The acceptable levels of inter-reader reproducibility at key cut-offs for PD-L1 expression testing in our study, using the VENTANA PD-L1 (SP263) and the Dako PD-L1 IHC PharmDx 22C3 assays, provide the ‘proof of principle’ evidence that the PD-L1 e-trainer tool can be used more frequently in the future to improve and confirm inter-reader consistency for TC PD-L1 scoring in NSCLC. The gene discussed is CD274; the disease is non-small cell lung carcinoma.