FDA approves new drug for rare blood disorder

The U.S. Food and Drug Administration (FDA) granted approval on August 31 to ropeginterferon alfa-2b-njft (Besremi), marking the first new treatment for essential thrombocythemia (ET) in nearly three decades. The decision expands options for adults with ET beyond established therapies such as hydroxyurea and anagrelide, according to regulatory documents.

Approval stemmed from the SURPASS ET phase 3 trial, which enrolled 174 adults whose ET had not responded adequately to hydroxyurea. Participants were divided into two groups: one receiving ropeginterferon, the other anagrelide. Dosing began at 250 micrograms every two weeks and increased to a maintenance level of 500 micrograms by week four.

After 12 months, ropeginterferon produced sustained responses in 43% of patients, compared to just 6% for anagrelide—a 36.5% absolute difference (95% confidence interval: 25.4%–47.7%). The drug also demonstrated greater reductions in disease markers: JAK2 V617F allele burden fell by 8.06% versus a 3.21% rise under anagrelide, while CALR allele burden dropped by 5.32% against a 1.45% decrease.

This FDA decision represents the first ET-specific approval since 1995. The drug’s design differs from prior options by targeting the disease mechanism rather than merely controlling symptoms, a point emphasized by Ruben Mesa, MD, a lead investigator at the Atrium Health Levine Cancer Institute. “In my experience, patients need treatment options that not only control blood counts but also address the underlying disease,” he said in an official release.

Common side effects with ropeginterferon include increased liver enzyme levels, anemia, fever, bacterial infections, skin irritation, and unintended weight loss. The medication is already licensed for polycythemia vera and is delivered via subcutaneous injection every two weeks.

PharmaEssentia, the drug’s manufacturer, highlighted its partnership with regulatory agencies, healthcare providers, and patient advocacy organizations to accelerate access. The approval aligns with ongoing efforts to develop new therapies for myeloproliferative neoplasms, a group of blood-related cancers.

Physicians advising patients on ropeginterferon should address practical considerations, including injection schedules, potential adverse reactions, and necessary monitoring protocols. While the approval introduces a new standard for ET management, its long-term effects on disease progression are still under investigation.