Engineered Protein Scaffolds for Tissue Penetration and Stability
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Solution Overview
Problem
Conventional antibodies face limitations such as poor extravasation, tissue penetration, long plasma clearance, thermal instability, and complex structures that hinder their effectiveness in diagnostic and therapeutic applications, particularly in targeting solid tumors and intracellular use.
Innovation Solution
Development of non-naturally occurring protein scaffolds with structural domains and loop regions that can be engineered for high affinity and specificity, allowing for targeted binding and stability, and can be produced in bacterial systems without disulfide bonds, facilitating intracellular use and improved biodistribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional antibodies are used for targeting, then binding specificity can be achieved, but extravasation and tissue penetration are poor
Solution Approach 1:
The patent segments the antibody structure by using only the variable domains (scFv or single-domain antibodies) rather than the complete antibody molecule. This segmentation reduces the overall size from the full antibody length to just the antigen-binding portion, enabling better tissue penetration while preserving binding specificity through the intact variable region structure.
Solution Approach 2:
The patent extracts and removes the Fc region and constant domains from the complete antibody structure, retaining only the variable domains that are responsible for antigen binding. This extraction eliminates the bulky portions that hinder tissue penetration while maintaining the essential binding function through the preserved variable regions.
2Reliability
If conventional antibodies are used, then binding affinity can be achieved, but plasma clearance time is prolonged
Solution Approach 1:
The patent removes the Fc region from the antibody structure, extracting only the variable domains that provide binding affinity. This extraction eliminates the portions responsible for prolonged plasma clearance while retaining the antigen-binding capability through the variable regions, resulting in faster clearance and reduced background signal.
3Reliability
If conventional antibodies are used, then therapeutic effect can be achieved, but thermal stability is poor
Solution Approach 1:
The patent adopts a disposable approach by using single-domain antibodies that are designed for stability and can be produced recombinantly. These simplified structures are inherently more stable than full antibodies and can be engineered for enhanced thermal stability through directed evolution or rational design, while their smaller size allows for easier production and formulation.
Solution Approach 2:
The patent applies parameter changes by modifying the antibody structure from full-length to single-domain formats, which fundamentally alters the thermal stability parameters. The single-domain structure lacks the complex quaternary structure of full antibodies that are prone to aggregation and degradation, resulting in improved thermal stability while maintaining therapeutic efficacy.
4Measurement precision
If conventional antibodies are used, then diagnostic capability can be achieved, but structural complexity increases
Solution Approach 1:
The patent segments the antibody into its functional components, using only the variable domains for diagnostic applications. This segmentation simplifies the overall structure from the complex full antibody to a streamlined single-domain format that is easier to produce, conjugate to imaging agents, and standardize across different diagnostic platforms while maintaining diagnostic precision.
Solution Approach 2:
The patent changes the structural parameters by adopting single-domain antibody formats that are inherently simpler than full antibodies. This parameter change reduces structural complexity, making the diagnostic agents easier to manufacture, store, and conjugate to imaging modalities, while the preserved variable regions maintain the necessary diagnostic capability through specific antigen recognition.
Data Source
AI summary
This disclosure describes non-naturally occurring protein scaffolds and methods of making and using the protein scaffolds. In one aspect, therefore, this disclosure describes a non-naturally occurring protein scaffold that includes a plurality of structural domains and a plurality of loop regions that include an amino acid sequence that varies from a naturally-occurring loop region by at least one amino acid deletion, substitution, or addition. Generally, the structural domain or domains can include at least one β structure and/or at least one a helix.