Two-year and post-hoc SURPASS-ET analyses highlight the impact of treatment timing, with durable responses and improved progression-free survival supporting consideration of earlier ropeginterferon alfa-2b use in high-risk ET following hydroxyurea intolerance or resistance

First presentation of integrated SURPASS-ET and EXCEED-ET data highlights consistent responses across treatment lines, mutation subtypes, and patient populations

BURLINGTON, Mass.--(BUSINESS WIRE)--May 22, 2026-- PharmaEssentia USA Corporation, a subsidiary of PharmaEssentia Corporation (TWSE: 6446), a global biopharmaceutical innovator based in Taiwan leveraging deep expertise and proven scientific principles to deliver new biologics in hematology and oncology, today announced five upcoming presentations at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting and European Hematology Association (EHA) 2026 Congress. The ASCO annual meeting will be held May 29-June 2 in Chicago, and the EHA2026 Congress will be held June 11-14 in Stockholm, Sweden.

PharmaEssentia will present new analyses from the Phase 3 SURPASS-ET study (NCT04285086) of ropeginterferon alfa-2b in patients with essential thrombocythemia (ET), including two-year outcomes comparing early versus delayed initiation (continuous treatment from baseline vs. initiation following prior anagrelide therapy) and post-hoc analyses of patients who transitioned from anagrelide. Ropeginterferon alfa-2b-njft is currently FDA-approved and marketed as BESREMi^® for the treatment of adults with polycythemia vera (PV). The use of ropeginterferon alfa-2b-njft for ET is currently still investigational, but it is currently under review by FDA with a PDUFA goal date of August 30, 2026.

Findings from SURPASS-ET demonstrate sustained hematologic control and progressive molecular improvement with longer interferon exposure, with deeper molecular responses and improved long-term disease control observed with earlier initiation. Patients who transitioned from anagrelide showed improved hematologic parameters over 12 weeks, supporting the feasibility of treatment transition. Importantly, estimated progression-free survival (PFS) at 24 months was 76.9% in patients who received ropeginterferon alfa-2b from baseline compared to 43.1% in those with delayed initiation. Together, these data support consideration of earlier ropeginterferon alfa-2b use in high-risk ET following hydroxyurea intolerance or resistance.

PharmaEssentia will also present an integrated analysis of the SURPASS-ET and Phase 2b EXCEED-ET (NCT05482971) trials. The analysis includes 182 patients across both studies and evaluates the consistency of clinical benefit across treatment lines, including treatment-naïve and previously treated populations, as well as across molecular subtypes and ethnicities. Results demonstrated clinically meaningful hematologic and molecular responses in both treatment-naïve and pretreated patients. Efficacy was consistent across driver mutation subtypes, and the presence of additional non-driver mutations did not adversely impact outcomes.

“These findings represent an important step forward in understanding the potential use of interferon-based approaches in essential thrombocythemia,” said Ruben Mesa, M.D., co-principal investigator, presenting author, and President of Advocate Health Cancer National Service Line. “Together, these data continue to build on the growing body of evidence supporting the use of ropeginterferon alfa-2b in ET and reinforce its potential role as a meaningful treatment option for patients.”

In addition, PharmaEssentia will present real-world data evaluating the association between neutrophil-to-lymphocyte ratio (NLR) and thrombotic risk in 11,809 U.S. veterans with PV. An online-only abstract will also report findings from a meta-analysis evaluating dosing strategies for ropeginterferon alfa-2b in PV, suggesting that a higher initial dose with accelerated titration (HIDAT) may lead to improved early hematologic and molecular response rates compared to lower-dose currently approved regimens.

ASCO
Poster Presentations

Title: Integrated Analysis of the Ropeginterferon alfa-2b Clinical Program in Essential Thrombocythemia to Demonstrate Molecular and Hematologic Responses with Safety Profile Across Treatment Lines, Ethnicities, and Driver Mutation Types
Abstract Number: 6576
Poster: 369
Presenter:Ruben Mesa, M.D.
Session: Hematologic Malignancies – Leukemia, Myelodysplastic Syndromes, and Allotransplant
Date:June 1^st
Time:9-12 pm CDT

Title: Association of neutrophil‑to‑lymphocyte ratio and thrombotic events in US Veterans with Polycythemia vera
Abstract Number: 6578
Poster: 371
Presenter:Ying Wang, PhD
Session: Hematologic Malignancies – Leukemia, Myelodysplastic Syndromes, and Allotransplant
Date:June 1^st
Time:9-12 pm CDT

Published Abstract

Title: Effect ofHigher Initial Dose and Accelerated Titration of Ropeginterferon Alfa-2b on Early Hematologic and Molecular Responses in Polycythemia Vera: A Meta-Analysis
Abstract Number: e18592

EHA
Oral Presentation
Title: Early versus Delayed Initiation of Ropeginterferon Alfa-2b in High-Risk Essential Thrombocythaemia: Two-Year Results from the Phase 3 SURPASS-ET Study
Abstract Number: S219
Presenter:Harry Gill, M.D.
Session: Myeloproliferative neoplasms - Clinical
Date:June 13^th
Time: 5:15 – 6:30 pm CEST

Poster Presentations

Title: Ropeginterferon alfa-2b Demonstrates Molecular and Hematologic Responses with a Favorable Safety Profile in Essential Thrombocythemia
Abstract Number: PS1986
Presenter:Harry Gill, M.D.
Session: Myeloproliferative neoplasms - Clinical
Date:June 13^th
Time: 6:45 – 7:45 pm CEST

