Bispecific Antibodies Targeting TFPI Epitopes for Hemophilia Treatment
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Solution Overview
Problem
Current antibodies targeting tissue factor pathway inhibitor (TFPI) have limitations, including incomplete inhibition of TFPI's inhibitory functions, especially at elevated concentrations, and can cause TFPI accumulation in circulation, leading to prolonged drug half-lives and higher doses, with existing antibodies failing to completely neutralize TFPIα activity.
Innovation Solution
Development of bispecific antibodies that specifically bind to two epitopes on TFPI, one in the KPI-1/KPI-2 region and another in the KPI-3 region, allowing for enhanced inhibition of TFPIα activity, even at elevated concentrations, and reducing binding to TFPIβ to minimize drug disposition issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single epitope-targeting antibodies are used to inhibit TFPI, then TFPI inhibition is achieved, but incomplete neutralization occurs especially at elevated concentrations
Solution Approach 1:
The patent combines two separate antibody specificities into a single bispecific antibody molecule that simultaneously targets two different epitopes on TFPI (one in the KPI-1/KPI-2 region and another in the KPI-3 region). This merging approach allows the single antibody to neutralize TFPIα activity more completely, especially at elevated concentrations, by blocking multiple functional domains of TFPI simultaneously.
Solution Approach 2:
The bispecific antibody is designed to perform multiple functions: it binds to two distinct epitopes on TFPI, neutralizes TFPIα activity through dual-site blocking, and selectively targets full-length TFPIα while minimizing binding to TFPIβ. This multi-functionality enables more reliable TFPI inhibition across a broader range of concentrations with a single agent.
2Reliability
If single epitope antibodies bind TFPI, then TFPI is inhibited, but TFPI accumulates in circulation leading to prolonged drug half-life
Solution Approach 1:
By merging two epitope-specific binding regions into one bispecific antibody, the patent achieves more complete TFPI neutralization that prevents TFPI accumulation in circulation. The dual-epitope binding ensures that even when one binding site is occupied, the other continues to enforce inhibition, preventing the feedback accumulation seen with single-epitope antibodies.
Solution Approach 2:
The patent changes the binding parameters by targeting two different epitopes with different affinities and functional roles. The first epitope in the KPI-1/KPI-2 region and the second epitope in the KPI-3 region provide complementary binding that alters the overall interaction kinetics, preventing TFPI accumulation and reducing drug half-life to more physiologically appropriate levels.
3Reliability
If antibodies target TFPI broadly, then TFPI inhibition occurs, but selectivity between TFPIα and TFPIβ is reduced
Solution Approach 1:
The bispecific antibody applies local quality by targeting specific regions of TFPI with different binding characteristics. The first epitope in the KPI-1/KPI-2 region and the second epitope in the KPI-3 region are strategically chosen to differentiate between TFPIα and TFPIβ isoforms, enabling selective neutralization of TFPIα while minimizing off-target effects on TFPIβ.
Solution Approach 2:
The asymmetric design of the bispecific antibody, with one arm targeting the N-terminal KPI-1/KPI-2 region and the other targeting the C-terminal KPI-3 region, exploits structural differences between TFPIα and TFPIβ. This asymmetric epitope pairing provides enhanced selectivity for TFPIα, which has both regions intact, versus TFPIβ which lacks the C-terminal basic region.
Data Source
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AI summary
The application discloses a combination of two monospecific TFPI antibodies, wherein one antibody is capable of specifically binding TFPI (1-181) and the other antibody is capable of specifically binding TFPI (182-276), as well as bispecific anti-TFPI antibodies derived from two such monospecific antibodies. Both the combination of the two monospecific antibodies and the bispecific antibody strongly enhance thrombin generation by neutralising full length TFPIα, even where the concentration of TFPI is abnormally elevated.