scFv-Transferrin Fusion With Cleavable Linker for Brain Delivery
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Solution Overview
Problem
Many antibodies face challenges in crossing biological barriers such as the blood-brain barrier and blood-eye barrier, and entering cancerous cells, reducing their efficacy and finding new applications due to the unnecessary activation of immune responses mediated by the Fc region, which is not required for initial binding to target proteins.
Innovation Solution
A single-chain variable fragment (scFv) is designed to retain antigen-binding properties without the Fc region, conjugated with the N-methyl lobe of transferrin protein to enhance transcytosis, using environment-sensitive linkers for targeted and controlled release within specific cellular environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Fc region is retained in the antibody structure, then immune effector functions (ADCC, ADCP) are activated, but this causes unnecessary immune responses and reduced efficacy when Fc function is not required
Solution Approach 1:
The invention extracts and removes the Fc region from the antibody structure, retaining only the scFv portion that contains the antigen-binding capability. This extraction eliminates the source of unnecessary immune responses while preserving the therapeutic function of binding to target proteins.
2Reliability
If the antibody uses transcytosis to cross biological barriers, then delivery efficacy is improved, but the molecular size and complexity increase
Solution Approach 1:
The invention merges the scFv antigen-binding fragment with the transferrin protein, creating a fusion construct that combines the small size advantage of scFv with the transcytosis capability of transferrin. This merging enables barrier crossing without requiring the full antibody structure.
Solution Approach 2:
The transferrin protein acts as an intermediary that facilitates transcytosis across biological barriers. By conjugating scFv to transferrin, the intermediary enables the antigen-binding fragment to cross barriers like the blood-brain barrier that it could not cross alone.
3Manufacturing precision
If environment-sensitive linkers are used for controlled release, then targeted delivery is improved, but the manufacturing complexity increases
Solution Approach 1:
The invention uses environment-sensitive linkers that change their state based on environmental parameters such as pH or enzymatic conditions. These linkers remain stable during manufacturing and conjugation but automatically cleave or change conformation in the target environment, enabling controlled release without complex manufacturing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The scFv-conjugate achieves enhanced delivery across biological barriers, improves therapeutic efficacy by reducing off-target effects, and allows for longer circulation and targeted delivery to target tissues, overcoming resistance mechanisms and enhancing metabolic activity in cancer cells.
Implementation Method 1
Many of these antibodies cross cell walls that can be challenging, reducing their efficacy, such as antibodies crossing the blood-brain barrier, the blood-eye barrier and also entering cancerous cells, among many other situations where transcytosis promotion can increase their efficacy
Implementation Method 2
conjugated with the N-methyl lobe of transferrin protein to enhance transcytosis, using environment-sensitive linkers for targeted and controlled release within specific cellular environments
Data Source
AI summary
The efficacy and indication of donanemab do not depend on the Fc region and are subject to transit across cell walls. They can be expanded by using their scFvs conjugated with N-methyl lobe of transferrin protein connected with an environment-sensitive cleavable linker to prevent exocytosis of the scFv yielding high exposure inside body cells such as in the brain, eye, and cancer cells that overexpress transferrin receptors.