What does PD-L1 mean in cancer immunotherapy?
According to the U.S. National Cancer Institute (NCI), PD-L1 is a protein that acts as a kind of "brake" to keep the body's immune responses under control. NCI explains that it may be found on some normal cells and in higher-than-normal amounts on some cancer cells; when PD-L1 binds to PD-1, a protein on T cells, it keeps those T cells from killing the PD-L1-containing cells, including cancer cells. Drugs called immune checkpoint inhibitors bind to PD-L1 and block this, leaving the T cells free to kill cancer cells. PD-L1 is also a biomarker doctors may test to help guide immunotherapy decisions, though such tests do not always accurately predict response. This is general information, not personal medical advice.
Last updated:
Verify at
NCI Dictionary of Cancer Terms — PD-L1 (opens in a new tab) — National Cancer Institute (NCI)
Related questions
- What does HER2-positive mean in breast cancer?
- What is a BRCA gene mutation and which cancers is it linked to?
- What is an EGFR mutation in lung cancer, and why does it matter for treatment?
- What is DCIS (ductal carcinoma in situ)?
- What is the difference between small cell and non-small cell lung cancer?
- What is triple-negative breast cancer?