Abstract 3175: Detection of tumor T-cell clones in mediastinal lymph nodes is associated with lower risk of tumor progression

Background: The presence of tumor metastases in standard of care lymph node biopsies during surgical resection is used to help determine clinical prognosis. Given the importance of T cells in mediating anti-tumor responses, we sought to assess the clinical significance of T-Cell Receptor (TCR) usage in matched hilar and mediastinal lymph nodes from non-small cell lung cancer (NSCLC) patients. Methods: TCR-Beta chains were quantified by the immunoSEQ® Assay (Adaptive Biotechnologies) in primary early-stage NSCLC tissue, matched hilar lymph nodes (proximal), and matched mediastinal lymph nodes (distal) for 27 patients, who were treated with surgical resection. Patients were selected such that half experienced recurrence and half remained recurrence-free over the 30+ months of patient follow-up. Results: T-cell clonality in resected tumors is significantly correlated (Spearman’s Rho = 0.52, p = 0.0005) but poorly concordant (Pearson’s R2 = 0.14, p = 0.05) with hilar and mediastinal lymph node clonality. The clonality of hilar and mediastinal lymph nodes is both significantly correlated and moderately concordant (Spearman’s Rho = 0.7, p