PD-L1
Pronunciation: P-D-L-one
Also written as: PD-L1 — Programmed Death-Ligand 1
Programmed death-ligand 1; a protein expressed on tumor cells that suppresses immune responses and serves as a predictive biomarker for immunotherapy.
Full Definition
PD-L1 is a transmembrane protein that binds to the PD-1 receptor on T cells, delivering an inhibitory signal that suppresses immune activation. Many tumors upregulate PD-L1 expression as a mechanism to evade immune surveillance. PD-L1 expression levels, measured by immunohistochemistry using various scoring systems and antibody clones, serve as a predictive biomarker for response to anti-PD-1 and anti-PD-L1 checkpoint inhibitors in several cancer types. However, the predictive value varies by tumor type, and some patients with low PD-L1 expression may still benefit from treatment.
Usage
Usage note: Always specify the antibody clone and scoring method when reporting expression levels.
In Context
- "PD-L1 expression was 85% by tumor proportion score using the 22C3 antibody." — Biomarker testing report
- "High PD-L1 expression predicted response to pembrolizumab monotherapy." — Clinical trial analysis