# PD-L1 TPS (tumour proportion score)

Source: https://onco.cc/biomarkers/pd-l1-tps/  
OnCo record `pd-l1-tps` (Biomarker). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

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.

## Summary

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.

## Fields

- Kind: Biomarker
- Last checked: 2026-09-23
- Also known as: 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%
- Tags: biomarker; pd-l1

## Sources

- KEYTRUDA prescribing information (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=9333c79b-d487-4538-a9f0-71b91a02b287
- LIBTAYO prescribing information (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4347ae1f-d397-4f18-8b70-03897e1c054a

## Connected records

- biomarkers: [PD-L1 CPS (combined positive score)](https://onco.cc/biomarkers/pd-l1-cps/), [PD-L1 IC score (immune-cell score, SP142)](https://onco.cc/biomarkers/pd-l1-ic-score/), [PD-L1 TC score (tumour-cell score, SP263 and 28-8)](https://onco.cc/biomarkers/pd-l1-tc-score/)
- cancers: [Lung cancer (all types)](https://onco.cc/cancers/lung-cancer/), [Non-small-cell lung cancer](https://onco.cc/cancers/nsclc/)
- drugs: [Cemiplimab](https://onco.cc/drugs/cemiplimab/), [PD-L1 IHC 22C3 pharmDx](https://onco.cc/drugs/dako-pd-l1-22c3-pharmdx/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/), [VENTANA PD-L1 (SP263) Assay](https://onco.cc/drugs/ventana-pd-l1-sp263/)
- terms: [Immunohistochemistry (IHC)](https://onco.cc/terms/ihc/), [PD-L1 expression testing (22C3, SP142, SP263)](https://onco.cc/terms/pd-l1-testing/), [Tumour proportion score (TPS)](https://onco.cc/terms/tps/)
- targets: [PD-L1](https://onco.cc/targets/pdl1/)

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