Myelofibrosis

Overview

Myelofibrosis is characterized by bone marrow fibrosis, symptom burden, splenomegaly, and cytopenias

Myelofibrosis is a Philadelphia chromosome–negative myeloproliferative neoplasm (MPN)¹ characterized by bone marrow fibrosis, symptom burden, splenomegaly, and cytopenias.² Myelofibrosis is a disease with significant heterogeneity in natural history and symptom burden. Patients with myelofibrosis fall along a spectrum that ranges from those who are essentially asymptomatic to those who have severe symptoms that affect daily functioning and quality of life.^3-5 Myelofibrosis can be a primary disease or it can be secondary to other conditions, including malignancies and other hematologic diseases.⁶

Although the precise etiology of myelofibrosis remains unknown, overactive Janus-associated kinase (JAK) pathway signaling is present in all patients with the disease.^7,8 Multiple mechanisms, including genetic mutations,^9-11 excessive production of cytokines,¹² increased JAK1 signaling,¹³ and damaged intracellular signaling¹⁴ may play a role in overactive JAK pathway signaling.

Because myelofibrosis has a heterogeneous presentation, determining a patient’s prognosis can be difficult.¹⁵ However, progress in understanding the clinical variables associated with myelofibrosis has led to the development of prognostic scoring systems, including the International Prognostic Scoring System (IPSS). The IPSS estimates prognosis based on risk factors present at diagnosis.¹⁶

Prevalence and demographics

Myelofibrosis is a rare disease, with a prevalence of 16,000 to 18,500 patients in the United States.¹⁷ Although myelofibrosis can occur at any age, the median age at diagnosis ranges from 60 to 67 years.^2,3 The disease affects both men and women.¹⁸