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Ruxolitnib (Jakafi) Wins FDA Nod for Treatment of Blood Cancer Patients
The FDA has approved ruxolitinib (Jakafi, Incyte Corporation) for the treatment of patients with polycythemia vera (PV) who have had an inadequate response to or are intolerant of hydroxyurea.
Ruxolitinib is the first drug approved by the FDA for PV, a rare and progressive blood cancer. It is also the only FDA-approved drug for the treatment of intermediate- or high-risk myelofibrosis, a closely related blood cancer.
PV is a myeloproliferative neoplasm that is typically characterized by elevated hematocrit (the volume percentage of red blood cells in whole blood), which can lead to thickening of the blood and an increased risk of blood clots, as well as elevated white blood cell and platelet counts. PV may occur at any age but often presents later in life, with a median age at diagnosis of 60 years.
Approximately 100,000 individuals in the U.S. have PV. Current standard treatment for the disorder is phlebotomy plus aspirin. When phlebotomy can no longer control PV, chemotherapy, such as hydroxyurea or interferon, is used. Approximately 25% of patients with PV are considered uncontrolled because they have shown an inadequate response to or are intolerant of hydroxyurea, the most commonly used chemotherapeutic agent for the disorder.
Patients with PV who fail to consistently maintain appropriate blood-count levels, including appropriate hematocrit levels, have an approximately four times higher risk of experiencing major thrombosis or cardiovascular death. Patients with PV can also develop splenomegaly and a significant symptom burden, which may be attributed to thickening of the blood and to a lack of oxygen to parts of the body. These symptoms commonly include fatigue, itching, night sweats, bone pain, fever, and weight loss.
Ruxolitinib is a Janus kinase 1 (JAK1) and JAK2 inhibitor that targets overactive JAK pathway signalling, which plays a critical role in the development of both PV and myelofibrosis.
The approval of ruxolitinib for the treatment of patients with PV who have shown an inadequate response to or are intolerant of hydroxyurea was based on data from the pivotal phase III RESPONSE trial. In that study, patients treated with ruxolitinib demonstrated superior hematocrit control and reductions in spleen volume compared with best available therapy. In addition, a greater proportion of patients in the ruxolitinib arm achieved complete hematologic remission (defined as achieving hematocrit control, and lowering platelet and white blood cell counts).
The most common hematologic adverse events (AEs) were thrombocytopenia and anemia. The most common non-hematologic AEs included headache, abdominal pain, diarrhea, dizziness, fatigue, pruritus, dyspnea, and muscle spasms.
Source: Incyte Corporation; December 4, 2014.