PT  - JOURNAL ARTICLE
AU  - Anjelica Hodgson
AU  - Danny Vesprini
AU  - Stanley K Liu
AU  - Bin Xu
AU  - Michelle R Downes
TI  - Correlation of mismatch repair protein deficiency, PD-L1 and CD8 expression in high-grade urothelial carcinoma of the bladder
AID  - 10.1136/jclinpath-2019-206256
DP  - 2020 Aug 01
TA  - Journal of Clinical Pathology
PG  - 519--522
VI  - 73
IP  - 8
4099  - http://jcp.bmj.com/content/73/8/519.short
4100  - http://jcp.bmj.com/content/73/8/519.full
SO  - J Clin Pathol2020 Aug 01; 73
AB  - Mismatch repair-deficient (d-MMR) tumours have been reported to show susceptibility to immune checkpoint inhibitors targeting programmed death-1/PD ligand-1 (PD-1/PD-L1). In this study, we sought to correlate the association of d-MMR, PD-L1 and CD8 expression in muscle invasive, high-grade urothelial carcinoma (HGUC) of bladder. A tissue microarray (TMA) was constructed from 201 cases and sequentially stained with PD-L1, CD8, MSH2, MSH6, MLH1 and PMS2. PD-L1 was assessed in tumour and immune cells. CD8 was assessed in a hotspot fashion with results averaged across cores. Loss of nuclear MMR expression on TMA sections was further assessed using corresponding whole tissue sections. d-MMR was identified in four cases (2%). The mean CD8 count was significantly higher in d-MMR tumours (10 vs 35, p=0.007) as was the proportion of PD-L1 positivity (75% vs 20%, p=0.031). d-MMR is uncommon in HGUC of bladder but shows strong correlation with cytotoxic T lymphocyte infiltration and PD-L1 tissue expression.