The U.S. Food and Drug Administration (FDA) approved a new use for ruxolitinib (Jakafi) to treat patients with polycythemia vera, a chronic type of bone marrow disease. Ruxolitinib, a JAK inhibitor, is the first drug approved by the FDA for this condition.
Polycythemia vera occurs when too many red blood cells are made in the bone marrow. Patients may also experience an increase in white blood cells and platelets. An overabundance of blood cells can cause the spleen to swell, bleeding problems, and blood clots in the veins near the skin surface. In addition, it puts patients at increased risk of stroke or heart attack.
Ruxolitinib’s new use is intended to treat polycythemia vera patients who have an inadequate response to or cannot tolerate hydroxyurea, which is often prescribed to reduce the number of red blood cells and platelets in the blood. The drug’s approval to treat polycythemia vera will help decrease the occurrence splenomegaly and the need for phlebotomy.
Ruxolitinib’s safety and effectiveness to treat polycythemia vera were evaluated in a clinical study involving 222 participants who had the disease for at least 24 weeks, had an inadequate response to or could not tolerate hydroxyurea, had undergone a phlebotomy procedure and exhibited an enlarged spleen. Participants were randomly assigned to receive ruxolitinib or the best available therapy, as determined by the investigator on a participant-by-participant basis.
The study was designed to measure the reduced need for phlebotomy beginning at week 8 and continuing through week 32, in addition to at least a 35% reduction in spleen volume at week 32. Results showed 21% of ruxolitinib-treated participants experienced a reduction in the need for a phlebotomy and a reduction in spleen volume, compared to 1% of participants who received best available therapy.
The most common side effects associated with use of ruxolitinib in participants with polycythemia vera were anemia and thrombocytopenia. The most common non-hematologic side effects were dizziness, constipation, and shingles.
The FDA reviewed ruxolitinib use for polycythemia vera under the agency’s priority review program because, at the time the application was submitted, the drug demonstrated the potential to be a significant improvement in safety or effectiveness over available therapy in the treatment of a serious condition.
In 2011, the FDA approved ruxolitinib for treatment of patients with intermediate- or high-risk myelofibrosis, including primary myelofibrosis, post–polycythemia vera myelofibrosis and post–essential thrombocythemia myelofibrosis. ■