Hemab Therapeutics Presents Positive Clinical and Preclinical Data Across Bleeding Disorder Pipeline at ISTH 2025 Congress

Sutacimig Phase 2 interim results demonstrate >50% reduction in treated bleeding event and prophylactic treatment potential in Glanzmann thrombasthenia

HMB-002 clinical proof-of-mechanism data in Von Willebrand disease support its potential as a first-in-class prophylactic therapy by elevating VWF levels and extending half-life

Natural history insights illuminate true patient burden and prophylactic opportunity to inform transformative, preventative solutions for underserved bleeding disorders

COPENHAGEN, Denmark and CAMBRIDGE, Mass., June 24, 2025 /PRNewswire/ -- Hemab Therapeutics, a clinical-stage biotechnology company developing novel prophylactic therapeutics for serious, underserved bleeding and thrombotic disorders, today announced clinical and preclinical results at the International Society on Thrombosis and Haemostasis (ISTH) 2025 Congress in Washington, DC. The company's 11 abstracts present breakthrough data for sutacimig (formerly HMB-001) and HMB-002, its lead therapeutic candidates, along with crucial insights from natural history studies.

"The data presented at ISTH underscore the potential for Hemab's impact in addressing the severe unmet needs of people with bleeding disorders," said Kate Madigan, Chief Medical Officer at Hemab. "Our sutacimig and HMB-002 data reveal important progress towards transformative, preventative solutions for these devastating diseases. We're demonstrating the possibilities to meaningfully reduce bleeding and elevate care for people living with Glanzmann thrombasthenia and Von Willebrand disease."

Highlights of Clinical Presentations

Sutacimig shows promising safety and efficacy in Glanzmann thrombasthenia (GT). The Phase 2 study is fully enrolled (N=34 in Part B), and data show a clinically meaningful reduction in treated bleeding events.

• Clinically meaningful bleeding reduction: Sutacimig treatment in the efficacy population (n=33) demonstrated a >50% reduction in median Annualized Treated Bleeding Rate (ATBR), with the median ATBR decreasing from 21.2 to 4.61. Select patient reports indicate a reduced severity of bleeds and decreased IV rFVIIa use.
• Safety profile: Sutacimig demonstrated a favorable safety profile, with most adverse events (AEs) being mild to moderate in severity, and no reported thromboses or discontinuations due to AEs in ongoing dose levels of 0.3 and 0.6 mg/kg.
• PK/PD insights: At ongoing dose levels of 0.3 and 0.6 mg/kg, Factor VIIa (FVIIa) accumulation reached 2-4 fold above baseline. Exploratory thrombin generation assays suggested hemostatic activity, with observed improvements comparable to those seen with clinically relevant concentrations of rFVIIa.

Late Breaking Abstract presentation of HMB-002 demonstrates positive proof of mechanism in Von Willebrand disease (VWD), with the first-in-human VELORA Pioneer study in Type 1 VWD patients.

• Favorable safety profile: No treatment-emergent AEs, injection-site reactions, hypersensitivity, or serious AEs were reported in the VELORA Pioneer Cohort A1.
• Encouraging endogenous Von Willebrand Factor (VWF) and FVIII accumulation: The VELORA Pioneer study demonstrated that the initial single 20mg subcutaneous dose of HMB-002 induced consistent and sustained increases in VWF and Factor VIII FVIII levels. Within 14 days, mean VWF rose >1.5-fold from baseline.
• Normalized APTT and improved thrombin generation: Parallel to the increases in VWF, levels of Factor VIII were corrected, resulting in normalization in APTT and thrombin generation.

Preclinical data highlights

• Sutacimig enhances rFVIIa efficacy in in vitro studies, enabling potentially lower doses for breakthrough bleeds. Studies also show sutacimig preserves the function of stored platelet concentrates (PCs), supporting its mechanism that could reduce both rFVIIa doses and PC volumes needed for bleeding control.
• Nonclinical safety evaluations of HMB-002 in cynomolgus monkeys and in vitro/ex vivo assays showed no adverse effects, immunotoxicity (including complement and platelet activation or cytokine release), or off-target binding, indicating a favorable safety profile.
• Extended half-life and infrequent dosing: Pharmacokinetic modeling estimated a long HMB-002 half-life, supporting infrequent subcutaneous dosing. In studies with cynomolgus monkeys, HMB-002 also extended exogenously administered recombinant VWF's half-life, leading to the time-dependent accumulation of endogenous VWF and FVIII, and resulted in an approximately 3-fold prolongation of recombinant VWF in circulation.

