FDA Approves Ropeginterferon Alfa-2b for Adult Patients With Essential Thrombocythemia

Clinical Summary:

• The FDA has approved ropeginterferon alfa-2b for adult patients with essential thrombocythemia, regardless of genotype or disease status, including newly diagnosed patients who are naïve to cytoreductive therapy. The approval was based on results from the phase 3 SURPASS ET trial. 
• Ropeginterferon alfa-2b demonstrated superior durable modified European Leukemia Net responses and durable hematologic control compared with anagrelide and reduced thromboembolic events over 12 months of treatment. 
• The approval introduces the first new FDA-approved treatment for essential thrombocythemia in nearly 3 decades and expands therapeutic options beyond cytoreduction, providing an interferon-based treatment designed to achieve durable hematologic and disease control across genotypes and disease settings. 

Based on results from the phase 3 SURPASS ET trial, the US Food and Drug Administration (FDA) has approved ropeginterferon alfa-2b (BESREMi; PharmEssentia) for adult patients with essential thrombocythemia, irrespective of genotype or prior disease management.

In this open-label, multicenter trial, 174 patients with high-risk essential thrombocythemia and leukocytosis who were intolerant to or resistant to hydroxyurea were randomized 1:1 to receive either ropeginterferon alfa-2b (n = 91) or anagrelide (n = 83). Ropeginterferon alfa-2b was administered subcutaneously every 2 weeks, beginning at 250 μg and titrated to 350 μg at week 2 and 500 μg from week 4 onward. Anagrelide was administered orally according to its FDA-approved prescribing information. The primary end point was durable response according to modified European Leukemia Net criteria at months 9 and 12.

At analysis, ropeginterferon alfa-2b achieved superior durable modified European Leukemia Net response rates compared with anagrelide and demonstrated durable hematologic control. Treatment with ropeginterferon alfa-2b was also associated with fewer thromboembolic events compared with anagrelide over 12 months of treatment. 

The prescribing information includes a boxed warning for the risk of serious disorders associated with interferon alfa products, including fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders. Patients should undergo periodic clinical and laboratory monitoring, with treatment withdrawal recommended for persistently severe or worsening manifestations. 

Ropeginterferon alfa-2b is contraindicated in patients with a history or presence of severe depression, suicidal ideation, or suicide attempt; hypersensitivity to interferons; moderate or severe hepatic impairment; active serious or untreated autoimmune disease; or a history of transplantation with ongoing immunosuppressive therapy.

Warnings and precautions also include endocrine, cardiovascular, hematologic, hypersensitivity, pancreatic, gastrointestinal, pulmonary, ophthalmologic, hepatic, renal, dental, and dermatologic toxicities.

“For nearly 30 years, people living with [essential thrombocythemia] and the physicians treating them have had limited treatment innovation,” stated principal investigator Ruben Mesa, MD, Atrium Health Levine Cancer Institute, Charlotte, North Carolina. “The approval of BESREMi 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.”

Source:

Business Wire. FDA approves PharmaEssentia’s BESREMi® (ropeginterferon alfa-2b-njft) for adults with essential thrombocythemia, a rare blood cancer. Accessed on: August 31, 2026. https://www.businesswire.com/news/home/20260831907028/en/FDA-Approves-PharmaEssentias-BESREMi-ropeginterferon-alfa-2b-njft-for-Adults-with-Essential-Thrombocythemia-A-Rare-Blood-Cancer

Mesa R, Gill H, Zhang L, et al. Ropeginterferon alfa-2b in hydroxyurea-intolerant or hydroxyurea-refractory essential thrombocythaemia (SURPASS ET): A multicentre, open-label, randomised, active-controlled, phase 3 study.  Lancet Oncol. Published online: November 1, 2025. doi: 10.1016/S2352-3026(25)00264-9