4P - PD-L1 in NSCLC cytology

Date 07 May 2017
Event ELCC 2017
Session Poster Display Session
Topics Non-Small-Cell Lung Cancer, Locally Advanced
Lung and other Thoracic Tumours
Pathology/Molecular Biology
Presenter Mile Kovacevic
Citation Annals of Oncology (2017) 28 (suppl_2): ii1-ii5. 10.1093/annonc/mdx090
Authors M. Kovacevic1, I. Kern2, S. Gabrič2
  • 1Cytology And Pathology Laboratory, University Clinic Golnik, 4204 - Golnik/SI
  • 2University Clinic Golnik, Golnik/SI

Abstract

Background

PD-L1 is a predictive biomarker for NSCLC, which is determined by immunohistochemistry. Significant number of NSCLCs are diagnosed from cytology samples. No study of PD-L1 expression in NSCLC cytology samples was published to date. The aim of this study was to evaluate possiblity of immunocytochemical determination of PD-L1 status in primary and metastatic NSCLC.

Methods

We examined 50 consecutive cytology samples from 50 patients (19 TBNAs of mediastinal lymph nodes, 9 FNABs of peripheral lymph nodes, 15 TBNAs of lung, 4 pleural effusions, 2 FNABs of subcutaneous mass and one US – guided FNAB of liver). Methanol – fixed cytospins were prepared for immunocytochemistry using PD-L1 mouse monoclonal antibody (clone 22C3, Dako, USA) on an automated staining platform (Benchmark, Ventana/Roche, USA). Samples containing 100 or more tumor cells were considered representative. PD-L1 expression was evaluated on tumor cells with membranous staining. PD-L1 positivity was defined by cutoff value of 1%. 18 patients had concurrent histology samples used for PD-L1 immunohistochemistry (FFPE sections, same PD-L1 antibody clone and platform).

Results

We found 37 (74%) adenocarcinomas, 7 (14%) squamous cell carcinomas, while 6 (12%) remained NSCLC-NOS. 74% of all NSCLC samples showed positive immunocytochemical reaction with PD-L1. 27 (73%) of all adenocarcinomas, 4 (57%) of all squamous cell carcinomas and 6 (100%) of all NSCLC-NOS showed positive immunocytochemical reaction with PD-L1. In patients with both cytology and histology samples, concordance in PD-L1 expression was 78%. All types of cytology samples examined in the study showed to be representative for evaluation. Most problems occurred in evaluation of pleural effusion due to nonspecific cytoplasmic staining for PD-L1 in histiocytes.

Conclusions

Cytology samples are adequate for evaluation of PD-L1 expression in primary and metastatic NSCLC.

Clinical trial identification

Legal entity responsible for the study

University Clinic Golnik

Funding

University Clinic Golnik

Disclosure

All authors have declared no conflicts of interest.