Abstract
Abstract Background: PD-L1 expression, as determined by immunohistochemistry (IHC), is the most commonly use predictive biomarker for anti-PD-1 and anti-PD-L1 agents in currently available in clinical practice. However, multiple antibodies have been utilized in IHC assays and interpretation of their results has not been standardized. Recently, several studies have compared different antibodies and IHC systems for PD-L1 tests. We aimed to evaluate the similarity and concordance between three validated, commercially available PD-L1 IHC assays for non-small cell lung cancer (Dako 22C3, Ventana SP263, and Ventana SP142). Methods: We evaluated 219 samples from patients with non-small cell lung cancer at the Daegu Catholic University Medical Center between June 2017 and July 2018. Each tumor sample was stained with PD-L1 IHC 22C3, SP263, and SP142. PD-L1 expression was scored at different cut-off levels for each IHC antibodies (22C3 assay: <1%, 1-49%, and ≥50%, SP263: <10%, ≥10 and <25%, and ≥25%, SP142: <1%, 1-4%, 5-49%, and ≥50%). Results: Among the 219 samples, three different antibodies showed well correlation for PD-L1 expression (22C3 vs. SP263; r=0.896, p<0.001, 22C3 vs. SP142; r=0.750, p<0.001, SP263 vs. SP142; r=0.728, p<0.001). 22C3 IHC assay produced the similar results with SP263 IHC assay (Kappa value=0.510, p<0.001). However, 22C3 vs. SP263 and SP263 vs. SP142 showed poor concordance (Kappa value=0.171, p=0.004, and Kappa value=0.240, p<0.001, respectively). Conclusions: 22C3, SP263, and SP142 IHC assays showed good correlation for PD-L1 expression. 22C3 IHC assay showed good concordance with SP263, but SP142. Citation Format: Chi Young Jung, Eun Jin Kim, Woo Jung Sung. Assessment of concordance among 22C3, SP263, and SP142 immunohistochemistry assay for PD-L1 expression in non-small cell lung cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A07.
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