TCR-Seq Identifies Distinct Repertoires of Distant-Metastatic and Nondistant-Metastatic Thyroid Tumors

Abstract

CONTEXT: Malignant thyroid tumor with distant metastasis is associated with poor outcome. Early detection of distant metastasis is of great clinical importance. OBJECTIVE: Thyroid tumor infiltrated with T cells can serve as a biomarker for monitoring metastasis. DESIGN: A retrospective analysis was performed of patient clinical samples collected between 2012 to 2018, using T-cell receptor sequencing (TCR-seq) for clinical exploration. SETTING: This study took place at Zhejiang Cancer Hospital. PATIENTS: Sixty-eight patients with papillary thyroid cancer (PTC) (distinct metastatic status) and 21 patients with benign nodules were enrolled. All patients had not received any treatment before surgery. MAIN OUTCOME MEASURE: The characteristics of TCRβ complementary-determining region 3 (CDR3) for each patient were determined by high-throughput sequencing. RESULTS: The TCRβ diversity of malignant tumors is significantly higher than benign nodules both in blood and tumor samples (Shannon index, blood, P < .01; tumor, P < .001). The malignant tumors with distant metastasis or invasiveness showed lower TCRβ diversity than nonmetastasis (Shannon index, P < .01) or noninvasive (Shannon index, P < .01) malignant tumors. Analysis of the Morisita-Horn similarity index indicated significant TCRβ repertoire similarity between tumor and blood in distant-metastatic patients (comparison with nonmetastasis, P < .05). According to the discrepancy of the CDR3 among patients with different clinicopathological status, the classifier was constructed to discriminate distant-metastatic individuals. A promising area under the curve value of 83.8% was obtained with the number of overlapping CDR3 clonotypes. CONCLUSION: The availability and reliability of TCR-seq render it prospective to translate these intrinsic attributes into clinical practice for monitoring distant metastasis in PTC patients.