CD274 and gastrointestinal stromal tumor: To identify PD‐L1 expression that was relevant in GIST, we performed quantitative real‐time PCR (qPCR) on freshly isolated tumour samples, which was a more accurate means of measuring the expression of PD‐L1 within the tumours than immunohistochemistry (Figure 1A).31, 32 The expression levels of PD‐L1 were variable and closely related to the modified NIH risk classification (Figure 1A).