Myelofibrosis medical therapy

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sabawoon Mirwais, M.B.B.S, M.D.[2]Sujit Routray, M.D. [3]

Red blood cell transfusion, danazol therapy, or thalidomide are recommended for patients who develop anemia. Ruxolitinib, an inhibitor of Janus kinase 1 (JAK1) and Janus kinase 2 (JAK2), can reduce the splenomegaly and the constitutional symptoms of weight loss, fatigue, and night sweats for patients with Janus kinase 2 (JAK2)-positive or Janus kinase 2 (JAK2)-negative primary myelofibrosis (PMF), post–essential thrombocythemia myelofibrosis, or post–polycythemia vera myelofibrosis. Hydroxyurea, chemotherapy, or radiotherapy are recommended for patients who develop splenomegaly.

Red blood cell transfusion

• The profound anemia that develops in this disease usually requires red blood cell transfusion.^[1][2]

Glucocorticoids

• Glucocorticoids can improve the red blood cell (RBC) survival, which can be markedly decreased in some patients.^[1][3]

Androgen therapy

• Danazol can be given to stimulate the production of red blood cells (RBCs).
• Preferred regimen: 600-800 mg/day till normalization of cell counts and then reduced to 200-400 mg/day

Erythropoietic growth factors

• Erythropoietin and darbepoetin can help if patients are not dependent on transfusion.
• Preferred regimen: SubQ: 150 to 300 mcg once weekly or 500 mcg once every 2 to 3 weeks

Thalidomide, lenalidomide, or pomalidomide

• These may help in improving the red blood cell counts, thus improving anemia and help in the reversal of splenomegaly. However, patients on these drugs require prophylaxis for avoiding thrombosis and careful monitoring for hematologic toxicity.^[1][4]
• Preferred regimen: Oral: 10 mg once daily

• Ruxolitinib, an inhibitor of Janus kinase 1 (JAK1) and Janus kinase 2 (JAK2), can reduce the splenomegaly and the symptoms of weight loss, fatigue, and night sweats in patients with Janus kinase 2 (JAK2)-positive or Janus kinase 2 (JAK2)-negative primary myelofibrosis, post-essential thrombocythemia myelofibrosis, or post-polycythemia vera myelofibrosis.^[1][5]
• Ruxolitinib can also be integrated as pretransplantation treatment.^[6]
• Ruxolitinib preferred regimen: Oral: Initial dose (based on platelet count, titrate dose thereafter based on efficacy and safety):

• Platelets >200,000/mm3: 20 mg twice daily
• Platelets 100,000 to 200,000/mm3: 15 mg twice daily
• Platelets 50,000 to <100,000/mm3: 5 mg twice daily

• Momelotinib is a JAK inhibitor that is currently in clinical trials.
• Pacritinib is a JAK inhibitor that is currently in clinical trials.

JAK2 inhibitor therapy

• Ruxolitinib can provide temporary relief.^[1][7] This medication is FDA-approved for intermediate- and high-risk myelofibrosis.

Hydroxyurea

• Hydroxyurea can reduce the splenomegaly but may have a potential leukemogenic effect.
• Preferred regimen: Starting dose of 500 mg/day and then subsequently adjusted to the individual efficacy.

Chemotherapy

• Drugs like thalidomide, lenalidomide, or cladribine may also reduce the spleen size, and relieve the pain symptoms.

Radiation therapy

• Radiation may be used to reduce the size of the spleen, when splenectomy is contraindicated.

Splenectomy

• Splenectomy can also be performed.

Interferon therapy

• Peg-interferon alpha 2a and peg-interferon alpha 2b have been shown to reduce spleen size, improve constitutional symptoms, and improve blood counts.

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