FDA Accepts sBLA for Ropeginterferon in Essential Thrombocytopenia

The FDA has accepted a supplemental biologics license application (sBLA) seeking expanded approval for ropeginterferon alfa-2b-njft (BESREMi®) among adults with essential thrombocytopenia, according to a press release from the developer, PharmaEssentia USA Corporation.¹

The FDA assigned a Prescription Drug User Fee Act date of August 30, 2026, for approving the agent’s use among those with essential thrombocytopenia. The FDA previously approved ropeginterferon as a treatment for adults with polycythemia vera in November 2021.²

“[Essential thrombocytopenia] is a rare blood cancer driven by excessive platelet production that can result in severe complications like organ damage and stroke. Despite these serious risks, no new therapies have been approved by the FDA for over 2 decades,” Ko-Chung Lin, PhD, founder and chief executive officer at PharmaEssentia, stated in the press release.¹ We look forward to collaborating with the FDA as they review our application, with the goal of bringing ropeginterferon alfa-2b-njft, an investigational therapy, to the [essential thrombocytopenia] community as quickly as possible.”

Supporting data for the sBLA came from the phase 3 SURPASS-ET trial (NCT04285086) and the confirmatory phase 2b EXCEED-ET trial (NCT05482971).

SURPASS-ET

Investigators previously presented data from the SURPASS-ET trial assessing ropeginterferon alfa vs anagrelide (Agrylin) among patients with essential thrombocytopenia at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting.³ Data revealed a modified European LeukemiaNet (ELN) response in 42.9% of those who received ropeginterferon alfa vs 6.0% of those who received anagrelide (P = .0001). Regarding individual modified ELN parameters, ropeginterferon alfa produced numerical improvements vs anagrelide in terms of platelet count responses (56.0% vs 21.7%), white blood cell count responses (73.6% vs 13.3%), and peripheral blood count remissions (56.0% vs 6.0%), among other categories.

The most common treatment-emergent adverse effects (TEAEs) of any grade in the ropeginterferon alfa and anagrelide arms, respectively, included alanine aminotransferase increases (31.9% vs 32.5%), aspartate aminotransferase increases (31.9% vs 31.3%), and anemia (27.5%). Grade 3 or higher TEAEs in the ropeginterferon alfa arm included single instances of increased alanine aminotransferase, increased aspartate aminotransferase, pruritus, and decreased weight.

Patients in the multicenter phase 3 trial were randomly assigned to receive ropeginterferon alfa (n = 91) or anagrelide at the labeled dose (n = 83). Treatment in the experimental arm consisted of ropeginterferon alfa at 250 μg in weeks 0 to 2, 350 μg in weeks 2 to 4, and a fixed dose of 500 μg for the remainder of the study period.

The trial’s primary end point was the modified ELN response rate at 9 and 12 months. Secondary end points included JAK2V617F and CALR allele burden, symptomatic improvement, thromboembolic events, and safety.

EXCEED-ET

In January 2026, developers announced findings from the EXCEED-ET trial showing efficacy with ropeginterferon alfa among patients with hydroxyurea-resistant or hydroxyurea-intolerant essential thrombocythemia with leukocytosis.⁴ At months 10 and 13, a modified ELN response occurred in 60.2% of those who received ropeginterferon alfa. Specifically, 63.7% had a reduction in peripheral blood counts, 94.5% showed improvement or a lack of worsening of disease-related signs, and all patients (100%) avoided bleeding or thrombotic events from months 10 to 13.

Patients in the single-arm, phase 2b trial were assigned to receive ropeginterferon alfa subcutaneously every 2 weeks.⁵ The trial’s primary end point was efficacy based on peripheral blood count remission. Patients 18 years and older with a diagnosis of essential thrombocytopenia per WHO 2016 guidelines and a platelet count of more than 450 x 10⁹/L at screening were eligible for enrollment.

References

1. FDA confirms a PDUFA goal date of August 30, 2026 for the sBLA submission of ropeginterferon alfa-2b-njft in essential thrombocythemia (ET). News release. PharmaEssentia USA Corporation. January 13, 2026. Accessed January 16, 2026. https://tinyurl.com/4j7y8an6
2. U.S. FDA approves BESREMi (ropeginterferon alfa-2b-njft) as the only interferon for adults with polycythemia vera. News release. PharmaEssentia Corporation. November 12, 2021. Accessed January 16, 2026. https://bwnews.pr/2YHruCT
3. Mesa RA, Gill H, Xiao Z, et al. Ropeginterferon alfa-2b versus anagrelide for the treatment of essential thrombocythemia: topline results of the phase 3 SURPASS-ET trial. J Clin Oncol. 2025;43(suppl 16):6500. doi:10.1200/JCO.2025.43.16_suppl.6500
4. PharmaEssentia announces positive topline phase 2b data from EXCEED-ET study evaluating ropeginterferon alfa-2b-njft for essential thrombocythemia. News release. PharmaEssentia USA Corporation. January 12, 2026. Accessed January 16, 2026. https://tinyurl.com/yes2t5m2
5. A single-arm, multicenter study to assess the efficacy, safety, and tolerability of P1101 in adults with ET. ClinicalTrials.gov. Updated August 13, 2025. Accessed January 16, 2026. https://tinyurl.com/426kudnk