PDL1 Immunohistochemical Expression in Thyroid Neoplasms: A Possible Therapeutic Target

Abstract Background: PD-L1 expression is being considered a potential biomarker for the response of PD-L1 agents. Aim of Study: We aimed to investigate the expression of PD-L1 in cases of thyroid neoplasms from Egyptian patients trying to correlate PD-L1 immunohistochemical expression and pertinent clincopathological features of thyroid neoplasms that will help to provide better treatment options that might be effective against aggressive malignancy. Material and Methods: Forty cases of benign and malig-nant thyroid neoplasms were tested for PD-L1 positivity scores based on the percentage positivity and staining intensity. A total score was then obtained (ranging from 0 to 7) by adding the percentage positivity scores and intensity scores for each section (H-Score). Correlation with clinico-pathological parameters was done. Results: PDL-1 expression positivity was seen in 82.5% of cases while 17.5% showed negative PDL-1 expression. H-score of studied cases was as follows; 0 (7 cases; one was bengin and 6 were malignant), 1(8 cases; three were benign and 5 were malignant), 2 (6 cases; four were benign and two were malignant), 3 (No case scored as 3), 4 (5 cases; all are malignant), 5 (4 cases; all are malignant), 6 (5 cases; 2 were benign and three were malignant) and 7 (5 cases; 2 were benign and three were malignant). Conclusion: The presence of PD-L1 in thyroid cancers indicates that there is a sizable group of thyroid cancer patients who might potentially benefit from immunetherapy. Unfortu-nately, PDL-1 could not be used to differentiate between benign and malignant thyroid neoplasms.