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Hemab Therapeutics, a biotech headquartered in Cambridge, Massachusetts, and Copenhagen, Denmark, announced receipt of US FDA Breakthrough Therapy Designation (BTD) for sutacimig, a subcutaneously administered bispecific antibody, for the prevention of bleeding episodes in patients with Glanzmann thrombasthenia (GT). Sutacimig, formerly designated HMB-001, binds and stabilizes endogenous Factor VIIa with one antibody arm while binding TLT-1 on activated platelets with the other, facilitating hemostatic plug formation. Hemab Therapeutics is a privately held company with no public stock ticker. BTD provides Hemab Therapeutics with intensive FDA guidance on drug development, organizational commitment from senior FDA managers, and eligibility for rolling review, which permits submission of completed sections of a marketing application before the entire filing is ready. Sutacimig’s clinical progress Sutacimig was originated and developed in-house by Hemab, which was founded in 2019 from academic research in Scandinavian coagulation biology. The BTD was granted on the basis of data from the completed Phase II multiple ascending dose portion of Hemab’s Phase I/II clinical trial (NCT06211634). In that study, the weekly dosing group achieved an estimated 87% reduction in annualized treated bleeding rate, with consistent reductions observed across bleed types, locations, and dosing cohorts. All tested doses produced over a 50% reduction in treated bleeding events. No major safety signals were reported in public disclosures from the Phase II portion. Hemab has stated plans to advance sutacimig into a pivotal Phase III study. Prior to this BTD, sutacimig had already received Fast Track Designation and Orphan Drug Designation from the FDA, orphan medicinal product designation in the European Union, and Innovative Licensing and Access Pathway (ILAP) designation from the UK Medicines and Healthcare products Regulatory Agency. Research context GT is a rare, inherited platelet disorder caused by deficiency or dysfunction of the glycoprotein IIb/IIIa complex, resulting in impaired platelet aggregation and recurrent, sometimes life-threatening bleeding. Data from the international GT360 natural history study reported that 88% of 117 participants experienced at least one bleed in the prior week, and 65% required a bleed-related hospital visit within six months. Over 80% had missed work or school, and more than 50% faced restrictions on social activities and travel. No prophylactic treatment for GT has received regulatory approval. The current standard of care relies on episodic, on-demand interventions, principally recombinant activated Factor VIIa (NovoSeven, Novo Nordisk) and platelet transfusions, neither of which was developed or approved as a prophylactic bleeding disorder treatment for GT. No novel drugs for GT have been approved in the past three years. The competitive landscape for therapies targeting von Willebrand factor or platelet glycoprotein receptors includes caplacizumab (an anti-vWF nanobody for thrombotic thrombocytopenic purpura), vonicog alfa (recombinant vWF for von Willebrand disease), and BT200 (a pegylated RNA aptamer targeting vWF). However, none of these molecules are in development for GT, and none share sutacimig’s bispecific mechanism simultaneously engaging Factor VIIa and activated platelet TLT-1. Unlike agents such as caplacizumab, which block vWF-platelet interactions to prevent pathological clotting, sutacimig is designed to promote hemostasis by concentrating endogenous Factor VIIa at the site of platelet activation — a mechanistically distinct, pro-hemostatic approach. No other bispecific antibody targeting both Factor VIIa and a platelet surface receptor for a pro-hemostatic indication was identified in active clinical development. Hemab’s pipeline also includes HMB-002 for von Willebrand disease and a Phase II trial of sutacimig in congenital Factor VII deficiency (NCT07347249), indicating broader ambitions for the bispecific platform across coagulation disorders. Your email address will not be published. Required fields are marked * Comment * Name * Email * Website