SURPASS-ET: Ropeg meets primary endpoint in essential thrombocythemia

Ropeginterferon alfa-2b outperformed anagrelide as a second-line treatment option for patients with essential thrombocythemia (ET). The novel interferon-based drug delivered better efficacy and safety data than anagrelide.

The phase 3 SURPASS-ET study (NCT04285086) compared ropeginterferon alfa-2b to anagrelide in patients with high-risk ET who had shown resistance or intolerance to hydroxyurea. A total of 174 predominantly Asian patients were randomised 1:1 to ropeginterferon alfa-2b or to anagrelide, and the primary endpoint was the modified European LeukemiaNet (ELN) response at months 9 and 12. Dr Harry Gill (University of Hong Kong, China) presented the key findings [1].

The ELN response rate at months 9 and 12 was 42.9% in the ropeginterferon alfa-2b arm, whereas this rate was only 6.0% in the anagrelide arm (P=0.0001). “In fact, all the individual components of the modified ELN response were significantly in favour of the ropeginterferon alfa-2b arm,” said Dr Gill. Furthermore, the overall molecular response rate at 12 months was 30.6% in the experimental arm, compared to 0% in the control arm. “We even saw 2 patients with CALR variant allele burden who had a complete molecular response,” according to Dr Gill. Next to that, the research team observed a larger improvement in symptoms in the ropeginterferon alfa-2b arm, with 53.2% of the patients in the experimental arm vs 38.5% of the patients in the control arm showing at least a 50% reduction in symptoms at 12 months.

Only 1 patient in the ropeginterferon alfa-2b arm had a major ET-related thrombotic event during the study, compared to 8 patients in the anagrelide arm. For major ET-related cardiovascular events, the corresponding numbers were 0 and 6. Also, treatment-emergent serious adverse events (AEs) were more common in the control arm (14.3% vs 30.0%).

“Ropeginterferon alfa-2b demonstrated superior efficacy compared to anagrelide, potentially representing a new second-line therapeutic option for patients with high-risk ET,” Dr Gill concluded his presentation.

1. Gill H, et al. Better safety and efficacy with ropeginterferon alfa-2b over anagrelide as second-line treatment of essential thrombocythemia in the topline results of the randomized phase 3 SURPASS-ET trial. S102, EHA2025 Congress, 12–15 June, Milan, Italy.

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Posted on 2 September 2025