Programmed death ligand 1 (PD-L1) expression in parathyroid tumors

Area of Science:

• Oncology
• Endocrinology
• Immunology

Background:

• Programmed death-ligand 1 (PD-L1) is a key immune checkpoint molecule implicated in cancer prognosis and response to immunotherapy.
• Previous research has identified PD-L1 expression in various endocrine tumors, but its status in parathyroid neoplasms remained uncharacterized.

Purpose of the Study:

• To investigate the expression of PD-L1 in parathyroid carcinoma and adenoma.
• To evaluate the consistency of PD-L1 detection using different antibody clones.

Main Methods:

• Analysis of 26 parathyroid carcinoma and 37 adenoma samples.
• Immunohistochemical staining for PD-L1 using FDA-approved 22C3 and SP263 assays.
• Assessment of PD-L1 expression in tumor cells and tumor-infiltrating immune cells, correlated with Ki-67 index and mitotic rate.

Main Results:

• A majority of parathyroid tumors exhibited deficient PD-L1 expression across both tumor cell and immune cell compartments.
• PD-L1 expression levels varied significantly between the SP263 and 22C3 antibody clones.
• A negative correlation was observed between PD-L1 expression and tumor proliferation markers (Ki-67, mitotic rate), with clone-dependent variations.

Conclusions:

• Parathyroid tumors generally show low PD-L1 expression.
• The choice of antibody clone significantly impacts PD-L1 scoring in parathyroid neoplasms.
• Further investigation is warranted to standardize PD-L1 assessment in this tumor type.