scFv-Transferrin Fusion Protein With Cleavable Linker for Transcytosis

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Solution Overview

Problem

Many antibodies face challenges in crossing biological barriers and delivering therapeutic agents effectively due to their size and the unnecessary activation of immune responses mediated by the Fc region, limiting their efficacy and application in certain tissues and diseases.

Innovation Solution

Designing a single-chain variable fragment (scFv) conjugated with the N-methyl lobe of transferrin protein, utilizing environment-sensitive linkers to facilitate transcytosis and targeted delivery across barriers like the blood-brain or blood-eye barrier, ensuring specific release of the therapeutic agent within target cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If whole antibodies are used for therapeutic delivery, then immune effector functions and half-life are enhanced, but penetration across biological barriers is reduced

Engineering Contradiction:

Improveimmune effector functionVSAvoidpenetration ability

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The antibody is segmented into its functional components: the scFv region retains antigen binding and effector functions while the Fc region is removed. This segmentation allows the therapeutic agent to maintain immune functionality while achieving better penetration across biological barriers due to its smaller size.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The Fc region is extracted from the complete antibody structure. By removing the Fc region that mediates immune effector functions, the invention creates a scFv-based fusion protein that can be engineered to achieve enhanced penetration while retaining necessary therapeutic activities through alternative mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

2Duration of action of stationary object

If Fc region is retained in antibodies, then half-life is prolonged, but transcytosis promotion is reduced

Engineering Contradiction:

Improvehalf-lifeVSAvoidtranscytosis efficiency

Core Design Contradiction:

Duration of action of stationary objectVSProductivity

Solution Approach 1:

Transferrin is introduced as an intermediary molecule that mediates transcytosis across biological barriers. The scFv is fused to transferrin, creating a fusion protein that utilizes transferrin's ability to promote transcytosis while the scFv portion maintains antigen binding and can be engineered for appropriate circulation characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Length of moving object

If scFv is used instead of whole antibody, then penetration and transcytosis are improved, but manufacturing complexity increases

Engineering Contradiction:

Improvepenetration abilityVSAvoidmanufacturing complexity

Core Design Contradiction:

Length of moving objectVSDevice complexity

Solution Approach 1:

The scFv antigen-binding fragment is merged with the transferrin molecule to create a single fusion protein. This merging simplifies manufacturing by producing one unified therapeutic agent rather than requiring separate administration of antibody fragments and transferrin, while maintaining the penetration advantages of scFv structure.

Inventive Principle:

Principle #5Merging (Combining)

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

Enhances the delivery and efficacy of therapeutic antibodies by improving penetration, reducing off-target effects, and extending circulation time, allowing for controlled release and targeted action within specific cellular environments.

Implementation Method 1

The smaller size of scFv, around 25-30 kDa, about 15% of the total antibody, allows for easier penetration in tissues and, in many instances, less hindered binding to the target protein. These property attributes are critical to discovering new indications, better safety profiles, and greater manufacturing ease and cost

Methodology Applied

Scientific EffectTranscytosis:

Implementation Method 2

utilizing environment-sensitive linkers to facilitate transcytosis and targeted delivery across barriers like the blood-brain or blood-eye barrier

Methodology Applied

Scientific EffectReceptor-mediated endocytosis:

Implementation Method 3

Methodology Applied

Scientific EffectEnvironment-sensitive linker cleavage:

Data Source

PatentUS20260049129A1Single-chain ranibizumab antibody-transferrin fusion protein for enhanced efficacy and indications

Publication Date: 2026.02.19 RNA THERAPEUTICS INC

AI summary

The efficacy and indication of ranibizumab 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.