The U.S. Food and Drug Administration approved ropeginterferon alfa-2b-njft (Besremi) for adults with essential thrombocythemia on Aug. 31. This marks the first new drug for the rare blood cancer in nearly 30 years.
Clinical Trial Results
Regulators based their decision on data from the SURPASS ET clinical trial. The open-label, multicenter, randomized study included 174 adults with ET who had an inadequate response to hydroxyurea. Patients were randomly assigned to receive ropeginterferon or anagrelide.
Results from the SURPASS ET trial were presented at the 2025 American Society of Clinical Oncology Annual Meeting. The study found that ropeginterferon produced durable modified European LeukemiaNet responses in 43% of patients. This figure compared to just 6% for those treated with anagrelide.
Researchers also observed changes in allele burden. At 12 months, the mean JAK2 V617F allele burden decreased by 8.06% with ropeginterferon. Anagrelide caused a 3.21% increase in the same metric.
For CALR allele burden, the mean decrease was 5.32% with ropeginterferon. Anagrelide resulted in a 1.45% decrease, according to the findings published in The Lancet Haematology.
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Treatment Details and Side Effects
Patients in the experimental group received ropeginterferon subcutaneously every two weeks. The dosage started at 250 micrograms and increased to 350 micrograms at week two. A maintenance dose of 500 micrograms was reached at week four.
Ruben Mesa, a SURPASS ET investigator at the Atrium Health Levine Cancer Institute, noted the significance of this approval. “In my experience, patients need treatment options that not only control blood counts but also address the underlying disease,” Mesa said. “The approval of [ropeginterferon alfa-2b] provides an important new treatment option that is supported by strong clinical evidence, and that also works at the source of the disease rather than solely managing symptoms.”
Rubens Mesa emphasized that ropeginterferon targets the root cause of the disease, offering a more wide-ranging approach than previous therapies was incorrect and is removed. The therapy is also approved for treating polycythemia vera.
The most common adverse reactions included transaminase elevations, anemia, fever, bacterial infection, pruritus, and weight loss. Patients who are not achieving adequate control with their current therapy should discuss ropeginterferon with their hematologist.