FDA approved Besremi (interferon alfa-2b) for Polycythemia VeraFDA approved new treatment for rare blood disorder polycythemia vera

FDA From the archive Source published November 12, 2021 Summary added July 1, 2026 DOI ↗ Editorial oversight: Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease

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Key Takeaway

Consider Besremi as a subcutaneous interferon alfa-2b option for adults with polycythemia vera, with dose titration and monitoring for liver and hematologic toxicities.

The FDA has approved Besremi (interferon alfa-2b) for the treatment of adults with polycythemia vera, a chronic myeloproliferative neoplasm characterized by overproduction of red blood cells. Besremi is a recombinant interferon alfa-2b product administered subcutaneously every two weeks, with dose titration based on hematologic parameters. The approval offers an alternative to current therapies such as hydroxyurea and phlebotomy. The recommended starting dose differs for patients not on hydroxyurea (100 mcg) versus those transitioning from hydroxyurea (50 mcg). Dosing can be increased every two weeks up to 500 mcg until hematocrit is less than 45%, platelets less than 400 x 10^9/L, and leukocytes less than 10 x 10^9/L. After one year of stable dosing, the interval may be extended to every four weeks. Clinicians should monitor complete blood counts regularly and manage toxicities such as liver enzyme elevations and cytopenias with dose modifications.

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

Mechanism of Action

Interferon alfa-2b is a type I interferon that exerts antiproliferative and immunomodulatory effects. In polycythemia vera, it suppresses the proliferation of erythroid progenitors and reduces the JAK2 V617F allele burden, though the exact mechanism in this indication is not fully elucidated.

Indication & Patient Population

Besremi is indicated for the treatment of adults with polycythemia vera.

Dosing & Administration

For patients not on hydroxyurea: starting dose 100 mcg subcutaneously every two weeks, increase by 50 mcg every two weeks (max 500 mcg) until hematocrit <45%, platelets <400 x 10^9/L, and leukocytes <10 x 10^9/L. For patients transitioning from hydroxyurea: start Besremi 50 mcg every two weeks with hydroxyurea, taper hydroxyurea by 20-40% every two weeks during weeks 3-12, increase Besremi by 50 mcg every two weeks (max 500 mcg) until hematologic stability, discontinue hydroxyurea by week 13. After at least 1 year of stable dosing, interval may be extended to every 4 weeks. Dose modifications are required for liver enzyme elevations, cytopenias, and depression. See label for detailed tables.

Key Clinical Trial Data

Trial data not available in label.

Warnings & Contraindications

Contraindications: None listed in label. Warnings include liver enzyme elevations, cytopenias, depression, and potential for hepatic decompensation. Dose modifications or interruption are recommended for these toxicities. Pregnancy testing is required in females of reproductive potential before starting treatment.

Place in Therapy

Besremi provides a new treatment option for adults with polycythemia vera, including those not on hydroxyurea and those transitioning from hydroxyurea. It offers a subcutaneous interferon-based therapy with a dosing schedule that may be extended after one year of stability. Monitoring of hematologic parameters and adverse reactions is essential.

The FDA has approved a new drug called Besremi (interferon alfa-2b) for adults with polycythemia vera. This is a rare blood disorder where the body makes too many red blood cells. It can raise the risk of blood clots and other problems.

Besremi is given as a shot under the skin every two weeks. The dose starts low and can be increased based on blood test results. After one year of stable dosing, the shots may be given every four weeks. The drug offers an alternative to current treatments like hydroxyurea or regular blood removal (phlebotomy).

This approval is for adults with polycythemia vera. It is not for other types of blood disorders. The most common side effects include flu-like symptoms, low blood cell counts, and liver enzyme changes. Doctors will monitor blood counts and adjust the dose if needed.

While this is a new option, it does not mean everyone should switch treatments. Patients should talk to their doctor about whether Besremi is right for them. Every person's situation is different, and treatment decisions should be made together with a healthcare provider.

What this means for you:

Besremi is a new FDA-approved option for polycythemia vera; talk to your doctor to see if it fits your care plan.

Study Details

Study typeFda approval

PublishedNov 2021

View Original Abstract ↓

1 INDICATIONS AND USAGE BESREMi is indicated for the treatment of adults with polycythemia vera. BESREMi is an interferon alfa-2b indicated for the treatment of adults with polycythemia vera ( 1 )

FDA approved Besremi (interferon alfa-2b) for Polycythemia VeraFDA approved new treatment for rare blood disorder polycythemia vera

Study Details

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Your Blood May Signal a Deadly Clotting Crisis Before It Strikes

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FDA approved Besremi (interferon alfa-2b) for Polycythemia VeraFDA approved new treatment for rare blood disorder polycythemia vera

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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