No Correlation between PD-L1 and NIS Expression in Lymph Node Metastatic Papillary Thyroid Carcinoma

Area of Science:

• Oncology
• Molecular Biology
• Immunology

Background:

• Differentiated thyroid cancers (DTCs), primarily papillary thyroid cancer (PTC), are common endocrine malignancies.
• Radioiodine (RAI) ablation is a standard treatment, but radioiodine-refractory DTC poses a therapeutic challenge.
• Dedifferentiation in thyroid cancer can lead to loss of radioiodine uptake due to impaired sodium/iodide symporter (NIS) expression, with increased programmed death ligand 1 (PD-L1) observed.

Purpose of the Study:

• To investigate the correlation between human sodium/iodide symporter (hNIS) and programmed death ligand 1 (PD-L1) expression in primary tumor samples of lymph node metastatic PTC.
• To analyze the co-expression patterns of NIS and PD-L1 in PTC to understand their potential roles in radioiodine refractoriness.

Main Methods:

• Immunohistochemistry was used to analyze the expression of hNIS and PD-L1 in primary tumor samples from patients with metastatic PTC.
• PD-L1 expression was evaluated based on the percentage of positive cells, and NIS expression was assessed by any subcellular localization (cytoplasmic or membranous).
• Data from 89 PTC cases for PD-L1 and 86 cases for NIS were analyzed.

Main Results:

• NIS expression was observed in 51 out of 86 (59.3%) PTC tumors, with most showing intracytoplasmic localization rather than plasma membrane expression.
• PD-L1 expression was detected in 64 out of 89 (71.9%) PTC tumors, with varying percentages of positive cells.
• No statistically significant correlation was found between PD-L1 expression levels and NIS expression in the analyzed PTC samples.

Conclusions:

• There is no observed correlation between PD-L1 and NIS expression in primary tumors of lymph node metastatic PTC.
• While PD-L1/PD-1 axis manipulation is a potential therapeutic strategy, this study does not support its direct link to restoring NIS function in PTC based on co-expression analysis.
• Further research is needed to explore indirect mechanisms or alternative therapeutic targets for radioiodine-refractory DTC.