Expression of programmed death-ligand 1 in common endocrine tumors: A potential marker for newer therapeutic target

Objectives: The immune system recognizes antigens expressed on tumor cells and tries to eliminate these cells. The immune system plays an essential role in tumor survival, as explained by the presence of lymphocytic infiltrate, reactive changes in sentinel lymph nodes, and increased incidence of some cancers in immunodeficient people. The immune checkpoints regulate the immune system-mediated tumor cell destruction, and PDL-1(programmed death-ligand 1) is one of these checkpoint inhibitors. We checked the PDL-1 expression in various endocrine tumors. Materials and methods: In the present study, we studied PDL-1 expression in various endocrine organ tumors. Results: Fifty-four cases were studied; 22 pituitary adenoma (PA), 20 papillary carcinoma of thyroid (PTC), two medullary carcinoma of thyroid (MTC), seven parathyroid adenomas, and three paraganglioma/pheochromocytoma. PDL-1 expressed in 50% PTC, 100% MTC, 57.1% in parathyroid adenoma, and 81% pituitary adenoma. None of the paraganglioma/pheochromocytomas expressed PDL-1. Conclusion: PDL-1 expression can be used as a therapeutic immunohistochemistry marker in advanced endocrine tumors if positive, the role of immunotherapy may be explored as similar to breast, lung cancers, and melanoma