PhD Student University Hospital Heidelberg, United States
Introduction: 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.
Methods: In our project, we propose to identify T cell receptors (TCRs) specifically targeting autologous myeloma cells. Tumor-reactive T cells were identified using the Berkeley Lights 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, IL¬ 2) and measurement of 4-1BB (CD137) surface expression.
Results: Tumor-reactive T cells showing various cytokine secretion patterns and 4-1BB expression profiles were detected in each myeloma patient (7 to 26 cells of approx. 1500 cells tested per patient). 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 individual multiple myeloma patients to reveal gene expression signatures 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.
Conclusions: 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.
