Ropeginterferon alfa-2b (Besremi)

Current understanding

Long-acting pegylated interferon, FDA-approved for PV. Reduces JAK2 V617F allele burden over time and may modify disease trajectory; well-tolerated for sustained use.

Evidence log

• 2026-09-29 — Rusfertide Approval Expands Options and Improves Burdens in Polycythemia Vera: cross-connection with rusfertide: Rusfertide and ropeginterferon now coexist as NCCN-endorsed non-chemotherapy PV options with distinct mechanisms (hepcidin mimetic vs. interferon). (novelty: 4)
• 2026-09-15 — Type 1 interferon perturbates clonal competition by reshaping human blood development.: Preclinical single-cell multiomics: IFNα polarizes human HSC differentiation into anti-inflammatory lymphoid vs inflammatory-myeloid states, and CALR- or JAK2-mutant stem cells gain clonal fitness by resisting the inflammatory-myeloid trajectory — offering a mechanistic account of how IFNα-class agents (including ropeginterferon) preferentially deplete mutant clones in MPN. (novelty: 4)
• 2026-08-31 — FDA Approves PharmaEssentia’s BESREMi (ropeginterferon alfa-2b-njft) for Adults with Essential Thrombocythemia: FDA approved ropeginterferon alfa-2b-njft (Besremi) for adults with essential thrombocythemia regardless of genotype or disease status, including cytoreductive-naïve patients — the first new ET drug approval in nearly three decades, expanding the label beyond PV. (novelty: 3)
• 2026-08-13 — P1101 in Treating Patients With Early PMF or Overt PMF at Low or Intermediate-1 Risk: Phase 3 double-blind placebo-controlled trial (trial-late) evaluating bi-weekly ropeginterferon alfa-2b (P1101) vs placebo (2:1 randomization) in adults with early PMF or overt PMF at low/intermediate-1 risk — first placebo-controlled test of ropeginterferon as disease-modifying therapy in early-stage PMF, a population with limited trial data. (novelty: 3)
• 2026-07-22 — Ropeginterferon Alfa-2b (P1101) vs. Anagrelide in Essential Thrombocythemia Patients With Hydroxyurea Resistance or Intolerance: Phase 3 randomized active-controlled head-to-head trial (trial-late) comparing ropeginterferon alfa-2b (P1101) vs anagrelide at 12 months as second-line therapy in HU-resistant/intolerant ET — will generate direct comparative efficacy, safety, and tolerability data in the post-HU ET setting. (novelty: 3)
• 2026-09-01 — FDA Approves First Blood Cancer Drug in 30 Years: Regulatory milestone (other): FDA approved ropeginterferon alfa-2b-njft (Besremi) for adults with essential thrombocythemia — the first new ET drug approval in nearly 30 years, extending its label beyond PV. (novelty: 3)
• 2026-06-10 — Ropeginterferon alfa-2b-njft treatment in essential thrombocythemia across different driver mutations: results from a North American, single-arm, multicentre study (EXCEED-ET).: EXCEED-ET (Phase 2b, single-arm, North American multicentre, trial-early): ropeginterferon alfa-2b-njft achieved a 60.2% durable modified ELN response in ET patients (both treatment-naive and HU-pretreated), with rapid hematologic responses, molecular responses stratified across JAK2/CALR/MPL driver mutations, splenomegaly/symptom benefit, and good tolerability — extends prior Asia-focused SURPASS-ET evidence to a North American population. (novelty: 3)
• 2025-06-26 — Efficacy and Safety of Ropeginterferon Alfa-2b in Low-Risk Polycythemia Vera.: Prospective efficacy/safety data (trial-early) in low-risk PV requiring cytoreduction: ropeginterferon alfa-2b substantially reduced phlebotomy need, produced high complete hematologic response rates, and reduced JAK2V617F allele burden with manageable safety — extends the case for cytoreductive use in the low-risk PV population. (novelty: 3)
• 2026-08-01 — Ropeginterferon alfa-2b in Polycythemia Vera: A systematic review and meta-analysis.: PRISMA systematic review and meta-analysis of 3 RCTs (n=522, meta-analysis): ropeginterferon alfa-2b showed no significant advantage over hydroxyurea for hematologic or molecular responses in PV, but was superior to phlebotomy alone for complete hematologic response, partial molecular response, and JAK2V617F allele-burden reduction — quantitatively confirms disease-modifying molecular benefit vs phlebotomy while tempering claims of superiority over HU. (novelty: 3)
