Tumour proportion score (TPS)

The PD-L1 score used in lung cancer: the percentage of tumour cells that stain positive.

Assessed with the 22C3 assay. TPS ≥50% ('high') supports pembrolizumab or cemiplimab monotherapy; 1-49% favours chemo-immunotherapy; <1% still benefits from chemo-IO or CTLA-4-containing regimens (POSEIDON). Distinct from CPS (used in breast, gastric, head and neck), which also counts immune cells.

Biomarkers: what this kind of term is about · animated schematic, not to scale