On February 8, 2021, global biopharmaceutical company Bristol Myers Squibb shared that the European Commission (EC) approved a Marketing Authorization Application (MAA) for Inrebic (fedratinib). For around 10 years, there have been few approved treatment options for patients with primary, post-polycythemia vera, or post-essential thrombocythemia myelofibrosis. However, Inrebic now offers a more accessible treatment option for these patients, for those who have either never been treated with a JAK inhibitor or whose prior ruxolitinib treatment was ineffective. In particular, Inrebic is designed for patients who have splenomegaly (an enlarged spleen) as a result of myelofibrosis.

Inrebic (fedratinib)

Inrebic (fedratinib) is an orally administered JAK2-selective inhibitor. The treatment works against wild type or mutationally activated JAK2 and FLT3. In many cases, mutated or abnormal JAK2 is linked to some of the health issues within myelofibrosis and polycythemia vera (PCV). The drug reduces the spread of cancerous cells and even prompts cancerous cell death. Inrebic has also been shown to reduce spleen enlargement and fibrosis (the formation of scar tissue). Although the recent authorization will allow the commercialization of the drug throughout Europe, the authorization does not cover the United Kingdom. In the United States, inrebic received Orphan Drug designation.

The recent EC decision hinged on data from the Phase 3 JAKARTA and Phase 2 JAKARTA2 clinical trials, which evaluated Inrebic against a placebo. Data showed that Inrebic significantly reduced splenomegaly, fibrosis, and other related symptoms as compared to a placebo. Throughout the entire drug development process, 608 patients received Inrebic doses. Of those, 8 patients experienced serious adverse reactions and one patient died.

Inrebic Safety Information

In patients treated with Inrebic, some developed Wernicke’s encephalopathy, a neurological emergency caused by Vitamin B1 deficiency. Symptoms include impaired coordination, confusion, involuntary eye movements, and impaired memory. If you are taking Inrebic and experience any of these symptoms, please call your doctor immediately.

Other potential side effects or adverse reactions include:

• Anemia (low red blood cell count)
• Thrombocytopenia (low platelet count)
• Nausea and vomiting
• Diarrhea
• Heightened ALT and AST levels

Primary Myelofibrosis

Primary myelofibrosis is a rare bone marrow disorder and leukemia caused by an idiopathic gene mutation. Generally, mutated JAK2, MPL, or CALR genes cause myelofibrosis. These mutations cause a hematopoietic stem cell to continually reproduce, crowding out healthy cells. Because it also causes fibrosis, or scarring, the bone marrow is unable to produce enough healthy blood cells also. Typically, myelofibrosis affects those after 50. An estimated 1 in every 500,000 people globally has primary myelofibrosis. While it affects males and females equally, the conditions is seen 2x more often in female children than male children. Symptoms include:

• Anemia (low red blood cell count)
• Pale skin
• Muscle weakness
• Spleen and liver enlargement
• Fatigue
• Shortness of breath
• Headaches
• Irritability
• Night sweats
• Excessive bruising and bleeding
• Frequent infections
• Gastrointestinal, lung, skin, liver, and spleen tumors
• Bone and joint pain

Learn more about myelofibrosis.

Polycythemia Vera (PCV)

A defective or mutated JAK2 gene causes polycythemia vera (PCV), a rare but slow-proliferating blood cancer. Normally, JAK2 plays a role in cell production regulation within bone marrow. When JAK2 is defective, red and white blood cells, and platelets, begin overproducing. This causes the thickening of blood, which can eventually lead to heart attack, stroke, or dangerous blood clots. Typically, patients with PCV do not experience symptoms until later stages. When symptoms appear, they include:

• Splenomegaly
• Abdominal pain and distention
• Double vision
• Muscle weakness
• Dizziness
• Joint pain
• Shortness of breath / difficulty breathing, which worsens when lying down
• Itchiness, which worsens after warm water exposure
• Headache
• Excessive sweating
• Unusual bleeding