1044P - UniTope & TraCR: Universal tagging and tracking system for TCR-T cells integrated directly in the TCR constant region

Background

For product development, GMP production, quality control for product release and immune monitoring of patient samples, three methods are typically used to identify rTCR expression in TCR-T populations: (1) detection of an extra tag that is co-expressed with the rTCR; (2) binding of antibodies specific for TCR Vß-chains, or (3) rTCR binding of peptide-HLA multimers. The latter two approaches must be tailored for each rTCR and high-quality reagents may not be readily available.

Methods

Using bioinformatics and 3D modeling of TCRs, novel synthetic epitopes were designed and inserted at different positions in multiple rTCR sequences. Internally tagged rTCRs were assessed for surface expression, functionality and target specificity, as well as for binding of an antibody (TraCR) detecting the synthetic epitopes of different length.

Results

Identifying a unique, synthetic epitope (UniTope) and optimal insertion sites localized in the rTCR constant regions permitted highly specific detection by the TraCR antibody. The UniTope & TraCR combination unambiguously distinguishes rTCRs expressed in recipient T cells from all endogenous TCRs found in PBL. The integrated UniTope tag exclusively binds TraCR antibody, and not alter functionality, established safety profiles or expression levels of any of the assessed rTCRs.

Conclusions

UniTope & TraCR is a universal detection system for rTCRs easy to adapt for multi-parameter flow cytometry. Seamless integration of UniTope in any rTCR structure bypasses need for co-expression of a separate gene sequence to universally tag rTCR-expressing T cells. Providing a standardized detection system, UniTope & TraCR simplifies supply and validation of quality control assays for TCR-T therapies covering all rTCRs, providing precise information for drug product dosing. It allows easy visualization, isolation and enrichment of TCR-T cells for direct study. GMP-grade TraCR can be applied for drug product enrichment and potentially also to trace TCR-T cell localization and persistence in vivo, supporting immune monitoring in patients. The UniTope & TraCR system is a high precision technology that facilitates optimized development of TCR-T therapies.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.