Myelofibrosis is a rare form of blood cancer. The sex- and age-adjusted incidence is estimated at approximately 1.5 cases per 100,000 people, with a prevalence of 12 patients per 100,000 people (Slowley et al., 2024). This would translate to a prevalence of more than 100,000 people with myelofibrosis in the EU, US, UK, and Japan.
The underlying cause of myelofibrosis is unknown. Patients with myelofibrosis have an abnormal production of blood-forming cells leading to the replacement of healthy bone marrow with scar tissue (fibrosis).
Due to the lack of normal blood cell production, patients typically show laboratory value abnormalities, such as anemia and changes in white blood cell counts, and blood cell-differentiation. Later symptoms include enlargement of the spleen, an increased risk for infections, night sweats and fever. Myelofibrosis is associated with shortened survival, due to for instance bone marrow failure and transformation into acute leukemia.
Current Treatments and Market
Myelofibrosis can be treated with bone marrow transplantation for eligible individuals, erythropoietin to manage anemia and JAK2 inhibitors to reduce spleen size. Today the following drugs are approved for these patients as symptom-directed therapy: Hydroxy-urea, ruxolitinib, momelotinib, fedratinib and pacritinib (the latter four are JAK2 inhibitors, JAKi). At present there are no approved treatment options that would reverse bone marrow fibrosis in myelofibrosis, and there are only limited treatment options available for myelofibrosis patients whose disease progress during JAKi treatment or cannot tolerate JAKi.