ASH 2025 | What are the key findings from the 12-month primary endpoint analysis of the ROP-ET phase III study?

During the 67th American Society of Hematology (ASH) Annual Meeting and Exposition, December 6–9, 2025, Orlando, US, the MPN Hub was pleased to speak with Jean-Jacques Kiladjian, Université Paris Cité, Paris, FR. We asked, What are the key findings from the 12-month primary endpoint analysis of the ROP-ET phase III study?

In this interview, Kiladjian first provided an overview of the phase III ROP-ET (NCT06514807) study design and key patient eligibility criteria. He then discussed the primary endpoint results, highlighting that the ROP-ET study met the primary endpoint – a composite durable hematologic and clinical response after 12 months. Finally, Kiladjian explored the safety profile of ropeginterferon alfa-2b observed in the study. 

Key points

• After 12 months, 48% of patients had durable hematologic and clinical response (primary endpoint).
  • Durable, complete hematological response was achieved in 65% of patients.
  • 96% of patients did not have a hemorrhagic or thrombotic event.
  • No patient experienced disease progression.
  • Durable improvement in symptoms was observed in 84% of patients.
• Median platelet and leukocyte counts reduced rapidly and then remained stable until the 12-month endpoint.
• Overall, 73% of patients experienced an adverse event (AE), with <1% experiencing a serious AE, and 2% discontinuing treatment due to treatment-related AEs.
• Ropeginterferon alfa-2b is a potential therapeutic option for patients with essential thrombocythemia who require cytoreduction but cannot receive other available therapies.

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