Another day, another orphan drug is approved. Following yesterday’s approval of Blincyto
to treat a rare form of acute lymphoblastic leukemia, the U.S. Food and Drug Administration ( FDA) announced the approval today of Jakafi (ruxolitinib) to treat patients with polycythemia vera, a chronic type of bone marrow disease.
Jakafi is the first drug approved for this polycythemia vera although the condition in often controlled by phlebotomy and /or off-label use of hydroxyurea. Jakafi is intended for those patients who are unresponsive to, or cannot tolerate hydroxyurea.
In a press release by Incyte
, Srdan Verstovsek, M.D., Ph.D., Professor, Department of Leukemia, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center said:
“The approval of Jakafi represents an important advance for patients with uncontrolled PV. For the first time we are able to provide these patients a treatment that has been shown to provide effective and consistent control of their blood counts and reduce spleen volume.”
Robert Rosen, Founder and Chairman of the MPN Research Foundation added:
“The FDA approval of this drug is good news for our community and provides a new treatment option for those patients who do not respond to other therapies. This news confirms the ongoing importance of continued research, and the critical role that the MPN Research Foundation plays in improving the lives of patients.”
Polycythemia vera a myeloproliferative neoplasm (MPN) and is typically characterized by elevated hematocrit,which can lead to a thickening of the blood and an increased risk of blood clots, as well as an elevated white blood cell and platelet count.
Approximately 100,000 patients in the U.S. have polycythemia vera. The current standard of care is phlebotomy plus aspirin. When phlebotomies can no longer control the condition, chemotherapy such as hydroxyurea, or interferon, is utilized. However, approximately one-quarter of patients (~25,000) are considered uncontrolled because they have an inadequate response to or are intolerant to hydroxurea. Jakafi is intended to treat those patients who have an inadequate response to, or cannot tolerate, hydroxyurea.
In an announcement from the FDA, Richard Pazdur, M.D., director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research said
“The approval of Jakafi for polycythemia vera underscores the importance of developing drugs matched to our increasing knowledge of the mechanisms of diseases.”
“The trial used to evaluate Jakafi confirmed clinically meaningful reductions in spleen size and the need for phlebotomies to control the disease.”
Jakafi’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 Jakafi 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 35% reduction in spleen volume at Week 32. Results showed 21% of Jakafi-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 Jakafi in participants with polycythemia vera 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.
Jakafi is also approved for the treatment of intermediate or high-risk myelofibrosis, a closely related blood cancer. Jakafi is a JAK1 and JAK2 inhibitor that targets overactive JAK pathway signaling, which plays a critical role in the development of both myelofibrosis and polycythemia vera.
Jakafi is marketed by Incyte Corp.