7AHV image
Entry Detail
PDB ID:
7AHV
Keywords:
Title:
Anti-FIXa Fab of mim8 in complex with human FIXa
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2020-09-25
Release Date:
2021-07-07
Method Details:
Experimental Method:
Resolution:
3.11 Å
R-Value Free:
0.28
R-Value Work:
0.22
R-Value Observed:
0.22
Space Group:
P 41 2 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:anti-FIXa Fab of mim8 heavy chain
Chain IDs:A
Chain Length:224
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:anti-FIXa Fab of mim8 light chain
Chain IDs:B
Chain Length:214
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Coagulation factor IX
Chain IDs:D (auth: H)
Chain Length:235
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Coagulation factor IX
Chain IDs:C (auth: L)
Chain Length:59
Number of Molecules:1
Biological Source:Homo sapiens
Primary Citation

Abstact

Hemophilia A is a bleeding disorder resulting from deficient factor VIII (FVIII), which normally functions as a cofactor to activated factor IX (FIXa) that facilitates activation of factor X (FX). To mimic this property in a bispecific antibody format, a screening was conducted to identify functional pairs of anti-FIXa and anti-FX antibodies, followed by optimization of functional and biophysical properties. The resulting bispecific antibody (Mim8) assembled efficiently with FIXa and FX on membranes, and supported activation with an apparent equilibrium dissociation constant of 16 nM. Binding affinity with FIXa and FX in solution was much lower, with equilibrium dissociation constant values for FIXa and FX of 2.3 and 1.5 µM, respectively. In addition, the activity of Mim8 was dependent on stimulatory activity contributed by the anti-FIXa arm, which enhanced the proteolytic activity of FIXa by 4 orders of magnitude. In hemophilia A plasma and whole blood, Mim8 normalized thrombin generation and clot formation, with potencies 13 and 18 times higher than a sequence-identical analogue of emicizumab. A similar potency difference was observed in a tail vein transection model in hemophilia A mice, whereas reduction of bleeding in a severe tail-clip model was observed only for Mim8. Furthermore, the pharmacokinetic parameters of Mim8 were investigated and a half-life of 14 days shown in cynomolgus monkeys. In conclusion, Mim8 is an activated FVIII mimetic with a potent and efficacious hemostatic effect based on preclinical data.

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Primary Citation of related structures