PD-L1 Expression in Relation to Patients With Thyroid Cancer

Christine Dierks, MD, senior physician at the University Hospital Freilburg in Germany, discusses how PD-L1 expression is used to determine treatment for patients with thyroid cancer.

Dierks says that regarding the PD-L1 levels used for the tumor proportion score (TPS) and combined positive score (CPS), physicians look at the PD-L1 expression on the membrane of the tumor cells. They also look at the frequency of the infiltrating immune cells and infiltrating lymphocytes to see if they express PD-L1 or PD-1 on the cell’s surface. To histologically characterize the immune phenotype of a tumor, they need to see the level of expression on these different parts of the tumor.

With differentiated thyroid carcinoma, physicians usually see TPS that is either negative or very low, below 10%. In over 70% of patients with anaplastic thyroid carcinoma, the TPS is often above 50% and the CPS above 75%, according to Dierks. She says these scores are some of the prognostic markers for response to immune checkpoint inhibitors in patients with non–small cell lung cancer.