PD-L1

PD-L1 (programmed death-ligand 1) is a protein found on the surface of some cells, including many cancer cells. It acts as a brake on the immune system: when it binds to the PD-1 receptor on immune cells, it tells them to stand down. Tumors that display a lot of PD-L1 can hide from the body's defenses. Doctors measure PD-L1 in a tumor sample to help decide whether immunotherapy is likely to help.

Origin

PD-L1 was identified in the late 1990s and early 2000s as research into immune checkpoints advanced. The receptor it binds, PD-1, was discovered in 1992 by Tasuku Honjo's lab in Japan, work that later earned a share of the 2018 Nobel Prize in Medicine.

Significance in Asbestos Context

For mesothelioma patients, PD-L1 testing can influence whether immunotherapy drugs, checkpoint inhibitors like nivolumab and ipilimumab, are offered. PD-L1 shows up in a pathology report when a lab stains the tumor for it and reports a percentage or score. Because the test uses tumor tissue, it's worth confirming enough sample remains before further procedures. The result is a biomarker in the medical record that documents the disease and the treatment decisions around it, which can matter to a claim.

Example Sentence

Her oncologist ordered PD-L1 staining on the pleural biopsy to see whether she was a candidate for checkpoint immunotherapy.

Related Terms

Immunotherapy, Biomarker Testing, Immunohistochemistry, Checkpoint Inhibitor, Pleural Mesothelioma

Notes

• Ask your oncologist whether PD-L1 was tested and what the score or percentage was.
• Confirm enough tumor tissue remains for PD-L1 and other biomarker tests before more procedures.
• Keep copies of the pathology and immunohistochemistry reports; they document diagnosis and treatment choices.