STAG2 Protein Expression in Non-muscle-invasive Bladder Cancer: Associations with Sex, Genomic and Transcriptomic Changes, and Clinical Outcomes

Naheema S Gordon, Nada Humayun-Zakaria, Anshita Goel, Ben Abbotts, Maurice P Zeegers, K K Cheng, Nicholas D James, Roland Arnold, Richard T Bryan, Douglas G Ward

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Background: Mutations in STAG2 cause complete loss of STAG2 protein in approximately one-third of non-muscle-invasive bladder cancers (NMIBCs). STAG2 protein expression is easily determined via immunohistochemistry (IHC) and published data suggest that loss of STAG2 expression is a good prognostic indicator in NMIBC.

Objective: To confirm the relationship between STAG2 protein expression and clinical outcomes and tumour characteristics in NMIBC.

Design setting and participants: IHC was used to determine STAG2 expression in 748 incident urothelial bladder cancers (UBCs) and recurrence-free, progression-free, and disease-specific survival were compared for patients with and without STAG2 loss. Exome and RNA sequencing were used to explore links between STAG2 loss and tumour molecular characteristics.

Results and limitations: STAG2 loss was observed in 19% of UBC patients and was 1.6-fold more common among female patients. Loss was frequent among grade 1 pTa tumours (40%), decreasing with stage and grade to only 5% among grade 3 pT2+ tumours. Loss was associated with fewer copy-number changes and less aggressive expression subtypes. In UBC, STAG2 loss was a highly significant prognostic indicator of better disease-free survival but was not independent of stage and grade. STAG2 loss was not a statistically significant predictor of NMIBC recurrence. STAG2 loss was significantly associated with better progression-free survival in NMIBC and appeared to be more prognostic for males than for females.

Conclusions: A simple IHC-based STAG2 test shows promise for identifying NMIBC patients at lower risk of progression to MIBC for whom more conservative treatments may be suitable.

Patient summary: A protein called STAG2 is frequently lost in early bladder cancers, most often in less aggressive tumours. STAG2 loss is easily measured and could be used as a biomarker to help guide treatment decisions.

Original languageEnglish
Pages (from-to)88-95
Number of pages8
JournalEuropean urology open science
Volume38
DOIs
Publication statusPublished - Apr 2022

Keywords

  • Biomarker
  • Bladder cancer
  • PROGRESSION
  • Prognosis
  • STAG2
  • SUBTYPES
  • TUMOR-SUPPRESSOR STAG2

Cite this