Title: Hematologic Control and Improved Safety Following Switch from Anagrelide to Ropeginterferon Alfa-2b in Patients with Essential Thrombocythemia: 12-Week Pre-/Post-Switch Analysis from the SURPASS-ET study
Abstract Number: PF912
Presenter:Lucia Masarova, M.D.
Session: Myeloproliferative neoplasms - Clinical
Date:June 12^th
Time: 6:45 – 7:45 pm CEST

About PharmaEssentia
PharmaEssentia USA Corporation, located in Burlington, Massachusetts, is a subsidiary of PharmaEssentia Corporation (TWSE: 6446). PharmaEssentia Corporation, headquartered in Taipei, Taiwan, is a global and rapidly growing biopharmaceutical innovator and the developer and owner of BESREMi^® (ropeginterferon alfa-2b-njft). Leveraging deep expertise and proven scientific principles, PharmaEssentia aims to deliver effective new biologics for challenging diseases in the areas of hematology, oncology, and immunology with one approved product and a diversifying pipeline. Founded in 2003 by a team of Taiwanese-American executives and renowned scientists from U.S. biotechnology and pharmaceutical companies, today PharmaEssentia is expanding its global presence with operations in the U.S., Japan, China, and Korea, along with a world-class biologics production facility in Taichung, Taiwan.

For more information about PharmaEssentia USA, visit the website, LinkedIn or X (formerly Twitter).

About Essential Thrombocythemia (ET)
Essential thrombocythemia is a rare blood disorder and type of myeloproliferative neoplasm (MPN). It is characterized by the bone marrow overproducing platelets. Patients with ET are at an increased risk of blood clots, abnormal bleeding and enlarged spleens. ET is often caused by genetic mutations such as a JAK2 genetic mutation.

About BESREMi^® (ropeginterferon alfa-2b-njft)
Ropeginterferon alfa-2b-njft is currently FDA-approved and marketed as BESREMi^® for the treatment of adults with polycythemia vera (PV). The Company plans to seek a ropeginterferon alfa-2b-njft label expansion to include ET and has submitted a sBLA with the U.S. FDA.

BESREMi^® holds orphan drug designation in the United States for the treatment of polycythemia vera (PV) in adults. It has received regulatory approval in over 40 countries, including from the European Medicines Agency (2019), the U.S. Food and Drug Administration (2021), and the Pharmaceuticals and Medical Devices Agency in Japan (2023). The product was developed by PharmaEssentia. PharmaEssentia retains full global intellectual property rights across all indications.

INDICATION
BESREMi^® is indicated for the treatment of adults with polycythemia vera.

IMPORTANT SAFETY INFORMATION
WARNING: RISK OF SERIOUS DISORDERS

Interferon alfa products may cause or aggravate fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders. Patients should be monitored closely with periodic clinical and laboratory evaluations. Therapy should be withdrawn in patients with persistently severe or worsening signs or symptoms of these conditions. In many, but not all cases, these disorders resolve after stopping therapy.

CONTRAINDICATIONS
Existence of or history of severe depression, suicidal ideation, or suicide attempt
Hypersensitivity to interferons or any inactive ingredients
Moderate or severe hepatic impairment
History or presence of active serious or untreated autoimmune disease
History of transplantation and receiving immunosuppressant agents

WARNINGS AND PRECAUTIONS
Patients exhibiting the following events should be closely monitored and may require dose reduction or discontinuation of therapy:

• Depression and Suicide: Monitor closely for symptoms and need for treatment.
• Endocrine Toxicity: Discontinue if endocrine disorders occur that cannot be medically managed.
• Cardiovascular Toxicity: Avoid use in patients with severe, acute or unstable cardiovascular disease. Monitor patients with history of cardiovascular disorders more frequently.
• Decreased Peripheral Blood Counts: Perform blood counts at baseline, every 2 weeks during titration, and at least every 3-6 months during maintenance treatment.
• Hypersensitivity Reactions: Stop treatment and immediately manage reaction.
• Pancreatitis: Consider discontinuation if confirmed pancreatitis
• Colitis: Discontinue if signs or symptoms of colitis
• Pulmonary Toxicity: Discontinue if pulmonary infiltrates or pulmonary function impairment
• Ophthalmologic Toxicity: Advise patients to have eye examinations before and during treatment. Evaluate eye symptoms promptly and discontinue if new or worsening eye disorders.
• Hyperlipidemia: Monitor serum triglycerides before BESREMi^® treatment and intermittently during therapy and manage when elevated.
• Hepatotoxicity: Monitor liver enzymes and hepatic function at baseline and during treatment. Reduce dose or discontinue depending on severity.
• Renal Toxicity: Monitor serum creatinine at baseline and during therapy. Discontinue if severe renal impairment develops.
• Dental and Periodontal Toxicity: Advise patients on good oral hygiene and to have regular dental examinations.
• Dermatologic Toxicity: Consider discontinuing if clinically significant dermatologic toxicity.
• Driving and Operating Machinery: Advise patients to avoid driving or using machinery if they experience dizziness, somnolence, or hallucination.

Please see full Prescribing Information, including Boxed Warning.

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Media Contact
Muriel Huang
Director, Investor Relations and Corporate Communication
muriel_huang@pharmaessentia.com

Source: PharmaEssentia USA Corporation