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The Food and Drug Administration has approved a new use for Jakafi (ruxolitinib)-for the treatment of patients with polycythemia vera. The new use is intended to treat patients who have inadequate response to or cannot tolerate hydroxyurea, another drug prescribed to treat the chronic bone marrow disease.

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The drug, marketed by Incyte Corp., works by inhibiting the enzymes Janus Associated Kinase (JAK) 1 and 2, which are involved in regulating blood and immunological functioning.


"The approval of Jakafi for polycythemia vera underscores the importance of developing drugs matched to our increasing knowledge of the mechanisms of diseases," Richard Pazdur, MD, Director of the FDA's Office of Hematology and Oncology Products, said in a news release.


"The trial used to evaluate Jakafi confirmed clinically meaningful reductions in spleen size and the need for phlebotomies to control the disease."


The drug's approval to treat polycythemia vera is intended to help decrease the occurrence of splenomegaly and the need for phlebotomy.


Jakafi's safety and effectiveness for this indication were evaluated in a clinical trial of 222 patients with polycythemia vera who had had the disease for at least 24 weeks and who had an inadequate response to or could not tolerate hydroxyurea, had undergone a phlebotomy procedure, and had exhibited an enlarged spleen.


The study was designed to measure the reduced need for phlebotomy and reduction in spleen volume. Patients received either Jakafi or best available therapy, as determined by the investigator.


The data showed that 21 percent of patients treated with Jakafi experienced a reduction in the need for a phlebotomy and a reduction in spleen volume, compared with one percent of patients who received best available therapy.


The most common side effects reported for the patients who received Jakafi were anemia and thrombocytopenia. The most common non-blood related side effects were dizziness, constipation, and shingles.


The FDA reviewed Jakafi's 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. Priority review provides an expedited review of a drug's application.


Jakafi also received Orphan Product designation because it is intended to treat a rare disease.


Jakafi had previously received FDA approval in 2011 for the treatment of patients with immediate or high-risk myelofibrosis, including primary myelofibrosis, post-polycythemia vera myelofibrosis, and post-essential thrombocythemia myelofibrosis.