Clinical Summary: 

• Design/Population: This integrated analysis evaluated outcomes in both treatment-naive and previously treated patients with essential thrombocythemia enrolled in the phase 3 SURPASS-ET and the phase 2b EXCEED-ET study. 
• Key Outcomes: Ropeginterferon alfa-2b demonstrated durable hematologic and molecular responses, improved blood count control, and fewer thrombotic events than anagrelide, with consistent efficacy across treatment lines, ethnicities, and molecular subtypes.
• Clinical Relevance: These findings support ropeginterferon alfa-2b as a potential disease-modifying treatment option regardless of mutation status, treatment history, or ethnicity.

Results from an integrated analysis of the SURPASS-ET and EXCEED-ET studies demonstrated consistent hematologic and molecular efficacy with ropeginterferon alfa-2b across diverse patient populations with essential thrombocythemia. 

These results were presented by Ruben Mesa, MD, Atrium Health Wake Forest Baptist Comprehensive Cancer Center, Winston-Salem, North Carolina, at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois.

In this analysis, researchers collected data from 182 patients enrolled in the phase 3 SURPASS-ET trial, which compared ropeginterferon alfa-2b with anagrelide in hydroxyurea-resistant or hydroxyurea-intolerant high-risk essential thrombocytopenia, and the phase 2b EXCEED-ET study, which enrolled both treatment-naive and previously treated patients. Key end points included durable modified European LeukemiaNet (ELN) responses, hematologic and molecular responses, thrombotic events, and safety.

In SURPASS-ET, ropeginterferon achieved a significantly higher durable modified ELN response rate at months 9 and 12 compared with anagrelide (42.9% vs 6.0%; P < .0001). Ropeginterferon also demonstrated superior platelet control (56.0% vs 21.7%), improved white blood cell normalization (73.6% vs 13.3%), greater reductions in JAK2V617F allele burden, and fewer major thrombotic events (1.1% vs 10%). 

In EXCEED-ET, durable modified ELN responses were observed in 60.2% of patients. Molecular response rates according to ELN 2009 criteria were 35% in patients with JAK2V617F mutations, 16% in those with CALR mutations, and 25% in those with MPL mutations. Investigators reported consistent efficacy across treatment lines, racial groups, and mutation subtypes.

The safety profile of ropeginterferon was favorable and generally manageable. Across the integrated analysis, grade ≥3 treatment-emergent adverse events occurred in 28.6% of patients receiving ropeginterferon and 33.8% of patients receiving anagrelide. Treatment-emergent adverse events leading to treatment discontinuation occurred less frequently with ropeginterferon than with anagrelide (8.8% vs 20%), as did serious adverse events (12.6% vs 30%). Fatal adverse events were reported only in the anagrelide group (3.8%).

Source: 

Mesa R, Masarova L, Reeves B, et al. Integrated analysis of the ropeginterferon alfa-2b clinical program in essential thrombocythemia to demonstrate molecular and hematologic responses with safety profile information across treatment lines, ethnicities, and driver mutation types. Presented at the ASCO Annual Meeting. May 29 - June 2, 2026. Chicago, Illinois. Abstract 6576.