Nguyen et al. used single-cell RNAseq and multiplex IHC on paired primary thyroid carcinomas and metastatic lymph nodes (LNs) to define immune determinants of nodal colonization. In metastatic LNs, thyrocytes and TAMs downregulated inflammatory cytokine receptors. including TNFRSF12A and CX3CR1, and were enriched for Tregs relative to matched primary tumors, which suggests suppression of T cell-mediated cytotoxicity. Tumor-infiltrating lymphocytes in metastatic LNs showed increased IL7R expression, and high IL7R levels within nodal metastases correlated with enhanced immune activation and improved progression-free survival in a validation cohort.

Contributed by Shishir Pant

ABSTRACT: Lymph node (LN) metastases are a major driver of mortality across solid cancers, including thyroid carcinomas, which are known for high rates of nodal colonization. To elucidate the determinants of nodal spread, we isolated tumor-infiltrating leukocytes from primary thyroid tumors and matched metastatic LNs for single-cell RNA sequencing with validation by multiplex immunohistochemistry. Comparing the microenvironmental alterations between primary tumors and their LNs, we found that thyrocytes and tumor-associated macrophages down-regulate the expression of multiple inflammatory cytokine receptors, including TNFRSF12A and CX3CR1, upon LN colonization. LNs were associated with the induction of regulatory T cells to suppress T cell-mediated cytotoxicity compared to matched primary tumors. Notably, tumor-infiltrating lymphocytes within LNs demonstrated increased expression of activation markers, including interleukin-7 receptor (IL7R). High LN expression of IL7R was significantly correlated with improved outcomes and can serve as a biomarker in this heterogeneous disease. Our findings on the dynamic equilibrium within LN metastases may offer conserved mechanisms for nodal colonization across solid tumors.

Author Info: (1) Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, CA, USA. Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA. Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (2) Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (3) Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (4) Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (5) Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (6) Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (7) Division of Endocrinology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (8) Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA. Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (9) Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (10) Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA. Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (11) Division of Medical Oncology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (12) Division of Medical Oncology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (13) Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, CA, USA. Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (14) Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, CA, USA. Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (15) Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, CA, USA. Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (16) Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (17) Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, CA, USA. Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA. Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA. (18) Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA. Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA.