CD274 and squamous cell carcinoma: Kitazono et al. studied PD-L1 IHC expression in 79 paired biopsy and resected specimen of NSCLC cases (45 adenocarcinomas, 23 squamous cell carcinomas and 11 other types) using a polyclonal clone (number 4059; ProSci, Poway, CA); using ≥ 1% cutoff they found positivity in 38% of cases with 92.4% concordance (κ value 0,8366, almost perfect agreement) while using ≥ 50% cutoff 21.8% of cases resulted positive with concordance in 83.5% (κ value 0,3969, fair agreement) [15].