Star Therapeutics, a clinical stage biotechnology company discovering and developing best-in-class antibodies for bleeding disorders and other diseases, today announced that the company will present an oral presentation on interim data from its Phase 1/2 multidose study of VGA039 for von Willebrand disease (VWD), along with additional posters on the program, at the 67th American Society of Hematology (ASH) Annual Meeting and Exposition, being held December 6-9, 2025, in Orlando, Fla. VGA039 is a first-in-class monoclonal antibody therapy with a novel mechanism of action that targets Protein S, thereby restoring balance to the blood clotting process.

Presentation details include:

Oral Presentation

• Title: Subcutaneous, Every-Four-Week Maintenance Dosing of a Novel Protein S Antibody is Well-Tolerated and Substantially Reduces Bleeding Rates: Results from a Phase 1/2 Multidose Study of VGA039 in Patients with Von Willebrand Disease
• Publication Number: 308
• Oral Session: 323. Disorders of Coagulation, Bleeding, or Fibrinolysis, Excluding Congenital Hemophilias: Clinical and Epidemiological: Novel Insights into Diagnostics and Therapeutics of Bleeding in Inherited, Acquired Coagulopathies and BDUC
• Presentation Date and Time: Saturday, December 6, 2025, 4:15 - 4:30 p.m. ET
• Presenter: Allison Wheeler, M.D., MSCI

Poster Presentations

• Title: The First Characterization of Disease Burden and Healthcare Resource Utilization for the Recent Definition of Severe Von Willebrand Disease Using a Large United States Real-World Dataset
• Publication Number: 2611
• Poster Session: 901. Health Services and Quality Improvement: Non-Malignant Conditions Excluding Hemoglobinopathies: Poster I
• Session Date and Time: Saturday, December 6, 2025, 5:30 - 7:30 p.m. ET
• Presenter: Angela Weyand, M.D.

• Title: VGA039 as a Protein S-Targeted Hemostatic Promoting Monoclonal Antibody, Promotes in-vitro Thrombin Generation in Plasma Samples from Subjects Across a Broad Range of Bleeding Disorders, Including Von Willebrand Disease, Hemophilia A, Hemophilia B and Hemophilia C
• Publication Number: 1277
• Poster Session: 321. Coagulation and Fibrinolysis: Basic and Translational: Poster I
• Session Date and Time: Saturday, December 6, 2025, 5:30 - 7:30 p.m. ET
• Presenter: Alina He, B.S.

• Title: A Protein S-Targeting Monoclonal Antibody, VGA039, Improves Both Primary and Secondary Hemostatic Activity of Von Willebrand Disease Patient Blood in an ex vivo Vascularized Hemostasis-on-a-Chip
• Publication Number: 3051
• Poster Session: 321. Coagulation and Fibrinolysis: Basic and Translational: Poster II
• Session Date and Time: Sunday, December 7, 2025, 6:00 - 8:00 p.m. ET
• Presenter: Yumiko Sakurai, M.S.

About VGA039

VGA039 is a monoclonal antibody therapy with a novel mechanism of action that targets Protein S, thereby restoring balance to the blood clotting process. VGA039 has potential to be a universal hemostatic therapy that can treat numerous bleeding disorders, starting with VWD. As a subcutaneously self-administered antibody therapy with a convenient once monthly dosing regimen, VGA039 has the potential to dramatically reduce treatment burden for patients. VGA039 has received Fast Track and orphan drug designations from the United States Food and Drug Administration (FDA).

Interim positive data from a Phase 1 single ascending dose study of VGA039 in patients with VWD were previously reported at the Annual Meeting of the American Society of Hematology (ASH) in December 2024. A Phase 1/2 multidose study is ongoing (NCT05776069), with an interim readout planned for presentation at the 2025 ASH Annual Meeting. VGA039 has advanced into a Phase 3 study (NCT07115004), a global single arm cross-over study designed to investigate the safety and efficacy of subcutaneous administration of VGA039 as prophylaxis for bleeding in patients with every type of VWD. For additional information on our VIVID trials of VGA039, including how to enroll, please visit the website here.

About von Willebrand disease

Von Willebrand disease (VWD) is the most common inherited bleeding disorder in which the blood does not clot properly, caused by absent or defective von Willebrand factor (VWF). VWD patients may experience excessive bleeding with variability in severity and frequency, negatively impacting their daily lives. Current therapies for VWD prophylaxis include factor replacement therapies requiring multiple intravenous (IV) infusions every week. More than 130,000 people in the U.S. are diagnosed with VWD.

About Star Therapeutics

Star Therapeutics is a clinical stage biotechnology company discovering and developing best-in-class antibodies to create life-changing therapies for patients, initially addressing unmet needs in hematology and immunology. The company applies its expertise in antibody innovation to interrogate areas of biology that have been overlooked and have the potential to address multiple diseases with a single therapy. Star’s leadership team has deep expertise in novel antibody drug development, having invented four first-in-class antibodies including the first approved drug (ENJAYMO^®) for cold agglutinin disease, a hematology disease, and other therapies that have demonstrated clinical proof of concept. Based in South San Francisco, Star has raised more than $300 million from leading life sciences investors. For more information, please visit Star-Therapeutics.com and follow us on LinkedIn and X.

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