NXT007-mediated hemostatic potential is suppressed by activated protein C-catalyzed inactivation of activated factor V

• Published in: Research and practice in thrombosis and haemostasis Vol. 8; no. 1; p. 102271
• Main Authors: Nakajima, Yuto, Ogiwara, Kenichi, Inaba, Keito, Kitazawa, Takehisa, Nogami, Keiji
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2024; Elsevier
• Subjects: antibodies; anticoagulants; factor V; factor VIII; hemophilia A; Original; anticoagulants; hemophilia A; antibodies; factor VIII; factor V
• ISSN: 2475-0379; 2475-0379
• DOI: 10.1016/j.rpth.2023.102271

Activated protein C (APC) inactivates activated factor (F) V (FVa) and FVIIIa. NXT007, an emicizumab-based engineered therapeutic bispecific antibody, enhances the coagulation potential of FVIII-deficient plasma (FVIIIdef-plasma) to near normal levels. However, little is known about the effect of APC-induced inactivation in NXT007-mediated hemostatic function. To investigate the contribution of APC-mediated reactions to NXT007-driven hemostasis. In pooled normal plasma (PNP) or FVIIIdef-plasma spiked with NXT007 (10 μg/mL), effects of APC (0-16 nM) were measured using a thrombin generation assay (TGA). The direct effects of APC on cofactor activity of NXT007 or FVIIIa in a FXa generation assay were also measured. The FVdef-plasma and FV Leiden plasma (FVLeiden plasma) were preincubated with 2 anti-FVIII monoclonal antibodies (termed FVIII-depleted), and the APC effect in the presence of NXT007 in FVIII-depleted FVdef-plasma with the addition of exogenous FV (7.5-30 nM) or FVIII-depleted FVLeiden plasma was investigated. The APC dose-dependent suppression effect in TGA of FVIIIdef-plasma spiked with NXT007 was similar to that of PNP. FXa generation with NXT007 was not impaired by the addition of APC, suggesting that the APC-induced reaction in TGA with NXT007 was attributed to the direct inactivation of FVa. The addition of APC to FVIII-depleted FVdef-plasma, along with NXT007 and various FV concentrations, showed a similar attenuation to PNP. The NXT007-driven thrombin generation in FVIII-depleted FVLeiden plasma was suppressed by APC, similar to the reaction in native FVLeiden plasma. NXT007 did not impair APC-mediated downregulation of FVa in FVIIIdef-plasmas, regardless of the presence of FV mutation with APC resistance. •NXT007 raises the coagulation function in patients with hemophilia A (PwHA) to a normal level.•The activated protein C (APC)-mediated regulation of NXT007-driven hemostasis in PwHA remains to be examined.•APC suppressed the coagulation potential in PwHA with NXT007 and in normal plasma.•APC can regulate the coagulation function of PwHA with NXT007 through factor Va inactivation.