BESREMi (ropeginterferon alfa-2b) is currently an FDA-approved treatment for patients with polycythemia vera. The company plans to pursue regulatory discussion with the FDA to seek a label expansion to include essential thrombocythemia.  As per Delveinsight’s analysis, there were around 167,500 diagnosed prevalent cases of essential thrombocythemia in the US in 2024. 

The company has currently presented positive Phase III SURPASS-ET trial data for essential thrombocythemia.  As per the results, overall, 42.9% of patients receiving ropeginterferon alfa-2b  achieved the primary endpoint, compared to 6.0% in the anagrelide group (p = 0.0001), with ropeginterferon alfa-2b exceeding anagrelide across sub-criteria for the primary endpoint including blood count normalization, maintenance or improvement of splenomegaly, symptom improvement or stability per the MPN-SAF, and absence of hemorrhagic/thrombotic events. 

Within the ropeginterferon alfa-2b cohort, one patient (1.1%) experienced an essential thrombocythemia-related thrombotic event, and there were no instances of progression to myelofibrosis or acute leukemia, whereas these complications occurred in seven (8.8%) and three (3.6%) anagrelide recipients, respectively. The JAK2V617F allele fraction declined from 33.7–25.3% at 12 months in the ropeginterferon alfa-2b arm, compared to a change from 39.7–37.3% with anagrelide.

Additionally, the secondary endpoint evaluation was done on the overall molecular response rate at 12 months, comparing ropeginterferon alfa-2b with anagrelide. The results showed a significant difference in molecular response rates between the two treatments. It demonstrated a higher total molecular response rate of 30.6%, with 27.8% achieving a partial molecular response (PMR) and 2.8% achieving a complete molecular response (CMR). In contrast, the Anagrelide arm showed no molecular response at 12 months.

It showed a more favorable safety profile than anagrelide in essential thrombocythemia, with fewer Grade ≥3 TEAEs (23.1% vs. 33.8%), serious adverse events (14.3% vs. 30.0%), and treatment discontinuations (5.5% vs. 20.0%). Although dose reductions were more frequent (45.1%), they likely reflect proactive management. Adverse events of special interest, including cardiovascular and thrombotic events, were also less common. No fatal events occurred with ropeginterferon alfa-2b, unlike anagrelide, which had a 3.8% fatality rate, supporting its superior tolerability and safety.

KOL insights

“We are extremely proud of the SURPASS-ET Phase III study outcome, which shows the potential of ropeginterferon alfa-2b as an important new treatment option for patients with essential thrombocythemia, a rare blood cancer that drastically increases the risk of heart attack or stroke. The data highlight the broad potential to apply our innovative monopegylated, long-acting interferon technology as a significant step forward for treating essential thrombocythemia, and potentially other myeloproliferative neoplasms, with non-chemotherapy treatments.” – Expert Opinion

Conclusion

Currently, only one marketed therapy is approved by the EMA, and there is no treatment specifically approved for essential thrombocythemia by the FDA. This creates a significant opportunity for BESREMi to establish a strong position in the essential thrombocythemia treatment landscape. Given its existing approval in polycythemia vera and encouraging outcomes in Phase II trials for myelofibrosis, ropeginterferon alfa-2b demonstrates the promising clinical potential and could address an unmet need in essential thrombocythemia. However, the market is currently dominated by off-label therapies such as hydroxyurea, anagrelide, and conventional interferons, which are widely used despite the lack of formal essential thrombocythemia-specific approvals. These entrenched options may pose strong competitive pressure, particularly in terms of physician familiarity and cost-effectiveness, potentially challenging the adoption of ropeginterferon alfa-2b in the future.

BESREMi is gaining traction as a preferred alternative to PEGASYS amid supply shortages, supported by NCCN and NHS guidance. It offers comparable efficacy, longer dosing intervals, and better tolerability, ensuring treatment continuity and potentially strengthening its market position. According to DelveInsight’s analysis, BESREMi is expected to be the top revenue-generating drug for essential thrombocythemia in the 7MM by 2034, highlighting a significant opportunity and establishing a strong market presence in essential thrombocythemia.