Intriguingly, while a high cytotoxic T lymphocyte (CTL) score was associated with an overall survival benefit, low levels of PHGDH expression abolished this benefit in cases of TNBC, melanoma, lung adenocarcinoma, and endometrial tumors (Fig. 5b; Supplementary Fig. 8a–d), highlighting the importance of de novo serine synthesis in predicting cancer immunotherapy outcomes in patients. This evidence concerns the gene PHGDH and melanoma.