In various solid tumours, PD-L1 expression has been found to be related to the density of certain subtypes of ICs, including CD4+ T helper cells (Ths), CD8+ cytotoxic T cells (CTLs), FOXP3+ regulatory T cells (Tregs), and CD163+ tumour-associated macrophages (TAMs) [28–32]. Here, CD4 is linked to neoplasm.