FVIII-VWF Chimeric Protein Architecture for Longer Half-Life
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Solution Overview
Problem
Current Factor VIII (FVIII) products have a short half-life, requiring frequent intravenous administration, which is inconvenient and necessitates the development of a FVIII product with a longer half-life to reduce dosing frequency.
Innovation Solution
A chimeric protein is developed by fusing Factor VIII with von Willebrand Factor (VWF) through an XTEN sequence, where the XTEN sequence contains less than 288 amino acids, and optionally includes Ig constant regions and additional XTEN sequences, linked by cleavable linkers, to enhance stability and prolong half-life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If FVIII is modified using pegylation, glycopegylation, or conjugation with albumin to extend half-life, then the half-life is extended to about 1.5 to 2 hours in preclinical models and up to 1.7 fold in humans, but the improvement is limited and other T1/2 limiting factors remain
Solution Approach 1:
The patent combines FVIII with VWF to form a heterodimeric complex, merging two proteins that naturally interact in vivo. This fusion leverages the natural protective effect of VWF on FVIII, extending half-life to greater than 2-fold without requiring complex chemical modifications like pegylation or albumin conjugation. The XTEN linker facilitates this merger while maintaining flexibility and solubility.
Solution Approach 2:
The invention creates a composite protein structure consisting of FVIII fused to VWF domains (D' and/or D3) via an XTEN linker. This composite achieves extended half-life by combining the hemostatic function of FVIII with the circulation-prolonging properties of VWF, avoiding the need for synthetic polymer attachments while achieving superior half-life extension compared to pegylation approaches.
2Duration of action of moving object
If FVIII is fused to Ig constant regions and VWF domains with XTEN linker to extend half-life, then half-life is extended greater than 2-fold, but the molecular complexity and structural design become more complex
Solution Approach 1:
The VWF component is segmented into specific domains (D' and/or D3) rather than using full-length VWF, reducing overall molecular complexity while retaining the half-life extending function. The XTEN linker is inserted at specific locations within the FVIII sequence to achieve the desired structural configuration without excessive complexity.
Solution Approach 2:
The XTEN linker serves multiple functions: it provides solubility, maintains flexibility, enables proper folding of the chimeric protein, and facilitates the interaction between FVIII and VWF domains. This multi-functional element achieves half-life extension without requiring complex structural design elsewhere in the molecule.
3Reliability
If frequent intravenous administration is used to maintain appropriate FVIII levels, then therapeutic efficacy is maintained, but patient convenience and treatment compliance deteriorate
Solution Approach 1:
The invention changes the pharmacokinetic parameter of FVIII half-life from 8-12 hours to greater than 2-fold extension through fusion with VWF domains. This parameter change directly reduces dosing frequency while maintaining therapeutic efficacy, improving patient convenience without compromising treatment reliability.
Data Source
AI summary
The present invention provides a chimeric protein comprising a first polypeptide which comprises a FVIII protein and a first Ig constant region or a portion thereof and a second polypeptide which comprises a VWF protein comprising the D′ domain and D3 domain of VWF, a XTEN sequence having less than 288 amino acids in length, and a second Ig constant region or a portion thereof, wherein the first polypeptide and the second polypeptide are associated with each other. The invention also includes nucleotides, vectors, host cells, methods of using the chimeric proteins.