Patients Taking Ruxolitinib for Myelofibrosis


ruxolitinibRuxolitinib, CAS number 941678-49-5, is a kinase inhibitor and used to treat myelofibrosis. The condition of myelofibrosis is one that involves the bone marrow being replaced by scar tissue, therefore causing a decreased blood cell production in patients. Ruxolitinib is effective at blocking the enzymes, janus-associated kinase, or JAK 1 and 2, which causes scar tissue to form in the bone marrow. Approved by the FDA on November 16, 2011, ruxolitinib is crucial for aiding patients by regulating both their blood and immunologic functioning. Myelofibrosis is a progressive disease, leading to anemia and thrombocytopenia, with scarred bone marrow tissue accumulating in organs such as the spleen and the liver. The approval of this novel kinase inhibitor has the potential to alter the landscape of treatment for this rare disease.

Clinical trials of ruxolitinib for myelofibrosis were deemed successful. Two trials of 538 patients with myelofibrosis and enlarged spleens took place, with patients enrolled who showed resistance to available treatment or were ineligible for allogeneic bone marrow transplantation. Clinical trial participants received ruxolitinib, a placebo, or the best available therapy, which consisted of hydroxyurea or glucocorticoids. Patients who received ruxolitinib experienced more than a 35 percent reduction in spleen size, when compared with patients who received a placebo or the best available therapy. In addition to this encouraging news, patients who received ruxolitinib gleaned a fifty percent reduction in their myelofibrosis-related symptoms. Patients who received the placebo unfortunately experienced not only a worsening of their symptoms, but also an increase in their spleen size.

Key steps of the JAK-STAT pathway

Key steps of the JAK-STAT pathway

Another trial, a phase III randomized study deemed COMFORT, or Controlled Myelofibrosis Study with Oral JAK Inhibitor Treatment, confirmed previous study results revealing ruxolitinib to be a superior treatment when compared with a placebo for treating patients with myelofibrosis. This study was presented by Dr. Srdan Verstovsek, of the University of Texas M. D. Anderson Cancer Center. A second study, the COMFORT-II trial was presented by Alessandro Maria Vannucchi, MD, of the University of Florence, Italy. The COMFORT-II trial compared ruxolitinib  to the best available treatment, such as glucocorticoids. Results showed ruxolitinib to be a formidable treatment, with the vast majority of patients who received ruxolitinib experiencing a sizable reduction in spleen size. Trial participants who were dosed with ruxolitinib also experienced a great reduction in burdensome symptoms, such as abdominal discomfort and bone and muscle pain, as well as a better quality of life. LGM Pharma provides ruxolitinib for research and development purposes.

Adverse side effects, which were uncommon, included thrombocytopenia, dizziness, headache, bruising and anemia. Starting doses of ruxolitinib are 20 milligrams, orally, given twice a day for patients with a platelet count less than 200 X 109/L. Patients with a platelet count between 100 and 200 X 109/L should receive 15 milligrams twice daily. Approved for use in patients with intermediate or high-risk myelofibrosis, which represents 80% to 90% of all patients with myelofibrosis, ruxolitinib is a promising treatment which is paving the way for future therapies to combat this rare disease.

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