A platform for parallel TCR cloning and testing enables anti-neoantigen tumor immunotherapy

Tumor-infiltrating CD8 cells recognize neoantigens created by tumor-specific mutations. Nonetheless, even after checkpoint inhibitor therapy, most patients' tumors progress. A deeper understanding of antitumor responses could facilitate development of better therapies. To enable such studies, we applied TCXpress, a high throughput platform that clones fully expressible TCRs from single cells into retroviral or lentiviral vectors without sequencing or gene synthesis, to study TCRs from CD8 cells infiltrating mouse MC38 tumors. We expressed cloned TCRs in reporter cells and interrogated TCR specificity by coculturing them with B6WT3 cells transduced with tandem minigenes encoding predicted neoantigens. We isolated TCRs reactive against epitopes from mutant Rpl18, Adpgk, Psmd2, and Zc3h7b along with self-reactive TCRs that recognized normal B6 and MC38 cells. Importantly, we successfully treated MC38-bearing mice with T cells transduced with anti-Rpl18 TCRs. These results establish a system that could be used to study many types of T cell responses and validate a therapeutic approach that could be tested in the clinic.