PD-L1 expression and the prognostic significance in gastric cancer: a retrospective comparison of three PD-L1 antibody clones (SP142, 28-8 and E1L3N).

ABSTRACT: BACKGROUND:Immunohistochemistry (IHC) for programmed cell death ligand 1 (PD-L1) displays staining diversity. We compared IHC staining of PD-L1 in gastric cancer (GC) by using three commercially available antibody clones, and analyzed the correlation with the prognosis. METHODS:IHC using PD-L1 antibodies (clones SP142, 28-8 and E1L3N) in 315 formalin-fixed paraffin-embedded samples was qualitatively compared at the 1, 5 and 10% cut-off by two pathologists on total, tumor and immune/stromal cells. We used computer - assisted scoring to quantitatively analyze and compare the "H-score" of PD-L1 expression in 66 samples on total cells. The antibody clone SP142 was selected to investigate the infiltration of PD-L1+CD8+ T cells using automated quantitative immunofluorescence analyses (n?=?50) and the prognostic significance. The prognoses were assessed by log-rank test. RESULTS:PD-L1 clones SP142 and 28-8 displayed great concordance by qualitative (??=?0.816, 0.810 for total cells and tumor cells at the 5% cut-off) and quantitative analyses (R2?=?0.7991, 0.8187 for positive percentage and "H-score"). PD-L1 clone SP142 showed the highest positivity in immune/stromal cells staining (18.41%) compared to 28-8 (7.62%), while clone E1L3N showed poor staining in both tumor and immune/stromal cells. Clone SP142, but not 28-8 and E1L3N, predicted a worse prognosis at the 5% cut-off (p?=?0.0243). Both the clone SP142 and 28-8 had high inter-pathologist correlation for tumor staining (R2?=?0.9805 and R2?=?0.9853), but a moderate correlation for stromal/immune cell staining (R2?=?0.5653 and R2?=?0.5745). Furthermore, a higher density of PD-L1+CD8+ T cells was correlated with a shorter survival time (R2?=?0.0909, p?=?0.0352). CONCLUSIONS:PD-L1 antibody clone SP142 was superior in cell staining, particularly in immune/stromal cell and prognosis. These findings are important for selection of PD-L1 antibody clones in the future diagnostic test.

SUBMITTER: Ma J 

PROVIDER: S-EPMC6249875 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature