, according to an agency press release.
Besremi has a longer half-life than do other pegylated interferon-alfas, allowing for dosing every 2 weeks instead of weekly. If red blood cell counts remain normal for a year, patients have the option of switching to once-monthly dosing. As with similar products, Besremi is self-administered as a subcutaneous injection.
It’s the first interferon approved in the United States specifically for polycythemia vera. Besremi is also approved for upfront therapy, unlike FDA’s first approval for the condition, the oral JAK inhibitor ruxolitinib (Jakafi), which is indicated only after hydroxyurea failure.
Taiwan-based maker PharmaEssentia said in another press release that it will roll Besremi out to the U.S. market in the coming weeks.
“As we begin working closely with the community to integrate this important treatment into clinical practice, we also continue to expand our scientific efforts to unlock the full potential of our pioneering molecule,” said Ko-Chung Lin, PhD, the company’s CEO.
As for unlocking the full potential, Besremi is under investigation for other interferon indications, including myelofibrosis, leukemia, and chronic hepatitis.
The FDA’s approval was based on results in 51 adults treated for an average of 5 years; 31 (61%) had a complete hematologic response, defined as a hematocrit below 45% with no phlebotomy for at least 2 months, plus normal platelet and white cell counts, normal spleen size, and no blood clots.
“Noninferiority to hydroxyurea regarding haematological response and normal spleen size was not shown at 12 months. However, response to ropeginterferon alfa-2b continued to increase over time with improved responses compared with hydroxyurea at 36 months,” investigators noted in an earlier report (Lancet Haematol. 2020 Mar;7[3]:e196-e208).
Besremi carries the same boxed warning as those of peginterferon alfa-2b (Pegintron) and peginterferon alfa-2a (Pegasys), which notes the risk of life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders. Related contraindications include severe depression and other psychiatric problems; liver impairment; serious or untreated autoimmune disease, and immunosuppression following organ transplant.
Influenza-like illness, arthralgia, fatigue, pruritis, nasopharyngitis, and musculoskeletal pain were the most common adverse events in studies, occurring in over 40% of subjects. Urinary tract infections, transient ischemic attacks, and depression were the most frequent serious complications, occurring in over 4%.
Labeling also notes the risk for fetal harm and the need for effective contraception.
Besremi was approved in Europe in 2019 and is approved in Taiwan and South Korea.
Polycythemia vera is a rare condition thought to be caused by acquired bone marrow stem cell mutations that trigger an overproduction of red blood cells. Patients are at increased risk of blood clots and emboli, and subsequent heart attacks, strokes, and other problems. There’s also the risk of transformation to secondary myelofibrosis or leukemia.