Phase III SURPASS-ET 2-year results: Early vs delayed ropeginterferon alfa-2b in high-risk ET

Results from the randomized, active-controlled, multicenter, open-label phase III SURPASS-ET (NCT04285086) extension study evaluating early vs delayed ropeginterferon alfa-2b in patients with high-risk essential thrombocythemia (ET) were presented by Gill at the European Hematology Association (EHA) 2026 Congress, June 11–14, 2026, Stockholm, SE. Patients either remained on ropeginterferon alfa-2b (continuous group; n = 80) or switched from anagrelide to ropeginterferon alfa-2b at 12 months (switched group; n = 39). Endpoints included modified European LeukemiaNet (ELN) Response Criteria rate, JAK2 V617F allele burden, occurrence of thromboembolic events, and progression-free survival (PFS). 

Key data: Modified ELN response rates with total symptom score (TSS) increased from 17.0% at Month 12 to 60.0% at Month 24 in the switched group vs 57.7% to 60.0% in the continuous group. Without TSS, response rates were 85.0% in the continuous group vs 55.0% in the switched group at 24 months. Peripheral blood count remission rates were 85.0% in the continuous group vs 65.2% in the switched group at 24 months. JAK2 V617F allelic burden gradually reduced over time in both groups. The estimated PFS rates at 24 months were 76.9% in the continuous group vs 43.1% in the switched group. Grade ≥3 treatment-emergent adverse events (TEAEs) occurred in 22.5% vs 51.3% of patients, respectively. 

Key learning: Continuous ropeginterferon alfa-2b demonstrated durable efficacy and manageable safety over 2 years. Patients switching from anagrelide to ropeginterferon alfa-2b demonstrated higher response rates and reduced a JAK2V617F allelic burden compared with prior anagrelide therapy.