Programmed death-ligand 1 (PD-L1) is a transmembrane protein that binds to the inhibitory receptor programmed death 1 (PD-1) causing a down regulation of immune responses. PD-L1 is typically expressed on normal cells but has been observed on tumor cells while PD-1 is typically expressed on certain immune cells [1]. Tumor cells can upregulate PD-L1 expression and avoid being attacked by the body’s immune system, making an interruption of the PD-1/PD-L1 interaction an attractive method for assisting the immune system in destroying tumor cells, see [2].
Assessment of PD-L1 can be achieved by use of immunohistochemistry (IHC), however, the activity of the PD-L1/PD-1 axis can also be assessed directly at the transcriptomic level using RNA in situ hybridization (ISH) techniques.
This APP works on RNAscope images and automatically detects cells and probe signals. The cells are classified according to the number of probes associated with the cells and a composite score is calculated and reported.