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Table 3 Preanalytic factors

From: Development of a programmed cell death ligand-1 immunohistochemical assay validated for analysis of non-small cell lung cancer and head and neck squamous cell carcinoma

Study outline Design Results
Tissue thickness NSCLC and HNSCC tissues sectioned at various thicknesses (3, 4, 5, 6, and 7 μm) Antibody demonstrated appropriate staining across all thicknesses tested and was representative of clinical PD-L1 status for each case
Tissue fixation Tonsil cases processed in 10 % NBF, zinc formalin, 95 % alcohol, AFA, Z5 and Prefer with multiple timepoints (1, 6, 12, 24, and 72 h) in each fixative Timepoints (6, 12, 24, and 72 h) in 10 % NBF, zinc formalin and Z5 were acceptable; 95 % alcohol, AFA and Prefer were not acceptable
Ischemia KARPASS 299 xenograft tissues with multiple cold ischemia times (0, 0.5, 1, 2, 6, and 24 h) No significant change in staining intensity from time 0 to hour 24
Cut-slide stability Four tissue samples; cut at 4 μm and stored at 2–8 and 30 °C. Stained at the Day 0 timepoint and at Day 3 and 14 and monthly Month 1 to 12 timepoints Staining results at different storage temperatures and at timepoints Day 3 and 14, and Months 1 to 12 consistent with results achieved on Day 0
  1. AFA acidified formal alcohol, HNSCC head and neck squamous cell carcinoma, NBF neutral buffered formalin, NSCLC non-small cell lung cancer, PD-L1 programmed cell death ligand-1