Cluster 1 (immune hot) tumours were marked by high expression of immune genes such as CCL5, NKG7, GZMA, GZMB, GBP5, LAG3, CD8A, CXCL9, CXCL10 and IDO1. Previous studies reported CCL5, NKG7, CXCL9 and CXCL10 as biomarkers for better survival in oesophageal squamous carcinoma and other cancer types50,51, and high expression of CD8A, GNLY, CCL5, CXCL9 and CXCL10 in pre-treated OAC tumours with high T-cell infiltrates was linked to complete response to neoadjuvant chemoradiotherapy28. This evidence concerns the gene IDO1 and cancer.