biomarkersBiomarker

PD-L1 TPS (tumour proportion score)

aka PD-L1 TPS, TPS, tumor proportion score, tumour proportion score, TPS >= 1%, TPS >= 50%, PD-L1 TPS 50, PD-L1 high, PD-L1 ≥50%, TPS≥50%, TPS≥1%

TPS is the share of tumour cells whose membrane stains for PD-L1, ignoring immune cells. In lung cancer it decides whether pembrolizumab or cemiplimab can be given alone: 1 percent opens the door, 50 percent is where single-agent treatment is strongest.

The tumour proportion score is the percentage of viable tumour cells showing partial or complete membrane staining at any intensity, read on the 22C3 pharmDx (and, for cemiplimab, also the SP263 assay). Pembrolizumab's US label uses TPS >= 1 percent for first-line single-agent treatment of stage III or metastatic NSCLC without EGFR or ALK alterations and for second-line treatment after platinum chemotherapy; cemiplimab's single-agent first-line indication requires TPS >= 50 percent. The KEYNOTE-024 trial that set the 50 percent bar and KEYNOTE-042 that lowered the gate to 1 percent are the sources of the two numbers. TPS is a lung-specific read; the same slide scored as CPS would include immune cells and give a different number.

Part ofPD-L1· CD274Other readoutsPD-L1 CPS PD-L1 IC score PD-L1 TC score All readouts

PD-L1: what it is and how drugs act on it · animated schematic, not to scale

Target · the protein and the cell it sits on
Drug · antibody, small molecule, cell or radioligand
Effect · signal, damage or kill

In plain words · PD-L1 is the tumour's side of the PD-1 brake, and also the biomarker that decides who gets immunotherapy.

TPS 3 approval thresholds

What it means for a patient

In lung cancer the report gives a percentage of tumour cells. At 50 percent or more the labels allow pembrolizumab or cemiplimab on their own as first treatment; between 1 and 49 percent pembrolizumab alone is still on label but chemotherapy combinations are usually chosen; below 1 percent immunotherapy is given with chemotherapy rather than alone. The score does not apply if the tumour has an EGFR or ALK alteration, which take priority.

Written only from the label or guideline text cited on this page. Not medical advice; your own report and the reading your team gives it come first.

Scoring rule

Percentage of viable tumour cells with partial or complete membrane staining of any intensity; at least 100 viable tumour cells must be present.

“PD-L1 protein expression [Tumor Proportion Score (TPS) ≥ 50%]”
FDA: List of FDA-Authorized Companion Diagnostic Devices

Thresholds used in approvals

Threshold	Drug	Cancer	Regulator	Source
TPS >= 1%	Pembrolizumab	Non-small-cell lung cancer	FDA	label
TPS >= 1% (after platinum chemotherapy)	Pembrolizumab	Non-small-cell lung cancer	FDA	label
TPS >= 50%	Cemiplimab	Non-small-cell lung cancer	FDA	label

Drugs whose label names it

Pembrolizumab Cemiplimab

Companion diagnostics (FDA list)

Device	Maker	Indication and sample	Drug	PMA / 510(k)
PD-L1 IHC 22C3 pharmDx	Agilent Technologies (Dako)	Non-Small Cell Lung Cancer (NSCLC) - Tissue	Pembrolizumab	P150013 (10/02/2015); updated P150013/S012 (04/16/2019)
PD-L1 IHC 22C3 pharmDx	Agilent Technologies (Dako)	Non-Small Cell Lung Cancer (NSCLC) - Tissue	Cemiplimab	P150013/S021 (02/22/2021)
Ventana PD-L1 (SP263) Assay	Ventana Medical Systems (Roche)	Non-Small Cell Lung Cancer (NSCLC) - Tissue	Cemiplimab	P160046/S013 (03/01/2023)

Tests that measure it

PD-L1 IHC 22C3 pharmDx VENTANA PD-L1 (SP263) Assay Labcorp OmniSeq INSIGHT

Trials that name this readout

Matched on the name and aliases of the readout in the title, setting and summary of each trial; a match is a mention, not proof the readout was an entry criterion.