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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.
In plain words · PD-L1 is the tumour's side of the PD-1 brake, and also the biomarker that decides who gets immunotherapy.
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.
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| 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 |
| 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) |
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.
It is the positive half of the tumour mutational burden story and it applies only to single-agent immunotherapy, which is the setting fewest patients are treated in.
It is the strongest case that mutation burden is real biology in lung cancer and, at the same time, the clearest demonstration that its threshold is not fixed, which is why it never became a reliable selector.
The Western counterpart to the Indian series, with lower rates and a prognostic signal in the opposite direction from what immunotherapy enthusiasts might hope. The TIGIT and CD155 finding names a second checkpoint for future trials.
The 98% figure shows how much antibody and scoring choices matter: it sits against 14.7% and 23% in the two large series. The tumour-size-dependent effect of T-cell density is a hypothesis about immune exhaustion in bulkier tumours.
It made tumour mutational burden measurable in routine practice and, in the same stroke, showed it is a second axis alongside PD-L1 rather than a replacement for it.
It is the reason a laboratory can run one stain and report against several drug labels, and the reason any decision resting on an immune-cell score rests on the least reproducible number in lung pathology.
The largest PD-L1 series from a high-incidence country; the one-in-four figure is the number quoted for gallbladder cancer, though the Western series with a different clone found fewer. No biliary approval uses PD-L1 to select patients.
Together with the Blueprint work it establishes that a PD-L1 percentage reports the assay as much as it reports the tumour, so the threshold and the antibody have to be quoted together.
Shares Association of high tumor mutation burden in non-small cell lung cancers with increased immune infiltration and improved clinical outcomes of PD-L1 blockade across PD-L1 expression levels, Associations of tissue tumour mutational burden and mutational status with clinical outcomes in KEYNOTE-042, Molecular determinants of response to anti-PD-1 and anti-PD-L1 blockade in patients with non-small-cell lung cancer profiled with targeted next-generation sequencing, Gallbladder cancer and the tag biomarker.
Shares PD-L1 CPS (combined positive score), Immunohistochemistry (IHC) and the tag biomarker.
Shares STK11 or KEAP1 loss in KRAS-mutant lung adenocarcinoma, Lung cancer (all types), Non-small-cell lung cancer and the tag biomarker.
Shares Immunohistochemistry (IHC), Non-small-cell lung cancer and the tag biomarker.
Shares STK11 or KEAP1 loss in KRAS-mutant lung adenocarcinoma, Non-small-cell lung cancer and the tag biomarker.
Shares Immunohistochemistry (IHC), Gallbladder cancer and the tag biomarker.
Shares Immunohistochemistry (IHC), Gallbladder cancer, Pembrolizumab and the tag biomarker.
Shares PD-L1 CPS (combined positive score) and the tag biomarker.