How To read PD-L1
Programmed death-ligand 1 (PD-L1) is a protein that is expressed on the surface of some cancer cells. It plays a role in the immune system by binding to a receptor called PD-1 on the surface of T cells, which can inhibit the immune response against the cancer cells.
To read a PD-L1 test, a sample of the patient’s tumor tissue is examined using an immunohistochemistry (IHC) assay. This assay uses specific antibodies to detect the presence of PD-L1 on the surface of the tumor cells. The test results are then reported as a percentage of tumor cells that express PD-L1.
There are different ways to interpret the results of a PD-L1 test, depending on the assay and scoring system used. Some common scoring systems include:
The 22C3 pharmDx assay, which uses a cut-off of 1% of tumor cells expressing PD-L1 to define positive results.
The 28-8 assay, which uses a cut-off of 50% of tumor cells expressing PD-L1 to define positive results.
A higher percentage of tumor cells expressing PD-L1 is generally associated with a poorer prognosis and a lower response to immunotherapy. However, it’s important to note that PD-L1 expression is not the only factor that determines response to immunotherapy, and other factors such as the patient’s overall health, the type and stage of cancer, and the specific immunotherapy drug used are also important.
It is important to consult with a medical professional and pathologist to accurately interpret the PD-L1 test results and to understand the patient’s treatment options and prognosis.
PD-L1 (Programmed cell death ligand 1) is a protein that is expressed on the surface of some cancer cells. It can be used as a marker to help identify patients who may benefit from treatment with immune checkpoint inhibitors, a type of cancer immunotherapy.
PD-L1 expression is typically assessed using a test called an immunohistochemistry (IHC) assay. The test involves taking a sample of the tumor tissue and staining it with an antibody that binds to PD-L1. The degree of staining is then evaluated by a pathologist using a microscope.
There are several different scoring systems used to interpret PD-L1 IHC results, but one of the most commonly used is the percentage of tumor cells that show PD-L1 expression (referred to as the PD-L1 tumor proportion score, or TPS).
A high TPS, typically greater than 50%, is considered to be a positive result, indicating that the tumor cells express PD-L1 and that the patient may benefit from treatment with an immune checkpoint inhibitor. A low TPS, typically less than 1%, is considered to be a negative result and that treatment with immune checkpoint inhibitors may not be beneficial.
It’s important to note that PD-L1 testing is not the only factor that’s used to determine treatment decisions, and other factors such as the patient’s overall health and the type of cancer they have are also taken into consideration.
source: openAi