The Food and Drug Administration (FDA) has approved Besremi® (ropeginterferon alfa-2b-njft), an interferon alfa-2b, for the treatment of adults with polycythemia vera.

Besremi is a monopegylated, long-acting interferon, which exhibits its cellular effects in polycythemia vera in the bone marrow by binding to a transmembrane receptor termed interferon alfa receptor. This initiated a downstream signaling cascade through the activation of kinases, specifically Janus kinase 1 and tyrosine kinase 2 and activator of transcription proteins.

The approval was based on data from the open-label, prospective, multicenter, phase 1/2 PEGINVERA study ( Identifier: NCT01193699), which evaluated the efficacy and safety of Besremi in 51 adults with polycythemia vera for 7.5 years.

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Findings showed that 61% (n=31/51; 95% CI, 46-74) of patients treated with Besremi achieved  complete hematological response (defined as hematocrit greater than 45% and no phlebotomy in the preceding 2 months, platelets 400 x 109/L or greater, leukocytes 10 x 109/L or greater, and normal spleen size). The median duration of response was 14.3 months (95% CI, 5.5-30.1).

As for safety, the most common adverse reactions (greater than 40%) were influenza-like illness, arthralgia, fatigue, pruritus, nasopharyngitis, and musculoskeletal pain. Besremi carries a Boxed Warning associated with the risk of serious disorders, including aggravation of fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders.

Besremi is supplied as a 500mcg/mL single-dose prefilled syringe and is expected to be available by the first week of December 2021. The product is administered subcutaneously once every 2 weeks.


  1. US FDA approves Besremi® (ropeginterferon alfa-2b-njft) as the only interferon for adults with polycythemia vera. News release. PharmaEssentia Corporation. Accessed November 15, 2021.
  2. FDA approves treatment for rare blood disease. News release. US Food and Drug Administration. Accessed November 15, 2021.
  3. Besremi. Package Insert. PharmaEssentia Corporation; 2021. Accessed November 15, 2021.

This article originally appeared on MPR