Anti-human MUC1 Fab Fragment Binding and Renal Excretion
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Solution Overview
Problem
Monovalent Fab fragments have attenuated binding activity due to being monovalent and suffer from rapid renal excretion, leading to short half-life and reduced effectiveness as diagnostic and therapeutic agents for cancer, particularly in visualizing cancer lesions and delivering targeted treatments.
Innovation Solution
Development of an anti-human MUC1 antibody Fab fragment with enhanced binding activity, comprising specific heavy and light chain variable regions that maintain affinity even after labeling with fluorescent dyes or chelating agents, allowing for effective cancer diagnosis and treatment by accumulating in cancer foci within 24 hours post-administration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If monovalent Fab fragments are used, then tissue penetration is improved, but binding activity is attenuated
Solution Approach 1:
The patent divides the antibody into separate heavy and light chain variable regions that can be independently optimized. The Fab fragment is segmented to contain only the antigen-binding portions (VH and VL domains) without the Fc region, enabling improved tissue penetration while maintaining binding activity through careful selection of variable region sequences
Solution Approach 2:
The patent changes the molecular parameters of the antibody by creating Fab fragments with specific amino acid sequences in the variable regions. By modifying the structural parameters (molecular weight, charge distribution, hydrophobicity) of the Fab fragment while maintaining the antigen-binding complementarity, the patent achieves both improved penetration and preserved binding activity
2Loss of substance
If Fab fragments are used, then renal excretion is reduced, but half-life is shortened
Solution Approach 1:
The patent modifies the physicochemical parameters of the Fab fragment including molecular weight, charge, and hydrophobicity by selecting specific variable region sequences. These parameter changes reduce renal filtration while the engineered sequences also promote renal reabsorption, thereby extending half-life without requiring PEGylation or Fc fusion
Solution Approach 2:
Instead of using expensive whole antibodies with long half-lives, the patent employs shorter-lived Fab fragments that are rapidly cleared but can be readministered. The reduced renal excretion of these Fab fragments extends their effective duration without requiring complex molecular modifications
3Measurement precision
If Fab fragments are labeled with fluorescent dyes or chelating agents, then diagnostic capability is improved, but binding activity is reduced
Solution Approach 1:
The patent performs preliminary optimization of the Fab fragment variable regions before labeling. By pre-selecting sequences with high affinity and stability, the Fab fragment can tolerate the attachment of fluorescent dyes or chelating agents without significant loss of binding activity. The labeling is done at predetermined sites that minimize interference with the antigen-binding interface
Data Source
AI summary
The problem to be solved is to provide an anti-human MUC1 antibody Fab fragment that is expected to be useful in the diagnosis and/or treatment of a cancer, particularly, the diagnosis and/or treatment of breast cancer or bladder cancer, and a diagnosis approach and/or a treatment approach using a conjugate comprising the Fab fragment. The solution is an anti-human MUC1 antibody Fab fragment comprising a heavy chain fragment comprising a heavy chain variable region consisting of the amino acid sequence represented by SEQ ID NO: 8 or 10, and a light chain comprising a light chain variable region consisting of the amino acid sequence represented by SEQ ID NO: 12, and a conjugate comprising the Fab fragment.