• 2026-07-22 — Disease Burden, Inadequate Hematocrit Control, and Thromboembolic Events in Patients with Polycythemia Vera Despite Current Standard of Care Treatment: A Retrospective Claims Study.: US retrospective claims analysis (n=11,311, observational): even with cytoreductive options including ropeginterferon available within the SoC landscape, PV patients broadly fail to sustain HCT <45% and continue to face thromboembolic events and treatment burden — reinforces the unmet need that ropeginterferon-based paradigm-shift arguments seek to address. (novelty: 3)
• 2026-07-23 — Complete Hematological Response Coupled with Molecular Response in Polycythemia Vera Treatment with Ropeginterferon Alfa-2b.: Small single-arm observational series (n=13, HU-intolerant high-risk PV): low-start slow-titration ropeginterferon alfa-2b with biweekly monitoring achieved complete hematological response in a mean of 4.15 months — well before the conventional 12-month assessment — with concurrent JAK2 VAF decline, pruritus resolution, and no thrombosis or adverse events, suggesting earlier response is achievable under close-monitoring protocols. (novelty: 3)
• 2026-09-01 — Type-I interferon-activated NK cells control polycythemia vera in vivo.: Preclinical mechanism (mouse PV model): the therapeutic effect of type-I interferons depends on NK cell activation and TNF-α-mediated preferential killing of JAK2V617F HSPCs, supporting an NK-immune-effector mechanism relevant to ropeginterferon’s molecular responses in PV. (novelty: 5)
• 2026-07-17 — Cross-study analyses of the ropeginterferon alfa-2b effect on phlebotomy in low- and high-risk patients with polycythemia vera.: Cross-study meta-analysis: ropeginterferon alfa-2b achieves durable hematocrit control and phlebotomy independence across low- and high-risk PV (including HU-resistant patients), with the accelerated HIDAT regimen producing faster phlebotomy-free responses and deeper JAK2V617F allele-burden reduction than slow titration — supporting HIDAT as a preferred dosing protocol. (novelty: 3)
• 2025-10-30 — Effective Treatment with Ruxolitinib and Ropeginterferon Alfa-2b for Refractory TAFRO-like Syndrome.: Case report: ropeginterferon alfa-2b combined with ruxolitinib successfully treated refractory TAFRO-like syndrome in a JAK2 V617F-positive PV patient — first reported use of this combination in a TAFRO-like presentation. (novelty: 3)
• 2026-06-10 — Ropeginterferon for High Risk JAK2 Clonal Hematopoiesis: Trial-early: ropeginterferon alfa-2b being evaluated for safety/feasibility in high-risk JAK2 clonal hematopoiesis without overt MPN — first disease-interception application of the drug at the pre-MPN CHIP stage. (novelty: 4)
• 2026-05-23 — PharmaEssentia to Present New Clinical Data Supporting Ropeginterferon Alfa-2b in Essential Thrombocythemia at ASCO and EHA 2026: PharmaEssentia to present new two-year SURPASS-ET data (Phase 3, trial-late) at ASCO and EHA 2026, including post-hoc analyses of early vs delayed ropeginterferon initiation in ET and outcomes in patients transitioning from anagrelide — extending the durability and sequencing evidence base for the pending ET indication. (novelty: 3)
• 2026-06-02 — Genomic insights transform diagnosis, prognosis, and therapy in BCR::ABL1-negative myeloproliferative neoplasms.: Comprehensive genomics-focused review (review-level) positions interferons including ropeginterferon within a mutation-aware MPN treatment framework, advocating integration of mutational profiling and functional biomarkers (e.g., platelet CREB3L1 mRNA) to guide disease-modifying therapy selection and molecular monitoring. (novelty: 3)
