Comprehensive analysis of T-cell receptor sequencing in resectable squamous cell lung cancer patients with neoadjuvant therapy of PD-1 inhibitor and chemotherapy.

Abstract

e21012 Background: Cancer therapies alter the tumor microenvironment such as the infiltration of T cells. Neoadjuvant therapy to squamous cell lung cancer patients using PD-1 inhibitor expands specific T cell clones. However, the T cell clones and diversity in tumors and lymph nodes according to different neoadjuvant settings remain largely unknown. In this study, we used T-cell receptor (TCR) sequencing technology to investigate the TCR clonotypes and diversities in squamous cell NSCLC patients who received neoadjuvant chemotherapy and PD-1 inhibitor plus chemotherapy. Methods: Tumor tissues, non-metastatic lymph nodes (NMLN)s, and available metastatic lymph nodes (MLNs) were collected from two patient groups. Each group enrolled three patients who received either neoadjuvant chemotherapy or PD-1 inhibitor plus chemotherapy. DNA samples were harvested and processed for multiplex PCR for the third complementary determining region (CDR3) of TCR-β chain followed by the next generation sequencing analysis. Differences of the CDR3 clonotypes and clonal diversities were analyzed by bioinformatics tools including the Mixcr software. Results: For all the six patients, TCR clonotypes in the tumor tissues were found to be fewer than those from the lymph nodes in the same patient, consistent with a hypothesis that most of the tumor infiltrated T cells after therapy derive from the lymph nodes. Some clonotypes among the top 10 highest frequencies were found in different samples from the same patient, further supporting the lymph node origin of the tumor infiltrating T cells after therapies. Interestingly, TCR clonal diversity was higher in the NMLNs compared with the MLNs, but clonotype overlap with tumor tissues was higher in the MLNs than NMLNs; these results could imply that TCR clonotypes in the primary lymph node were more stimulated. Additionally, there were very few clonotypes shared between different patients, indicating the heterogeneity of immune response for different individuals. Due to the limited sample size, we could not find the systemic difference between the two patient groups. Conclusions: TCR sequencing technology can detect the CDR3 clonotypes in tumor tissues and lymph nodes of cancer patients, providing new opportunities for revealing patients' response to chemotherapy and immunotherapy. Further analysis will be performed to investigate TCR clonotype differences caused by immunotherapy.