PD-L1 LDT

Programmed cell death ligand 1 (PD-L1) is a transmembrane protein involved in cellular and humoral immune response regulation. PD-L1 expression has been found in a variety of cancers expressed on tumor and/or immune cells. This lab developed test uses the Zeta PD-L1 monoclonal antibody clone ZR3 to detect PD-L1 in formalin-fixed paraffin-embedded tissues. The utility of PD-L1 (ZR3) in predicting the response to anti-PD-1/PD-L1 has not been determined and no standardized scoring criteria currently exist. For therapies and indications that have an FDA-approved PD-L1 companion diagnostic, it is recommended to use the associated FDA approved PD-L1 test. Scoring for this test is called Total PD-L1 Expression and is calculated by dividing the sum of the number of staining tumor cells and inflammatory cells by the total number of viable tumor cells.