Peptide Epitope Tags for Low-Immunogenic Engineered Cell Tracking
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Solution Overview
Problem
Existing epitope tags for engineered immune cells, such as CAR-T cells, are large, immunogenic, and disrupt protein function or signaling, posing regulatory hurdles and safety concerns.
Innovation Solution
A small, hypoimmunogenic peptide epitope tag (SHARP-tag) and its binding agent (SABR) system, allowing for minimal disruption and reliable detection, purification, and modulation of engineered cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large protein tags (e.g., tEGFR, RQR8) are used for cell selection and tracking, then reliable detection and purification are achieved, but the tag size adds complexity and expression burden
Solution Approach 1:
The patent extracts only the essential binding epitope from large protein tags like tEGFR and RQR8, creating a minimal peptide version (5-20 amino acids) that retains the ability to be recognized by clinical antibodies. This extraction eliminates unnecessary protein structure while preserving the core function of detection and selection.
Solution Approach 2:
The patent changes the size parameter of the tag from large protein (100-200 amino acids) to small peptide (5-20 amino acids), and modifies the immunogenicity parameter by selecting epitopes from human proteins or using humanized sequences. This transforms the tag into a minimal functional unit that reduces expression burden while maintaining reliability.
2Adaptability or versatility
If foreign epitope tags are introduced into engineered cells, then detection and selection capabilities are improved, but immunogenicity may provoke immune neutralization
Solution Approach 1:
The patent applies local quality by selecting epitopes from specific regions of human proteins (e.g., CD34, CD20) that are known to be low immunogenicity. The epitope sequences are optimized locally to match human protein sequences, creating a tag that is biocompatible and unlikely to trigger immune responses while maintaining detection capability.
Solution Approach 2:
The patent converts the potential harm of foreign epitopes into a benefit by using human protein epitopes that are already present in normal human cells. This approach turns what would be immunogenic foreign sequences into benign human sequences that can still serve as detection targets, thereby eliminating the immune neutralization risk.
3Reliability
If epitope tags are inserted into CAR polypeptides, then tracking and selection are enabled, but improper placement can sterically hinder antigen binding or signaling
Solution Approach 1:
The patent segments the CAR polypeptide into distinct functional domains (antigen binding domain, transmembrane domain, intracellular signaling domain) and places the epitope tag in specific segments (usually N-terminal or C-terminal extracellular regions) where it is most likely to be exposed and accessible. This segmentation allows optimization of tag placement to avoid interference with critical functional regions.
Solution Approach 2:
The patent uses partial action by inserting only a minimal epitope sequence (5-20 amino acids) rather than a full protein tag, reducing the likelihood of steric hindrance. The small size of the peptide tag means it occupies minimal space on the CAR surface, allowing it to be detected without blocking antigen binding or signaling functions.
4Object-affected harmful factors
If clinically approved antibodies are used to recognize epitope tags, then safety for human use is improved, but regulatory hurdles arise for clinical application
Solution Approach 1:
The patent creates a universal system where a single epitope tag design can be recognized by multiple clinically approved antibodies (e.g., anti-CD34, anti-CD20). This multi-functionality allows the same tag to enable both detection and selective depletion using different approved reagents, simplifying regulatory compliance by leveraging existing approved therapies rather than requiring new ones.
Solution Approach 2:
The patent uses the epitope tag as an intermediary element that bridges the engineered cell and the clinically approved antibody. The tag is derived from human proteins, making it biocompatible, and serves as a target that can be recognized by existing therapeutic antibodies, thereby enabling safe clinical application without requiring novel regulatory approvals for the tag itself.
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 SHARP-tag system provides a compact, safe, and versatile marker for engineered cells, enabling robust tracking, selection, and on-demand regulation, overcoming regulatory and immunogenicity issues.
Implementation Method 1
a binding agent (SABR) that specifically binds to the peptide epitope tag (SHARP-tag)
Data Source
AI summary
The application provides novel peptide epitope tags and recombinant polynucleotide, polypeptides, vectors, cells and compositions comprising the tags. The application also provides novel designs for synthetic antigen receptors (SARs), novel antigen binding domains, novel SAR constructs and novel methods for manufacturing of cell therapy products. These novel methods and compositions have broad uses in cellular therapy.