Concordance of tumor cell (TC) and immune cell (IC) staining with Ventana SP142, Ventana SP263, Dako 28-8 and Dako 22C3 PD-L1 IHC tests in NSCLC patient samples.

7Background: PD-1/PD-L1 directed antibodies are emerging as effective therapeutics in multiple oncology settings. Multiple diagnostic PD-L1 tests are being used to understand how PD-L1 expression predicts response to these therapies. It is vital to compare these assays to understand the risk if assays are used interchangeably. Tumor cell (TC) PD-L1 expression by the Ventana SP263 and the Dako 28-8 and 22C3 assays has proven concordant at multiple clinically relevant cut offs.(Ratcliffe et al AACR 2016 [LB-094]); (Ratcliffe et al ESMO 2016 [955PD]). The current study builds on the previous study by inclusion of immune cell (IC) scoring and the Ventana SP142 assay. Methods: 493 tumor biopsy samples from NSCLC patients stained with the Ventana SP263 and Dako 22C3 and 28-8 were scored for IC PD-L1 expression, calculated as % of infiltrating IC expressing PD-L1 at any intensity. A subset of 200 tumor blocks from this cohort were sectioned and stained with SP142 and serial sections restained with SP263 to ensur...