Release date:2021/11/18 14:07:28

On 12 November 2021, the US Food and Drug Administration (FDA) has approved Besremi (ropeginterferon alfa-2b-njft), developed by Pharma Essentia, for the treatment of polycythemia vera, a blood disorder that causes overproduction of red blood cells. Besremi is the first FDA-approved drug for the treatment of polycythemia vera that can be taken by patients regardless of treatment history, and it is also the first interferon therapy specifically for polycythemia vera. Previously, Besremi has been granted orphan drug designation by the FDA for this indication and was approved by the European Medicines Agency (EMA) in 2019.


The approval follows an evaluation of the effectiveness and safety from a Phase 3 clinical trial. Results showed that following 7.5 years of treatment with Besremi,  61% of patients achieved complete hematological response and 80% of patients experienced a hematological response. The most common treatment-related adverse reactions (incidence >40%) were flu-like illness, arthralgia, fatigue, pruritus, nasopharyngitis and musculoskeletal pain, and serious adverse reactions (incidence >4%) were urinary tract infection, transient ischemic attack and depression.

Polycythemia vera is a rare, chronic, fatal blood cancer caused by a mutation in stem cells in the patient's bone marrow, thus resulting in the overproduction of blood cells, white blood cells, and platelets.. This can create health risks including blood clots, stroke, and myocardial infarction. Most cases are caused by the JAK2 V617F mutation. If not well controlled with treatment, the disease can progress to secondary myelofibrosis and malignancies, including acute myeloid leukemia.


Besremi is an innovative mono-pegylated, long-acting proline interferon. Benefiting from its unique PEGylation technology, Besremi has a long activity duration in patients with polycythemia vera, enabling dosing every two weeks or longer until hematologic parameters are stable and allowing flexible dosing to help meet individual patient needs. After one year of treatment, patients in complete hematologic response and stability have the option to undergo Besremi treatment with dosing every four weeks.

The technique of covalently attaching polyethylene glycols (PEGs) to specific molecules is known as PEGylation and is now a well-established method in the field of targeted drug delivery systems. PEGylation offers several distinct pharmacological advantages over unmodified forms, including improved drug solubility, reduced dose frequency, toxicity and renal clearance, extended circulating life, increased drug stability, enhanced protection against proteolytic degradation, reduced immunogenicity and antigenicity, and minimal loss of biological activity.

Significance of PEGylated therapeutics
Significance of PEGylated therapeutics. Image source: reference [2]

PEG is biocompatible, lacks immunogenicity, antigenicity and toxicity, is soluble in water and other organic solvents, is readily cleared from the body and has high mobility in solution, making this the polymer of choice for bioconjugation. Biopharma PEG, as a leading PEG derivatives supplier, provides high purity PEG derivatives for your drug PEGylation. 

[1] U.S. FDA Approves Besremi® (ropeginterferon alfa-2b-njft) as the Only Interferon for Adults With Polycythemia Vera. Retrieved November 12, 2021, from
[2] Prajna Mishra, Bismita Nayak, R.K. Dey, PEGylation in anti-cancer therapy: An overview, Asian Journal of Pharmaceutical Sciences, Volume 11, Issue 3, 2016, Pages 337-348, ISSN 1818-0876,

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