The U.S. Food and Drug Administration (FDA) approved a new use for the drug Jakafi (ruxolitinib) to treat patients for polycythemia vera, a chronic bone marrow disease. This is the first drug approved by the FDA for this condition.
Polycythemia vera occurs when too many red blood cells are created in the bone marrow; patients suffering from the condition could also experience an increase in white blood cells and platelets. These effects can cause the spleen to swell as well as bleeding problems and blood clots.
The drug could be used to treat patients who cannot tolerate hydroxyurea, which lowers the number of red blood cells and platelets in the blood. Jakafi works by inhibiting enzymes called Janus Associated Kinase (JAK) 1 and 2 that regulate blood and immunological function and could help decrease the occurrences of enlarged spleens.
"The approval of Jakafi for polycythemia vera underscores the importance of developing drugs matched to our increasing knowledge of the mechanisms of diseases," said Richard Pazdur, M.D., director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research. "The trial used to evaluate Jakafi confirmed clinically meaningful reductions in spleen size and the need for phlebotomies to control the disease."
The drug was evaluated in a clinical study involving 222 participants who had the disease for at least 24 weeks and did not respond well to hydroxyurea, had undergone a phlebotomy procedure, and exhibited an enlarged spleen. The participants were randomly assigned to receive either Jakafi or the best available therapy.
Results of the study showed 21 percent of Jakafi-treated participants exhibited a reduction in the need for a phlebotomy as well as a reduction in spleen volume, compared to 1 percent of participants who received the other therapy.
The most common side effects of the drug were "low red blood cell counts (anemia) and low blood platelet counts (thrombocytopenia). The most common non-blood related side effects were dizziness, constipation and shingles," the FDA reported.
