Blood-Tumor overlapping TCR repertoire predicts the clinical responses of PD-1 blockade in patients with gastrointestinal cancer [TCR-Seq]

As the anti-PD-1 monoclonal antibody (mAb) becomes to be used in many types of cancers, the needs for the predictive biomarker of PD-1 blockade are growing. T cell receptor (TCR) repertoire—which reflects the anti-tumor T-cell responses based on the antigen specificity—is a potential biomarker of cancer immunotherapy. Here, we analyzed the TCR repertoire of patients with advanced gastrointestinal cancer and explored its association with clinical responses. Eight patients with advanced gastrointestinal cancer were treated with an anti-PD-1 monoclonal antibody (nivolumab) every 3 weeks until disease progression. The TCR repertoire of the peripheral blood CD4+ and CD8+ T cells was analyzed once before and three times after the initiation of treatment, whereas in case of tumor biopsy it was analyzed before and after 6 weeks of initiation of the treatment.