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New Treatment for Myelofibrosis
The FDA has approved Inrebic (fedratinib) capsules to treat adult patients with certain types of myelofibrosis, a rare chronic bone disorder in which scar tissue forms in the bone marrow and the production of the blood cells moves from the bone marrow to the spleen and liver, causing organ enlargement.
Inrebic is only the second drug approved for this disease. The approval for intermediate-2 or high-risk primary or secondary myelofibrosis was based on the results of a clinical trial in which 289 patients with myelofibrosis were randomized to receive two different doses (400 mg or 500 mg daily by mouth) of fedratinib or placebo. Of 96 patients treated with the recommended fedratinib 400 mg daily dose, 35 experienced a significant therapeutic effect (≥ 35% reduction from baseline in spleen volume at the end of cycle 6 [week 24]).
As a result of treatment with Inrebic, 36 patients experienced 50% or more reduction in myelofibrosis-related symptoms, such as night sweats, itching, abdominal discomfort, feeling full sooner than normal, pain under ribs on the left side, and bone or muscle pain.
The prescribing information for Inrebic includes a Boxed Warning to advise healthcare professionals and patients about the risk of serious and fatal encephalopathy, including Wernicke's, a neurologic emergency related to a deficiency in thiamine. Healthcare professionals are advised to assess thiamine levels in all patients prior to starting Inrebic, during treatment and as clinically indicated. If encephalopathy is suspected, Inrebic should be immediately discontinued.
Common side effects for patients taking Inrebic are diarrhea, nausea, vomiting, fatigue and muscle spasms. Healthcare professionals are cautioned that patients may experience severe anemia and thrombocytopenia. Patients should be monitored for gastrointestinal toxicity and for hepatic toxicity. The dose should be reduced or stopped if a patient develops severe diarrhea, nausea or vomiting. Treatment with anti-diarrhea medications may be recommended. Patients may develop high levels of amylase and lipase in their blood and should be managed by dose reduction or stopping the mediation. Inrebic must be dispensed with a patient Medication Guide that describes important information about the drug's uses and risks.
Source: fda.gov, Aug. 16, 2019