Despite the potential for underestimation in determining PD-L1 status due to the focal nature of protein expression in malignant and immune cells, the use of serial TMA sections might have facilitated a more standardised and less subjective evaluation of cancer specimens as shown in previous studies.9 Moreover, in the clinic, the issue of sampling bias is unavoidable as PD-L1 status requires evaluation in biopsy samples, where the quantity of tissue is limited and not dissimilar to that available in a standard TMA section. The gene discussed is CD274; the disease is cancer.