1. Determinants of variability of five programmed death ligand-1 immunohistochemistry assays in non-small cell lung cancer samples
- Author
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Maria Cynthia Herrera, Mohd Feroz Mohd Omar, Benhur Amanuel, Nguyen Hoang Diem Phuong, Zul Fazreen, Ju Ee Seet, Richie Soong, Joey Sze Yun Lim, David J Byrne, Shona Hendry, Barry Iacopetta, Ross A. Soo, Bernadette Reyna Asuncion, and Stephen B. Fox
- Subjects
0301 basic medicine ,programmed death ligand-1 ,Pathology ,medicine.medical_specialty ,Concordance ,03 medical and health sciences ,0302 clinical medicine ,Cytology ,medicine ,Lung cancer ,non-small cell lung cancer ,biology ,business.industry ,medicine.disease ,Ligand (biochemistry) ,Staining ,030104 developmental biology ,Oncology ,030220 oncology & carcinogenesis ,immunohistochemistry ,biology.protein ,Immunohistochemistry ,immunotherapy ,Antibody ,business ,Research Paper ,Programmed death - Abstract
Programmed death ligand-1 (PD-L1) expression as determined by immunohistochemistry (IHC) is potentially predictive of clinical outcome. The aim of this study was to assess the concordance of reported PD-L1 IHC assays and investigate factors influencing variability. Consecutive sections from 20 non-small cell lung cancers (NSCLCs) comprising resection, core biopsy, cytology and pleural fluid samples underwent IHC with 5 different antibody/autostainer combinations: 22C3/Link48, 28-8/BOND-MAX, E1L3N/BOND-MAX, SP142/BenchMark and SP263/BenchMark. PD-L1 RNA levels were assessed using RNAscope. The frequency of positive cases using scoring thresholds from clinical trials was 72%, 33%, 61%, 56%, and 33% for the 5 IHC protocols respectively, and 33% for RNAscope. Pairwise agreement on the classification of cases as positive or negative for PD-L1 expression ranged from 61%-94%. On a continuous scale, the lowest correlation was between 28-8/BOND-MAX and SP142/BenchMark (R2=0.25) and highest was between 22C3/Link48 and E1L3N/BOND-MAX (R2=0.71). When cases were ordered according to tumor cell (TC)%, a similar ranking of cases across IHC protocols could be observed, albeit with different quanta and limits of detection. Single-slide OPAL 7-color fluorescence IHC analysis revealed a high degree of co-localization of staining from the 5 PD-L1 antibodies. Using SP142 antibody in a BOND-MAX protocol led to increased TC% quanta, while retaining a similar ranking of samples according to TC%. The results of this study highlight tumor PD-L1 status can vary significantly according to IHC protocol. Protocol-dependent staining intensities and nominated thresholds for positivity contribute to this variability, while the antibody used appears to be less of a factor.
- Published
- 2018