FDA Approves Prefilled Pen for Ropeginterferon Alfa-2b in Polycythemia Vera

The FDA has approved a prefilled pen device for the administration of ropeginterferon alfa-2b-njft (Besremi) in adult patients with polycythemia vera (PV).¹

The pen offers a more convenient self-administration option compared with the currently available prefilled syringe. The pen’s commercial launch in the United States is anticipated in the coming weeks, according to a news release from the drug’s developer, PharmaEssentia.

Ropeginterferon alfa-2b was first approved by the FDA in November 2021 for the treatment of adult patients with PV.² The pen device does not change the approved indication or dosing; it provides an alternative delivery method for the same agent.¹

“Treatment consistency is critical for managing PV, and this device has the potential to make a meaningful positive impact on patients’ lives by simplifying self-administration and supporting better adherence,” John Mascarenhas, MD, director of the Center of Excellence for Blood Cancers and Myeloid Disorders at Mount Sinai, stated in the news release.

What data supported the initial FDA approval of ropeginterferon alfa-2b?

Ropeginterferon alfa-2b is a long-acting, mono-pegylated proline interferon. The agent is administered subcutaneously once every 2 weeks, with the option of once every 4 weeks during long-term maintenance.²

The 2021 approval was based on safety data from the phase 1/2 PEGINVERA (NCT01193699) and phase 3 PROUD-PV (NCT01949805) and CONTINUATION-PV (NCT02218047; CONTI-PV) studies and efficacy findings from the PEGINVERA clinical study program.

Following 7.5 years of treatment with ropeginterferon alfa-2b, 61% of patients achieved a complete hematological response, defined as a hematocrit level of less than 45% without phlebotomy for at least 2 months since the last phlebotomy, a platelet count of 400 x 10⁹/L or less, a leukocyte count of 10 x 10⁹/L or less, and normal spleen size. A total of 80% of patients experienced a hematological response based on objective laboratory parameters alone, excluding normal spleen size and thrombosis.

How were the PROUD-PV and CONTI-PV trials designed?

PROUD-PV and its extension study, CONTI-PV, were open-label, controlled trials conducted at 48 clinics in Europe.³ Eligible patients were 18 years of age or older with an early-stage PV diagnosis per the World Health Organization 2008 criteria.

Patients were randomly assigned 1:1 to receive subcutaneous ropeginterferon alfa-2b given biweekly at a starting dose of 100 μg, or oral hydroxyurea at a starting daily dose of 500 mg, with the option to enroll in CONTI-PV at 1 year.

The primary objective of PROUD-PV was to establish the noninferiority of ropeginterferon alfa-2b vs hydroxyurea with regard to complete hematological response with normal spleen size at 12 months. The coprimary end points of CONTI-PV were complete hematological response with normalization of spleen size and improved disease burden.

In the PROUD-PV trial, 21% of patients who received ropeginterferon alfa-2b (n = 26122) and 28% of those given standard treatment (n = 34/123) achieved the composite primary end point of complete hematological response. Improved disease burden was met in 53% (n = 50) of patients treated in the investigational arm compared with 38% (n = 28) of 74 patients treated in the hydroxyurea arm at 36 months (P = .044). The rates of complete hematological response without meeting the spleen criterion were 43% vs 46%, respectively, at 12 months in PROUD-PV (P = .63) and 71% vs 51%, respectively, at 36 months in CONTI-PV (P = .012).³

What is the safety profile of ropeginterferon alfa-2b?

In the pooled safety population for data supporting the approval, the most common toxicities included influenza-like illness, arthralgia, fatigue, pruritus, nasopharyngitis, and musculoskeletal pain.² Serious adverse effects included urinary tract infection, transient ischemic attack, and depression.

The prescribing information carries a boxed warning noting that interferon alfa products may cause or aggravate fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders, and that patients should be monitored closely with periodic clinical and laboratory evaluations.

References

1. PharmaEssentia announces FDA approval and U.S. launch of BESREMi Pen (ropeginterferon alfa-2b-njft) for polycythemia vera. News release. PharmaEssentia. June 26, 2026. Accessed June 27, 2026. https://us.pharmaessentia.com/pharmaessentia-announces-fda-approval-and-u-s-launch-of-besremi-pen-ropeginterferon-alfa-2b-njft-for-polycythemia-vera/
2. US FDA approves Besremi (ropeginterferon alfa-2b-njft) as the only interferon for adults with polycythemia vera. News release. PharmaEssentia Corporation. November 12, 2021. Accessed June 27, 2026. https://bwnews.pr/3nbXCYO
3. Gisslinger H, Klade C, Georgiev P, et al. Ropeginterferon alfa-2b versus standard therapy for polycythaemia vera (PROUD-PV and CONTINUATION-PV): a randomised, non-inferiority, phase 3 trial and its extension study. Lancet Haematol. 2020;7(3):e196-e208. doi:10.1016/S2352-3026(19)30236-4