FDA approved Inrebic (fedratinib) for Intermediate-2 or High-Risk MyelofibrosisFDA approved new pill Inrebic for rare bone marrow cancer.

FDA From the archive Source published August 16, 2019 Summary added July 24, 2026 DOI ↗ Editorial oversight: Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease

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Key Takeaway

Consider thiamine prophylaxis and monitoring in all patients starting Inrebic for myelofibrosis.

The FDA has approved Inrebic (fedratinib), a kinase inhibitor, for the treatment of adult patients with intermediate-2 or high-risk primary or secondary myelofibrosis (post-polycythemia vera or post-essential thrombocythemia). The approval provides a new oral option for patients with this myeloproliferative neoplasm. The recommended dosage is 400 mg taken orally once daily with or without food for patients with a baseline platelet count of at least 50 × 10^9/L. A notable safety requirement is that all patients must receive daily thiamine (vitamin B1) prophylaxis to reduce the risk of Wernicke's encephalopathy, a serious neurological condition. Dose reductions are required for patients taking strong CYP3A4 inhibitors or those with severe renal impairment. The label includes specific instructions for dose modifications in response to hematologic and nonhematologic adverse reactions.

＋ Clinical Details (Mechanism · Dosing · Trial Data · Warnings)

Mechanism of Action

Fedratinib is a kinase inhibitor that inhibits Janus Associated Kinase 2 (JAK2) and FMS-like tyrosine kinase 3 (FLT3). It also inhibits other kinases including RET, AXL, and CSF1R. The inhibition of JAK2 is thought to contribute to its therapeutic effect in myelofibrosis.

Indication & Patient Population

Inrebic is indicated for the treatment of adult patients with intermediate-2 or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis (MF).

Dosing & Administration

The recommended dosage is 400 mg orally once daily with or without food for patients with a baseline platelet count of ≥50 × 10^9/L. For patients who have difficulty swallowing capsules whole or those with a nasogastric tube, the capsule contents may be dispersed in Ensure Plus. Dose reduction to 200 mg once daily is recommended for patients taking strong CYP3A4 inhibitors or with severe renal impairment (CrCl 15-29 mL/min). All patients should receive prophylaxis with thiamine 100 mg orally daily. Baseline thiamine levels should be assessed prior to initiation.

Key Clinical Trial Data

Trial data not available in label.

Warnings & Contraindications

Wernicke's encephalopathy (WE) has been reported with Inrebic. Assess thiamine levels prior to starting treatment; do not start in patients with thiamine deficiency. All patients should receive daily thiamine prophylaxis. If WE is suspected, discontinue Inrebic and initiate parenteral thiamine. Other warnings include thrombocytopenia, anemia, neutropenia, gastrointestinal toxicity, hepatic toxicity, and renal toxicity. Monitor complete blood counts, hepatic panel, amylase, lipase, and renal function.

Place in Therapy

Inrebic is a JAK2 inhibitor approved for intermediate-2 or high-risk myelofibrosis. It may be used in patients who have not received prior JAK inhibitor therapy or after ruxolitinib. Patients on ruxolitinib must taper and discontinue before starting Inrebic. The requirement for thiamine prophylaxis and monitoring is unique to this agent.

The U.S. Food and Drug Administration has approved a new drug called Inrebic (fedratinib) for adults with a rare bone marrow cancer known as myelofibrosis. This condition causes scarring in the bone marrow, leading to anemia, fatigue, and an enlarged spleen. Inrebic is a pill taken once a day, and it is for patients with intermediate-2 or high-risk forms of the disease, including those whose myelofibrosis developed after other blood disorders.

This approval offers a new oral treatment option for patients who may have limited choices. Inrebic works by blocking certain enzymes that help cancer cells grow. Because the drug can cause a serious brain condition called Wernicke's encephalopathy, all patients must take vitamin B1 (thiamine) every day while on treatment. Doctors will also need to adjust the dose for patients taking certain other medicines or with kidney problems.

While this is encouraging news, it is important to remember that Inrebic is not a cure. Patients should talk to their doctor to see if this drug is right for them, and to understand the risks and benefits. As with any new treatment, ongoing monitoring and communication with your healthcare team are essential.

What this means for you:

Inrebic is a new daily pill for myelofibrosis, but patients must take vitamin B1 to prevent a serious brain side effect.

Study Details

Study typeFda approval

PublishedAug 2019

View Original Abstract ↓

1 INDICATIONS AND USAGE INREBIC ® is indicated for the treatment of adult patients with intermediate-2 or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis (MF). INREBIC is a kinase inhibitor indicated for the treatment of adult patients with intermediate-2 or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis (MF) ( 1 ).

FDA approved Inrebic (fedratinib) for Intermediate-2 or High-Risk MyelofibrosisFDA approved new pill Inrebic for rare bone marrow cancer.

Study Details

Biomarkers and clinical factors show statistical associations with sepsis-induced coagulopathy in 37,459 patients

Your Blood May Signal a Deadly Clotting Crisis Before It Strikes

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FDA approved Inrebic (fedratinib) for Intermediate-2 or High-Risk MyelofibrosisFDA approved new pill Inrebic for rare bone marrow cancer.

Study Details

Biomarkers and clinical factors show statistical associations with sepsis-induced coagulopathy in 37,459 patients

Your Blood May Signal a Deadly Clotting Crisis Before It Strikes

Clinical research that matters. Delivered to your inbox.

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