Primary Myelofibrosis Medication

Updated: Jan 30, 2017
  • Author: Asheesh Lal, MBBS, MD; Chief Editor: Emmanuel C Besa, MD  more...
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Medication

Medication Summary

Chemotherapeutics have mainly been used as cytoreductive therapy to control leukocytosis, thrombocytosis, or organomegaly. Hydroxyurea is the preferred agent, but other drugs (eg, interferon, cladribine) have also been used. Busulfan has been used, but it is not a preferred agent in view of the lesser toxicity of hydroxyurea. Ruxolitinib is indicated for myelofibrosis and is an effective agent to reduce splenomegaly. Patients with primary myelofibrosis are especially prone to developing myelotoxicity with these agents, which should therefore be used with caution.

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Antineoplastic Agents

Class Summary

Antineoplastic agents are predominantly used as cytoreductive therapy to control leukocytosis, thrombocytosis, and organomegaly. Patients with primary myelofibrosis are especially prone to developing myelotoxicity with these agents; therefore, use them with caution.

Hydroxyurea (Droxia, Hydrea)

Hydroxyurea is an inhibitor of deoxynucleotide synthesis. It is less leukemogenic than alkylating agents (busulfan) are. Hydroxyurea's myelosuppressive effects last a few days to a week and are easier to control than those associated with alkylating agents. It is lethal to cells in the S phase and is cell-cycle specific.

This agent is used mainly to control counts and alleviate constitutional symptoms or symptoms resulting from hepatic enlargement. It can be administered at higher doses in patients with extremely high WBC counts (>300,000/µL) and adjusted accordingly as WBC and platelet counts fall. Hydroxyurea can be administered as a single daily dose or divided into 2-3 doses at a higher dose range.

Busulfan (Myleran, Busulfex)

Hydroxyurea is an inhibitor of deoxynucleotide synthesis. It is less leukemogenic than alkylating agents (busulfan) are. Hydroxyurea's myelosuppressive effects last a few days to a week and are easier to control than those associated with alkylating agents. It is lethal to cells in the S phase and is cell-cycle specific.

This agent is used mainly to control counts and alleviate constitutional symptoms or symptoms resulting from hepatic enlargement. It can be administered at higher doses in patients with extremely high WBC counts (>300,000/µL) and adjusted accordingly as WBC and platelet counts fall. Hydroxyurea can be administered as a single daily dose or divided into 2-3 doses at a higher dose range.

Cladribine (Leustatin)

Cladribine is a synthetic antineoplastic agent for continuous intravenous (IV) infusion. The enzyme deoxycytidine kinase phosphorylates this compound into active 5'-triphosphate derivative, which then breaks DNA strands and inhibits DNA synthesis. Cladribine disrupts cell metabolism, causing death to resting and dividing cells.

Ruxolitinib (Jakafi)

JAK1/JAK2 kinase inhibitor indicated for treatment of patients with intermediate or high-risk myelofibrosis, including primary myelofibrosis, post-polycythemia vera myelofibrosis, and post-essential thrombocythemia myelofibrosis. Janus-associated kinases (JAKs) JAK1 and JAK2 mediate the signaling of a number of cytokines and growth factors that are important for hematopoiesis and immune function.

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Biological Response Modulators

Class Summary

Immunotherapy (biotherapy) currently used to treat patients with melanoma includes IFN and IL-2.

Interferon alfa-2b (Intron A)

This is a protein product manufactured by recombinant DNA technology. Its mechanism of antitumor activity is not clearly understood; however, direct antiproliferative effects against malignant cells and modulation of host immune response may play important roles. Its immunomodulatory effects include suppression of tumor cell proliferation, enhancement of macrophage phagocytic activity, and augmentation of lymphocyte cytotoxicity.

Peginterferon alfa-2b (Pegintron, Pegintron Redipen, Sylatron)

This is a protein product manufactured by recombinant DNA technology. Its mechanism of antitumor activity is not clearly understood, but direct antiproliferative effects against malignant cells and modulation of host immune response may play important roles.

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Androgens

Class Summary

Androgens improve symptoms of anemia and decrease transfusion requirements in patients with primary myelofibrosis.

Oxymetholone (Anadrol-50)

Oxymetholone is used to manage anemias resulting from deficient RBC production.

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Corticosteroids

Class Summary

Corticosteroids have anti-inflammatory properties and cause profound and varied metabolic effects. These agents modify the body's immune response to diverse stimuli.

Prednisone

Prednisone inhibits phagocytosis of platelets and may improve RBC survival.

Prednisolone (Orapred ODT, Prelone, Millipred)

Prednisolone decreases autoimmune reactions, possibly by suppressing key components of the immune system. This agent does not need to undergo hepatic metabolism.

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Immunomodulators

Class Summary

Agents in this category may have antiangiogenesis and immunomodulatory effects.

Thalidomide (Thalomid)

Thalidomide's mechanism of action not clearly known, but the drug is thought to work by immunomodulatory effects and antiangiogenesis.

Lenalidomide (Revlimid)

A thalidomide analogue, lenalidomide is an immunomodulatory agent with antiangiogenic and antineoplastic properties.

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