FDA Accepts sBLA for Ropeginterferon-Alfa-2b for Essential Thrombocythemia

The FDA has accepted a supplemental biologics license application (sBLA) seeking the approval of ropeginterferon alfa-2b-njft (Besremi) for the treatment of adult patients with essential thrombocythemia (ET).¹

The FDA has set a Prescription Drug User Fee Act target action date of August 30, 2026, for this decision.

The sBLA was supported by findings from the phase 3 SURPASS-ET (NCT04285086) and the phase 2b EXCEED-ET (NCT05482971) trials.

“Living with ET can be exhausting—physically and emotionally—for patients who must navigate a chronic cancer with limited treatment choices,” Ruben Mesa, MD, principal investigator of the SURPASS-ET trial and president of Advocate Health’s Cancer National Service Line, which includes Atrium Health Levine Cancer Institute and the Comprehensive Cancer Center at Atrium Health Wake Forest Baptist in North Carolina, stated in a news release. “If approved, ropeginterferon alfa-2b could offer clinicians a meaningful new treatment option for their patients with ET.”

Notably, the potential final approved indication for ropeginterferon alfa-2b in ET and changes to the prescribing information will be addressed during the review process, which will be a standard review process. This sBLA submission aims to expand the ropeginterferon alfa-2b label, which currently includes an indication for the treatment of adult patients with polycythemia vera.

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

What is the design of the SURPASS-ET trial?

SURPASS-ET enrolled patients at least 18 years of age with high-risk ET who were resistant or intolerant to hydroxyurea.² Patients were randomly assigned 1:1 to receive subcutaneous ropeginterferon alfa-2b every 2 weeks at 250 μg during weeks 0 to 2, 350 μg during weeks 2 to 4, and then at a fixed dose of 500 μg thereafter; or oral anagrelide at the labeled dose.

The primary end point was modified European LeukemiaNet (ELN) response rate at 9 and 12 months. Secondary end points included JAK2 V617F and CALR allele burdens, symptomatic improvement, the occurrence of thromboembolic events, and safety.

What findings from SURPASS-ET are important to note?

In this trial, the rate of patients who achieved a durable modified ELN criteria response at months 9 and 12 was significantly higher among patients who received ropeginterferon alfa-2b (n = 91), at 42.9% vs 6.0% among those who received anagrelide (n = 83; P = .0001). Additionally, the mean JAK2 V617F allele burden decreased from a baseline rate of 33.7% to 25.3% at 12 months among patients in the ropeginterferon alfa-2b arm; conversely, the mean allele burdens at these respective time points in the anagrelide arm increased from 37.3% to 39.7%. Furthermore, 53.2% of patients in the ropeginterferon alfa-2b arm achieved a 50% or greater reduction in symptoms at 12 months vs 39.5% of those in the anagrelide arm. Moreover, the rates of major ET-related thromboembolic events by month 12 in these respective arms were 1.1% vs 10.0%.

What is the design of the EXCEED-ET trial?

The single-arm EXCEED-ET trial enrolled patients at least 18 years of age with ET who were naive to cytoreductive treatment or had prior exposure to hydroxyurea and/or anagrelide.³ Patients also needed to have adequate hepatic function, a creatinine clearance of at least 40 mL per minute, and a platelet count above 450 x 10⁹/L at screening.

Patients received ropeginterferon alfa-2b via subcutaneous injection from a pre-filled syringe every 2 weeks over 13 months. The primary end point is efficacy based on peripheral blood count as defined by hematocrit levels lower than 45%, white blood cell counts of 10 x 10⁹/L or lower, and platelet counts of 400 x 10⁹/L or lower in at least 80% of biweekly measurements over 32 consecutive weeks.

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 13, 2026. https://www.businesswire.com/news/home/20260113168572/en/FDA-Confirms-a-PDUFA-Goal-Date-of-August-30-2026-for-the-sBLA-Submission-of-Ropeginterferon-Alfa-2b-njft-in-Essential-Thrombocythemia-ET
2. 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
3. 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 13, 2026. https://www.clinicaltrials.gov/study/NCT05482971