2022 World Conference on Lung Cancer (ePosters)-EP11.01-002. Malignant Pleural Effusion Cell Blocks Are Reliable Resources for PD-L1 Analysis in Advanced Lung Adenocarcinomas

EP11.01-002. Malignant Pleural Effusion Cell Blocks Are Reliable Resources for PD-L1 Analysis in Advanced Lung Adenocarcinomas

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The study aimed to determine if malignant pleural effusion (MPE) cell blocks can be used as reliable resources for programmed death ligand-1 (PD-L1) analysis in advanced lung adenocarcinomas. PD-L1 expression in tumor cells is a predictive biomarker for immunotherapy in this type of cancer. The researchers analyzed MPE samples from 43 patients with lung adenocarcinoma and found that 25 cases showed PD-L1 positivity in at least 1% of tumor cells. Of these, 13 cases had low expression (1% to 49%) and 12 cases had high expression (50%).11 patients had paired histology samples available, and PD-L1 positivity was concordant in 10 of these cases. There was no significant difference in PD-L1 positivity based on age, sex, or the presence of EGFR, ALK-1, or ROS1 mutations.<br /><br />The study concluded that PD-L1 expression in MPE cell blocks showed good concordance with expression levels in histology samples. It was deemed feasible to use MPE cell blocks for PD-L1 testing, and the concurrent use of CD163 immunostains aided in the manual assessment of PD-L1 tumor proportion scores (TPS). Representative photomicrographs of PD-L1 staining on MPE cell blocks were provided, showing high, low, and negative expression.<br /><br />The researchers performed immunocytochemistry (ICC) for PD-L1 using MPE cell blocks and patient-matched histology samples. The Ventana PD-L1 SP263 assay was used, and CD163 staining was done to highlight macrophages in cases with any degree of PD-L1 expression. The slides were digitized and analyzed using a digital slide scanner.<br /><br />In summary, the study demonstrated that MPE cell blocks can be reliable resources for PD-L1 analysis in advanced lung adenocarcinomas. It provided evidence of the feasibility and concordance of PD-L1 testing in MPE cell blocks compared to histology samples. The findings have implications for the use of MPE samples as a source of tumor tissue for diagnosis and biomarker testing in this type of cancer.

Asset Subtitle

Aruna Nambirajan

Meta Tag

Speaker Aruna Nambirajan

Topic Pathology - Genomics & Analytics

Keywords

malignant pleural effusion

cell blocks

programmed death ligand-1

PD-L1 analysis

lung adenocarcinomas

tumor cells

immunotherapy

predictive biomarker

histology samples

CD163 immunostains