PB1003 - CT-001 is a Rapid Clearing Factor VIIa with Enhanced Hemostatic Activity and Safety in Mouse Models of Acute Bleeding

Background: Acute bleeding leads to significant morbidity and mortality. Recombinant wildtype Factor VIIa (WT FVIIa) had been reported to have some therapeutic effects in some clinical trials. However, its use was associated with thromboembolic events.

Aims: We sought to develop a novel FVIIa molecule (CT-001) with enhanced activity and lower thrombogenicity.

Methods: CT-001 has 4 N-glycans (T106N/N145/V253N/N322) with terminal sialic acid removed to promote active clearance via the asialoglycoprotein receptor, and P10Q/K32E substitutions introduced to its Gla-domain for enhanced phospholipid affinity and activity.

Results: In mice, CT-001 had half-lives of 0.048 h and 0.087 h and clearance of 963 mL/h/kg and 467 mL/h/kg at 1 and 3 mg/kg respectively, which were significantly faster than WT FVIIa (at 3 mg/kg, t1/2 = 1.8 h, Cl = 39 mL/h/kg). Interestingly, CT-001 was efficacious in reducing blood loss even with its rapid clearance. In a severe hemorrhage mouse model with tail amputated 5 cm from the tip, 1 mg/kg CT-001 treatment provided comparable efficacy as 3 mg/kg WT FVIIa (Fig 1). The fast clearance of CT-001 resulted in significantly reduced thrombogenicity in a FeCl3-induced carotid artery thrombosis mouse model (Fig 2). The low thrombogenicity of CT-001was further confirmed in a soluble tissue factor-induced thrombosis model. Mice treated with 1 and 3 mg/kg of WT FVIIa had significantly lower survival rates of 38.9% (P < 0.005, log rank test) and 35.0% (P < 0.0015) respectively, in comparison to the survival rate of 87% for the saline-treated mice. The survival rates with 1 and 3 mg/kg of CT-001 were 94.4% and 83.3% respectively.

Conclusion(s): The data on CT-001 demonstrate that a short duration of highly active FVIIa procoagulant activity can be an optimal treatment paradigm for acute bleeding.