PD-L1 expression in gastric cancer: interchangeability of 22C3 and 28-8 pharmDx assays for responses to immunotherapy
- Authors
- Ahn, S[Ahn, Soomin]; Kim, KM[Kim, Kyoung-Mee]
- Issue Date
- Sep-2021
- Publisher
- SPRINGERNATURE
- Citation
- MODERN PATHOLOGY, v.34, no.9, pp.1719 - 1727
- Indexed
- SCIE
SCOPUS
- Journal Title
- MODERN PATHOLOGY
- Volume
- 34
- Number
- 9
- Start Page
- 1719
- End Page
- 1727
- URI
- https://scholarworks.bwise.kr/skku/handle/2021.sw.skku/1913
- DOI
- 10.1038/s41379-021-00823-9
- ISSN
- 0893-3952
- Abstract
- Recent clinical trials have shown the promising therapeutic effects of pembrolizumab and nivolumab in patients with advanced gastric cancer. Currently, the programmed death ligand-1 (PD-L1) 22C3 pharmDx assay is the only companion diagnostic assay for assessing the safety and effectiveness of pembrolizumab. The purpose of this study was to compare 22C3 pharmDx and 28-8 pharmDx, a complementary diagnostic assay for nivolumab, in gastric cancer. In this study, 22C3 and 28-8 pharmDx assays were performed on the same formalin-fixed, paraffin-embedded tissue blocks of gastric adenocarcinoma clinical samples (n = 55). The concordance rate was evaluated using combined positive score (CPS) cutoffs of 1, 10, and 50. PD-L1 positivity with CPS >= 1 was 45.5% using the 22C3 pharmDx assay and 49.1% using the 28-8 pharmDx assay. At a CPS cutoff of 1, the overall percentage agreement was 96.4%. The positive and negative percentage agreements were 93.3% and 100%, respectively. All cases positive for PD-L1 using the 22C3 pharmDx assay were also positive using the 28-8 pharmDx assay. At a CPS cutoff of 10, the overall percentage agreement was 96.4%. At a CPS cutoff of 50, the two assays exhibited 100% concordance. Nonspecific cytoplasmic staining in the background tissues and tumor cells was often observed in the 28-8 pharmDx assay. When the results of the two assays were matched for response to immunotherapy, the overall response rate was higher in patients with a PD-L1 CPS >= 1 than in PD-L1-negative patients (22C3 pharmDx, P = 0.001; 28-8 pharmDx, P = 0.002). In conclusion, PD-L1 22C3 and 28-8 pharmDx assays were highly comparable at CPS cutoffs of 1, 10, and 50 in gastric cancer. These results provide evidence for the potential interchangeability of the two PD-L1 assays in gastric cancer.
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Collections - Medicine > Department of Medicine > 1. Journal Articles
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