Medication for Myeloproliferative Disorders

Because this disorder is associated with the production of too many red blood cells, the first treatment doctors use to manage polycythemia vera is phlebotomy, or the removal of blood from the body. Sometimes, that approach does not control red blood cell levels and doctors prescribe medications to slow blood cell production. Also, some people may prefer medications to phlebotomy.

Hydroxyurea

Hydroxyurea is a medication that decreases the levels of blood cells produced by the bone marrow. NYU Langone doctors carefully tailor the dosage of hydroxyurea to reach a target level of red blood cells in people with polycythemia vera. The percentage of red blood cells found in the blood, called hematocrit, should be 45 percent in men and 42 percent in women to avoid complications such as clotting.

Side effects of hydroxyurea may include nausea, vomiting, diarrhea, leg ulcers, and loss of appetite, which can often be managed by changing the dosage or by prescribing other medications.

Janus Kinase 2 Inhibitors

Doctors may recommend a Janus kinase 2 (JAK2) inhibitor called ruxolitinib for people with polycythemia vera that is progressing to secondary myelofibrosis or is not controlled by hydroxyurea. This happens when the increased production of blood cells damages the bone marrow, causing fibrous tissue and scarring. Secondary myelofibrosis may also lead to a painfully enlarged spleen. It can also result in lowered blood cell levels, leading to anemia, and low platelet levels, requiring frequent blood transfusions.

JAK2 inhibitors may also be recommended for people who cannot tolerate hydroxyurea or whose blood cell levels were not controlled by hydroxyurea.

Ruxolitinib interferes with the function of the JAK2 protein and a related protein called JAK1. As a result, the production of red blood cells slows, helping to normalize these levels and reducing symptoms, such as an enlarged spleen.

JAK2 inhibitors may cause bloating, dizziness, or headache, which may go away over time. They can also cause changes in blood cell levels, leading to fever, increased risk of infection, bleeding, or anemia. Your doctor can adjust the dosage to help manage these side effects.

Low-Dose Aspirin

Because an overproduction of red blood cells can cause the blood to thicken and clot, doctors recommend daily low-dose aspirin, a well-tolerated medication that can thin the blood by preventing platelets from clumping.

Some of the medications used to manage polycythemia vera are also used to treat people with essential thrombocythemia.

Hydroxyurea

Hydroxyurea suppresses the production of blood cells in the bone marrow and can lower platelet levels in people with essential thrombocythemia. NYU Langone doctors aim to reduce platelet levels to 400,000 per microliter of blood or lower.

The dosage of hydroxyurea used to manage essential thrombocythemia may cause open sores called ulcers on the legs, or it can lower red blood cell levels too much, causing anemia. To avoid these side effects, doctors adjust the dosage or prescribe a different medication.

Anagrelide

Anagrelide helps to slow the production of platelets by interfering with their maturation process in the bone marrow.

Usually better tolerated than hydroxyurea, anagrelide can cause headache, dizziness, and nausea. Also, it may not be as effective as hydroxyurea in reducing complications, such as blood clots, bleeding, and myelofibrosis. For these reasons, anagrelide is generally used when hydroxyurea does not work.

Doctors can adjust the dosage or prescribe other medications to help alleviate the side effects of anagrelide.

Low-Dose Aspirin

Doctors also recommend that people with essential thrombocythemia take daily low-dose aspirin to thin the blood, which can help prevent blood clots caused by high platelet levels. Low-dose aspirin is typically well tolerated.

Clinical Trials

If people with essential thrombocythemia cannot tolerate the medications typically used to manage the condition, they may be eligible for a clinical trial. Researchers are studying three injections a week of a medication called interferon, which is made of naturally occurring proteins, to help reduce platelet production in the bone marrow.

Interferon may cause flu-like symptoms such as fever, chills, and headache, which usually subside.

Your doctor can discuss whether a clinical trial is right for you.

NYU Langone doctors often recommend a stem cell transplant for people with primary myelofibrosis, because the condition can permanently scar the bone marrow. However, if you are not healthy enough to have this procedure, doctors prescribe medication.

JAK2 Inhibitors

Doctors may prescribe the JAK2 inhibitor ruxolitinib to people who aren’t eligible for stem cell transplantation. The JAK2 gene mutation can contribute to anemia, in which a person has low levels of healthy red blood cells. It’s also associated with abnormal levels of platelets and white blood cells and the formation of scar tissue in the bone marrow.

Ruxolitinib interferes with the function of JAK2 and a related protein called JAK1. This helps normalize blood cell levels and reduce symptoms, such as an enlarged spleen.

New JAK2 inhibitors for primary myelofibrosis are available through clinical trials. Your doctor can discuss whether a clinical trial is right for you.