A safeguard eliminates T cell receptor gene-modified autoreactive T cells after adoptive transfer

By transfer of T cell receptor (TCR) genes, antigen specificity of T cells can be redirected to target any antigen. Adoptive transfer of TCR-redirected T cells into patients has shown promising results. However, this immunotherapy bears the risk of autoreactive side effects if the TCR recognizes antigens on self-tissue. Here, we introduce a safeguard based on a TCR-intrinsic depletion mechanism to eliminate autoreactive TCR-redirected T cells in vivo. By the introduction of a 10-aa tag of the human c-myc protein into murine (OT-I, P14) and human (gp100) TCR sequences, we were able to deplete T cells that were transduced with these myc-tagged TCRs with a tag-specific antibody in vitro. T cells transduced with the modified TCR maintained equal properties compared with cells transduced with the wild-type receptor concerning antigen binding and effector function. More importantly, therapeutic in vivo depletion of adoptively transferred T cells rescued mice showing severe signs of autoimmune insulitis from lethal diabetes. This safeguard allows termination of adoptive therapy in case of severe side effects

MHC multimer-guided and cell culture-independent isolation of functional T cell receptors from single cells facilitates TCR identification for immunotherapy.

Adoptive therapy using T cells redirected to target tumor- or infection-associated antigens is a promising strategy that has curative potential and broad applicability. In order to accelerate the screening process for suitable antigen-specific T cell receptors (TCRs), we developed a new approach circumventing conventional in vitro expansion-based strategies. Direct isolation of paired full-length TCR sequences from non-expanded antigen-specific T cells was achieved by the establishment of a highly sensitive PCR-based T cell receptor single cell analysis method (TCR-SCAN). Using MHC multimer-labeled and single cell-sorted HCMV-specific T cells we demonstrate a high efficacy (approximately 25%) and target specificity of TCR-SCAN receptor identification. In combination with MHC-multimer based pre-enrichment steps, we were able to isolate TCRs specific for the oncogenes Her2/neu and WT1 even from very small populations (original precursor frequencies of down to 0.00005% of CD3(+) T cells) without any cell culture step involved. Genetic re-expression of isolated receptors demonstrates their functionality and target specificity. We believe that this new strategy of TCR identification may provide broad access to specific TCRs for therapeutically relevant T cell epitopes