Abstract 1988P
Background
In diagnostic workup, pathologists test Non-Small Cell Lung Carcinoma (NSCLC) with PD-L1. Fine needle aspiration (FNA) cytology is a common technique. To assess reproducibility of VENTANA PD-L1 (SP263) Assay (SP263 Assay) immunohistochemical (IHC) testing in formalin-fixed paraffin embedded (FFPE) FNA cell blocks, we performed reader and staining precision assessments.
Methods
Precision Study: 20 FNA samples were stained with the SP263 Assay over three non-consecutive days. Concordance of PD-L1 expression at ≥1% tumor cell (TC) cutoff was assessed by positive, negative, and overall percent agreement (PPA, NPA, OPA). 40 FNA samples were scored by three readers, two assessments each. Concordance was calculated by average positive and negative and overall percent agreement (APA, ANA, OPA) across and within readers. IHC Staining and Interpretation: Commercially procured FFPE FNA cell blocks were stained with SP263 Assay according to the manufacturer’s procedure. TC membrane staining of any intensity was assessed while cytoplasmic and immune cell (IC) staining was not. As per the CE-IVD label for biopsies and resections, the same scoring approach was utilized; estimates of TC membrane staining.
Results
Cytomorphology evaluation was essential emphasizing identification of IC populations, which could mimic TCs. Full slide assessment was required as cells/cell fragments could be scattered, posing a challenge for assessment of total TC staining with increased possibility of missing positive and negative TCs. Without stromal architecture and a relatively light counterstain, a pathologist may fail to appreciate weak staining or mistake cytoplasmic for membrane staining. Table: 1988P
Precision of VENTANA PD-L1 (SP263) Assay in NSCLC FNA cell blocks at the ≥1% TC cutoff showing inter-reader, intra-reader, and inter-day precision all >96%
| Precision Study | APA | ANA | OPA |
| Inter-Reader Precision | 96.5% | 96.8% | 96.7% |
| Intra-Reader Precision | 98.2% | 98.4% | 98.3% |
| PPA | NPA | OPA | |
| Inter-Day Precisions | 100.0% | 100.0% | 100.0% |
Conclusions
FFPE FNA samples stained with the SP263 Assay demonstrate consistent staining and reproducible interpretation. Investigation of SP263 Assay staining concordance in paired FNA/biopsy specimens will be valuable. Studies of sample heterogeneity, adequacy, and FNA passes may provide guidance on use of FNA samples with this assay.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Roche Tissue Diagnostics.
Funding
Roche Tissue Diagnostics.
Disclosure
D. Hayden: Shareholder/Stockholder/Stock options, Full/Part-time employment: Roche. B. Roland: Shareholder/Stockholder/Stock options, Full/Part-time employment: Roche. K. Saufkie: Full/Part-time employment: Roche. S. Largo: Full/Part-time employment: Roche. P. Ahmadi: Full/Part-time employment: Roche. M. Vasquez: Full/Part-time employment: Roche. A.E. Hanlon Newell: Shareholder/Stockholder/Stock options, Full/Part-time employment: Roche. K. Schnittker: Full/Part-time employment: Roche.