• 2026-03-09 — Efficacy and safety of a three-step dose escalation regimen of ropeginterferon alfa-2b in Japanese patients with polycythemia vera: a phase 3b, single-arm, multicenter study.: Phase 3b single-arm Japanese PV study (trial-early): accelerated three-step dose escalation (250→350→500 µg over 4 weeks) achieved 57.1% complete hematologic response at week 24 with no additional safety signals vs standard slower titration, supporting faster titration as a viable protocol option. (novelty: 3)
• 2026-04-08 — A paradigm shift in the treatment of patients with polycythemia vera. The initial early use of recombinant interferon-alpha.: Review (synthesis of 35 years of evidence including PROUD-PV/CONTINUATION-PV and Low-PV trials) argues for ropeginterferon alfa-2b as initial therapy in both low- and high-risk PV, citing superior molecular response and reduced disease progression vs hydroxyurea and phlebotomy-only — a proposed paradigm shift in PV treatment sequencing. (novelty: 3)
• May 17, 20 — MPN | Tumor | CURE: Regulatory milestone (other): FDA accepted supplemental application for ropeginterferon alfa-2b (Besremi) in essential thrombocythemia, advancing a potential label expansion beyond PV. (novelty: 3)
• 2026-04-14 — Mechanism of Action of Interferon in the Treatment of Myeloproliferative Neoplasms: Mechanism review (review-level): IFNα drives hematological and molecular responses in MPN with preferential activity against JAK2V617F clones, while CALR-mutant patients show heterogeneous and generally lower molecular responses; mechanisms of HSC targeting and DMR predictors remain open questions. (novelty: 3)
• 2026-04-17 — Tolerability of Ropeginterferon Alfa-2b Add-on to Ongoing Ruxolitinib Therapy in Myelofibrosis (RopeRux in Myelofibrosis): Trial-early (RopeRux in Myelofibrosis): ropeginterferon alfa-2b being evaluated as add-on to ongoing ruxolitinib in MF — first formal test of ropeginterferon in the MF setting (its approved indication is PV/ET) and first ropeginterferon + JAKi combination, probing tolerability of dual JAKi/IFN exposure. (novelty: 4)
• 2026-03-04 — Phase IIa Study on Flonoltinib Maleate Tablets in the Treatment of Patients With Polycythemia Vera: Interferon-resistant/intolerant PV serves as eligibility criterion for a Phase IIa trial (trial-early) of flonoltinib maleate, framing the post-interferon salvage setting. (novelty: 4)
• 2026-03-03 — A Clinical Study of Gecacitinib Combined With Pegylated Interferon in Patients With PV: Pegylated interferon is being evaluated in combination with Gecacitinib (novel JAK inhibitor) in a 24-week PV trial with hematological remission as the primary endpoint, exploring potential synergy with JAK inhibition. (novelty: 4)
• 2026-03-06 — Identification of Factors Associated With Treatment Response in Patients With Polycythemia Vera, Essential Thrombocythemia, and Pre-myelofibrosis.: Observational protocol proposing baseline NGS mutational profile and cytokine profile as predictors of 12-month hematological response to pegylated interferon in PV, ET, and pre-MF — frames a precision-medicine selection rationale but reports no results. (novelty: 3)
• 2026-04-14 — Ropeginterferon Alfa-2b Yields Durable Responses in Essential Thrombocythemia: SURPASS-ET (Phase 3 RCT, trial-late): ropeginterferon alfa-2b achieved 43% response vs 6% for anagrelide at months 9–12 in HU-intolerant/refractory ET, supporting a pending 2026 FDA approval for the ET indication. (novelty: 4)
• 2026-04-28 — MITHRIDATE: Ruxolitinib Versus Hydroxycarbamide or Interferon as First Line Therapy in High Risk Polycythemia Vera: MITHRIDATE (phase III RCT, trial-late): interferon alpha is a comparator arm against ruxolitinib (and hydroxycarbamide) as first-line therapy in high-risk PV — will generate head-to-head efficacy data versus JAK inhibition. (novelty: 4)
• March 30, — NCCN Updates Guidance on Interferon in Essential Thrombocythemia: NCCN guidelines (review-level) upgraded interferon to category 1 designation for essential thrombocythemia, elevating its standing as a preferred cytoreductive option in ET alongside its established PV indication. (novelty: 3)

Open questions

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