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
|
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.