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Poster Display session (Friday) (ID 65)
- Event: ELCC 2018
- Type: Poster Display session
- Presentations: 1
- Coordinates: 4/13/2018, 12:30 - 13:00, Hall 1
4P - Assessment of PD-L1 expression by immunohistochemistry in histological and cytological non-small cell lung carcinoma (NSCLC) in the era of immunotherapy: A national Irish study (ID 630)
12:30 - 13:00 | Presenting Author(s): A. Fabre
Evasion of immune system is a hallmark of cancer, which enables cancer cells to escape the attack from immune cells, by expression of immune inhibitory signalling proteins such as programmed death-ligand-1 (PD-L1); PD-L1 binds to programmed death-1 (PD-1) expressed on immune cells (T, B, dendritic and NK T-cells) to suppress anti-cancer immunity. Anti PD-L1antibodies (such as pembrolizumab) are now being used for the treatment of some cancers.
We assessed the expression of PD-L1 on NSCLC by immunohistochemistry using the Dako IHC22C3 pharmDx® kit on the Dako Autostainer link48®. Slides were read and scored using the Dako guidelines based on a Tumour Proportion Score (TPS) (% of tumour cells expressing PD-L1, ≤1% (negative), 1–49% (low), ≥50% (positive)). Immune cells were not scored.
The 16 months-patient cohort was made up of 870 patients, from SVUH (43.9%) and Irish national hospitals (61.2%), 49.5% females and 51.5% males. Overall staining patterns were as follows: 31.5% positive (high TPS >50%), 23.1% low (low TPS 1–49%), 42.8% negative (TPS <1%). Specimens included cytology (22.9%, of which 57% were EBUS samples), biopsy (77.1%, 39% were lung/bronchial biopsies) and surgical (15.6%) specimens. Adenocarcinomas represented 59.3% of all NSCLC and 33.5% had a high TPS (≥50%) score. Squamous cell carcinomas (33.7%) were positive (≥50%) in 29.7%. Histology and cytology samples had similar distribution of high, low and negative TPS cases.
This is the first comprehensive collection of PD-L1 testing data in NSCLC in Ireland. Our results broadly with the KEYNOTE-010 study validating our scoring. Some of these patients are now receiving pembrolizumab treatment. Heterogenous tumour populations and strong staining of inflammatory cells can make assessment difficult.
Clinical trial identification:
Legal entity responsible for the study:
St. Vincent's University Hospital Dublin
A. Fabre, K. Breen, J. McCormack: Financial funding received from MSD.
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