PDCD1 and melanoma: For example, m6A modification of related mRNA can be inhibited by knockout of methyltransferase METTL3/14, and the production of CD8 positive T cells, IFN‐γ, CXCL‐9 and CXCL‐10 in the tumour microenvironment can be increased through IFN‐γ‐STAT1‐IRF1 signalling pathway, thus enhancing the effect of anti‐PD‐1 therapy in the treatment of melanoma.11