Natural history highlights

• GT: Recent findings complementing previous natural history data confirm the severe, often underestimated disease burden of GT. The ATHN Transcends GT study quantifies this with a mean Annualized Bleeding Rate (ABR) of 72.0, with most bleeds requiring treatment (ATBR of 51.9) and 56% of participants experiencing a severe disease burden. A separate retrospective analysis of US-based real-world patient records reveals how this frequent blood loss initiates a self-perpetuating cycle of blood loss and iron deficiency anemia that worsens complications for all patients. This cycle creates a disproportionate unmet need for women, who report high rates of hemorrhage (75%) and anemia (23%), often triggered by heavy menstrual bleeding. Men are also heavily burdened, with significantly higher rates of gastrointestinal bleeding (36%) and hematomas (30%). A systematic care gap compounds the clinical crisis: management is mainly limited to on-demand treatments administered post-bleed, and a large proportion of patients are cared for outside of specialized hematology centers, contributing to ongoing underdiagnosis and underestimation of disease prevalence. This highlights a critical need for improved access to expert care and effective prophylactic therapies for all individuals with GT.
• VWD: New lived-experience data from the VWD360 study reveals a much higher than previously reported unmet need in VWD, highlighting a significant socioeconomic and psychological burden, especially the disproportionate impact on women suffering from heavy menstrual bleeding. The study found that participants averaged 1.33 bleeds weekly, with 71% missing work and high rates of low mood (73%). Crucially, data from a VWD360 substudy and VELORA Discover challenge historical assumptions, showing Type 1 VWD bleeding rates are comparable to, or even higher than, other subtypes, revealing a major care gap for this neglected patient population.

Benny Sorensen, MD, PhD, CEO of Hemab, stated, "Our multiple ISTH presentations underscore Hemab's commitment to leveraging the biotechnological revolution and deep hemostasis expertise to develop innovative prophylactic therapies for patients with bleeding disorders. Our dedication to always listening to the people living with these diseases has generated extensive natural history data revealing substantially greater unmet medical need than previously recognized, driving our continued clinical advancement."

About Glanzmann Thrombasthenia
Glanzmann thrombasthenia (GT) is a severe bleeding disorder marked by debilitating, sometimes life-threatening bleeding episodes. Results from an international Glanzmann's 360 (GT360) natural history study revealed the substantial burden of this disease: 88% of the 117 participants reported at least one bleed in the previous week, with 34% of those bleeds requiring medical treatment. These bleeding episodes significantly impact patients' mental health and quality of life, with 67% reporting low mood, 52% reporting emotional problems, and 46% experiencing social isolation. Additionally, 81% of participants reported missing school or work due to bruising or bleeding. To date, there are no effective prophylactic treatment options for GT.

About Sutacimig (formerly HMB-001)
Sutacimig is a subcutaneously administered bispecific antibody that binds and stabilizes endogenous Factor VIIa with one antibody arm and binds to TLT-1 on activated platelets with the other arm. This mechanism allows for the accumulation of endogenous Factor VIIa in the body and recruitment of Factor VIIa directly to the surface of the activated platelets, where it facilitates hemostatic plug formation. Sutacimig is designed to be a first-in-class prophylactic treatment for Glanzmann thrombasthenia (GT) with the potential to treat other debilitating bleeding disorders. The U.S. Food and Drug Administration granted Fast Track Designation and Orphan Drug Designation to sutacimig for the treatment of GT while the UK Medicines and Healthcare products Regulatory Agency has awarded it designation under the Innovative Licensing and Access Pathway (ILAP). For more information, please visit clinicaltrials.gov (NCT06211634).

About Von Willebrand Disease
Von Willebrand Disease (VWD) is the most common inherited bleeding disorder, characterized by quantitative or qualitative defects in Von Willebrand Factor (VWF), often resulting in frequent mucocutaneous bleeding events and heavy menstrual bleeding in women. The severity of bleeding ranges from low-volume events to potentially life-threatening hemorrhages. Chronic blood loss frequently leads to iron deficiency anemia, exacerbating the disease burden and reducing quality of life, particularly for those with clinically understated subtypes. Despite its prevalence, current treatment options for VWD primarily focus on managing symptoms rather than addressing the underlying defect in VWF production or function.

About HMB-002
HMB-002 is a monovalent human antibody developed as the first-in-class prophylactic treatment for Von Willebrand Disease targeting the underlying root cause of the disease, a condition driven by a deficiency or defect in Von Willebrand Factor (VWF), a key regulator of hemostasis. By specifically targeting the C-terminal CK domain of VWF, which is distinct from regions critical to its essential interactions, HMB-002 shields the protein from degradation, boosting endogenous levels without compromising its function. Clinical and nonclinical data suggest strong potential for meaningful therapeutic benefit. For more information, please visit clinicaltrials.gov (NCT06610201 and NCT06754852).

About Hemab Therapeutics
Hemab is a multiple clinical-asset biotechnology company developing novel prophylactic therapeutics for serious, underserved bleeding and thrombotic disorders. Based in Cambridge, MA, and Copenhagen, Denmark, Hemab is progressing a pipeline of innovative therapeutic solutions, leveraging a variety of cutting-edge technologies and approaches to transform the treatment paradigm for patients with high unmet need. The company's strategic guidance, Hemab 1-2-5^TM, targets building a pipeline of development programs to deliver long-awaited innovation for patients with high unmet need diseases like Glanzmann thrombasthenia, Factor VII Deficiency, Von Willebrand Disease, and others. Learn more at hemab.com. Follow us on LinkedIn, Facebook, Instagram, and X.

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SOURCE Hemab Therapeutics