Abstract 14: Identification of tumor-reactive T cell receptors through functional single cell interaction analyses for personalized T cell therapy

Abstract Innovative immunotherapy approaches such as adoptive transfer of chimeric antigen receptor (CAR) T cells or tumor infiltrating lymphocytes (TILs) have shown great success in the treatment of solid tumors and hematological malignancies. Although treatment of multiple myeloma with CAR T cells can induce deep responses, relapses frequently occur due to antigen escape and limited CAR T cell persistence. TCR-engineered T cells may show prolonged persistence in vivo and could mediate sustained antitumor effects. A further benefit of TCR transgenic T cells is the ability to target intracellular antigens that are inaccessible to CAR T cells, expanding the range of potential targets for immunotherapy. In our project, we propose to identify T cell receptors (TCRs) specifically targeting autologous myeloma cells. Tumor-reactive T cells were identified using the Bruker Cellular Analysis Lightning® platform, allowing simultaneous functional analysis of up to 1500 individual T cell/target cell interactions on a chip. Reactive T cells were identified upon detection of secreted cytokines (IFNγ, TNFα, IL2) and measurement of 4-1BB (CD137) surface expression. Tumor-reactive T cells showing various cytokine secretion patterns and 4-1BB expression profiles were detected in each myeloma patient (on average 11. 9 T cells out of 1243 cells tested per assay run). Individual tumor-reactive T cells have been isolated and their TCRs were sequenced. TCR sequences of tumor-reactive T cells were mapped to single-cell RNA sequencing data of T cells from the same patiens to reveal a gene expression signature of myeloma-reactive T cells. TCR genes of reactive T cells were cloned and overexpressed in autologous T cells for functional validation and analysis of tumor derived neoepitope specificity. In summary, we present a pipeline allowing identification of myeloma-recognizing T cells and recovery of bona fide tumor-reactive TCRs eligible for patient-individualized T cell therapy. Citation Format: Tim Robin Wagner, Niklas Kehl, Simon Steiger, Michael Kilian, Bruno Schönfelder, Tamara Boschert, Katharina Lindner, Patrick Schmidt, Karsten Rippe, Hartmut Goldschmidt, Marc-Steffen Raab, Michael Platten, Mirco Friedrich, Stefan B. Eichmüller. Identification of tumor-reactive T cell receptors through functional single cell interaction analyses for personalized T cell therapy abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 14.