# uPAR (urokinase plasminogen activator receptor)

Source: https://nuclide.cc/targets/upar/  
Nuclide record `upar` (Target). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

A protein that helps cancer cells break through surrounding tissue and spread. Higher amounts on a tumour are linked to more aggressive disease, and a PET tracer built on a small peptide can measure how much of it a tumour has.

## Summary

uPAR is a glycosylphosphatidylinositol-anchored cell-surface receptor for urokinase-type plasminogen activator (uPA); the uPA/uPAR system focuses proteolytic activity (activation of plasmin, which degrades extracellular matrix) at the cell surface, driving tumour cell invasion, matrix remodelling and metastasis. uPAR overexpression is an established biomarker of tumour aggressiveness across several common cancers, including prostate, breast, bladder and glioma, and correlates with independent prognostic information beyond PSA and Gleason score in prostate cancer.

The PET ligand 68Ga-NOTA-AE105 (and the earlier 64Cu-DOTA-AE105), based on the high-affinity peptide antagonist AE105, has been evaluated in first-in-human and phase 2 studies in prostate cancer, breast cancer, bladder cancer and glioma. In localised prostate cancer, tumour SUVmax on 68Ga-NOTA-AE105 PET correlated significantly with Gleason score (Spearman ρ = 0.55), and a SUVmax cut-off achieved 96% sensitivity for detecting Gleason score ≥3+4, raising the possibility of uPAR PET reducing the number of repeat biopsies needed in active surveillance. In glioma, uPAR-PET uptake was associated with worse overall and progression-free survival.

As a target, uPAR's strength is a genuine link to tumour aggressiveness and metastatic potential across multiple tumour types, giving it prognostic as well as localising value. Its main limitation to date is that all published clinical PET data come from small studies run predominantly by one research group, so multicentre validation is still needed, and no uPAR-targeted therapeutic radioligand has reached clinical use.

## Fields

- Kind: Target
- Last checked: 2026-09-22
- Also known as: uPAR; PLAUR
- Tags: invasion; prostate cancer; prognostic biomarker
- Symbol: PLAUR
- Class: surface-antigen
- Biology: A GPI-anchored cell-surface receptor for urokinase-type plasminogen activator that focuses proteolytic activity at the cell surface, activating plasmin to degrade extracellular matrix and drive tumour invasion and metastasis. Its overexpression is an established biomarker of tumour aggressiveness in prostate, breast, bladder cancer and glioma.
- Where found: Prostate cancer: uPAR expression correlates with Gleason score and aggressiveness; Glioma: uPAR-PET uptake associated with tumour grade and worse survival; Breast cancer and urinary bladder cancer: uPAR overexpression linked to invasive and metastatic potential; Normal tissue: low background expression, contributing to good image contrast

## Sources

- JNM: uPAR PET/MRI (68Ga-NOTA-AE105) and Gleason score correlation in prostate cancer: https://jnm.snmjournals.org/content/62/3/354
- PMC: PET imaging of uPAR in prostate cancer (review): https://pmc.ncbi.nlm.nih.gov/articles/PMC5118403/
- JNM: first-in-human study of 68Ga-NOTA-AE105 for uPAR PET imaging: https://jnm.snmjournals.org/content/58/3/379
- EJNMMI Research: phase 2 trial of 68Ga-NOTA-AE105 uPAR PET in glioma, survival correlation: https://ejnmmires.springeropen.com/articles/10.1186/s13550-024-01164-9

## Connected records

- indications: [Prostate cancer](https://nuclide.cc/indications/prostate/)
- trials: [Safety and Diagnostic Performance of uPAR PET Imaging in Localised, Untreated Prostate Cancer](https://nuclide.cc/trials/nct06474806/)
- isotopes: [Copper-64](https://nuclide.cc/isotopes/cu-64/), [Gallium-68](https://nuclide.cc/isotopes/ga-68/)

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