TCR validation toward gene therapy for cancer.

The speed of T cell receptor (TCR) discovery has been revolutionized by barcode-based TCR sequencing approaches that allow the reconstitution of a T cell's paired alpha and beta TCR chain, and the process of TCR discovery promises to become ever faster and cheaper with the continuing development single cell analysis techniques. This technological progress has generated an urgent need to develop efficient TCR validation platforms for the rapid and safe clinical translation of TCRs into therapeutic agents. Whereas much attention has in the past focused on CD8-positive cytotoxic T cells recognizing MHC class I presented epitopes, the increasing demand to validate TCRs expressed on neoepitope-reactive CD4 T cells requires the implementation of large-scale T cell activation-based readout assays to complement existing multimer and cytotoxicity-based assays. Here, we present commonly used TCR validation assays, and include detailed guidance on TCR synthesis, delivery, and appropriate experimental control TCRs. We also comment on upcoming methods that hold promise for further speeding the process of TCR validation, hastening the translation of TCRs from the laboratory into the clinic.