E1l3n rabbit monoclonal antibody

Analysis of PD-L1 expression was performed on formalin-fixed paraffin-embedded tumor tissue sections from metastatic lesions or primary tumors (if sufficient metastatic tissue was unavailable). The tumor sections were stained with a validated anti-PD-L1 antibody (1:100; E1L3N rabbit monoclonal antibody; Cell Signaling Technology, according to a standard protocol),9 10 (link) using a Bond RX Autostainer (Leica Biosystems) and a Polymer Refine Detection kit (DS9800; Leica Biosystems). Antigen retrieval was carried out using the Bond Epitope Retrieval Solution 2 (EDTA, pH=9.0) for 30 min. Slides were counterstained with hematoxylin, dehydrated in graded ethanol and xylene, and cover-slipped. The percentage of PD-L1 positive tumor cells was independently scored by three pathologists who were blinded to clinical outcomes. Discrepancies in scores were resolved by consensus review. For patients with PD-L1 measures from both metastatic and primary lesions, preference was given to the metastatic lesion score. For statistical analysis, PD-L1 scores were categorized as either 0%, 1–5%, >5%–20% or >20% to study for association with clinical outcomes. The baseline PD-L1 score was used for analysis of efficacy in Part B.

Analysis of PD-L1 expression was performed on formalin-fixed paraffin-embedded tumor tissue sections from metastatic lesions or primary tumors (if sufficient metastatic tissue was unavailable). The tumor sections were stained with an anti–PD-L1 antibody (1:100; E1L3N rabbit monoclonal antibody; Cell Signaling Technology, Danvers, MA) according to a standard protocol.^{8 (link),9 (link)} The percentage of PD-L1–positive tumor cells was independently scored by three pathologists who were blinded to clinical outcomes. Discrepancies in scores were resolved by consensus review. For patients with PD-L1 measures from both metastatic and primary lesions, preference was given to the metastatic lesion score. For statistical analysis, PD-L1 scores were categorized as 0%, 1%-5%, > 5%-20%, or > 20% to study for association with clinical outcomes. The baseline PD-L1 score was used for analysis of efficacy in part B.