The move marks the first FDA-approved treatment for the condition in nearly three decades.
Last month the FDA approved the ropeginterferon alfa-2b-njft injection (Besremi, PharmaEssentia) for use in adults with essential thrombocythemia.
Ropeginterferon alfa-2b-nift is an N-terminal monopegylated covalent conjugate of proline interferon alfa-2b. It binds to the interferon alfa receptor (INFAR) and activates a downstream signalling cascade involving Janus and tyrosine kinases.
Essential thrombocythemia is a rare chronic blood cancer where there is an overproduction of platelets, leading to an increased risk of blood clots and bleeding.
The safety and efficacy of the ropeginterferon injection was proven in the SURPASS ET study, published in The Lancet Haematology in 2025.
One hundred and seventy-four patients aged ≥18 years with high-risk, hydroxyurea-intolerant or hydroxyurea-resistant essential thrombocythemia and white blood cell (WBC) count >10 × 109 cells/L were recruited as part of this open-label, randomised, phase 3 trial undertaken at 55 sites across eight countries including China, Japan, the US, and Canada.
Ninety-one of the 174 patients received ropeginterferon and 83 received anagrelide. Treatment was administered every two weeks, with doses increasing at week two and then again at week four.
A greater proportion of patients in the ropeginterferon group displayed durable responses as per the modified European LeukemiaNet criteria after nine and 12 months compared to the anagrelide group (43% versus 6%).
Serious adverse events occurred in 1% of patients who received ropeginterferon and 8% of patients who received anagrelide.
The most common serious adverse vent was cerebral infarction, which occurred in 5% of patients in the anagrelide group and in 0% of patients in the ropeginterferon group.
“For nearly 30 years, people living with ET and the physicians treating them have had limited treatment innovation,” said Ruben Mesa, MD, principal investigator of the SURPASS ET trial, in a statement following the FDA’s announcement.
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“In my experience, patients need treatment options that not only control blood counts but also address the underlying disease. The approval of Berseem 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.”
The FDA advised that the recommended starting dose for ropeginterferon was 250mcg by subcutaneous injection.
“The dosage should be increased to 350mcg at two weeks and then to the maintenance dosage of 500mcg at four weeks. The maintenance dose should be given every two weeks unless a dose modification is required due to tolerability,” the FDA in its announcement.
Last year the Myeloproliferative Neoplasms Alliance Australia announced that ropeginterferon was not available in Australia, but that another form of pegylated interferon was.
Ropeginterferon has also received regulatory approval for the treatment of essential thrombocythemia in Japan and Taiwan. PharmaEssentia did not respond to Oncology Republic’s queries about plans to submit regulatory approvals for ropeginterferon in Australia.
